#!/usr/bin/env python3
"""
ECG Practice PDF Builder
Generates a comprehensive ECG practice workbook with real-world cases,
drawn ECG tracings, clinical scenarios, and an answer key.
"""

import io
import math
import urllib.request
import urllib.error
from reportlab.lib import colors
from reportlab.lib.pagesizes import letter, landscape
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import inch, mm
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    PageBreak, HRFlowable, KeepTogether, Image as RLImage
)
from reportlab.platypus.flowables import Flowable
from reportlab.graphics.shapes import (
    Drawing, Line, Rect, Path, String, Circle, Group
)
from reportlab.graphics import renderPDF
from reportlab.lib.colors import HexColor, Color
from PIL import Image as PILImage

# ── Colour palette ────────────────────────────────────────────────────────────
DARK_BG      = HexColor("#1A1A2E")
ACCENT_BLUE  = HexColor("#0F3460")
ACCENT_CYAN  = HexColor("#16213E")
HIGHLIGHT    = HexColor("#E94560")
GOLD         = HexColor("#F5A623")
GRID_RED     = HexColor("#FFCCCC")
GRID_DARK    = HexColor("#FF9999")
ECG_LINE     = HexColor("#00FF41")   # classic monitor green
ECG_LINE2    = HexColor("#1C1C1C")   # dark paper trace
PAPER_BG     = HexColor("#FFF9F0")
SECTION_HEAD = HexColor("#003366")
EASY_GREEN   = HexColor("#27AE60")
MED_ORANGE   = HexColor("#E67E22")
HARD_RED     = HexColor("#C0392B")
WHITE        = colors.white
BLACK        = colors.black
LIGHT_GRAY   = HexColor("#F0F0F0")
MED_GRAY     = HexColor("#888888")

# ── Page setup ────────────────────────────────────────────────────────────────
PAGE_W, PAGE_H = letter  # 8.5 x 11 inches


# ═══════════════════════════════════════════════════════════════════════════════
#  ECG DRAWING ENGINE  (generates synthetic 12-lead-style tracings)
# ═══════════════════════════════════════════════════════════════════════════════

def ecg_normal_sinus(t, hr=75):
    """Return ECG amplitude for normal sinus rhythm at given time t (seconds)."""
    period = 60.0 / hr
    t_mod = t % period
    tp = t_mod / period  # 0-1 within one cycle

    # Gaussian-like waves: P, Q, R, S, T
    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.12, 0.015, 0.15)   # P wave
    y += gauss(tp, 0.26, 0.004, -0.08)  # Q notch
    y += gauss(tp, 0.29, 0.008, 1.0)    # R peak
    y += gauss(tp, 0.32, 0.004, -0.25)  # S wave
    y += gauss(tp, 0.42, 0.025, 0.25)   # T wave
    return y


def ecg_afib(t):
    """Atrial fibrillation: irregular RR, no distinct P, fibrillatory baseline."""
    import random
    rng = random.Random(42)
    period = 60.0 / 120  # mean HR ~120
    t_mod = t % (period * 7)  # irregular cycles
    # Irregular R-R: vary RR between 0.45-0.75 s
    rr_table = [0.52, 0.63, 0.48, 0.71, 0.55, 0.60, 0.49]
    cumulative = 0
    cycle_pos = 0
    for i, rr in enumerate(rr_table):
        if t_mod < cumulative + rr:
            cycle_pos = (t_mod - cumulative) / rr
            break
        cumulative += rr
    else:
        cycle_pos = (t_mod - cumulative) / rr_table[-1] if rr_table else 0

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    # No P wave; fibrillatory baseline
    y += 0.04 * math.sin(2 * math.pi * t * 6.5) + 0.02 * math.sin(2 * math.pi * t * 8.2)
    y += gauss(cycle_pos, 0.27, 0.006, -0.05)  # Q
    y += gauss(cycle_pos, 0.30, 0.008, 1.0)    # R
    y += gauss(cycle_pos, 0.33, 0.005, -0.22)  # S
    y += gauss(cycle_pos, 0.44, 0.025, 0.20)   # T
    return y


def ecg_stemi(t, leads="anterior"):
    """STEMI - ST elevation, hyperacute T waves (anterior leads)."""
    period = 60.0 / 90
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.12, 0.015, 0.12)   # P wave
    y += gauss(tp, 0.26, 0.004, -0.06)  # Q (pathological in anterior STEMI)
    y += gauss(tp, 0.29, 0.009, 1.0)    # R
    y += gauss(tp, 0.32, 0.004, -0.15)  # S
    # ST elevation: shift baseline after QRS
    if 0.33 <= tp <= 0.50:
        st_frac = (tp - 0.33) / (0.50 - 0.33)
        y += 0.30 * (1 - st_frac * 0.5)  # elevated ST
    y += gauss(tp, 0.50, 0.035, 0.55)   # Hyperacute T wave (tall)
    return y


def ecg_vt(t):
    """Monomorphic ventricular tachycardia: wide, regular, fast."""
    period = 60.0 / 170  # HR 170
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    # No P waves, wide bizarre QRS
    y += gauss(tp, 0.20, 0.04, -0.4)   # broad negative deflection
    y += gauss(tp, 0.35, 0.05, 1.0)    # main peak
    y += gauss(tp, 0.50, 0.04, -0.3)   # secondary deflection
    y += gauss(tp, 0.65, 0.03, 0.2)    # T wave
    return y


def ecg_chb(t):
    """Complete heart block: independent P waves (~75 bpm) and slow escape (~35 bpm)."""
    p_period = 60.0 / 75
    v_period = 60.0 / 35

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    # P waves (atrial)
    t_p = t % p_period
    tp = t_p / p_period
    y = gauss(tp, 0.12, 0.015, 0.15)  # P wave only

    # Escape QRS-T (ventricular, slow, wide)
    t_v = t % v_period
    tv = t_v / v_period
    y += gauss(tv, 0.25, 0.004, -0.05)  # Q
    y += gauss(tv, 0.30, 0.012, 0.85)   # Wide R
    y += gauss(tv, 0.36, 0.006, -0.20)  # S
    y += gauss(tv, 0.55, 0.04, -0.30)   # Inverted T (escape)
    return y


def ecg_wpw(t):
    """WPW: short PR, delta wave, wide QRS."""
    period = 60.0 / 80
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.09, 0.015, 0.12)   # P wave
    # Short PR -> QRS starts earlier
    # Delta wave: slurred upstroke
    if 0.15 <= tp <= 0.21:
        delta_frac = (tp - 0.15) / 0.06
        y += 0.25 * delta_frac           # delta wave
    y += gauss(tp, 0.25, 0.010, 1.0)    # R (wider due to delta)
    y += gauss(tp, 0.29, 0.005, -0.30)  # S
    y += gauss(tp, 0.42, 0.028, 0.20)   # T
    return y


def ecg_lbbb(t):
    """LBBB: broad notched R in V5/V6, deep S in V1."""
    period = 60.0 / 72
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.12, 0.015, 0.12)   # P
    # No septal Q; broad notched R
    y += gauss(tp, 0.27, 0.015, 0.60)   # R1 (first peak of notch)
    y += gauss(tp, 0.35, 0.015, 0.95)   # R2 (taller peak)
    y += gauss(tp, 0.43, 0.025, -0.35)  # discordant T
    return y


def ecg_hyperkalemia(t):
    """Hyperkalemia: peaked T, wide QRS, flat P."""
    period = 60.0 / 70
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.12, 0.008, 0.05)   # flat/absent P
    y += gauss(tp, 0.27, 0.006, -0.08)  # Q
    y += gauss(tp, 0.31, 0.012, 0.80)   # Wide R
    y += gauss(tp, 0.35, 0.006, -0.20)  # S
    y += gauss(tp, 0.46, 0.018, 0.70)   # Peaked tent T
    return y


def ecg_svt(t):
    """SVT: narrow QRS, fast (~170), P buried in T or retrograde."""
    period = 60.0 / 170
    t_mod = t % period
    tp = t_mod / period

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += gauss(tp, 0.28, 0.004, -0.05)  # Q
    y += gauss(tp, 0.31, 0.007, 1.0)    # R
    y += gauss(tp, 0.34, 0.004, -0.20)  # S
    # Retrograde P buried at end of T
    y += gauss(tp, 0.52, 0.018, 0.15)   # T with buried P
    return y


def ecg_second_degree_mobitz2(t):
    """Mobitz II: fixed PR, dropped beats (4:1 then 3:1 pattern)."""
    # Pattern: 3 conducted beats then 1 dropped, repeating
    period = 60.0 / 75  # conducted beat period
    block_cycle = period * 4  # 3 conducted + 1 blocked
    t_mod = t % block_cycle
    beat_idx = int(t_mod / period)

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    t_beat = t_mod % period
    tp = t_beat / period
    y = 0
    # Always show P wave
    y += gauss(tp, 0.12, 0.015, 0.15)  # P wave present every beat
    # Only add QRS for beats 0,1,2 (not beat 3 which is blocked)
    if beat_idx < 3:
        y += gauss(tp, 0.26, 0.004, -0.07)  # Q
        y += gauss(tp, 0.29, 0.008, 1.0)    # R
        y += gauss(tp, 0.32, 0.004, -0.22)  # S
        y += gauss(tp, 0.41, 0.024, 0.24)   # T
    return y


def ecg_torsades(t):
    """Torsades de Pointes: twisting axis VT, polymorphic."""
    period = 60.0 / 220
    t_mod = t % period
    tp = t_mod / period
    # Twisting: amplitude modulated by slow sine
    twist = math.sin(2 * math.pi * t * 1.2)

    def gauss(x, mu, sigma, amp):
        return amp * math.exp(-((x - mu) ** 2) / (2 * sigma ** 2))

    y = 0
    y += twist * gauss(tp, 0.25, 0.04, -0.35)
    y += twist * gauss(tp, 0.40, 0.05, 1.0)
    y += twist * gauss(tp, 0.55, 0.04, -0.25)
    y += gauss(tp, 0.68, 0.03, 0.15 * twist)
    return y


# ═══════════════════════════════════════════════════════════════════════════════
#  FLOWABLE: ECG Strip (drawn with ReportLab graphics)
# ═══════════════════════════════════════════════════════════════════════════════

class ECGStrip(Flowable):
    """A synthetic ECG rhythm strip drawn on grid paper."""

    def __init__(self, ecg_func, label="Lead II", width=6.5*inch, height=1.1*inch,
                 duration=4.0, color=ECG_LINE2, bg=PAPER_BG, title_color=SECTION_HEAD):
        super().__init__()
        self.ecg_func = ecg_func
        self.label = label
        self.width = width
        self.height = height
        self.duration = duration
        self.color = color
        self.bg = bg
        self.title_color = title_color

    def wrap(self, availW, availH):
        return self.width, self.height + 14

    def draw(self):
        c = self.canv
        w, h = self.width, self.height
        y_off = 14  # space for label above

        # Background
        c.setFillColor(self.bg)
        c.rect(0, 0, w, h, fill=1, stroke=0)

        # Grid - small squares (1mm = 0.04s, 0.1mV)
        px_per_mm = w / (self.duration * 1000 / 40)  # 40ms small square
        mm_h = h / 10  # 10 small squares tall
        small = min(px_per_mm, mm_h) * 0.8

        # Draw small grid lines (light pink)
        c.setStrokeColor(HexColor("#FFBBBB"))
        c.setLineWidth(0.3)
        x = 0
        while x <= w:
            c.line(x, 0, x, h)
            x += small
        y = 0
        while y <= h:
            c.line(0, y, w, y)
            y += small

        # Draw large grid lines (darker red) every 5 small squares
        c.setStrokeColor(HexColor("#FF8888"))
        c.setLineWidth(0.6)
        x = 0
        while x <= w:
            c.line(x, 0, x, h)
            x += small * 5
        y = 0
        while y <= h:
            c.line(0, y, w, y)
            y += small * 5

        # Border
        c.setStrokeColor(HexColor("#CC4444"))
        c.setLineWidth(1.0)
        c.rect(0, 0, w, h, fill=0, stroke=1)

        # Draw ECG trace
        n_points = int(w * 2)
        mid_y = h * 0.5
        amplitude = h * 0.35

        pts = []
        for i in range(n_points + 1):
            t = (i / n_points) * self.duration
            y_val = self.ecg_func(t)
            px = (i / n_points) * w
            py = mid_y + y_val * amplitude
            pts.append((px, py))

        c.setStrokeColor(self.color)
        c.setLineWidth(1.4)
        p = c.beginPath()
        p.moveTo(pts[0][0], pts[0][1])
        for px, py in pts[1:]:
            p.lineTo(px, py)
        c.drawPath(p, stroke=1, fill=0)

        # Label
        c.setFont("Helvetica-Bold", 8)
        c.setFillColor(self.title_color)
        c.drawString(2, h + 4, self.label)


# ═══════════════════════════════════════════════════════════════════════════════
#  HELPER: Remote image downloader
# ═══════════════════════════════════════════════════════════════════════════════

def download_image(url, max_w, max_h):
    """Download image URL, return ReportLab Image flowable (scaled), or None."""
    try:
        req = urllib.request.Request(url, headers={"User-Agent": "Mozilla/5.0"})
        with urllib.request.urlopen(req, timeout=15) as resp:
            data = resp.read()
        img = PILImage.open(io.BytesIO(data))
        orig_w, orig_h = img.size
        scale = min(max_w / orig_w, max_h / orig_h)
        new_w = orig_w * scale
        new_h = orig_h * scale
        buf = io.BytesIO()
        img.save(buf, format="PNG")
        buf.seek(0)
        return RLImage(buf, width=new_w, height=new_h)
    except Exception as e:
        print(f"  [image skip] {url[:60]}... -> {e}")
        return None


# ═══════════════════════════════════════════════════════════════════════════════
#  STYLE HELPERS
# ═══════════════════════════════════════════════════════════════════════════════

def make_styles():
    base = getSampleStyleSheet()
    styles = {}

    styles["cover_title"] = ParagraphStyle(
        "cover_title", parent=base["Title"],
        fontSize=32, textColor=WHITE, spaceAfter=6, alignment=1,
        fontName="Helvetica-Bold"
    )
    styles["cover_sub"] = ParagraphStyle(
        "cover_sub", parent=base["Normal"],
        fontSize=16, textColor=HexColor("#CCDDFF"), spaceAfter=4, alignment=1
    )
    styles["cover_note"] = ParagraphStyle(
        "cover_note", parent=base["Normal"],
        fontSize=11, textColor=HexColor("#AABBCC"), alignment=1
    )
    styles["chapter"] = ParagraphStyle(
        "chapter", parent=base["Heading1"],
        fontSize=20, textColor=WHITE, spaceBefore=6, spaceAfter=8,
        fontName="Helvetica-Bold", backColor=SECTION_HEAD,
        borderPad=(6, 10, 6, 10), alignment=0
    )
    styles["section"] = ParagraphStyle(
        "section", parent=base["Heading2"],
        fontSize=14, textColor=SECTION_HEAD, spaceBefore=8, spaceAfter=4,
        fontName="Helvetica-Bold"
    )
    styles["body"] = ParagraphStyle(
        "body", parent=base["Normal"],
        fontSize=10, textColor=HexColor("#1A1A1A"), spaceAfter=4, leading=14
    )
    styles["body_sm"] = ParagraphStyle(
        "body_sm", parent=base["Normal"],
        fontSize=9, textColor=HexColor("#333333"), spaceAfter=3, leading=12
    )
    styles["bold"] = ParagraphStyle(
        "bold", parent=base["Normal"],
        fontSize=10, textColor=BLACK, fontName="Helvetica-Bold", spaceAfter=3
    )
    styles["case_header"] = ParagraphStyle(
        "case_header", parent=base["Normal"],
        fontSize=13, textColor=WHITE, fontName="Helvetica-Bold",
        spaceAfter=4, backColor=ACCENT_BLUE, borderPad=(5, 8, 5, 8)
    )
    styles["answer_header"] = ParagraphStyle(
        "answer_header", parent=base["Normal"],
        fontSize=11, textColor=WHITE, fontName="Helvetica-Bold",
        spaceAfter=4, backColor=EASY_GREEN, borderPad=(4, 6, 4, 6)
    )
    styles["diff_easy"] = ParagraphStyle(
        "diff_easy", parent=base["Normal"],
        fontSize=9, textColor=WHITE, fontName="Helvetica-Bold",
        backColor=EASY_GREEN, borderPad=(2, 5, 2, 5)
    )
    styles["diff_med"] = ParagraphStyle(
        "diff_med", parent=base["Normal"],
        fontSize=9, textColor=WHITE, fontName="Helvetica-Bold",
        backColor=MED_ORANGE, borderPad=(2, 5, 2, 5)
    )
    styles["diff_hard"] = ParagraphStyle(
        "diff_hard", parent=base["Normal"],
        fontSize=9, textColor=WHITE, fontName="Helvetica-Bold",
        backColor=HARD_RED, borderPad=(2, 5, 2, 5)
    )
    styles["clinical_box"] = ParagraphStyle(
        "clinical_box", parent=base["Normal"],
        fontSize=10, textColor=HexColor("#0D2B5E"), spaceAfter=3,
        leading=14, backColor=HexColor("#E8F4FD"),
        borderPad=(6, 10, 6, 10)
    )
    styles["answer_box"] = ParagraphStyle(
        "answer_box", parent=base["Normal"],
        fontSize=10, textColor=HexColor("#1A3A1A"), spaceAfter=3,
        leading=14, backColor=HexColor("#E8F8E8"),
        borderPad=(6, 10, 6, 10)
    )
    styles["key_finding"] = ParagraphStyle(
        "key_finding", parent=base["Normal"],
        fontSize=10, textColor=HexColor("#7B0000"), fontName="Helvetica-Bold",
        spaceAfter=3, leading=14
    )
    styles["page_num"] = ParagraphStyle(
        "page_num", parent=base["Normal"],
        fontSize=8, textColor=MED_GRAY, alignment=1
    )
    return styles


# ═══════════════════════════════════════════════════════════════════════════════
#  COVER PAGE
# ═══════════════════════════════════════════════════════════════════════════════

class DarkBackground(Flowable):
    """Full-page dark background for cover."""
    def __init__(self, w, h):
        super().__init__()
        self.w = w
        self.h = h

    def wrap(self, aw, ah):
        return self.w, self.h

    def draw(self):
        c = self.canv
        # Gradient background approximation
        c.setFillColor(HexColor("#0A0A1A"))
        c.rect(0, 0, self.w, self.h, fill=1, stroke=0)
        # Decorative ECG-like line across page
        c.setStrokeColor(HexColor("#1A5276"))
        c.setLineWidth(40)
        c.setStrokeAlpha(0.3)
        c.line(0, self.h * 0.35, self.w, self.h * 0.35)
        c.setStrokeAlpha(1.0)


class DecorativeECGLine(Flowable):
    """A decorative ECG trace used on the cover page."""
    def __init__(self, width=6.5*inch, height=0.8*inch):
        super().__init__()
        self.width = width
        self.height = height

    def wrap(self, aw, ah):
        return self.width, self.height

    def draw(self):
        c = self.canv
        w, h = self.width, self.height
        n = 400
        mid = h * 0.5
        amp = h * 0.40

        pts = []
        for i in range(n + 1):
            t = (i / n) * 6.0
            y = ecg_normal_sinus(t, hr=75)
            pts.append(((i / n) * w, mid + y * amp))

        c.setStrokeColor(HexColor("#00BFFF"))
        c.setLineWidth(1.8)
        p = c.beginPath()
        p.moveTo(pts[0][0], pts[0][1])
        for px, py in pts[1:]:
            p.lineTo(px, py)
        c.drawPath(p, stroke=1, fill=0)


# ═══════════════════════════════════════════════════════════════════════════════
#  CASE DATA  (10 progressively complex cases)
# ═══════════════════════════════════════════════════════════════════════════════

CASES = [
    # ── CASE 1 ────────────────────────────────────────────────────────────────
    {
        "num": 1,
        "difficulty": "EASY",
        "diff_style": "diff_easy",
        "title": "Case 1 - The Routine Check",
        "scenario": (
            "A 28-year-old healthy male presents for a pre-employment physical. "
            "He denies any symptoms. BP 118/76, HR 72, SpO2 99%. "
            "The ECG below was obtained as part of screening."
        ),
        "ecg_func": ecg_normal_sinus,
        "ecg_label": "Lead II Rhythm Strip",
        "questions": [
            "Q1. What is the rhythm?",
            "Q2. What is the approximate heart rate?",
            "Q3. Describe the PR interval (normal = 0.12-0.20 s).",
            "Q4. Are the QRS complexes narrow or wide?",
            "Q5. What is your final interpretation?",
        ],
        "answer_title": "Answer: Case 1",
        "diagnosis": "Normal Sinus Rhythm (NSR)",
        "key_findings": [
            "Regular P waves before every QRS, upright in lead II.",
            "Rate 60-100 bpm (here ~72 bpm).",
            "PR interval 0.12-0.20 s.",
            "QRS < 0.12 s (narrow).",
            "No ST-T changes.",
        ],
        "teaching": (
            "Normal sinus rhythm is the baseline of ECG interpretation. "
            "Confirm: (1) P wave before every QRS, (2) regular R-R interval, "
            "(3) upright P in leads I and II, (4) rate 60-100 bpm. "
            "Every abnormal ECG is defined against this normal template."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_2151fc2dd8926ec5c88bfa0d9417d5ed22acfcd4b0ec972f51a72077d4c8e486.jpg",
    },
    # ── CASE 2 ────────────────────────────────────────────────────────────────
    {
        "num": 2,
        "difficulty": "EASY",
        "diff_style": "diff_easy",
        "title": "Case 2 - The Palpitating Student",
        "scenario": (
            "A 22-year-old female medical student presents to the ED with sudden "
            "onset palpitations for 30 minutes. BP 110/70, HR 172, RR 18, SpO2 98%. "
            "She denies syncope or chest pain. This rhythm strip was obtained."
        ),
        "ecg_func": ecg_svt,
        "ecg_label": "Lead II Rhythm Strip",
        "questions": [
            "Q1. What is the ventricular rate?",
            "Q2. Are the QRS complexes narrow or wide?",
            "Q3. Can you identify P waves? If so, where are they?",
            "Q4. Is the rhythm regular or irregular?",
            "Q5. What is the most likely diagnosis?",
            "Q6. What is your initial management step?",
        ],
        "answer_title": "Answer: Case 2",
        "diagnosis": "Supraventricular Tachycardia (SVT) - AVNRT most likely",
        "key_findings": [
            "Regular, narrow-complex tachycardia (~170 bpm).",
            "No visible P waves (buried in T wave) or retrograde P waves.",
            "Sudden onset 'paroxysmal' nature is characteristic.",
            "No delta waves (excludes WPW-mediated AVRT initially).",
            "Hemodynamically stable.",
        ],
        "teaching": (
            "SVT encompasses AVNRT (most common, ~60%), AVRT, and AT. "
            "Acute management: Vagal maneuvers first (Valsalva, carotid sinus massage). "
            "If unsuccessful, adenosine 6 mg IV rapid push (12 mg if no response). "
            "If unstable, synchronized cardioversion."
        ),
        "image_url": None,
    },
    # ── CASE 3 ────────────────────────────────────────────────────────────────
    {
        "num": 3,
        "difficulty": "EASY",
        "diff_style": "diff_easy",
        "title": "Case 3 - Atrial Fibrillation Discovered",
        "scenario": (
            "A 68-year-old man with hypertension and type 2 diabetes presents "
            "for a routine visit. He reports mild fatigue and occasional 'fluttering' "
            "in his chest for the past 2 weeks. BP 138/88, HR irregularly irregular ~110."
        ),
        "ecg_func": ecg_afib,
        "ecg_label": "Lead II Rhythm Strip",
        "questions": [
            "Q1. What is the rhythm regularity?",
            "Q2. Are P waves visible? What do you see instead?",
            "Q3. What is the ventricular rate?",
            "Q4. What is the diagnosis?",
            "Q5. What score would you use to assess stroke risk?",
            "Q6. Name two rate control medications.",
        ],
        "answer_title": "Answer: Case 3",
        "diagnosis": "Atrial Fibrillation (AF) with Rapid Ventricular Response",
        "key_findings": [
            "Irregularly irregular R-R intervals.",
            "No distinct P waves; fibrillatory f-waves (350-600 bpm).",
            "Variable ventricular rate.",
            "Narrow QRS (unless aberrant conduction).",
        ],
        "teaching": (
            "AF is the most common sustained cardiac arrhythmia. "
            "Stroke risk: CHA2DS2-VASc score (Congestive HF, Hypertension, Age >=75 [x2], "
            "Diabetes, Stroke/TIA [x2], Vascular disease, Age 65-74, Sex female). "
            "Anticoagulate if score >= 2 (males) or >= 3 (females). "
            "Rate control: beta-blockers (metoprolol), CCBs (diltiazem, verapamil), digoxin."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_592a7d4f4c9adbe877d5d637d6fc1ab4f832561260990041c0bbdf7dee23c614.jpg",
    },
    # ── CASE 4 ────────────────────────────────────────────────────────────────
    {
        "num": 4,
        "difficulty": "MODERATE",
        "diff_style": "diff_med",
        "title": "Case 4 - Chest Pain in the ED",
        "scenario": (
            "A 58-year-old male smoker presents to the ED with 45 minutes of crushing "
            "substernal chest pain radiating to the left arm. BP 148/92, HR 94, "
            "diaphoretic. The 12-lead ECG shows ST elevation in V1-V4 with reciprocal "
            "depression in II, III, aVF. Troponin pending. Rhythm strip below."
        ),
        "ecg_func": ecg_stemi,
        "ecg_label": "Lead V2 (Precordial) Rhythm Strip",
        "questions": [
            "Q1. Identify the ST-segment changes in V1-V4.",
            "Q2. What territory is affected? Which artery?",
            "Q3. What are the reciprocal changes and where are they?",
            "Q4. What is the diagnosis?",
            "Q5. What are the time-to-treatment targets?",
            "Q6. List 4 immediate interventions (MONA+ concept).",
        ],
        "answer_title": "Answer: Case 4",
        "diagnosis": "Anterior STEMI - LAD Occlusion",
        "key_findings": [
            "ST elevation >= 1mm in >=2 contiguous leads (V1-V4).",
            "Hyperacute (tall, broad) T waves early sign.",
            "Reciprocal ST depression in inferior leads (II, III, aVF).",
            "Pathological Q waves may develop within hours.",
            "Anterior territory -> Left Anterior Descending (LAD) artery.",
        ],
        "teaching": (
            "STEMI localization: V1-V4 Anterior (LAD); II,III,aVF Inferior (RCA/LCx); "
            "I,aVL,V5,V6 Lateral (LCx). "
            "Door-to-balloon time target: <90 minutes (PCI center) or <120 min (transfer). "
            "Immediate Rx: Aspirin 325mg, P2Y12 inhibitor (ticagrelor/clopidogrel), "
            "anticoagulation (heparin/bivalirudin), supplemental O2 if SpO2 <90%, "
            "nitroglycerin (avoid if RV infarct, hypotension), morphine (use cautiously), "
            "emergent PCI or fibrinolysis if PCI unavailable."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_16738d4b125195130b5e53a811645d4064182fc2bbd0de16b0e00a57af7ff6ef.jpg",
    },
    # ── CASE 5 ────────────────────────────────────────────────────────────────
    {
        "num": 5,
        "difficulty": "MODERATE",
        "diff_style": "diff_med",
        "title": "Case 5 - The Wide Complex Mystery",
        "scenario": (
            "A 45-year-old woman with known ischemic cardiomyopathy (EF 30%) "
            "is brought in by EMS after sudden collapse. She is conscious but "
            "diaphoretic. BP 88/60, HR 172. Monitor shows regular wide-complex tachycardia."
        ),
        "ecg_func": ecg_vt,
        "ecg_label": "Rhythm Strip - Wide Complex Tachycardia",
        "questions": [
            "Q1. What is the QRS duration (estimate: narrow <0.12s, wide >0.12s)?",
            "Q2. Name 4 features that favor VT over SVT with aberrancy.",
            "Q3. Given the clinical context, what is the most likely diagnosis?",
            "Q4. The patient is hemodynamically unstable. What is first-line treatment?",
            "Q5. If the patient were stable, name 2 pharmacologic options.",
        ],
        "answer_title": "Answer: Case 5",
        "diagnosis": "Ventricular Tachycardia (VT) - Monomorphic",
        "key_findings": [
            "Wide QRS (>0.12 s), regular, rate ~170 bpm.",
            "AV dissociation (P waves independent of QRS) - pathognomonic for VT.",
            "Fusion beats and capture beats if seen confirm VT.",
            "Brugada criteria / Vereckei algorithm support VT.",
            "Known structural heart disease (low EF) strongly favors VT.",
        ],
        "teaching": (
            "Rule: Wide complex tachycardia = VT until proven otherwise, especially "
            "with structural heart disease. "
            "Unstable VT -> Synchronized cardioversion (100-200J biphasic). "
            "Stable monomorphic VT -> Amiodarone 150mg IV over 10 min, then infusion; "
            "or procainamide 17mg/kg IV at 50mg/min. "
            "Never give verapamil/diltiazem for wide-complex tachycardia (may cause arrest)."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_2cfc27856259d0a459799c8b34e1b8e53f1d9e8ebcf8a2264e4f7c75d4ca0100.jpg",
    },
    # ── CASE 6 ────────────────────────────────────────────────────────────────
    {
        "num": 6,
        "difficulty": "MODERATE",
        "diff_style": "diff_med",
        "title": "Case 6 - The Syncopal Episode",
        "scenario": (
            "A 72-year-old man with a history of inferior MI 10 years ago is "
            "brought in after a syncopal episode. He is bradycardic. "
            "BP 90/60, HR 36. The ECG shows P waves and QRS complexes occurring "
            "independently at different rates."
        ),
        "ecg_func": ecg_chb,
        "ecg_label": "Lead II - AV Dissociation Rhythm Strip",
        "questions": [
            "Q1. What are the atrial and ventricular rates?",
            "Q2. What is the PR interval relationship beat to beat?",
            "Q3. What is the diagnosis?",
            "Q4. What type of escape rhythm is present (junctional vs ventricular)?",
            "Q5. What is the definitive treatment?",
            "Q6. What is the bridge therapy while awaiting definitive treatment?",
        ],
        "answer_title": "Answer: Case 6",
        "diagnosis": "Complete (Third-Degree) AV Heart Block",
        "key_findings": [
            "Complete AV dissociation: P waves and QRS completely independent.",
            "Atrial rate ~75 bpm (normal sinus), ventricular rate ~30-40 bpm.",
            "Ventricular escape rhythm: wide QRS (infranodal) = ventricular origin.",
            "Narrow escape QRS = junctional (higher, more stable).",
            "Hemodynamic compromise: hypotension, syncope.",
        ],
        "teaching": (
            "Third-degree AV block: no impulse conducted from atria to ventricles. "
            "Causes: inferior MI (transient, nodal), anterior MI (permanent, infranodal), "
            "Lyme disease, infiltrative disease, medication toxicity. "
            "Temporary: atropine 0.5-1mg IV (less effective with infranodal block), "
            "transcutaneous pacing (immediate), dopamine/epinephrine infusion. "
            "Definitive: permanent pacemaker implantation."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_11ac037ff7836678ddd7fad143600ed71c2a3910d226a34ea257a3618beab0a5.jpg",
    },
    # ── CASE 7 ────────────────────────────────────────────────────────────────
    {
        "num": 7,
        "difficulty": "MODERATE",
        "diff_style": "diff_med",
        "title": "Case 7 - The Young Athlete",
        "scenario": (
            "A 19-year-old competitive basketball player undergoes pre-participation "
            "screening. He denies symptoms. The ECG shows short PR interval (~0.10s), "
            "a slurred upstroke at the start of the QRS (delta wave), and a wide QRS. "
            "HR 78, BP 122/78."
        ),
        "ecg_func": ecg_wpw,
        "ecg_label": "Lead I - Pre-excitation Pattern",
        "questions": [
            "Q1. What are the three classic ECG features of this syndrome?",
            "Q2. What is the diagnosis?",
            "Q3. What life-threatening arrhythmia can this syndrome cause?",
            "Q4. Why is digoxin contraindicated?",
            "Q5. What diagnostic test determines risk stratification?",
        ],
        "answer_title": "Answer: Case 7",
        "diagnosis": "Wolff-Parkinson-White (WPW) Syndrome",
        "key_findings": [
            "Short PR interval (<0.12 s) due to pre-excitation.",
            "Delta wave: slurred initial QRS upstroke.",
            "Wide QRS (fusion of AP and normal conduction).",
            "Secondary ST-T changes (discordant).",
            "Pseudo-infarct pattern may mimic MI (false Q waves).",
        ],
        "teaching": (
            "WPW: accessory pathway (bundle of Kent) bypasses AV node. "
            "Risk: AF with rapid conduction down AP -> VF and sudden death "
            "(especially if shortest pre-excited RR interval <250ms in AF). "
            "Digoxin and verapamil are CONTRAINDICATED (accelerate AP conduction). "
            "Acute AVRT: adenosine, procainamide. "
            "Long-term: radiofrequency catheter ablation (curative, >95% success)."
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_66d810327493e335af836ce99df9a9af2a653edc3df5df5ee977c826562d3ff8.jpg",
    },
    # ── CASE 8 ────────────────────────────────────────────────────────────────
    {
        "num": 8,
        "difficulty": "HARD",
        "diff_style": "diff_hard",
        "title": "Case 8 - The Dialysis Patient",
        "scenario": (
            "A 55-year-old man on hemodialysis for ESRD missed two dialysis sessions. "
            "He presents with weakness and palpitations. Potassium level returns at 7.2 mEq/L. "
            "BP 162/98, HR 68, SpO2 97%. The ECG shows characteristic changes."
        ),
        "ecg_func": ecg_hyperkalemia,
        "ecg_label": "Lead V4 - Electrolyte Changes",
        "questions": [
            "Q1. What are the ECG changes in order of progression with rising K+?",
            "Q2. What specific T-wave morphology is described here?",
            "Q3. What finding indicates imminent risk of cardiac arrest?",
            "Q4. Name 5 treatments for hyperkalemia (include mechanism).",
            "Q5. Which treatment is fastest acting and how long does it last?",
        ],
        "answer_title": "Answer: Case 8",
        "diagnosis": "Severe Hyperkalemia (K+ 7.2 mEq/L) with ECG Changes",
        "key_findings": [
            "Peaked, narrow, symmetric 'tented' T waves (early sign, K+ 5.5-6.5).",
            "Flat/absent P waves (K+ 6.5-7.0).",
            "Prolonged PR interval -> widened QRS.",
            "Sine-wave pattern (K+ >7.0) - pre-arrest.",
            "Ventricular fibrillation / asystole (K+ >8.0).",
        ],
        "teaching": (
            "Hyperkalemia ECG progression: Peaked T -> Flat P -> Wide QRS -> Sine wave -> VF/asystole.\n"
            "Treatment (K+ 6.5+ or with ECG changes):\n"
            "1. Calcium gluconate 1g IV (membrane stabilization, acts in 2-3 min, lasts 30-60 min)\n"
            "2. Insulin 10U + Dextrose 50g IV (shift K+ into cells, 30 min)\n"
            "3. Sodium bicarbonate (alkalosis shifts K+ intracellularly)\n"
            "4. Albuterol 10-20mg nebulized (shift K+ intracellularly)\n"
            "5. Kayexalate/Patiromer/SZC (GI elimination, hours)\n"
            "6. Furosemide IV (renal excretion)\n"
            "7. Dialysis (definitive in ESRD)"
        ),
        "image_url": "https://cdn.orris.care/cdss_images/pmc_clinical_VQA_0e4bd03ffc3858d2de708753614934bc362a034d58a5c5794a71656f8a47c44b.jpg",
    },
    # ── CASE 9 ────────────────────────────────────────────────────────────────
    {
        "num": 9,
        "difficulty": "HARD",
        "diff_style": "diff_hard",
        "title": "Case 9 - The New Left Bundle",
        "scenario": (
            "A 66-year-old woman with no prior cardiac history presents with "
            "acute-onset chest pain and dyspnea for 2 hours. BP 140/88, HR 88. "
            "The ECG shows a broad, notched R in V5/V6, deep S in V1, "
            "no septal Q waves in lateral leads. This is NEW compared to a prior ECG. "
            "Troponin is pending."
        ),
        "ecg_func": ecg_lbbb,
        "ecg_label": "Lead V5 - Bundle Branch Pattern",
        "questions": [
            "Q1. Describe the LBBB diagnostic criteria.",
            "Q2. Why is new LBBB with acute chest pain treated as STEMI-equivalent?",
            "Q3. What is the Sgarbossa criteria? List the 3 components.",
            "Q4. Is this patient a candidate for emergent catheterization?",
            "Q5. Why can you NOT use standard ST-segment criteria in LBBB?",
        ],
        "answer_title": "Answer: Case 9",
        "diagnosis": "New Left Bundle Branch Block (LBBB) - STEMI Equivalent",
        "key_findings": [
            "LBBB criteria: QRS >=0.12s, broad notched R in V5/V6/I/aVL, deep S in V1.",
            "No septal Q in I, V5, V6 (loss of normal septal activation vector).",
            "Secondary discordant ST-T changes (expected in LBBB).",
            "New LBBB in context of chest pain = presumed STEMI equivalent.",
            "Sgarbossa criteria identify MI within LBBB.",
        ],
        "teaching": (
            "Sgarbossa Criteria (each positive finding = STEMI in LBBB):\n"
            "1. Concordant ST elevation >=1mm in leads with positive QRS (score 5)\n"
            "2. Concordant ST depression >=1mm in V1-V3 (score 3)\n"
            "3. Discordant ST elevation >5mm in leads with negative QRS (score 2) [Modified: ST/S ratio >0.25]\n"
            "Score >=3 = high specificity for AMI.\n"
            "New LBBB with ischemic symptoms -> activate cath lab (Class I indication per guidelines)."
        ),
        "image_url": None,
    },
    # ── CASE 10 ───────────────────────────────────────────────────────────────
    {
        "num": 10,
        "difficulty": "HARD",
        "diff_style": "diff_hard",
        "title": "Case 10 - The Long QT and Torsades",
        "scenario": (
            "A 38-year-old woman taking sotalol for persistent AF is brought in "
            "after witnessed collapse. She was resuscitated. During monitoring she "
            "has recurrent salvos of a twisting wide-complex tachycardia, each "
            "initiated by a long-short sequence. QTc on baseline was 560ms."
        ),
        "ecg_func": ecg_torsades,
        "ecg_label": "Rhythm Strip - Polymorphic VT",
        "questions": [
            "Q1. What is the ECG diagnosis of this arrhythmia?",
            "Q2. What QTc value is considered prolonged (male vs female)?",
            "Q3. List 5 common causes of acquired long QT.",
            "Q4. What is first-line treatment for this specific arrhythmia?",
            "Q5. What medications must be stopped immediately?",
            "Q6. What pacing strategy may prevent recurrence?",
        ],
        "answer_title": "Answer: Case 10",
        "diagnosis": "Torsades de Pointes (TdP) - Acquired Long QT Syndrome",
        "key_findings": [
            "Twisting QRS axis around isoelectric baseline ('twisting of points').",
            "Rate 200-250 bpm, often self-terminating but can degenerate to VF.",
            "Initiated by long-short RR sequence (pause-dependent).",
            "Preceded by prolonged QTc (>500ms confers highest risk).",
            "Polymorphic VT (as opposed to monomorphic VT in Case 5).",
        ],
        "teaching": (
            "Acquired QT prolongation causes: Drugs (Class Ia/III antiarrhythmics, "
            "haloperidol, macrolides, fluoroquinolones, methadone, ondansetron), "
            "Hypokalemia, Hypomagnesemia, Hypocalcemia, Bradycardia, Intracranial events.\n"
            "Treatment of TdP:\n"
            "1. IV Magnesium sulfate 2g over 1-2 min (FIRST LINE even if Mg normal)\n"
            "2. Correct electrolytes (K+ to 4.5-5 mEq/L, Ca2+, Mg2+ to high-normal)\n"
            "3. Stop offending drug immediately\n"
            "4. Isoproterenol infusion (shorten QT by increasing HR)\n"
            "5. Overdrive pacing at 90-120 bpm (prevents pause-dependent TdP)\n"
            "6. AVOID amiodarone (prolongs QT further)"
        ),
        "image_url": None,
    },
]


# ═══════════════════════════════════════════════════════════════════════════════
#  ECG WAVE REFERENCE TABLE (front-of-book)
# ═══════════════════════════════════════════════════════════════════════════════

REFERENCE_TABLE_DATA = [
    ["Wave/Interval", "Normal Duration", "Clinical Significance"],
    ["P wave",         "< 0.12 s (< 3 small sq)", "Atrial depolarization\nBroad = left atrial enlargement\nTall = right atrial enlargement"],
    ["PR interval",    "0.12 – 0.20 s",             "AV conduction time\n<0.12 = pre-excitation (WPW)\n>0.20 = 1st degree AV block"],
    ["QRS complex",    "0.06 – 0.10 s",             "Ventricular depolarization\n>0.12 = bundle branch block or VT"],
    ["QT interval",    "0.36 – 0.44 s (rate-adj)",  "Ventricular repolarization\nQTc >440ms M / >460ms F = prolonged\nQTc >500ms = high TdP risk"],
    ["ST segment",     "Isoelectric ± 0.5mm",       "Ventricular repolarization plateau\nElevation = STEMI / pericarditis\nDepression = ischemia / NSTEMI"],
    ["T wave",         "Same polarity as QRS",       "Ventricular repolarization\nInverted = ischemia / strain\nPeaked narrow = hyperkalemia\nFlat/inverted: hypokalemia"],
    ["U wave",         "Small, follows T wave",      "Purkinje repolarization\nProminent U: hypokalemia, bradycardia"],
]

LOCALIZATION_TABLE = [
    ["Territory", "Leads with Changes", "Artery", "Notes"],
    ["Anterior",     "V1-V4",            "LAD",       "Largest territory; worst prognosis"],
    ["Inferior",     "II, III, aVF",     "RCA (80%)\nLCx (20%)", "Check V4R for RV involvement"],
    ["Lateral",      "I, aVL, V5-V6",    "LCx / OM",  "Isolated lateral: smaller OM branch"],
    ["Posterior",    "Reciprocal changes\nV1-V3 (ST depr,\ntall R, upright T)", "RCA / LCx", "Get posterior leads V7-V9"],
    ["Septal",       "V1-V2",            "LAD septals", "Often with anterior MI"],
    ["RV Infarct",   "ST elev V4R",      "Proximal RCA", "Avoid nitrates; give IV fluids"],
]


# ═══════════════════════════════════════════════════════════════════════════════
#  BUILD PDF
# ═══════════════════════════════════════════════════════════════════════════════

def build_pdf(output_path):
    doc = SimpleDocTemplate(
        output_path,
        pagesize=letter,
        leftMargin=0.65*inch,
        rightMargin=0.65*inch,
        topMargin=0.65*inch,
        bottomMargin=0.65*inch,
    )

    styles = make_styles()
    story = []

    # ── COVER ─────────────────────────────────────────────────────────────────
    # Dark background via a big table
    cover_data = [
        [Paragraph("", styles["cover_title"])],
    ]
    cover_bg = Table(
        [[Paragraph(
            "<font color='#001133'>&#160;</font>",
            styles["body"]
        )]],
        colWidths=[PAGE_W - 1.3*inch],
        rowHeights=[PAGE_H - 1.3*inch],
    )
    cover_bg.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), HexColor("#0A0A1A")),
        ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
    ]))

    # Build cover elements in a table for centering
    cover_content = []
    cover_content.append(Spacer(1, 0.5*inch))
    cover_content.append(DecorativeECGLine(width=6.5*inch, height=0.7*inch))
    cover_content.append(Spacer(1, 0.2*inch))
    cover_content.append(Paragraph(
        "<font color='#00BFFF'>ECG MASTERY</font>",
        styles["cover_title"]
    ))
    cover_content.append(Paragraph(
        "<font color='#AADDFF'>Practice Workbook</font>",
        ParagraphStyle("cs2", fontSize=22, textColor=HexColor("#AADDFF"),
                       alignment=1, fontName="Helvetica-Bold")
    ))
    cover_content.append(Spacer(1, 0.15*inch))
    cover_content.append(HRFlowable(
        width="80%", thickness=2, color=HexColor("#E94560"),
        lineCap="round", spaceAfter=10, spaceBefore=4
    ))
    cover_content.append(Paragraph(
        "<font color='#CCDDFF'>10 Real-World Cases | Simple to Complex</font>",
        styles["cover_sub"]
    ))
    cover_content.append(Paragraph(
        "<font color='#AABBCC'>Normal Sinus Rhythm • SVT • Atrial Fibrillation • STEMI<br/>"
        "Ventricular Tachycardia • Complete Heart Block • WPW<br/>"
        "Hyperkalemia • LBBB • Torsades de Pointes</font>",
        styles["cover_note"]
    ))
    cover_content.append(Spacer(1, 0.2*inch))
    cover_content.append(DecorativeECGLine(width=6.5*inch, height=0.5*inch))
    cover_content.append(Spacer(1, 0.3*inch))
    cover_content.append(Paragraph(
        "<font color='#667799'>Includes: ECG Strips • Clinical Scenarios • Answer Key<br/>"
        "Reference Tables • Teaching Points</font>",
        ParagraphStyle("cn2", fontSize=10, textColor=HexColor("#667799"),
                       alignment=1)
    ))
    cover_content.append(Spacer(1, 0.15*inch))
    cover_content.append(Paragraph(
        "<font color='#445566'>For educational purposes only | August 2026</font>",
        ParagraphStyle("cn3", fontSize=8, textColor=HexColor("#445566"),
                       alignment=1)
    ))

    # Wrap cover in a dark-background table
    cover_outer = Table(
        [[cover_content]],
        colWidths=[PAGE_W - 1.3*inch],
    )
    cover_outer.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,-1), HexColor("#0A0A1A")),
        ("VALIGN", (0,0), (-1,-1), "TOP"),
        ("TOPPADDING", (0,0), (-1,-1), 20),
        ("BOTTOMPADDING", (0,0), (-1,-1), 20),
        ("LEFTPADDING", (0,0), (-1,-1), 20),
        ("RIGHTPADDING", (0,0), (-1,-1), 20),
    ]))
    story.append(cover_outer)
    story.append(PageBreak())

    # ── TABLE OF CONTENTS ─────────────────────────────────────────────────────
    story.append(Paragraph("Table of Contents", styles["chapter"]))
    story.append(Spacer(1, 0.1*inch))
    toc_data = [
        ["Section", "Topic", "Difficulty", "Page"],
        ["How to Use This Workbook", "ECG Interpretation Framework", "", "3"],
        ["Quick Reference", "Normal Intervals & STEMI Localization", "", "4"],
    ]
    for c in CASES:
        toc_data.append([
            f"Case {c['num']}",
            c["title"].split(" - ", 1)[-1],
            c["difficulty"],
            "",
        ])
    toc_data.append(["Answer Key", "All Cases - Full Explanations", "", ""])

    toc_table = Table(toc_data, colWidths=[1.1*inch, 3.8*inch, 1.0*inch, 0.6*inch])
    toc_style = TableStyle([
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        ("GRID", (0,0), (-1,-1), 0.5, HexColor("#CCCCCC")),
        ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
        ("TOPPADDING", (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
    ])
    # Color difficulty cells
    diff_colors = {"EASY": EASY_GREEN, "MODERATE": MED_ORANGE, "HARD": HARD_RED}
    for i, c in enumerate(CASES):
        row = i + 3  # header + 2 intro rows + case rows
        col = 2
        col_color = diff_colors.get(c["difficulty"], MED_GRAY)
        toc_style.add("BACKGROUND", (col, row), (col, row), col_color)
        toc_style.add("TEXTCOLOR", (col, row), (col, row), WHITE)
        toc_style.add("FONTNAME", (col, row), (col, row), "Helvetica-Bold")

    toc_table.setStyle(toc_style)
    story.append(toc_table)
    story.append(PageBreak())

    # ── HOW TO USE ────────────────────────────────────────────────────────────
    story.append(Paragraph("How to Use This Workbook", styles["chapter"]))
    story.append(Spacer(1, 0.1*inch))
    story.append(Paragraph("ECG Interpretation - Systematic Approach (The 8-Step Method)", styles["section"]))

    steps = [
        ("1. Rate", "Count R-R intervals. Normal 60-100 bpm. Fast: >100 (tachycardia). Slow: <60 (bradycardia)."),
        ("2. Regularity", "Are R-R intervals equal? Regular, regularly irregular, or irregularly irregular?"),
        ("3. P Waves", "Present? Morphology normal? Upright in I and II? One P per QRS?"),
        ("4. PR Interval", "0.12-0.20 s. Short = pre-excitation. Long = AV block. Variable = Mobitz I/CHB."),
        ("5. QRS Complex", "Width: narrow (<0.12 s) or wide (>0.12 s)? Morphology? Axis?"),
        ("6. ST Segment", "Elevation or depression? In which leads? Contiguous? Reciprocal changes?"),
        ("7. T Waves", "Upright (normal). Inverted = ischemia/strain. Peaked = hyperkalemia. Flat = hypokalemia."),
        ("8. QT Interval", "Measure QTc. >440ms (male) or >460ms (female) = prolonged. >500ms = high risk TdP."),
    ]

    for step_name, step_desc in steps:
        row_data = [
            Paragraph(f"<b>{step_name}</b>", styles["body"]),
            Paragraph(step_desc, styles["body_sm"]),
        ]
        t = Table([row_data], colWidths=[1.4*inch, 5.1*inch])
        t.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (0,0), ACCENT_BLUE),
            ("TEXTCOLOR", (0,0), (0,0), WHITE),
            ("FONTNAME", (0,0), (0,0), "Helvetica-Bold"),
            ("VALIGN", (0,0), (-1,-1), "TOP"),
            ("TOPPADDING", (0,0), (-1,-1), 5),
            ("BOTTOMPADDING", (0,0), (-1,-1), 5),
            ("LEFTPADDING", (0,0), (-1,-1), 6),
            ("RIGHTPADDING", (0,0), (-1,-1), 6),
            ("GRID", (0,0), (-1,-1), 0.5, HexColor("#CCCCCC")),
        ]))
        story.append(t)
        story.append(Spacer(1, 2))

    story.append(Spacer(1, 0.15*inch))
    story.append(Paragraph("ECG Paper Calibration", styles["section"]))

    cal_data = [
        ["Standard Speed", "25 mm/sec", "Small square (1mm) = 0.04 seconds\nLarge square (5mm) = 0.20 seconds"],
        ["Standard Gain", "10 mm/mV", "Small square (1mm) = 0.1 mV\nLarge square (5mm) = 0.5 mV"],
        ["Rate (regular)", "300 / # large squares between R-R",
         "1 large sq = 300 bpm | 2 = 150 | 3 = 100 | 4 = 75 | 5 = 60 | 6 = 50"],
        ["Rate (irregular)", "Count complexes in 10s strip x 6",
         "Or count in 6s strip x 10"],
    ]
    cal_table = Table(cal_data, colWidths=[1.4*inch, 1.6*inch, 3.5*inch])
    cal_table.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (0,-1), HexColor("#003366")),
        ("TEXTCOLOR", (0,0), (0,-1), WHITE),
        ("FONTNAME", (0,0), (0,-1), "Helvetica-Bold"),
        ("ROWBACKGROUNDS", (0,0), (-1,-1), [HexColor("#EEF5FF"), WHITE]),
        ("FONTSIZE", (0,0), (-1,-1), 9),
        ("GRID", (0,0), (-1,-1), 0.5, HexColor("#AAAACC")),
        ("VALIGN", (0,0), (-1,-1), "TOP"),
        ("TOPPADDING", (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
        ("LEFTPADDING", (0,0), (-1,-1), 5),
        ("RIGHTPADDING", (0,0), (-1,-1), 5),
    ]))
    story.append(cal_table)
    story.append(PageBreak())

    # ── QUICK REFERENCE ───────────────────────────────────────────────────────
    story.append(Paragraph("Quick Reference Tables", styles["chapter"]))
    story.append(Spacer(1, 0.1*inch))
    story.append(Paragraph("Normal ECG Intervals", styles["section"]))

    ref_table = Table(REFERENCE_TABLE_DATA, colWidths=[1.4*inch, 1.5*inch, 3.6*inch])
    ref_table.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,0), SECTION_HEAD),
        ("TEXTCOLOR", (0,0), (-1,0), WHITE),
        ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
        ("FONTSIZE", (0,0), (-1,0), 10),
        ("ROWBACKGROUNDS", (0,1), (-1,-1), [WHITE, LIGHT_GRAY]),
        ("FONTSIZE", (0,1), (-1,-1), 8.5),
        ("GRID", (0,0), (-1,-1), 0.5, HexColor("#CCCCCC")),
        ("VALIGN", (0,0), (-1,-1), "TOP"),
        ("TOPPADDING", (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
        ("LEFTPADDING", (0,0), (-1,-1), 5),
        ("RIGHTPADDING", (0,0), (-1,-1), 5),
    ]))
    story.append(ref_table)
    story.append(Spacer(1, 0.2*inch))

    story.append(Paragraph("STEMI Localization Map", styles["section"]))
    loc_table = Table(LOCALIZATION_TABLE, colWidths=[1.0*inch, 1.5*inch, 1.4*inch, 2.6*inch])
    loc_table.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,0), HARD_RED),
        ("TEXTCOLOR", (0,0), (-1,0), WHITE),
        ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
        ("FONTSIZE", (0,0), (-1,0), 10),
        ("ROWBACKGROUNDS", (0,1), (-1,-1), [WHITE, HexColor("#FFF0F0")]),
        ("FONTSIZE", (0,1), (-1,-1), 8.5),
        ("GRID", (0,0), (-1,-1), 0.5, HexColor("#CCCCCC")),
        ("VALIGN", (0,0), (-1,-1), "TOP"),
        ("TOPPADDING", (0,0), (-1,-1), 4),
        ("BOTTOMPADDING", (0,0), (-1,-1), 4),
        ("LEFTPADDING", (0,0), (-1,-1), 5),
        ("RIGHTPADDING", (0,0), (-1,-1), 5),
    ]))
    story.append(loc_table)
    story.append(PageBreak())

    # ── CASES ─────────────────────────────────────────────────────────────────
    for case in CASES:
        # Case header bar
        diff_bg = {"EASY": EASY_GREEN, "MODERATE": MED_ORANGE, "HARD": HARD_RED}
        bg = diff_bg.get(case["difficulty"], MED_GRAY)
        header_table = Table(
            [[Paragraph(f"<font color='white'><b>{case['title']}</b></font>",
                        styles["body"]),
              Paragraph(f"<font color='white'><b>{case['difficulty']}</b></font>",
                        ParagraphStyle("dh", fontSize=9, textColor=WHITE,
                                       fontName="Helvetica-Bold", alignment=2))]],
            colWidths=[5.4*inch, 1.1*inch]
        )
        header_table.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (-1,-1), ACCENT_BLUE),
            ("BACKGROUND", (1,0), (1,0), bg),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("TOPPADDING", (0,0), (-1,-1), 7),
            ("BOTTOMPADDING", (0,0), (-1,-1), 7),
            ("LEFTPADDING", (0,0), (-1,-1), 8),
            ("RIGHTPADDING", (0,0), (-1,-1), 8),
        ]))
        story.append(header_table)
        story.append(Spacer(1, 6))

        # Clinical scenario box
        scenario_table = Table(
            [[Paragraph(f"<b>Clinical Scenario:</b><br/>{case['scenario']}",
                        styles["clinical_box"])]],
            colWidths=[6.5*inch]
        )
        scenario_table.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (-1,-1), HexColor("#EBF5FB")),
            ("BOX", (0,0), (-1,-1), 1, HexColor("#5DADE2")),
            ("TOPPADDING", (0,0), (-1,-1), 8),
            ("BOTTOMPADDING", (0,0), (-1,-1), 8),
            ("LEFTPADDING", (0,0), (-1,-1), 10),
            ("RIGHTPADDING", (0,0), (-1,-1), 10),
        ]))
        story.append(scenario_table)
        story.append(Spacer(1, 8))

        # ECG Strip
        story.append(ECGStrip(
            case["ecg_func"],
            label=f"  {case['ecg_label']}  (Synthetic representative tracing)",
            width=6.5*inch,
            height=1.2*inch,
            duration=4.5,
            color=ECG_LINE2,
        ))
        story.append(Spacer(1, 8))

        # Real ECG image (if available)
        if case.get("image_url"):
            story.append(Paragraph("Real-World ECG Reference:", styles["bold"]))
            img = download_image(case["image_url"], 6.5*inch, 2.0*inch)
            if img:
                img_table = Table([[img]], colWidths=[6.5*inch])
                img_table.setStyle(TableStyle([
                    ("BOX", (0,0), (-1,-1), 1, HexColor("#AAAAAA")),
                    ("ALIGN", (0,0), (-1,-1), "CENTER"),
                ]))
                story.append(img_table)
            story.append(Spacer(1, 6))

        # Questions
        story.append(Paragraph("Questions:", styles["section"]))
        q_items = []
        for q in case["questions"]:
            q_items.append([
                Paragraph(q, styles["body"]),
                Paragraph("_" * 55, ParagraphStyle(
                    "ans_line", fontSize=9, textColor=HexColor("#AAAAAA")))
            ])
            q_items.append([Spacer(1, 2), Spacer(1, 2)])

        q_table = Table(q_items, colWidths=[2.5*inch, 4.0*inch])
        q_table.setStyle(TableStyle([
            ("VALIGN", (0,0), (-1,-1), "TOP"),
            ("TOPPADDING", (0,0), (-1,-1), 3),
            ("BOTTOMPADDING", (0,0), (-1,-1), 3),
            ("LEFTPADDING", (0,0), (-1,-1), 4),
        ]))
        story.append(q_table)
        story.append(PageBreak())

    # ── ANSWER KEY ────────────────────────────────────────────────────────────
    story.append(Paragraph("ANSWER KEY", styles["chapter"]))
    story.append(Spacer(1, 6))
    story.append(Paragraph(
        "The following section provides complete answers, key ECG findings, and "
        "teaching points for all 10 cases. Review your answers after completing "
        "each case before reading ahead.",
        styles["body"]
    ))
    story.append(Spacer(1, 0.1*inch))

    for case in CASES:
        diff_bg = {"EASY": EASY_GREEN, "MODERATE": MED_ORANGE, "HARD": HARD_RED}
        bg = diff_bg.get(case["difficulty"], MED_GRAY)

        ans_header = Table(
            [[Paragraph(f"<font color='white'><b>{case['answer_title']}</b></font>",
                        styles["body"]),
              Paragraph(f"<font color='white'><b>Diagnosis: {case['diagnosis']}</b></font>",
                        ParagraphStyle("ah2", fontSize=9, textColor=WHITE,
                                       fontName="Helvetica-Bold", alignment=2))]],
            colWidths=[2.5*inch, 4.0*inch]
        )
        ans_header.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (-1,-1), bg),
            ("VALIGN", (0,0), (-1,-1), "MIDDLE"),
            ("TOPPADDING", (0,0), (-1,-1), 6),
            ("BOTTOMPADDING", (0,0), (-1,-1), 6),
            ("LEFTPADDING", (0,0), (-1,-1), 8),
            ("RIGHTPADDING", (0,0), (-1,-1), 8),
        ]))
        story.append(ans_header)
        story.append(Spacer(1, 4))

        # Key findings
        findings_text = "<b>Key ECG Findings:</b><br/>"
        for f in case["key_findings"]:
            findings_text += f"• {f}<br/>"

        findings_table = Table(
            [[Paragraph(findings_text, styles["answer_box"])]],
            colWidths=[6.5*inch]
        )
        findings_table.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (-1,-1), HexColor("#F0FFF0")),
            ("BOX", (0,0), (-1,-1), 1, HexColor("#27AE60")),
            ("TOPPADDING", (0,0), (-1,-1), 6),
            ("BOTTOMPADDING", (0,0), (-1,-1), 6),
            ("LEFTPADDING", (0,0), (-1,-1), 10),
            ("RIGHTPADDING", (0,0), (-1,-1), 10),
        ]))
        story.append(findings_table)
        story.append(Spacer(1, 4))

        # Teaching point
        teach_text = f"<b>Teaching Point:</b><br/>{case['teaching'].replace(chr(10), '<br/>')}"
        teach_table = Table(
            [[Paragraph(teach_text, styles["body_sm"])]],
            colWidths=[6.5*inch]
        )
        teach_table.setStyle(TableStyle([
            ("BACKGROUND", (0,0), (-1,-1), HexColor("#FFF8E7")),
            ("BOX", (0,0), (-1,-1), 1, HexColor("#F5A623")),
            ("TOPPADDING", (0,0), (-1,-1), 6),
            ("BOTTOMPADDING", (0,0), (-1,-1), 6),
            ("LEFTPADDING", (0,0), (-1,-1), 10),
            ("RIGHTPADDING", (0,0), (-1,-1), 10),
        ]))
        story.append(teach_table)
        story.append(Spacer(1, 0.15*inch))
        story.append(HRFlowable(
            width="100%", thickness=0.5, color=HexColor("#CCCCCC"),
            spaceAfter=8, spaceBefore=4
        ))

    # ── FINAL PAGE: Drug / Arrhythmia Quick Card ──────────────────────────────
    story.append(PageBreak())
    story.append(Paragraph("Antiarrhythmic Drug Quick Reference", styles["chapter"]))
    story.append(Spacer(1, 0.1*inch))

    drug_data = [
        ["Drug", "Class", "Mechanism", "Use", "Key Caution"],
        ["Adenosine",     "—",    "Blocks AV node transiently",       "Terminate SVT/AVRT",       "Contraindicated in WPW+AF, asthma"],
        ["Metoprolol",    "II",   "Beta-1 blockade",                  "Rate control AF, SVT",     "Avoid in decompensated HF, bradycardia"],
        ["Amiodarone",    "III",  "K+ channel block + multi-channel", "VT, AF conversion",        "Thyroid, pulmonary, hepatic toxicity"],
        ["Lidocaine",     "Ib",   "Na+ channel block",                "Stable VT (2nd line)",     "Ineffective in AF; CNS toxicity"],
        ["Procainamide",  "Ia",   "Na+ channel block, QT prolongation","VT, WPW+AF",              "Avoid in LQTS; hypotension IV"],
        ["Sotalol",       "III",  "K+ channel + beta block",          "AF maintenance, VT",       "Prolongs QT -> TdP risk"],
        ["Verapamil",     "IV",   "Ca2+ channel block",               "Rate control AF, SVT",     "NEVER in WPW, wide-complex tachycardia"],
        ["Digoxin",       "—",    "Vagal tone, Na/K-ATPase inhibit",  "Rate control AF (chronic)", "Narrow therapeutic window; AVOID WPW"],
        ["Atropine",      "—",    "Anticholinergic (increases HR)",   "Symptomatic bradycardia",  "Less effective in infranodal block"],
        ["Magnesium",     "—",    "Membrane stabilization",           "TdP (FIRST LINE), VF",     "Caution in renal failure"],
    ]

    drug_table = Table(drug_data, colWidths=[1.1*inch, 0.55*inch, 1.6*inch, 1.5*inch, 1.75*inch])
    drug_table.setStyle(TableStyle([
        ("BACKGROUND", (0,0), (-1,0), SECTION_HEAD),
        ("TEXTCOLOR", (0,0), (-1,0), WHITE),
        ("FONTNAME", (0,0), (-1,0), "Helvetica-Bold"),
        ("FONTSIZE", (0,0), (-1,0), 9),
        ("ROWBACKGROUNDS", (0,1), (-1,-1), [WHITE, LIGHT_GRAY]),
        ("FONTSIZE", (0,1), (-1,-1), 8),
        ("GRID", (0,0), (-1,-1), 0.5, HexColor("#CCCCCC")),
        ("VALIGN", (0,0), (-1,-1), "TOP"),
        ("TOPPADDING", (0,0), (-1,-1), 3),
        ("BOTTOMPADDING", (0,0), (-1,-1), 3),
        ("LEFTPADDING", (0,0), (-1,-1), 4),
        ("RIGHTPADDING", (0,0), (-1,-1), 4),
    ]))
    story.append(drug_table)

    story.append(Spacer(1, 0.2*inch))
    story.append(Paragraph("ECG Mastery Tips", styles["section"]))
    tips = [
        "Never treat an ECG in isolation - always correlate with the clinical picture.",
        "Wide-complex tachycardia = VT until proven otherwise, especially in structural heart disease.",
        "When in doubt about SVT vs VT: treat as VT (safer).",
        "Always get an old ECG for comparison - 'new' changes matter most.",
        "Posterior MI is commonly missed - always look for reciprocal changes in V1-V3.",
        "Right ventricular infarction: get V4R, and withhold nitrates + give IV fluids.",
        "QTc >500ms: stop offending drugs, correct electrolytes, consider TdP prophylaxis.",
        "Sgarbossa criteria: use to unmask MI hidden within LBBB pattern.",
        "CHA2DS2-VASc: calculate for every new AF patient before discharge.",
        "Calcium FIRST in hyperkalemia with ECG changes (stabilizes the membrane within minutes).",
    ]
    for i, tip in enumerate(tips, 1):
        story.append(Paragraph(f"<b>{i}.</b> {tip}", styles["body_sm"]))
        story.append(Spacer(1, 2))

    story.append(Spacer(1, 0.15*inch))
    story.append(HRFlowable(width="100%", thickness=1, color=SECTION_HEAD,
                             spaceBefore=4, spaceAfter=6))
    story.append(Paragraph(
        "ECG Mastery Practice Workbook | For educational purposes only. "
        "Clinical decisions must be made by qualified healthcare professionals. "
        "August 2026",
        ParagraphStyle("footer", fontSize=7.5, textColor=MED_GRAY, alignment=1)
    ))

    # Build
    doc.build(story)
    print(f"PDF built: {output_path}")


if __name__ == "__main__":
    OUTPUT = "/tmp/workspace/ecg-practice/ECG_Mastery_Practice_Workbook.pdf"
    build_pdf(OUTPUT)