import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.patches as mpatches
from matplotlib.patches import FancyBboxPatch, FancyArrowPatch
import matplotlib.patheffects as pe

# ── Canvas ────────────────────────────────────────────────────────────────────
fig, ax = plt.subplots(figsize=(22, 34))
ax.set_xlim(0, 22)
ax.set_ylim(0, 34)
ax.axis('off')
fig.patch.set_facecolor('#F8FAFC')

# ── Colour palette ─────────────────────────────────────────────────────────
C = {
    'title':    '#1A237E',
    'start':    '#0D47A1',
    'diamond':  '#1565C0',
    'green':    '#1B5E20',
    'orange':   '#E65100',
    'red':      '#B71C1C',
    'purple':   '#4A148C',
    'teal':     '#004D40',
    'grey':     '#37474F',
    'action':   '#E3F2FD',
    'action2':  '#E8F5E9',
    'action3':  '#FFF3E0',
    'action4':  '#FCE4EC',
    'warn':     '#FFF8E1',
    'arrow':    '#37474F',
    'text_dk':  '#0D0D0D',
    'white':    '#FFFFFF',
    'line':     '#90A4AE',
}

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

def box(ax, x, y, w, h, text, facecolor, edgecolor, fontsize=8.5,
        textcolor='#0D0D0D', bold=False, style='round,pad=0.1', wrap=True,
        radius=0.15):
    """Draw a rounded rectangle with centred, wrapped text."""
    rect = FancyBboxPatch((x - w/2, y - h/2), w, h,
                          boxstyle=f'round,pad={radius}',
                          facecolor=facecolor, edgecolor=edgecolor,
                          linewidth=1.8, zorder=3)
    ax.add_patch(rect)
    weight = 'bold' if bold else 'normal'
    ax.text(x, y, text, ha='center', va='center',
            fontsize=fontsize, color=textcolor, weight=weight,
            wrap=True, zorder=4,
            multialignment='center',
            linespacing=1.35)

def diamond(ax, x, y, w, h, text, facecolor, edgecolor, fontsize=8.5,
            textcolor='white'):
    """Draw a diamond shape."""
    dx, dy = w/2, h/2
    coords = [[x, y+dy], [x+dx, y], [x, y-dy], [x-dx, y]]
    patch = plt.Polygon(coords, closed=True,
                        facecolor=facecolor, edgecolor=edgecolor,
                        linewidth=2, zorder=3)
    ax.add_patch(patch)
    ax.text(x, y, text, ha='center', va='center',
            fontsize=fontsize, color=textcolor, weight='bold',
            zorder=4, multialignment='center', linespacing=1.3)

def arrow(ax, x1, y1, x2, y2, label='', color='#37474F', lw=1.6,
          label_side='right', fontsize=7.5):
    ax.annotate('', xy=(x2, y2), xytext=(x1, y1),
                arrowprops=dict(arrowstyle='->', color=color,
                                lw=lw, mutation_scale=16),
                zorder=2)
    if label:
        mx = (x1+x2)/2
        my = (y1+y2)/2
        offset = 0.22 if label_side == 'right' else -0.22
        ax.text(mx + offset, my, label, fontsize=fontsize,
                color=color, weight='bold', ha='center', va='center',
                zorder=5)

def hline(ax, x1, x2, y, color='#37474F', lw=1.4):
    ax.plot([x1, x2], [y, y], color=color, lw=lw, zorder=2)

def vline(ax, x, y1, y2, color='#37474F', lw=1.4):
    ax.plot([x, x], [y1, y2], color=color, lw=lw, zorder=2)


# ══════════════════════════════════════════════════════════════════════════════
# TITLE
# ══════════════════════════════════════════════════════════════════════════════
ax.add_patch(FancyBboxPatch((0.4, 32.8), 21.2, 1.0,
             boxstyle='round,pad=0.15', facecolor=C['title'],
             edgecolor='none', zorder=3))
ax.text(11, 33.32, 'CLINICAL MANAGEMENT FLOWCHART', ha='center', va='center',
        fontsize=15, color='white', weight='bold', zorder=4)
ax.text(11, 32.98, 'Acute Watery Diarrhoea in Paediatrics  |  WHO / Nelson Guidelines',
        ha='center', va='center', fontsize=9.5, color='#90CAF9', zorder=4)

# ══════════════════════════════════════════════════════════════════════════════
# STEP 1 – PRESENTATION
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 11, 32.1, 7.5, 0.75,
    'CHILD PRESENTS WITH ACUTE WATERY DIARRHOEA\n(≥3 loose/liquid stools in 24 h, duration <14 days)',
    '#0D47A1', '#0D47A1', fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 31.72, 11, 31.2)

# ══════════════════════════════════════════════════════════════════════════════
# STEP 2 – RED FLAGS
# ══════════════════════════════════════════════════════════════════════════════
diamond(ax, 11, 30.75, 8, 0.9,
        'RED FLAGS PRESENT?\n(Blood in stool / bilious vomit / peritoneal signs\n/ age <3 months / altered mental status)',
        C['red'], C['red'], fontsize=8.2)

# YES → right
arrow(ax, 15, 30.75, 17.5, 30.75, label='YES', color=C['red'], label_side='right')
box(ax, 19.5, 30.75, 4.2, 0.9,
    'URGENT EVALUATION\n• Surgical consult (appendicitis, volvulus)\n• Consider HUS, sepsis, DKA\n• Admit & IV access',
    '#FCE4EC', C['red'], fontsize=7.8, textcolor=C['red'], bold=False)

# NO → down
arrow(ax, 11, 30.3, 11, 29.75, label='NO', color=C['green'], label_side='right')

# ══════════════════════════════════════════════════════════════════════════════
# STEP 3 – HISTORY & EXAM
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 11, 29.3, 9.5, 0.82,
    'HISTORY & PHYSICAL EXAMINATION\nDuration • Stool frequency/consistency • Vomiting • Fever • Urine output\nTravel history • Food history • Contact with sick persons • Immunisation status',
    C['action'], C['grey'], fontsize=8, textcolor=C['text_dk'])

arrow(ax, 11, 28.89, 11, 28.35)

# ══════════════════════════════════════════════════════════════════════════════
# STEP 4 – DEHYDRATION ASSESSMENT
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 11, 27.95, 10.5, 0.75,
    'ASSESS DEGREE OF DEHYDRATION  (WHO Classification)',
    '#1565C0', '#1565C0', fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 27.57, 11, 27.05)

# ── Dehydration table ─────────────────────────────────────────────────────
# Three columns: None, Mild-Mod, Severe
col_x = [4.2, 11, 17.8]
col_fc = [C['action2'], C['action3'], C['action4']]
col_ec = [C['green'], C['orange'], C['red']]
col_titles = ['NONE / MINIMAL\n(<3% body weight)',
              'MILD–MODERATE\n(3–9% body weight)',
              'SEVERE\n(>9% body weight)']
col_content = [
    'Alert, well\nNormal eyes/tears\nMoist mucosa\nNormal pulse/BP\nNormal skin turgor\nNormal urine output',
    'Restless/irritable\nSunken eyes, ↓tears\nDry/sticky mucosa\nNormal–↑HR\nReduced skin turgor\nDecreased urine',
    'Lethargic/unconscious\nVery sunken eyes, no tears\nVery dry mucosa\nTachycardia, weak pulse\nVery poor turgor (>2s)\nMinimal/no urine',
]

for i, (cx, fc, ec, title, content) in enumerate(
        zip(col_x, col_fc, col_ec, col_titles, col_content)):
    # header
    box(ax, cx, 26.65, 5.0, 0.65, title, ec, ec,
        fontsize=8, textcolor='white', bold=True)
    # body
    box(ax, cx, 25.5, 5.0, 1.55, content, fc, ec, fontsize=7.5, textcolor=C['text_dk'])

# Arrows from dehydration box down to each column header
for cx in col_x:
    arrow(ax, 11, 27.05, cx, 26.98, color=C['arrow'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 5 – MANAGEMENT BRANCHES
# ══════════════════════════════════════════════════════════════════════════════
mgmt_y_start = 24.6   # top of management boxes

# ── None/Minimal ──────────────────────────────────────────────────────────
arrow(ax, col_x[0], 24.72, col_x[0], mgmt_y_start)
box(ax, col_x[0], 23.85, 5.0, 1.45,
    'PLAN A  –  HOME MANAGEMENT\n\n'
    '• Continue breastfeeding\n'
    '• Extra fluids after each stool:\n'
    '  < 2 yrs: 50–100 mL ORS\n'
    '  ≥ 2 yrs: 100–200 mL ORS\n'
    '• Continue normal diet\n'
    '• Zinc: 10 mg/day (<6 m)\n'
    '  20 mg/day (≥6 m) × 10–14 days\n'
    '• Return if worsens',
    C['action2'], C['green'], fontsize=7.5, textcolor=C['text_dk'])

# ── Mild–Moderate ─────────────────────────────────────────────────────────
arrow(ax, col_x[1], 24.72, col_x[1], mgmt_y_start)
box(ax, col_x[1], 23.85, 5.0, 1.45,
    'PLAN B  –  ORT IN FACILITY\n\n'
    '• ORS 75 mL/kg over 3–4 hours\n'
    '• Reassess every 1–2 hours\n'
    '• Replace ongoing losses:\n'
    '  10 mL/kg per stool\n'
    '  2 mL/kg per vomit\n'
    '• If vomiting: 5 mL q2–3 min\n'
    '• NG-ORS if repeated vomiting\n'
    '• Ondansetron 0.15 mg/kg PO\n'
    '• Zinc supplementation',
    C['action3'], C['orange'], fontsize=7.5, textcolor=C['text_dk'])

# ── Severe ────────────────────────────────────────────────────────────────
arrow(ax, col_x[2], 24.72, col_x[2], mgmt_y_start)
box(ax, col_x[2], 23.85, 5.0, 1.45,
    'PLAN C  –  IV REHYDRATION\n\n'
    '• IV access immediately\n'
    '• NS or Lactated Ringer\'s:\n'
    '  20 mL/kg bolus over 15–30 min\n'
    '  Repeat until haemodynamically stable\n'
    '• Check: glucose, electrolytes,\n'
    '  BUN, creatinine, Ca²⁺\n'
    '• Treat hypoglycaemia if present\n'
    '• Switch to ORS when tolerated\n'
    '• ADMIT',
    C['action4'], C['red'], fontsize=7.5, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# ORS COMPOSITION BOX (inset, right side)
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 19.2, 22.2, 4.6, 1.3,
    'WHO REDUCED-OSMOLARITY ORS\n'
    '─────────────────────────────\n'
    'Glucose       75 mmol/L\n'
    'Sodium        75 mmol/L\n'
    'Potassium     20 mmol/L\n'
    'Chloride      65 mmol/L\n'
    'Citrate       10 mmol/L\n'
    'Osmolarity   245 mOsm/L',
    '#EDE7F6', '#4A148C', fontsize=7.5, textcolor='#1A0050')

# ══════════════════════════════════════════════════════════════════════════════
# STEP 6 – REASSESSMENT AFTER PLAN B
# ══════════════════════════════════════════════════════════════════════════════
# Arrow down from Plan B
arrow(ax, col_x[1], 23.07, col_x[1], 22.45)

diamond(ax, col_x[1], 22.0, 5.2, 0.82,
        'REASSESS AFTER ORT\n(Improving?)',
        '#1565C0', '#1565C0', fontsize=8.2)

# Yes → left (Plan A)
arrow(ax, 8.4, 22.0, 6.8, 22.0, label='YES', color=C['green'], label_side='right')
box(ax, 5.1, 22.0, 3.0, 0.62,
    'STEP DOWN TO PLAN A\n+ Discharge with instructions',
    C['action2'], C['green'], fontsize=7.5, textcolor=C['text_dk'])

# No → right (Plan C)
arrow(ax, 13.6, 22.0, 15.0, 22.0, label='NO', color=C['red'], label_side='right')
box(ax, 16.5, 22.0, 3.0, 0.62,
    'ESCALATE TO PLAN C\n+ Admit for IV fluids',
    C['action4'], C['red'], fontsize=7.5, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 7 – NUTRITIONAL MANAGEMENT
# ══════════════════════════════════════════════════════════════════════════════
arrow(ax, col_x[1], 21.59, col_x[1], 21.15)
box(ax, 11, 20.75, 10.5, 0.68,
    'NUTRITIONAL MANAGEMENT  (All Plans)',
    C['teal'], C['teal'], fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 20.41, 11, 20.0)
box(ax, 11, 19.5, 10.5, 0.85,
    '• Continue breastfeeding throughout illness  •  Formula-fed: continue usual formula (do NOT dilute)\n'
    '• Restart age-appropriate diet EARLY (do not fast)  •  No BRAT diet — nutritionally incomplete\n'
    '• Avoid fruit juices, sports drinks, plain water in infants  •  Lactase-containing foods if post-viral lactose intolerance',
    '#E0F2F1', C['teal'], fontsize=7.6, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 8 – SPECIFIC AETIOLOGY / ANTIBIOTICS
# ══════════════════════════════════════════════════════════════════════════════
arrow(ax, 11, 19.07, 11, 18.55)

diamond(ax, 11, 18.1, 7.5, 0.82,
        'BLOODY STOOL / SUSPECTED BACTERIAL CAUSE\n/ TRAVEL HISTORY / IMMUNOCOMPROMISED?',
        '#4A148C', '#4A148C', fontsize=8)

# YES – right
arrow(ax, 14.75, 18.1, 16.4, 18.1, label='YES', color='#4A148C', label_side='right')
box(ax, 18.8, 18.1, 4.8, 0.88,
    'STOOL CULTURE + TARGETED ANTIBIOTICS\n'
    'Shigella → Azithromycin 20 mg/kg/day × 3–5 d\n'
    'Cholera → Azithromycin (children)\n'
    'Salmonella typhi → Ceftriaxone\n'
    'Giardia → Metronidazole 15 mg/kg/day × 5–7 d\n'
    'C. diff → Stop causative abx; Metronidazole/Vancomycin\n'
    'ETEC (traveller\'s) → Azithromycin',
    '#F3E5F5', '#4A148C', fontsize=7.2, textcolor='#1A0050')

# NO – down
arrow(ax, 11, 17.69, 11, 17.2, label='NO', color=C['green'], label_side='right')
box(ax, 11, 16.85, 7.5, 0.62,
    'VIRAL AETIOLOGY LIKELY  –  SUPPORTIVE CARE ONLY\n'
    'No antibiotics  •  Probiotics optional (L. rhamnosus GG or S. boulardii)',
    C['action2'], C['green'], fontsize=7.8, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 9 – MONITOR FOR COMPLICATIONS
# ══════════════════════════════════════════════════════════════════════════════
arrow(ax, 11, 16.54, 11, 16.05)
box(ax, 11, 15.65, 10.5, 0.68,
    'MONITOR FOR COMPLICATIONS',
    '#B71C1C', '#B71C1C', fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 15.31, 11, 14.9)
box(ax, 11, 14.3, 10.5, 1.05,
    'HUS: ↓Hb + ↓platelets + ↑creatinine → STOP antibiotics, nephrology consult\n'
    'Hyponatraemia / Hypernatraemia: correct slowly (Na change ≤10–12 mEq/L/day)\n'
    'Hypoglycaemia: dextrose 0.5–1 g/kg IV bolus (D10W: 5–10 mL/kg)\n'
    'Hypokalaemia: add KCl to IV fluids (K⁺ 20–40 mEq/L)\n'
    'Seizures (Shigella): benzodiazepine + antibiotic cover\n'
    'Persistent diarrhoea (>14 days): assess for secondary lactose intolerance, post-infectious enteropathy',
    '#FFF5F5', '#B71C1C', fontsize=7.5, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 10 – DISCHARGE CRITERIA
# ══════════════════════════════════════════════════════════════════════════════
arrow(ax, 11, 13.77, 11, 13.3)
box(ax, 11, 12.88, 10.5, 0.68,
    'DISCHARGE CRITERIA',
    C['teal'], C['teal'], fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 12.54, 11, 12.1)
box(ax, 11, 11.6, 10.5, 0.85,
    '✔ Clinically well, alert, and oriented  ✔ Vital signs within normal limits for age\n'
    '✔ Tolerating oral feeds adequately  ✔ Urine output adequate during hydration period\n'
    '✔ Intake ≥ ongoing losses  ✔ Caregiver educated on ORS, diet, warning signs',
    C['action2'], C['teal'], fontsize=7.8, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# STEP 11 – PREVENTION
# ══════════════════════════════════════════════════════════════════════════════
arrow(ax, 11, 11.17, 11, 10.7)
box(ax, 11, 10.28, 10.5, 0.68,
    'PREVENTION',
    '#1B5E20', '#1B5E20', fontsize=9, textcolor='white', bold=True)

arrow(ax, 11, 9.94, 11, 9.55)
box(ax, 11, 9.1, 10.5, 0.8,
    'Rotavirus vaccine (RotaTeq ×3 or Rotarix ×2)  •  Hand hygiene (↓ incidence by ~30%)  •  Exclusive breastfeeding\n'
    'Safe water & sanitation (WASH)  •  Proper food handling  •  Alcohol-based hand sanitiser in schools/daycare',
    '#E8F5E9', '#1B5E20', fontsize=7.8, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# RETURN SIGNS box (bottom-left)
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 3.8, 9.1, 6.2, 0.68,
    'RETURN SIGNS (Advise caregivers)', '#E65100', '#E65100',
    fontsize=8.5, textcolor='white', bold=True)
arrow(ax, 3.8, 8.76, 3.8, 8.3)
box(ax, 3.8, 7.75, 6.2, 0.95,
    '• Many watery stools or worsening diarrhoea\n'
    '• Repeated vomiting / unable to drink\n'
    '• Blood in stool\n'
    '• Fever >38°C (infant <3 months: any fever)\n'
    '• Marked decrease in activity / lethargy\n'
    '• Not improved after 3–5 days',
    '#FFF3E0', '#E65100', fontsize=7.5, textcolor=C['text_dk'])

# ══════════════════════════════════════════════════════════════════════════════
# KEY REMINDERS box (bottom-right)
# ══════════════════════════════════════════════════════════════════════════════
box(ax, 18.2, 9.1, 6.2, 0.68,
    'KEY CLINICAL REMINDERS', '#1A237E', '#1A237E',
    fontsize=8.5, textcolor='white', bold=True)
arrow(ax, 18.2, 8.76, 18.2, 8.3)
box(ax, 18.2, 7.6, 6.2, 1.15,
    '⚠ Loperamide CONTRAINDICATED in children\n'
    '⚠ NO antibiotics for routine viral diarrhoea\n'
    '⚠ Do NOT stop antibiotics in STEC/HUS\n'
    '   → nephrology consult urgently\n'
    '⚠ Bilious vomiting = malrotation until\n'
    '   proven otherwise\n'
    '⚠ Always check glucose in infants\n'
    '✔ ORT is always preferred over IV\n'
    '   (no difference in efficacy; shorter LOS)',
    '#E8EAF6', '#1A237E', fontsize=7.4, textcolor='#1A0050')

# ══════════════════════════════════════════════════════════════════════════════
# Footer
# ══════════════════════════════════════════════════════════════════════════════
ax.add_patch(FancyBboxPatch((0.4, 0.15), 21.2, 0.45,
             boxstyle='round,pad=0.1', facecolor='#ECEFF1',
             edgecolor='#B0BEC5', zorder=3))
ax.text(11, 0.38,
        'Based on WHO IMCI Guidelines · Nelson\'s Textbook of Pediatrics · AAP/ESPGHAN Recommendations',
        ha='center', va='center', fontsize=7.5, color='#546E7A', zorder=4)

# ══════════════════════════════════════════════════════════════════════════════
# Save
# ══════════════════════════════════════════════════════════════════════════════
out = '/home/daytona/workspace/awd-flowchart/AWD_Pediatrics_Flowchart.png'
plt.tight_layout(pad=0)
plt.savefig(out, dpi=180, bbox_inches='tight', facecolor=fig.get_facecolor())
plt.close()
print(f'Saved: {out}')