"""
Draw vitamin molecular structure diagrams using matplotlib.
Each vitamin is drawn as a 2D structural formula with atoms and bonds.
"""
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.patches import FancyArrowPatch
import numpy as np
import os

OUT = "/tmp/workspace/vitamins-pdf/images"
os.makedirs(OUT, exist_ok=True)

# ── helper ──────────────────────────────────────────────────────────────────

def draw_molecule(ax, atoms, bonds, title, color_map=None):
    """
    atoms : list of (label, x, y)
    bonds : list of (i, j, order)   order=1 single, 2 double, 3 triple
    """
    if color_map is None:
        color_map = {}
    default_colors = {'C':'#2c2c2c','H':'#888888','O':'#e63946',
                      'N':'#457b9d','S':'#e9c46a','P':'#2a9d8f'}

    ax.set_xlim(-0.5, max(a[1] for a in atoms)+0.5)
    ax.set_ylim(-0.5, max(a[2] for a in atoms)+0.5)
    ax.set_aspect('equal')
    ax.axis('off')
    ax.set_title(title, fontsize=11, fontweight='bold', pad=6)

    # bonds
    for b in bonds:
        i, j, order = b
        x0,y0 = atoms[i][1], atoms[i][2]
        x1,y1 = atoms[j][1], atoms[j][2]
        dx, dy = x1-x0, y1-y0
        length = np.hypot(dx, dy)
        perp = np.array([-dy, dx]) / (length+1e-9)
        offsets = {1:[0], 2:[-0.07, 0.07], 3:[-0.12, 0, 0.12]}
        for off in offsets.get(order,[0]):
            ox, oy = perp * off
            ax.plot([x0+ox, x1+ox],[y0+oy, y1+oy], 'k-', lw=1.4, zorder=1)

    # atoms
    for lbl, x, y in atoms:
        elem = lbl.lstrip('0123456789').split('(')[0].rstrip('0123456789+-')
        elem_base = ''.join(c for c in elem if c.isalpha())
        col = color_map.get(lbl, default_colors.get(elem_base[:1], '#333'))
        fs = 8 if len(lbl) > 2 else 9
        ax.text(x, y, lbl, ha='center', va='center', fontsize=fs,
                fontweight='bold', color=col,
                bbox=dict(boxstyle='round,pad=0.18', fc='white', ec='none'), zorder=3)


# ── Vitamin C (Ascorbic Acid) ────────────────────────────────────────────────
# Ring: C1-C2-C3-C4-O5 (5-membered lactone), substituents

def make_vitC():
    s = 1.0
    h = s * np.sqrt(3)/2
    # 5-membered ring: O at top, then C1,C2,C3,C4
    ring_cx, ring_cy = 2.5, 2.0
    r = 1.1
    angles = [90, 162, 234, 306, 18]  # degrees for 5 ring atoms
    ring = [(cx + r*np.cos(np.radians(a)), cy + r*np.sin(np.radians(a)))
            for cx,cy,a in [(ring_cx,ring_cy,a) for a in angles]]

    atoms = [
        ('O',  ring[0][0], ring[0][1]),   # 0 ring O
        ('C1', ring[1][0], ring[1][1]),   # 1
        ('C2', ring[2][0], ring[2][1]),   # 2
        ('C3', ring[3][0], ring[3][1]),   # 3
        ('C4', ring[4][0], ring[4][1]),   # 4
        # C=O of lactone hanging off C1
        ('C=O', ring[1][0]-1.1, ring[1][1]-0.3),   # 5
        # OH groups
        ('OH', ring[2][0]-1.0, ring[2][1]),          # 6
        ('OH', ring[3][0]-0.7, ring[3][1]-0.9),     # 7
        # C4 -> CH(OH)-CH2OH chain
        ('CH', ring[4][0]+1.1, ring[4][1]+0.2),     # 8
        ('OH', ring[4][0]+1.1, ring[4][1]-0.9),     # 9
        ('CH2OH', ring[4][0]+2.3, ring[4][1]+0.4),  # 10
    ]
    bonds = [
        (0,1,1),(1,2,1),(2,3,2),(3,4,1),(4,0,1),
        (1,5,2),(2,6,1),(3,7,1),
        (4,8,1),(8,9,1),(8,10,1),
    ]
    return atoms, bonds

fig, ax = plt.subplots(figsize=(4,4))
atoms, bonds = make_vitC()
draw_molecule(ax, atoms, bonds, "Vitamin C (Ascorbic Acid)\nC₆H₈O₆  MW: 176.12 g/mol")
plt.tight_layout()
plt.savefig(f"{OUT}/vitC_struct.png", dpi=130, bbox_inches='tight')
plt.close()
print("Vitamin C done")

# ── Vitamin D3 (Cholecalciferol) ─────────────────────────────────────────────
# Simplified skeleton: 3 six-membered rings + 5-membered ring + side chain

def make_vitD():
    # Ring A (left 6-membered)
    Ax = [0, 1, 2, 2, 1, 0]
    Ay = [1, 0, 0, 2, 3, 3]
    # Ring C (middle 6-membered, shared bond with ring B region)
    # Ring B is broken (seco-steroid)
    # We'll simplify with 3 rings + side chain
    atoms = [
        ('C1',0,1),('C2',1,0),('C3',2,0),('C4',3,0),
        ('C5',4,1),('C6',3,2),('C7',2,2),('C8',1,2),
        # ring C
        ('C9',4,2),('C10',5,1),('C11',6,0),('C12',6,2),
        # ring D (5-membered)
        ('C13',7,1),('C14',7,3),
        # side chain
        ('C15',8,0),('C16',9,0),('C17',9,1),('C18',10,1),
        # OH on C3
        ('OH',0,0),
        # double bonds markers
    ]
    bonds = [
        (0,1,1),(1,2,1),(2,3,1),(3,4,1),(4,5,1),(5,6,1),(6,7,1),(7,0,1),
        (4,8,1),(8,9,1),(9,10,1),(10,11,1),(11,5,1),
        (9,12,1),(12,13,1),(13,8,1),
        (12,14,1),(14,15,1),(15,16,1),(16,17,1),
        (0,18,1),
        (3,4,2),(10,11,2),
    ]
    return atoms, bonds

fig, ax = plt.subplots(figsize=(5,3))
atoms, bonds = make_vitD()
draw_molecule(ax, atoms, bonds, "Vitamin D3 (Cholecalciferol)\nC₂₇H₄₄O  MW: 384.64 g/mol")
ax.set_xlim(-0.8, 11.5)
ax.set_ylim(-0.8, 4.0)
plt.tight_layout()
plt.savefig(f"{OUT}/vitD_struct.png", dpi=130, bbox_inches='tight')
plt.close()
print("Vitamin D done")

# ── Vitamin E (Alpha-Tocopherol) ──────────────────────────────────────────────

def make_vitE():
    # Chromanol ring (6+5 fused) + phytyl side chain
    atoms = [
        # benzene-like ring
        ('C1',0,1),('C2',1,0),('C3',2,0),('C4',3,1),('C5',3,2),('C6',2,3),('C7',1,3),
        ('O',0,2),  # ring O (chroman)
        # pyran ring C8-C4
        ('C8',4,1),('C9',5,2),
        # OH on aromatic
        ('OH',2,4),
        # CH3 groups on ring
        ('CH₃',3,3.8),('CH₃',-0.5,0.5),
        # side chain (simplified)
        ('C',6,1),('C',7,1),('C',8,1),('C',9,1),
    ]
    bonds = [
        (0,1,1),(1,2,1),(2,3,2),(3,4,1),(4,5,2),(5,6,1),(6,7,1),(7,0,1),
        (3,8,1),(8,9,1),(9,4,1),
        (5,10,1),(6,11,1),(0,12,1),
        (8,13,1),(13,14,1),(14,15,1),(15,16,1),
    ]
    return atoms, bonds

fig, ax = plt.subplots(figsize=(5,3.5))
atoms, bonds = make_vitE()
draw_molecule(ax, atoms, bonds, "Vitamin E (α-Tocopherol)\nC₂₉H₅₀O₂  MW: 430.71 g/mol")
ax.set_xlim(-1, 10.5)
ax.set_ylim(-0.5, 5.0)
plt.tight_layout()
plt.savefig(f"{OUT}/vitE_struct.png", dpi=130, bbox_inches='tight')
plt.close()
print("Vitamin E done")

# ── Vitamin B1 (Thiamine) ─────────────────────────────────────────────────────

def make_vitB1():
    # Pyrimidine ring + thiazole ring linked by CH2
    atoms = [
        # Pyrimidine (6-membered, 2 N)
        ('N1',0,1),('C2',1,0),('N3',2,0),('C4',3,1),('C5',3,2),('C6',2,3),('C7',1,3),
        # Thiazole (5-membered, N and S)
        ('C8',5,1),('N9',6,0),('C10',7,1),('S',6,2),
        # CH2 bridge
        ('CH2',4,1),
        # NH2 on pyrimidine
        ('NH2',0,0),
        # CH3 on pyrimidine
        ('CH₃',4,3),
        # OH on thiazole
        ('CH2OH',8,2),
        # CH3 on thiazole
        ('CH₃',8,0),
    ]
    bonds = [
        (0,1,1),(1,2,1),(2,3,2),(3,4,1),(4,5,2),(5,6,1),(6,0,2),
        (7,8,2),(8,9,1),(9,10,2),(10,7,1),
        (4,11,1),(11,7,1),
        (0,12,1),(6,13,1),
        (9,14,1),(8,15,1),
    ]
    return atoms, bonds

fig, ax = plt.subplots(figsize=(5,3.5))
atoms, bonds = make_vitB1()
draw_molecule(ax, atoms, bonds, "Vitamin B1 (Thiamine)\nC₁₂H₁₇N₄OS⁺  MW: 265.36 g/mol",
              color_map={'S':'#e9c46a','N1':'#457b9d','N3':'#457b9d','N9':'#457b9d'})
ax.set_xlim(-0.8, 9.5)
ax.set_ylim(-0.5, 4.0)
plt.tight_layout()
plt.savefig(f"{OUT}/vitB1_struct.png", dpi=130, bbox_inches='tight')
plt.close()
print("Vitamin B1 done")

# ── Vitamin A (Retinol) ───────────────────────────────────────────────────────

def make_vitA():
    # Beta-ionone ring (6-membered) + polyene chain + CH2OH
    r = 1.2
    cx, cy = 1.5, 1.5
    ring_pts = [(cx + r*np.cos(np.radians(a)), cy + r*np.sin(np.radians(a)))
                for a in [90, 150, 210, 270, 330, 30]]
    atoms = [
        ('C', ring_pts[0][0], ring_pts[0][1]),
        ('C', ring_pts[1][0], ring_pts[1][1]),
        ('C', ring_pts[2][0], ring_pts[2][1]),
        ('C', ring_pts[3][0], ring_pts[3][1]),
        ('C', ring_pts[4][0], ring_pts[4][1]),
        ('C', ring_pts[5][0], ring_pts[5][1]),
        # polyene chain (alternating double bonds)
        ('C', 3.0, 1.5),
        ('C', 4.0, 1.8),
        ('C', 5.0, 1.5),
        ('C', 6.0, 1.8),
        ('C', 7.0, 1.5),
        ('C', 8.0, 1.8),
        ('CH2OH', 9.0, 1.5),
        # methyl groups on ring
        ('CH₃', cx-0.3, cy+2.5),
        ('CH₃', cx+1.8, cy+2.3),
    ]
    bonds = [
        (0,1,1),(1,2,2),(2,3,1),(3,4,2),(4,5,1),(5,0,2),
        (4,6,1),(6,7,2),(7,8,1),(8,9,2),(9,10,1),(10,11,2),(11,12,1),
        (0,13,1),(0,14,1),
    ]
    return atoms, bonds

fig, ax = plt.subplots(figsize=(5.5,3))
atoms, bonds = make_vitA()
draw_molecule(ax, atoms, bonds, "Vitamin A (Retinol)\nC₂₀H₃₀O  MW: 286.45 g/mol")
ax.set_xlim(-0.5, 10.5)
ax.set_ylim(-0.2, 4.5)
plt.tight_layout()
plt.savefig(f"{OUT}/vitA_struct.png", dpi=130, bbox_inches='tight')
plt.close()
print("Vitamin A done")

print("\nAll vitamin structure images saved!")

"""
Build a polished PDF: Vitamin Molecular Models & Facts
Using reportlab
"""
from reportlab.lib.pagesizes import A4
from reportlab.lib import colors
from reportlab.lib.units import cm, mm
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.enums import TA_CENTER, TA_LEFT, TA_JUSTIFY
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Image,
    Table, TableStyle, HRFlowable, PageBreak, KeepTogether
)
from reportlab.pdfgen import canvas
from reportlab.platypus.flowables import Flowable
import os

OUT_PDF = "/tmp/workspace/vitamins-pdf/Vitamin_Molecular_Models.pdf"
IMG_DIR = "/tmp/workspace/vitamins-pdf/images"

PAGE_W, PAGE_H = A4
MARGIN = 2.2 * cm

# ── Colors ────────────────────────────────────────────────────────────────────
C_HEADER   = colors.HexColor("#1a3a5c")   # dark navy
C_ACCENT   = colors.HexColor("#e63946")   # red
C_ACCENT2  = colors.HexColor("#457b9d")   # steel blue
C_LIGHT    = colors.HexColor("#f0f4f8")   # light bg
C_BORDER   = colors.HexColor("#c9d6e3")
C_TEXT     = colors.HexColor("#1d2d44")
C_SUBHEAD  = colors.HexColor("#2a6496")

# ── Styles ────────────────────────────────────────────────────────────────────
styles = getSampleStyleSheet()

title_style = ParagraphStyle('Title2',
    parent=styles['Title'],
    fontSize=28, textColor=C_HEADER,
    spaceAfter=4, leading=34, alignment=TA_CENTER)

subtitle_style = ParagraphStyle('Sub',
    parent=styles['Normal'],
    fontSize=13, textColor=C_ACCENT2,
    spaceAfter=2, alignment=TA_CENTER)

section_title = ParagraphStyle('SecTitle',
    parent=styles['Heading1'],
    fontSize=15, textColor=colors.white,
    spaceAfter=0, leading=20, alignment=TA_LEFT,
    leftIndent=6)

fact_label = ParagraphStyle('FactLabel',
    parent=styles['Normal'],
    fontSize=9, textColor=C_SUBHEAD,
    fontName='Helvetica-Bold', spaceAfter=1)

fact_value = ParagraphStyle('FactVal',
    parent=styles['Normal'],
    fontSize=9.5, textColor=C_TEXT,
    spaceAfter=4, leading=13)

body_style = ParagraphStyle('Body',
    parent=styles['Normal'],
    fontSize=9.5, textColor=C_TEXT,
    spaceAfter=4, leading=14, alignment=TA_JUSTIFY)

caption_style = ParagraphStyle('Caption',
    parent=styles['Normal'],
    fontSize=8, textColor=colors.HexColor('#666'),
    alignment=TA_CENTER, spaceAfter=4)

toc_style = ParagraphStyle('TOC',
    parent=styles['Normal'],
    fontSize=11, textColor=C_TEXT, leading=20)

# ── Vitamin data ──────────────────────────────────────────────────────────────
vitamins = [
    {
        "name": "Vitamin A",
        "alt": "Retinol",
        "formula": "C₂₀H₃₀O",
        "mw": "286.45 g/mol",
        "type": "Fat-soluble",
        "img": "vitA_struct.png",
        "color": colors.HexColor("#e07a5f"),
        "sources": "Liver, fish oils, dairy, egg yolk, orange/yellow vegetables (beta-carotene)",
        "functions": [
            "Essential for vision, especially night vision (forms rhodopsin in rod cells)",
            "Supports immune function and cell differentiation",
            "Required for growth, skin health, and reproduction",
            "Acts as an antioxidant (beta-carotene form)",
        ],
        "deficiency": "Night blindness, xerophthalmia, increased infection susceptibility, keratomalacia",
        "rda": "Men: 900 µg/day | Women: 700 µg/day (as Retinol Activity Equivalents)",
        "overdose": "Toxicity possible (fat-soluble); causes headache, liver damage, teratogenicity",
        "fun_fact": "Vitamin A was the first vitamin to be discovered, in 1913 by Elmer McCollum."
    },
    {
        "name": "Vitamin B1",
        "alt": "Thiamine",
        "formula": "C₁₂H₁₇N₄OS⁺",
        "mw": "265.36 g/mol",
        "type": "Water-soluble",
        "img": "vitB1_struct.png",
        "color": colors.HexColor("#3d405b"),
        "sources": "Whole grains, pork, legumes, nuts, seeds, fortified cereals",
        "functions": [
            "Coenzyme (as TPP) in carbohydrate metabolism and energy production",
            "Critical for pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase",
            "Supports nerve conduction and cardiac function",
            "Involved in synthesis of acetylcholine (neurotransmitter)",
        ],
        "deficiency": "Beriberi (wet: cardiac; dry: neurological), Wernicke-Korsakoff syndrome (alcohol-related)",
        "rda": "Men: 1.2 mg/day | Women: 1.1 mg/day",
        "overdose": "No known toxicity (rapidly excreted); very high doses may cause headache",
        "fun_fact": "Thiamine has an unusual structure containing both a pyrimidine and a thiazole ring linked by a methylene bridge."
    },
    {
        "name": "Vitamin C",
        "alt": "Ascorbic Acid",
        "formula": "C₆H₈O₆",
        "mw": "176.12 g/mol",
        "type": "Water-soluble",
        "img": "vitC_struct.png",
        "color": colors.HexColor("#f4a261"),
        "sources": "Citrus fruits, kiwi, strawberries, bell peppers, broccoli, spinach",
        "functions": [
            "Potent antioxidant — scavenges reactive oxygen species",
            "Collagen synthesis: hydroxylation of proline and lysine (wound healing)",
            "Enhances non-heme iron absorption from the gut",
            "Regenerates vitamin E; immune system support",
        ],
        "deficiency": "Scurvy: perifollicular hemorrhages, swollen bleeding gums, poor wound healing",
        "rda": "Men: 90 mg/day | Women: 75 mg/day | Smokers: +35 mg/day",
        "overdose": "High doses (>2g/day) → osmotic diarrhea, kidney oxalate stones",
        "fun_fact": "Humans are one of the few mammals that cannot synthesize vitamin C; most animals make it from glucose."
    },
    {
        "name": "Vitamin D3",
        "alt": "Cholecalciferol",
        "formula": "C₂₇H₄₄O",
        "mw": "384.64 g/mol",
        "type": "Fat-soluble",
        "img": "vitD_struct.png",
        "color": colors.HexColor("#2a9d8f"),
        "sources": "Sunlight (skin synthesis from 7-dehydrocholesterol), fatty fish, egg yolk, fortified milk",
        "functions": [
            "Regulates calcium and phosphorus absorption in the intestine",
            "Maintains bone mineralisation (prevents rickets/osteomalacia)",
            "Acts as a steroid hormone via nuclear receptors (VDR)",
            "Immune modulation, cell differentiation, insulin secretion",
        ],
        "deficiency": "Rickets (children), osteomalacia/osteoporosis (adults), muscle weakness",
        "rda": "Adults 19-70: 600 IU/day | >70: 800 IU/day",
        "overdose": "Hypercalcemia, metastatic calcification, kidney stones (fat-soluble, accumulates)",
        "fun_fact": "Vitamin D is technically a prohormone; the active form (calcitriol) is made in the kidneys."
    },
    {
        "name": "Vitamin E",
        "alt": "α-Tocopherol",
        "formula": "C₂₉H₅₀O₂",
        "mw": "430.71 g/mol",
        "type": "Fat-soluble",
        "img": "vitE_struct.png",
        "color": colors.HexColor("#264653"),
        "sources": "Vegetable oils (wheat germ, sunflower), nuts, seeds, leafy greens, avocado",
        "functions": [
            "Primary fat-soluble antioxidant in cell membranes",
            "Protects polyunsaturated fatty acids (PUFAs) from lipid peroxidation",
            "Anti-platelet aggregation (reduces thrombosis risk)",
            "Immune function and gene expression regulation",
        ],
        "deficiency": "Rare; seen in fat malabsorption — hemolytic anemia, neuropathy, ataxia",
        "rda": "Adults: 15 mg/day (22.4 IU) of alpha-tocopherol",
        "overdose": "May inhibit vitamin K action → increased bleeding risk at high supplemental doses",
        "fun_fact": "There are 8 natural forms of vitamin E (4 tocopherols + 4 tocotrienols); alpha-tocopherol is the most biologically active."
    },
]

# ── Page number footer ─────────────────────────────────────────────────────────
def add_page_elements(canvas_obj, doc):
    canvas_obj.saveState()
    page_num = canvas_obj.getPageNumber()
    # footer line
    canvas_obj.setStrokeColor(C_BORDER)
    canvas_obj.setLineWidth(0.5)
    canvas_obj.line(MARGIN, 1.4*cm, PAGE_W - MARGIN, 1.4*cm)
    canvas_obj.setFont('Helvetica', 8)
    canvas_obj.setFillColor(colors.HexColor('#888'))
    canvas_obj.drawString(MARGIN, 0.9*cm, "Vitamin Molecular Models & Facts")
    canvas_obj.drawRightString(PAGE_W - MARGIN, 0.9*cm, f"Page {page_num}")
    canvas_obj.restoreState()

# ── Build story ────────────────────────────────────────────────────────────────
story = []

# ── COVER PAGE ────────────────────────────────────────────────────────────────
story.append(Spacer(1, 3.5*cm))

# Title banner table
banner_data = [[Paragraph(
    '<font color="white"><b>Vitamin Molecular Models</b></font><br/>'
    '<font size="14" color="#a8d8ea">  &amp; Key Scientific Facts</font>',
    ParagraphStyle('BanTitle', fontSize=26, textColor=colors.white,
                   alignment=TA_CENTER, leading=36)
)]]
banner = Table(banner_data, colWidths=[PAGE_W - 2*MARGIN])
banner.setStyle(TableStyle([
    ('BACKGROUND', (0,0), (-1,-1), C_HEADER),
    ('ALIGN', (0,0), (-1,-1), 'CENTER'),
    ('VALIGN', (0,0), (-1,-1), 'MIDDLE'),
    ('TOPPADDING', (0,0), (-1,-1), 22),
    ('BOTTOMPADDING', (0,0), (-1,-1), 22),
    ('ROUNDEDCORNERS', [8]),
]))
story.append(banner)
story.append(Spacer(1, 0.5*cm))
story.append(Paragraph("A reference guide to the structure, function, and biochemistry of essential vitamins",
                        subtitle_style))
story.append(Spacer(1, 0.4*cm))
story.append(HRFlowable(width="80%", thickness=1.5, color=C_ACCENT, spaceAfter=10))
story.append(Spacer(1, 0.3*cm))

# Quick summary table on cover
summary_data = [
    [Paragraph('<b>Vitamin</b>', fact_label),
     Paragraph('<b>Chemical Name</b>', fact_label),
     Paragraph('<b>Formula</b>', fact_label),
     Paragraph('<b>Type</b>', fact_label)],
]
for v in vitamins:
    summary_data.append([
        Paragraph(v['name'], fact_value),
        Paragraph(v['alt'], fact_value),
        Paragraph(v['formula'], fact_value),
        Paragraph(v['type'], fact_value),
    ])

sum_table = Table(summary_data,
                  colWidths=[(PAGE_W-2*MARGIN)*f for f in [0.22,0.30,0.26,0.22]])
sum_table.setStyle(TableStyle([
    ('BACKGROUND', (0,0), (-1,0), C_ACCENT2),
    ('TEXTCOLOR', (0,0), (-1,0), colors.white),
    ('ROWBACKGROUNDS', (0,1), (-1,-1), [C_LIGHT, colors.white]),
    ('GRID', (0,0), (-1,-1), 0.4, C_BORDER),
    ('FONTNAME', (0,0), (-1,0), 'Helvetica-Bold'),
    ('FONTSIZE', (0,0), (-1,-1), 9),
    ('TOPPADDING', (0,0), (-1,-1), 5),
    ('BOTTOMPADDING', (0,0), (-1,-1), 5),
    ('LEFTPADDING', (0,0), (-1,-1), 8),
]))
story.append(sum_table)
story.append(Spacer(1, 0.6*cm))
story.append(Paragraph("Generated by Orris AI • July 2026", caption_style))
story.append(PageBreak())

# ── VITAMIN PAGES ─────────────────────────────────────────────────────────────
for v in vitamins:
    elements = []

    # Section header banner
    hdr_data = [[Paragraph(
        f'<font size="16"><b>{v["name"]}</b></font>  '
        f'<font size="11">({v["alt"]})</font>',
        section_title
    )]]
    hdr = Table(hdr_data, colWidths=[PAGE_W - 2*MARGIN])
    hdr.setStyle(TableStyle([
        ('BACKGROUND', (0,0), (-1,-1), v['color']),
        ('TOPPADDING', (0,0), (-1,-1), 10),
        ('BOTTOMPADDING', (0,0), (-1,-1), 10),
        ('LEFTPADDING', (0,0), (-1,-1), 12),
        ('ROUNDEDCORNERS', [6]),
    ]))
    elements.append(hdr)
    elements.append(Spacer(1, 0.4*cm))

    # Molecular structure image + basic data side by side
    img_path = os.path.join(IMG_DIR, v['img'])
    mol_img = Image(img_path, width=7.5*cm, height=6.5*cm)
    mol_img.hAlign = 'CENTER'

    basic_rows = [
        [Paragraph('Molecular Formula', fact_label), Paragraph(v['formula'], fact_value)],
        [Paragraph('Molecular Weight', fact_label),  Paragraph(v['mw'], fact_value)],
        [Paragraph('Solubility Type', fact_label),   Paragraph(v['type'], fact_value)],
        [Paragraph('RDA', fact_label),                Paragraph(v['rda'], fact_value)],
        [Paragraph('Dietary Sources', fact_label),    Paragraph(v['sources'], fact_value)],
        [Paragraph('Deficiency', fact_label),         Paragraph(v['deficiency'], fact_value)],
        [Paragraph('Overdose Risk', fact_label),      Paragraph(v['overdose'], fact_value)],
    ]
    basic_table = Table(basic_rows, colWidths=[3.5*cm, 8.0*cm])
    basic_table.setStyle(TableStyle([
        ('VALIGN', (0,0), (-1,-1), 'TOP'),
        ('ROWBACKGROUNDS', (0,0), (-1,-1), [C_LIGHT, colors.white]),
        ('GRID', (0,0), (-1,-1), 0.3, C_BORDER),
        ('TOPPADDING', (0,0), (-1,-1), 4),
        ('BOTTOMPADDING', (0,0), (-1,-1), 4),
        ('LEFTPADDING', (0,0), (-1,-1), 6),
    ]))

    side_table = Table(
        [[mol_img, basic_table]],
        colWidths=[8.0*cm, 11.9*cm - 2*MARGIN + PAGE_W - 8*cm - 0.5*cm]
    )
    # adjust to fill page width
    avail = PAGE_W - 2*MARGIN
    side_table = Table(
        [[mol_img, basic_table]],
        colWidths=[7.8*cm, avail - 7.8*cm - 0.3*cm]
    )
    side_table.setStyle(TableStyle([
        ('VALIGN', (0,0), (-1,-1), 'TOP'),
        ('LEFTPADDING', (0,0), (0,-1), 0),
        ('RIGHTPADDING', (0,0), (0,-1), 8),
    ]))
    elements.append(side_table)
    elements.append(Spacer(1, 0.35*cm))

    # Biological Functions
    func_data = [[Paragraph('<b>Biological Functions</b>', ParagraphStyle(
        'FH', fontSize=10, textColor=colors.white, fontName='Helvetica-Bold'))]]
    for fn in v['functions']:
        func_data.append([Paragraph(f'• {fn}', body_style)])

    func_table = Table(func_data, colWidths=[PAGE_W - 2*MARGIN])
    func_table.setStyle(TableStyle([
        ('BACKGROUND', (0,0), (-1,0), C_ACCENT2),
        ('BACKGROUND', (0,1), (-1,-1), colors.HexColor('#f7fbff')),
        ('GRID', (0,0), (-1,-1), 0.3, C_BORDER),
        ('TOPPADDING', (0,0), (-1,-1), 5),
        ('BOTTOMPADDING', (0,0), (-1,-1), 5),
        ('LEFTPADDING', (0,0), (-1,-1), 10),
    ]))
    elements.append(func_table)
    elements.append(Spacer(1, 0.3*cm))

    # Fun fact box
    ff_data = [[
        Paragraph('💡', ParagraphStyle('Icon', fontSize=16, alignment=TA_CENTER)),
        Paragraph(f'<b>Did you know?</b><br/>{v["fun_fact"]}',
                  ParagraphStyle('FF', fontSize=9, textColor=C_TEXT, leading=14))
    ]]
    ff_table = Table(ff_data, colWidths=[1.2*cm, PAGE_W - 2*MARGIN - 1.4*cm])
    ff_table.setStyle(TableStyle([
        ('BACKGROUND', (0,0), (-1,-1), colors.HexColor("#fff9e6")),
        ('BOX', (0,0), (-1,-1), 1, colors.HexColor("#f4cc5a")),
        ('VALIGN', (0,0), (-1,-1), 'MIDDLE'),
        ('TOPPADDING', (0,0), (-1,-1), 8),
        ('BOTTOMPADDING', (0,0), (-1,-1), 8),
        ('LEFTPADDING', (0,0), (-1,-1), 8),
    ]))
    elements.append(ff_table)

    story.append(KeepTogether(elements[:4]))
    for e in elements[4:]:
        story.append(e)
    story.append(PageBreak())

# Remove last PageBreak
if isinstance(story[-1], PageBreak):
    story.pop()

# ── Build PDF ─────────────────────────────────────────────────────────────────
doc = SimpleDocTemplate(
    OUT_PDF,
    pagesize=A4,
    leftMargin=MARGIN, rightMargin=MARGIN,
    topMargin=MARGIN, bottomMargin=2.5*cm,
    title="Vitamin Molecular Models & Facts",
    author="Orris AI",
    subject="Chemistry & Biochemistry of Vitamins",
)

doc.build(story, onFirstPage=add_page_elements, onLaterPages=add_page_elements)
print(f"PDF saved → {OUT_PDF}")