from pptx import Presentation
from pptx.util import Inches, Pt, Emu
from pptx.dml.color import RGBColor
from pptx.enum.text import PP_ALIGN, MSO_ANCHOR
from pptx.util import Inches, Pt
import json, subprocess, base64
from io import BytesIO

# ── Colour palette ────────────────────────────────────────────────────────────
NAVY       = RGBColor(0x0A, 0x1F, 0x44)   # slide background / header bar
TEAL       = RGBColor(0x00, 0x8B, 0x8B)   # accent / sub-headings
GOLD       = RGBColor(0xF0, 0xA5, 0x00)   # highlights
WHITE      = RGBColor(0xFF, 0xFF, 0xFF)
LIGHT_GREY = RGBColor(0xF5, 0xF5, 0xF5)
DARK_GREY  = RGBColor(0x33, 0x33, 0x33)
RED_C      = RGBColor(0xCC, 0x33, 0x33)
GREEN_C    = RGBColor(0x33, 0x88, 0x44)
BLUE_C     = RGBColor(0x22, 0x55, 0xCC)

prs = Presentation()
prs.slide_width  = Inches(13.333)
prs.slide_height = Inches(7.5)
blank = prs.slide_layouts[6]   # fully blank layout

# ── Helper functions ──────────────────────────────────────────────────────────

def add_rect(slide, x, y, w, h, fill_color, alpha=None):
    shape = slide.shapes.add_shape(
        1,  # MSO_SHAPE_TYPE.RECTANGLE
        Inches(x), Inches(y), Inches(w), Inches(h)
    )
    shape.line.fill.background()           # no border
    shape.fill.solid()
    shape.fill.fore_color.rgb = fill_color
    return shape

def add_text(slide, text, x, y, w, h,
             font_name="Calibri", size=18, bold=False, italic=False,
             color=DARK_GREY, align=PP_ALIGN.LEFT, wrap=True,
             v_anchor=MSO_ANCHOR.TOP):
    tb = slide.shapes.add_textbox(Inches(x), Inches(y), Inches(w), Inches(h))
    tf = tb.text_frame
    tf.word_wrap = wrap
    tf.vertical_anchor = v_anchor
    tf.margin_left = Pt(4)
    tf.margin_right = Pt(4)
    tf.margin_top = Pt(2)
    tf.margin_bottom = Pt(2)
    p = tf.paragraphs[0]
    p.alignment = align
    run = p.add_run()
    run.text = text
    run.font.name = font_name
    run.font.size = Pt(size)
    run.font.bold = bold
    run.font.italic = italic
    run.font.color.rgb = color
    return tf

def add_bullet_box(slide, bullets, x, y, w, h,
                   font_name="Calibri", size=16, color=DARK_GREY,
                   bullet_color=TEAL):
    """Add a text box with bullet points."""
    tb = slide.shapes.add_textbox(Inches(x), Inches(y), Inches(w), Inches(h))
    tf = tb.text_frame
    tf.word_wrap = True
    tf.margin_left = Pt(4)
    tf.margin_right = Pt(4)
    tf.margin_top = Pt(2)
    tf.margin_bottom = Pt(2)
    first = True
    for bullet in bullets:
        if first:
            p = tf.paragraphs[0]
            first = False
        else:
            p = tf.add_paragraph()
        p.space_before = Pt(4)
        run = p.add_run()
        run.text = "• " + bullet
        run.font.name = font_name
        run.font.size = Pt(size)
        run.font.color.rgb = color
    return tf

def slide_header(slide, title, subtitle=None):
    """Add the standard navy top bar with title."""
    add_rect(slide, 0, 0, 13.333, 1.1, NAVY)
    add_text(slide, title,
             x=0.3, y=0.05, w=12.5, h=0.75,
             font_name="Calibri", size=30, bold=True, color=WHITE,
             align=PP_ALIGN.LEFT, v_anchor=MSO_ANCHOR.MIDDLE)
    if subtitle:
        add_text(slide, subtitle,
                 x=0.3, y=0.78, w=12.5, h=0.35,
                 font_name="Calibri", size=16, color=GOLD,
                 align=PP_ALIGN.LEFT)

def add_footer(slide, text="Theories of Colour Vision | 4th Year Ophthalmology"):
    add_rect(slide, 0, 7.2, 13.333, 0.3, NAVY)
    add_text(slide, text,
             x=0.2, y=7.2, w=12.9, h=0.3,
             font_name="Calibri", size=10, color=WHITE,
             align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 1 – Title slide
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, NAVY)

# Coloured stripe
for i, (col, xpos) in enumerate([(RED_C, 0), (GREEN_C, 4.44), (BLUE_C, 8.88)]):
    add_rect(slide, xpos, 6.8, 4.44, 0.7, col)

add_text(slide, "THEORIES OF COLOUR VISION",
         x=1, y=1.5, w=11.3, h=1.2,
         font_name="Calibri", size=44, bold=True, color=WHITE,
         align=PP_ALIGN.CENTER)
add_text(slide, "Mechanisms, Psychophysics & Clinical Relevance",
         x=1, y=2.9, w=11.3, h=0.6,
         font_name="Calibri", size=22, color=GOLD,
         align=PP_ALIGN.CENTER)
add_text(slide, "4th Year MBBS  |  Ophthalmology",
         x=1, y=3.55, w=11.3, h=0.45,
         font_name="Calibri", size=18, color=WHITE,
         align=PP_ALIGN.CENTER)
add_text(slide, "Department of Ophthalmology",
         x=1, y=4.1, w=11.3, h=0.4,
         font_name="Calibri", size=16, italic=True, color=LIGHT_GREY,
         align=PP_ALIGN.CENTER)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 2 – Learning Objectives
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Learning Objectives")
add_footer(slide)

objectives = [
    "Describe the anatomy of the retinal photoreceptors involved in colour vision",
    "Explain the Young-Helmholtz Trichromatic Theory and the role of the three cone types",
    "Describe the Opponent-Process (Hering) Theory and colour-opponent channels",
    "Understand the Dual Process Theory integrating both theories",
    "List types of colour blindness (congenital and acquired) with genetic basis",
    "Know the clinical tests for colour vision (Ishihara, Farnsworth-Munsell, HRR)",
    "Recognise clinical scenarios where colour vision testing guides diagnosis",
]
add_rect(slide, 0.4, 1.3, 12.5, 5.7, WHITE)
add_bullet_box(slide, objectives, 0.7, 1.45, 12.0, 5.5, size=17)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 3 – Anatomy of photoreceptors
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Photoreceptors & Colour Vision", subtitle="The cellular basis")
add_footer(slide)

# Left column
add_rect(slide, 0.4, 1.25, 6.2, 5.9, WHITE)
add_text(slide, "CONES – Photopic Vision",
         x=0.6, y=1.35, w=5.8, h=0.45,
         size=18, bold=True, color=TEAL)
cone_bullets = [
    "~6 million in the human retina; concentrated at the fovea",
    "Responsible for daylight (photopic) and colour vision",
    "Three subtypes by opsin:",
    "   S-cones (blue)  — peak ~430 nm",
    "   M-cones (green) — peak ~530 nm",
    "   L-cones (red)   — peak ~560 nm",
    "Broad spectral sensitivity with overlapping ranges",
    "Color perception = RATIO of activation across three cone types",
]
add_bullet_box(slide, cone_bullets, 0.6, 1.85, 5.8, 4.8, size=15)

# Right column
add_rect(slide, 6.9, 1.25, 6.1, 5.9, WHITE)
add_text(slide, "RODS – Scotopic Vision",
         x=7.1, y=1.35, w=5.7, h=0.45,
         size=18, bold=True, color=NAVY)
rod_bullets = [
    "~120 million; distributed in peripheral retina",
    "Active at low light levels (scotopic vision)",
    "Single photopigment: rhodopsin (peak ~498 nm)",
    "Cannot discriminate wavelength — no colour information",
    "In complete darkness, colour perception is ABSENT",
]
add_bullet_box(slide, rod_bullets, 7.1, 1.85, 5.7, 3.0, size=15)

add_text(slide, "Key Point",
         x=7.1, y=5.0, w=5.7, h=0.35,
         size=14, bold=True, color=GOLD)
add_text(slide, "Colour perception depends entirely on the cones and requires "
                "adequate illumination (photopic conditions).",
         x=7.1, y=5.35, w=5.7, h=1.0,
         size=14, color=DARK_GREY, wrap=True)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 4 – Young-Helmholtz Trichromatic Theory
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Young-Helmholtz Trichromatic Theory",
             subtitle="The first theory of colour vision (1802 / 1850s)")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

# Proposers panel
add_rect(slide, 0.5, 1.35, 5.9, 1.4, NAVY)
add_text(slide, "Thomas Young (1802)",
         x=0.6, y=1.4, w=2.8, h=0.5, size=14, bold=True, color=WHITE)
add_text(slide, "All colours can be created by mixing red, green & blue light in the correct proportions",
         x=0.6, y=1.9, w=2.6, h=0.75, size=12, color=LIGHT_GREY, wrap=True)
add_text(slide, "Hermann von Helmholtz (1850s)",
         x=3.5, y=1.4, w=2.8, h=0.5, size=14, bold=True, color=WHITE)
add_text(slide, "Championed & extended Young's ideas; invented the ophthalmoscope (1851)",
         x=3.5, y=1.9, w=2.6, h=0.75, size=12, color=LIGHT_GREY, wrap=True)

add_text(slide, "Core Tenets",
         x=0.6, y=2.9, w=5.8, h=0.4, size=16, bold=True, color=TEAL)
tenets = [
    "Retina contains THREE types of cone photoreceptors",
    "Each cone type has maximal sensitivity to a different wavelength range",
    "Brain assigns colours based on the COMPARATIVE output of all three cone types",
    "Mixing R + G + B light in equal intensity → White light perceived",
    "Any colour can be matched by varying the ratio of three primaries",
]
add_bullet_box(slide, tenets, 0.6, 3.35, 5.8, 3.4, size=14)

# Right panel – cone sensitivity diagram (described as coloured boxes)
add_text(slide, "Spectral Sensitivity of Cones",
         x=6.8, y=1.35, w=5.9, h=0.4, size=16, bold=True, color=TEAL)

# Simulated spectral diagram using coloured rectangles
y_base = 1.85
bar_height = 0.35
labels = [("S (Blue)  ~430 nm", BLUE_C, 0.0, 2.5),
          ("M (Green) ~530 nm", GREEN_C, 0.5, 3.5),
          ("L (Red)   ~560 nm", RED_C, 1.0, 4.5)]
for label, col, x_off, bar_w in labels:
    add_rect(slide, 6.8 + x_off, y_base, bar_w + 1.0, bar_height, col)
    add_text(slide, label,
             x=6.8 + x_off + bar_w + 1.05, y=y_base, w=2.5, h=bar_height,
             size=13, color=col, bold=True)
    y_base += 0.55

add_text(slide, "← Short        Wavelength (nm)       Long →",
         x=6.8, y=3.7, w=6.0, h=0.35, size=12, color=DARK_GREY)

add_text(slide, "Overlap is intentional: colour perception arises from the "
                "ratio of activation, not absolute output of any single cone type.",
         x=6.8, y=4.1, w=6.0, h=1.2,
         size=13, color=DARK_GREY, wrap=True)

add_text(slide, "Support: Confirmed by electrophysiology — three distinct cone opsin genes "
                "on chromosomes X (L & M) and 7 (S).",
         x=6.8, y=5.5, w=6.0, h=1.1,
         size=12, italic=True, color=NAVY, wrap=True)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 5 – Opponent Process Theory
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Opponent-Process Theory (Hering, 1878)",
             subtitle="Explains post-receptoral colour processing")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

add_text(slide, "Ewald Hering proposed THREE opponent colour pairs:",
         x=0.6, y=1.35, w=12.0, h=0.4, size=16, bold=True, color=TEAL)

pairs = [
    (RED_C,   GREEN_C, "Red  vs  Green",
     "Stimulated by red light — INHIBITED by green light (and vice versa)"),
    (BLUE_C,  RGBColor(0xFF, 0xD7, 0x00), "Blue vs Yellow",
     "Stimulated by blue light — INHIBITED by yellow light"),
    (WHITE,   DARK_GREY, "White vs Black (Luminance)",
     "Responds to overall luminance; not a hue channel per se"),
]

y_pos = 1.85
for col_a, col_b, label, desc in pairs:
    add_rect(slide, 0.6, y_pos, 1.3, 0.55, col_a)
    add_rect(slide, 1.95, y_pos, 1.3, 0.55, col_b)
    add_text(slide, label,
             x=3.4, y=y_pos, w=3.0, h=0.55, size=15, bold=True, color=DARK_GREY)
    add_text(slide, desc,
             x=6.5, y=y_pos, w=6.1, h=0.55, size=13, color=DARK_GREY, wrap=True)
    y_pos += 0.7

add_text(slide, "Neural Implementation",
         x=0.6, y=4.2, w=12.0, h=0.4, size=16, bold=True, color=TEAL)
neural = [
    "P-type (midget) retinal ganglion cells = colour-opponent center-surround receptive fields",
    "Example: R+G- cell — excited by red in centre, INHIBITED by green in surround",
    "Blue-ON / Yellow-OFF cells: small bistratified ganglion cells (S-cone input)",
    "Signals relayed via Parvocellular pathway → LGN → V4 (colour processing cortex)",
]
add_bullet_box(slide, neural, 0.6, 4.65, 12.0, 2.35, size=14)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 6 – Dual Process / Zone Theory
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Dual Process (Zone) Theory",
             subtitle="Integrating Trichromatic & Opponent-Process theories")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

add_text(slide, "Neither theory alone fully explains colour vision. The Dual Process (Zone) theory reconciles both:",
         x=0.6, y=1.35, w=12.0, h=0.5, size=15, color=DARK_GREY, wrap=True)

# Zone diagram
zones = [
    (RED_C, "ZONE 1 — Receptors\n(Trichromatic Stage)",
     "Three types of cones (S, M, L) absorb light and generate graded receptor potentials.\n"
     "Each cone responds to a broad wavelength range.\nBasis: Young-Helmholtz trichromacy."),
    (TEAL, "ZONE 2 — Retinal Processing\n(Opponent Stage)",
     "Bipolar cells, horizontal cells & ganglion cells reorganise signals into opponent channels:\n"
     "  • Red-Green channel\n  • Blue-Yellow channel\n  • Luminance (achromatic) channel\nBasis: Hering's opponent process."),
    (NAVY, "ZONE 3 — Cortical Processing",
     "Visual cortex (V1, V2, V4) recombines opponent signals.\n"
     "V4 is the dedicated colour area; lesions cause cerebral achromatopsia.\n"
     "Only ~10% of cortical neurons are primarily colour-selective."),
]

x_start = 0.6
box_w = 3.8
for i, (col, title, body) in enumerate(zones):
    x = x_start + i * (box_w + 0.35)
    add_rect(slide, x, 1.95, box_w, 0.65, col)
    add_text(slide, title,
             x=x+0.05, y=1.98, w=box_w-0.1, h=0.6,
             size=13, bold=True, color=WHITE, align=PP_ALIGN.CENTER,
             v_anchor=MSO_ANCHOR.MIDDLE)
    add_rect(slide, x, 2.65, box_w, 3.8, LIGHT_GREY)
    add_text(slide, body,
             x=x+0.1, y=2.7, w=box_w-0.2, h=3.65,
             size=12, color=DARK_GREY, wrap=True)

    # Arrow between boxes
    if i < 2:
        ax = x + box_w + 0.05
        add_text(slide, "→",
                 x=ax, y=2.9, w=0.3, h=0.4,
                 size=22, bold=True, color=TEAL)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 7 – Colour Blindness
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Colour Vision Deficiency (CVD)",
             subtitle="Types, genetics and prevalence")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

# Table header
cols_x = [0.5, 2.8, 5.1, 7.4, 10.1]
cols_w = [2.3, 2.3, 2.3, 2.7, 2.9]
headers = ["Type", "Missing/Abnormal", "Defect", "Prevalence (Males)", "Genetics"]
for i, (h, x, w) in enumerate(zip(headers, cols_x, cols_w)):
    add_rect(slide, x, 1.35, w-0.05, 0.45, NAVY)
    add_text(slide, h, x=x+0.05, y=1.35, w=w-0.1, h=0.45,
             size=13, bold=True, color=WHITE, align=PP_ALIGN.CENTER,
             v_anchor=MSO_ANCHOR.MIDDLE)

rows = [
    ("Protanopia",       "L-cone absent",    "Red blind",        "1%",     "X-linked"),
    ("Protanomaly",      "L-cone abnormal",  "Red weak",         "1%",     "X-linked"),
    ("Deuteranopia",     "M-cone absent",    "Green blind",      "1%",     "X-linked"),
    ("Deuteranomaly",    "M-cone abnormal",  "Green weak",       "5%",     "X-linked"),
    ("Tritanopia",       "S-cone absent",    "Blue-yellow blind","<0.01%", "Autosomal"),
    ("Achromatopsia",    "All cones absent", "Total colour blind","<0.001%","Autosomal"),
]
row_colors = [WHITE, LIGHT_GREY] * 4
for r_idx, (row, bg) in enumerate(zip(rows, row_colors)):
    y = 1.85 + r_idx * 0.6
    for c_idx, (cell, x, w) in enumerate(zip(row, cols_x, cols_w)):
        add_rect(slide, x, y, w-0.05, 0.55, bg)
        add_text(slide, cell, x=x+0.05, y=y+0.02, w=w-0.1, h=0.5,
                 size=12, color=DARK_GREY, align=PP_ALIGN.CENTER,
                 v_anchor=MSO_ANCHOR.MIDDLE)

add_text(slide, "Prevalence: ~8% Northern European men, 0.5% women  |  "
                "Red-green genes on X chromosome; Blue gene on Chromosome 7",
         x=0.5, y=5.55, w=12.1, h=0.55,
         size=12, italic=True, color=NAVY, wrap=True)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 8 – Acquired Colour Vision Defects
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Acquired Colour Vision Defects",
             subtitle="Important clinical correlations")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

add_text(slide, "OPTIC NERVE LESIONS",
         x=0.6, y=1.35, w=5.7, h=0.4, size=16, bold=True, color=RED_C)
on_bullets = [
    "Classically produce RED-GREEN colour defects",
    "Due to preferential damage to P-cell (parvo) fibres",
    "Dyschromatopsia may precede visual acuity loss",
    "Simple screening: Ask patient to compare brightness / saturation of red target in each eye",
    "Examples: Optic neuritis, compressive optic neuropathy, glaucoma",
]
add_bullet_box(slide, on_bullets, 0.6, 1.8, 5.8, 3.5, size=14)

add_text(slide, "MACULAR / RETINAL DISEASE",
         x=6.8, y=1.35, w=5.7, h=0.4, size=16, bold=True, color=BLUE_C)
mac_bullets = [
    "Typically produce BLUE-YELLOW (tritan) defects",
    "Cone photoreceptor dysfunction at fovea",
    "Examples: Age-related macular degeneration, Central serous chorioretinopathy",
    "Acquired tritan defect also seen in glaucoma (early stages)",
]
add_bullet_box(slide, mac_bullets, 6.8, 1.8, 5.7, 3.0, size=14)

add_rect(slide, 0.6, 5.4, 12.0, 1.6, RGBColor(0xFF, 0xF0, 0xD0))
add_text(slide, "Clinical Pearl",
         x=0.7, y=5.45, w=11.8, h=0.35, size=14, bold=True, color=GOLD)
add_text(slide, "In a patient with glaucoma, neuroimaging should be considered if there is "
                "deterioration of colour vision or if the visual field defect is not consistent "
                "with retinal nerve fibre layer loss. (Kanski's Clinical Ophthalmology)",
         x=0.7, y=5.8, w=11.8, h=1.1,
         size=13, italic=True, color=DARK_GREY, wrap=True)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 9 – Colour Vision Tests
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Clinical Colour Vision Tests",
             subtitle="Screening and diagnostic tools")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

tests = [
    ("Ishihara Plates",
     "SCREEN",
     GREEN_C,
     ["Pseudoisochromatic plates using coloured dots",
      "Screens specifically for red-green (protan/deutan) defects",
      "16 plates + 1 test plate; patient identifies embedded numbers",
      "Cannot detect tritan (blue-yellow) or acquired defects reliably",
      "If test plate not read → suspect non-organic visual loss"]),
    ("Hardy-Rand-Rittler (HRR)",
     "SCREEN",
     BLUE_C,
     ["Similar principle to Ishihara",
      "Detects ALL THREE congenital colour defects (protan, deutan, tritan)",
      "More comprehensive than Ishihara alone"]),
    ("City University Test",
     "DIAGNOSE",
     TEAL,
     ["10 plates; patient picks the closest colour match",
      "Classifies type and severity of defect",
      "Useful for monitoring acquired colour changes"]),
    ("Farnsworth-Munsell\n100-Hue Test",
     "QUANTIFY",
     NAVY,
     ["Sensitive but time-consuming (~30 min)",
      "Patient arranges 85 coloured caps in order of hue",
      "Detects and quantifies both congenital and acquired defects",
      "Produces error score plotted on polar diagram"]),
]

x_pos = 0.5
for test_name, badge, col, bullets in tests:
    box_w = 2.9
    add_rect(slide, x_pos, 1.35, box_w, 0.55, col)
    add_text(slide, test_name,
             x=x_pos+0.05, y=1.35, w=box_w-0.1, h=0.55,
             size=13, bold=True, color=WHITE,
             align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)
    add_rect(slide, x_pos, 1.95, box_w, 0.3, GOLD)
    add_text(slide, badge,
             x=x_pos+0.05, y=1.95, w=box_w-0.1, h=0.3,
             size=11, bold=True, color=NAVY,
             align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)
    add_rect(slide, x_pos, 2.3, box_w, 4.5, LIGHT_GREY)
    add_bullet_box(slide, bullets, x_pos+0.1, 2.35, box_w-0.2, 4.4, size=12)
    x_pos += box_w + 0.23

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 10 – Visual Pathway & Colour Processing
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Colour Processing in the Visual Pathway",
             subtitle="From retina to cortex")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

stages = [
    ("RETINA", TEAL,
     "• L, M, S cones → phototransduction\n"
     "• Midget bipolar cells (one-to-one with cone in fovea)\n"
     "• P-type ganglion cells → colour-opponent (R+G-, G+R-, B+Y-, Y+B-)\n"
     "• M-type ganglion cells → luminance (not colour-selective)\n"
     "• Small bistratified cells → Blue-ON / Yellow-OFF"),
    ("LATERAL GENICULATE\nNUCLEUS (LGN)", RED_C,
     "• Parvocellular layers (P pathway) → carry colour & fine detail\n"
     "• Magnocellular layers (M pathway) → motion & low spatial frequency\n"
     "• Koniocellular layers → S-cone (blue) signals\n"
     "• Colour opponency maintained and enhanced"),
    ("VISUAL CORTEX", NAVY,
     "• V1 (striate): colour blob regions (cytochrome oxidase rich)\n"
     "• V2: thin stripes → relay colour info\n"
     "• V4: primary colour area; lesion → cerebral achromatopsia\n"
     "• Only ~10% of V1 neurons preferentially colour-selective\n"
     "• Final percept: integration of wavelength, brightness & context"),
]

x_pos = 0.6
box_w = 3.7
for i, (title, col, body) in enumerate(stages):
    add_rect(slide, x_pos, 1.4, box_w, 0.65, col)
    add_text(slide, title,
             x=x_pos+0.05, y=1.4, w=box_w-0.1, h=0.65,
             size=14, bold=True, color=WHITE,
             align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)
    add_rect(slide, x_pos, 2.1, box_w, 4.85, LIGHT_GREY)
    add_text(slide, body,
             x=x_pos+0.1, y=2.15, w=box_w-0.2, h=4.7,
             size=12, color=DARK_GREY, wrap=True)
    if i < 2:
        add_text(slide, "→",
                 x=x_pos + box_w + 0.05, y=2.9, w=0.3, h=0.5,
                 size=22, bold=True, color=TEAL)
    x_pos += box_w + 0.35

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 11 – Comparison Summary Table
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Comparing the Theories — At a Glance")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

col_headers = ["Feature", "Trichromatic Theory", "Opponent-Process Theory", "Dual Process Theory"]
col_xs      = [0.5, 3.0, 6.1, 9.5]
col_ws      = [2.45, 3.05, 3.35, 3.4]

# Header row
for h, x, w in zip(col_headers, col_xs, col_ws):
    add_rect(slide, x, 1.35, w-0.05, 0.5, NAVY)
    add_text(slide, h, x=x+0.05, y=1.35, w=w-0.1, h=0.5,
             size=13, bold=True, color=WHITE,
             align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)

table_rows = [
    ("Proposed by",    "Young (1802),\nHelmholtz (1850s)", "Hering (1878)", "Von Kries, Hurvich\n& Jameson (20th c.)"),
    ("Site",           "Retinal cones (receptors)", "Retinal ganglion cells\n& beyond", "Both receptor &\npost-receptor"),
    ("Mechanism",      "3 cone types with different\nspectral sensitivities", "Opponent colour pairs\n(R-G, B-Y, W-Bk)", "Combines both\nmechanisms"),
    ("Explains",       "Colour matching,\ntrichromatism", "After-images,\nsimultaneous contrast, colour opponency", "Most colour\nphenomena"),
    ("Does NOT explain","After-images,\ncolour opponency", "Why 3 primary colours\nare needed for mixing", "(Most complete)"),
    ("Clinical use",   "Basis of CVD classification\n(protan/deutan/tritan)", "Explains acquired\noptic nerve vs. macular patterns", "Framework for all\nclinical colour testing"),
]

for r_idx, row in enumerate(table_rows):
    y = 1.9 + r_idx * 0.73
    bg = WHITE if r_idx % 2 == 0 else LIGHT_GREY
    for cell, x, w in zip(row, col_xs, col_ws):
        add_rect(slide, x, y, w-0.05, 0.68, bg)
        add_text(slide, cell, x=x+0.05, y=y+0.02, w=w-0.1, h=0.65,
                 size=11, color=DARK_GREY, wrap=True,
                 align=PP_ALIGN.CENTER, v_anchor=MSO_ANCHOR.MIDDLE)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 12 – Summary & Key Clinical Points
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "Summary & Key Clinical Takeaways")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

summary_left = [
    "Young-Helmholtz Theory: Three cone types (S, M, L) at the receptor level underlie colour vision",
    "Opponent-Process Theory: Colour signals reorganised into R-G and B-Y channels at ganglion cell level",
    "Dual Process: Both theories are correct; they describe different stages in the visual pathway",
    "Congenital CVD: X-linked recessive; ~8% males; red-green most common",
    "Acquired CVD: Optic nerve → red-green defect; Macular disease → blue-yellow (tritan) defect",
]
add_text(slide, "Theory & Science",
         x=0.6, y=1.35, w=5.9, h=0.4, size=15, bold=True, color=TEAL)
add_bullet_box(slide, summary_left, 0.6, 1.8, 5.9, 5.1, size=14)

summary_right = [
    "Ishihara: Screens red-green only; 17/17 = normal",
    "HRR: Screens all three types (protan, deutan, tritan)",
    "FM 100-hue: Quantifies severity of any CVD",
    "Colour vision testing is a sensitive early indicator of optic nerve dysfunction",
    "Children with CVD benefit from early career counselling",
    "Glaucoma: Neuroimaging warranted if colour vision worsens incongruously",
]
add_text(slide, "Clinical Practice",
         x=7.0, y=1.35, w=5.5, h=0.4, size=15, bold=True, color=RED_C)
add_bullet_box(slide, summary_right, 7.0, 1.8, 5.5, 5.1, size=14)

# ─────────────────────────────────────────────────────────────────────────────
# SLIDE 13 – References
# ─────────────────────────────────────────────────────────────────────────────
slide = prs.slides.add_slide(blank)
add_rect(slide, 0, 0, 13.333, 7.5, LIGHT_GREY)
slide_header(slide, "References")
add_footer(slide)

add_rect(slide, 0.4, 1.25, 12.5, 5.9, WHITE)

refs = [
    "Kanski JJ & Bowling B. Kanski's Clinical Ophthalmology: A Systematic Approach, 10th ed. Elsevier, 2020.",
    "Bear MF, Connors BW, Paradiso MA. Neuroscience: Exploring the Brain, 5th ed. Wolters Kluwer, 2020.",
    "Kandel ER et al. Principles of Neural Science, 6th ed. McGraw-Hill, 2021.",
    "Ganong's Review of Medical Physiology, 26th ed. McGraw-Hill.",
    "Hurvich LM & Jameson D. An Opponent-Process Theory of Color Vision. Psychol Rev 1957;64(6):384–404.",
    "Neitz J & Neitz M. The genetics of normal and defective color vision. Vision Res 2011;51(7):633–651.",
]
add_bullet_box(slide, refs, 0.6, 1.45, 12.0, 5.6, size=14)

# ─────────────────────────────────────────────────────────────────────────────
# SAVE
# ─────────────────────────────────────────────────────────────────────────────
out_path = "/tmp/workspace/colour-vision-ppt/Theories_of_Colour_Vision_Ophthalmology.pptx"
prs.save(out_path)
print(f"Saved → {out_path}")
print(f"Slides: {len(prs.slides)}")