from reportlab.lib.pagesizes import A4
from reportlab.lib.styles import getSampleStyleSheet, ParagraphStyle
from reportlab.lib.units import cm, mm
from reportlab.lib import colors
from reportlab.platypus import (
    SimpleDocTemplate, Paragraph, Spacer, Table, TableStyle,
    HRFlowable, Image, KeepTogether, PageBreak
)
from reportlab.lib.enums import TA_LEFT, TA_CENTER, TA_JUSTIFY
from reportlab.platypus.flowables import BalancedColumns
import os

OUTPUT = '/tmp/workspace/pre-endo-pdf/Pre_Endodontic_Restorations.pdf'
BASE = '/tmp/workspace/pre-endo-pdf/'

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

MAROON = colors.HexColor('#7B1D1D')
GOLD   = colors.HexColor('#C8960C')
LGRAY  = colors.HexColor('#F5F5F5')
DGRAY  = colors.HexColor('#333333')
MID    = colors.HexColor('#555555')
BLUE   = colors.HexColor('#1A3A6B')

title_style = ParagraphStyle('Title', parent=styles['Title'],
    fontSize=22, textColor=MAROON, spaceAfter=4,
    fontName='Helvetica-Bold', alignment=TA_CENTER, leading=26)

subtitle_style = ParagraphStyle('Subtitle', parent=styles['Normal'],
    fontSize=11, textColor=BLUE, spaceAfter=2,
    fontName='Helvetica', alignment=TA_CENTER, leading=14)

h1 = ParagraphStyle('H1', parent=styles['Heading1'],
    fontSize=13, textColor=MAROON, spaceBefore=14, spaceAfter=4,
    fontName='Helvetica-Bold', leading=16,
    borderPad=4, backColor=None)

h2 = ParagraphStyle('H2', parent=styles['Heading2'],
    fontSize=11, textColor=BLUE, spaceBefore=10, spaceAfter=3,
    fontName='Helvetica-Bold', leading=14)

body = ParagraphStyle('Body', parent=styles['Normal'],
    fontSize=10, textColor=DGRAY, spaceAfter=5, leading=14,
    alignment=TA_JUSTIFY, fontName='Helvetica')

bullet = ParagraphStyle('Bullet', parent=styles['Normal'],
    fontSize=10, textColor=DGRAY, spaceAfter=3, leading=13,
    leftIndent=14, bulletIndent=4, fontName='Helvetica')

caption = ParagraphStyle('Caption', parent=styles['Normal'],
    fontSize=8.5, textColor=MID, spaceAfter=8, leading=11,
    alignment=TA_CENTER, fontName='Helvetica-Oblique')

box_style = ParagraphStyle('Box', parent=styles['Normal'],
    fontSize=10, textColor=DGRAY, spaceAfter=4, leading=14,
    leftIndent=8, rightIndent=8, fontName='Helvetica',
    backColor=LGRAY, borderPad=6)

def hr(): return HRFlowable(width='100%', thickness=1, color=GOLD, spaceAfter=6, spaceBefore=2)
def space(n=6): return Spacer(1, n)
def b(t): return f'<b>{t}</b>'
def i(t): return f'<i>{t}</i>'

def heading1(text): return Paragraph(text, h1)
def heading2(text): return Paragraph(text, h2)
def para(text): return Paragraph(text, body)
def bul(text): return Paragraph(f'&#8226; {text}', bullet)
def boxpara(text): return Paragraph(text, box_style)

# ── Table helper ─────────────────────────────────────────────────────────────
def make_table(headers, rows, col_widths=None):
    data = [[Paragraph(b(h), ParagraphStyle('TH', parent=styles['Normal'],
                fontSize=9.5, textColor=colors.white, fontName='Helvetica-Bold',
                alignment=TA_CENTER, leading=12)) for h in headers]]
    for row in rows:
        data.append([Paragraph(str(c), ParagraphStyle('TD', parent=styles['Normal'],
                    fontSize=9, textColor=DGRAY, fontName='Helvetica',
                    alignment=TA_LEFT, leading=12, spaceAfter=2)) for c in row])
    ts = TableStyle([
        ('BACKGROUND', (0,0), (-1,0), MAROON),
        ('ROWBACKGROUNDS', (0,1), (-1,-1), [colors.white, LGRAY]),
        ('GRID', (0,0), (-1,-1), 0.5, colors.HexColor('#CCCCCC')),
        ('TOPPADDING', (0,0), (-1,-1), 5),
        ('BOTTOMPADDING', (0,0), (-1,-1), 5),
        ('LEFTPADDING', (0,0), (-1,-1), 6),
        ('RIGHTPADDING', (0,0), (-1,-1), 6),
        ('VALIGN', (0,0), (-1,-1), 'TOP'),
    ])
    t = Table(data, colWidths=col_widths, repeatRows=1)
    t.setStyle(ts)
    return t

def img_block(path, width_cm, caption_text):
    items = []
    if os.path.exists(path):
        try:
            im = Image(path, width=width_cm*cm, height=width_cm*0.65*cm)
            items.append(im)
        except Exception:
            pass
    items.append(Paragraph(caption_text, caption))
    return items

# ── Document ─────────────────────────────────────────────────────────────────
doc = SimpleDocTemplate(OUTPUT, pagesize=A4,
    leftMargin=2*cm, rightMargin=2*cm,
    topMargin=2.2*cm, bottomMargin=2.2*cm,
    title='Pre-Endodontic Restorations',
    author='Orris Medical Notes')

story = []

# ── HEADER BLOCK ─────────────────────────────────────────────────────────────
story.append(Paragraph('Pre-Endodontic Restorations', title_style))
story.append(Paragraph('10-Mark Answer | Endodontics', subtitle_style))
story.append(hr())
story.append(space(4))

# ── 1. INTRODUCTION ──────────────────────────────────────────────────────────
story.append(heading1('1. Introduction and Definition'))
story.append(para(
    'A <b>pre-endodontic restoration</b> (also called a <b>pre-endodontic build-up</b>) is a '
    'temporary or semi-permanent restoration placed in a tooth <i>before</i> or <i>during</i> '
    'root canal treatment (RCT) to restore lost coronal tooth structure. '
    'It is indicated when a tooth has extensive caries, fractured walls, or missing cusps that '
    'make rubber dam isolation impossible, the access cavity walls unsupported, or the canal '
    'system prone to salivary contamination during treatment.'
))
story.append(para(
    'The concept is based on the principle that <b>coronal integrity is a prerequisite for '
    'successful endodontic treatment.</b> Failure to seal the access cavity adequately is a '
    'leading cause of endodontic failure (coronal leakage).'
))
story.append(space(4))

# ── 2. RATIONALE / NEED ──────────────────────────────────────────────────────
story.append(heading1('2. Rationale and Need for Pre-Endodontic Restoration'))
story.append(para('A pre-endodontic build-up is needed when:'))
story.append(bul('Extensive caries destruction leaves insufficient tooth structure for rubber dam clamp retention'))
story.append(bul('Fractured cusps or walls cannot provide a sealed access cavity to prevent salivary contamination'))
story.append(bul('Missing proximal walls lead to difficulty with matrix band placement for final restoration'))
story.append(bul('An open cavity allows irrigation solutions (NaOCl) to flood into the oral cavity'))
story.append(bul('Canal orifices are deep below the cavosurface margin, making direct instrument access difficult'))
story.append(bul('Periodontal surgery (crown lengthening) prior to RCT is planned but immediate surgery is required'))
story.append(space(4))

# ── 3. INDICATIONS ───────────────────────────────────────────────────────────
story.append(heading1('3. Indications'))
story.append(make_table(
    ['Indication', 'Clinical Scenario'],
    [
        ['Extensive caries with missing walls', 'Large MOD caries destroying buccal/lingual walls of molars; premolars with proximal walls lost'],
        ['Fractured crown', 'Ellis Class III or IV fracture with loss of labial/palatal wall in anteriors; cusp fracture in posteriors'],
        ['Subgingival caries margins', 'Caries extending below cementoenamel junction making rubber dam placement and canal access difficult'],
        ['Existing large restorations', 'Tooth with old failing amalgam or composite with open margins; replacement needed before RCT'],
        ['Orthodontic band removal site', 'Tooth recently debonded with residual cement and weakened enamel'],
        ['Pre-existing crown with inadequate margins', 'Leaking crown over a tooth requiring RCT; crown cannot be removed; access through crown'],
        ['Canal projection technique (Donut technique)', 'Multi-rooted molar with deep canal orifices needing composite walls to lift cavosurface level'],
    ],
    col_widths=[6*cm, 10.5*cm]
))
story.append(space(6))

# ── 4. CONTRAINDICATIONS ─────────────────────────────────────────────────────
story.append(heading1('4. Contraindications'))
story.append(bul('Non-restorable tooth - insufficient tooth structure even for build-up (ferrule < 1 mm circumferentially)'))
story.append(bul('Hopeless periodontal prognosis (bone loss >50%, Grade III furcation involvement)'))
story.append(bul('Vertical root fracture confirmed - extraction is indicated'))
story.append(bul('Patient refuses RCT and will proceed to extraction'))
story.append(space(4))

# ── 5. MATERIALS ─────────────────────────────────────────────────────────────
story.append(heading1('5. Materials Used for Pre-Endodontic Restoration'))
story.append(make_table(
    ['Material', 'Type', 'Advantages', 'Disadvantages'],
    [
        ['Composite resin', 'Light-cured / dual-cure resin', 'Bonds to tooth, good seal, tooth-colored, fast set, easily removed', 'Technique sensitive, moisture intolerant'],
        ['Glass ionomer cement (GIC)', 'RMGIC or conventional GIC', 'Moisture tolerant, fluoride release, bonds to dentine, easy to use', 'Lower strength, dissolves in NaOCl if not well set'],
        ['Resin-modified GIC (RMGIC)', 'Dual-cured GIC hybrid', 'Best of both - bond + fluoride + faster set + better moisture tolerance', 'Slightly more technique sensitive than GIC'],
        ['Amalgam', 'Silver alloy', 'Strong, durable, good marginal seal when set', 'No adhesion, mercury concerns, requires 24h before access, obsolete'],
        ['IRM (Intermediate Restorative Material)', 'Reinforced ZOE', 'Easy to manipulate, good temporary seal', 'ZOE may inhibit resin bonding if composite planned later'],
        ['Cavit / TERM', 'Temporary cement', 'Quick placement, self-setting', 'Only for short-term; inadequate for structural support'],
        ['Stainless Steel Crown (SSC)', 'Preformed metal crown', 'Excellent full-coverage protection for molars; pediatric cases', 'Requires coronal reduction, not tooth-colored'],
    ],
    col_widths=[3.2*cm, 3.2*cm, 5.5*cm, 5.5*cm]
))
story.append(space(6))

# ── 6. TECHNIQUES ────────────────────────────────────────────────────────────
story.append(heading1('6. Techniques of Pre-Endodontic Restoration'))

story.append(heading2('A. Simple Build-Up (Composite / RMGIC)'))
story.append(para('Used when 1-2 walls are missing but the remaining tooth structure provides a foundation.'))
story.append(bul('<b>Step 1:</b> Remove all caries completely under rubber dam if possible, or at least isolate with cotton rolls'))
story.append(bul('<b>Step 2:</b> Apply matrix band (Tofflemire / sectional matrix) to replace missing wall'))
story.append(bul('<b>Step 3:</b> Apply dentine bonding agent (for composite) or condition with polyacrylic acid (for GIC)'))
story.append(bul('<b>Step 4:</b> Incrementally place and cure composite resin or mix and place GIC in one increment'))
story.append(bul('<b>Step 5:</b> Allow full cure/set, remove matrix, check occlusion'))
story.append(bul('<b>Step 6:</b> Now prepare access cavity through the build-up'))
story.append(space(4))

story.append(heading2('B. Canal Projection Technique (Doughnut / Donut Technique)'))
story.append(para(
    'Indicated in molars where canal orifices are at the level of or below the cavosurface '
    'margin, making rubber dam clamping impossible and direct access difficult. '
    'This technique projects the canal orifices coronally by building up the walls around them.'
))

# Image 1 - Donut technique
story.append(space(4))
img1_items = img_block(BASE + 'img1.jpg', 13,
    'Fig. 1 - Canal Projection (Doughnut) Technique: (a) Access cavity with canal orifices exposed. '
    '(b) GP points inserted as spacers in canal orifices. '
    '(c) Completed composite build-up with projected canal openings for instrument access.')
for item in img1_items:
    story.append(item)
story.append(space(4))

story.append(para('<b>Steps of Doughnut Technique:</b>'))
story.append(bul('<b>Step 1:</b> Remove all caries; open access cavity; locate all canal orifices'))
story.append(bul('<b>Step 2:</b> Insert <b>gutta-percha (GP) points</b> (size 20-25, greater taper) into each canal orifice to act as spacers/templates'))
story.append(bul('<b>Step 3:</b> Etch and bond the remaining tooth structure around the canal orifices'))
story.append(bul('<b>Step 4:</b> Apply composite resin around the GP points (matrix band placed if walls missing)'))
story.append(bul('<b>Step 5:</b> Light cure the composite; remove the GP points - this leaves perfectly sized projected canal openings from each orifice to the new cavosurface'))
story.append(bul('<b>Step 6:</b> Apply rubber dam; instruments now have direct, unimpeded access down each canal without interference from walls'))
story.append(space(4))

story.append(para('<b>Advantages of Doughnut Technique:</b>'))
story.append(bul('Creates a closed, bacteria-tight chamber during treatment'))
story.append(bul('Prevents NaOCl and irrigants from escaping into the oral cavity'))
story.append(bul('Correct canal orifice alignment and instrument access maintained'))
story.append(bul('Prevents food/debris impaction between appointments'))
story.append(space(4))

story.append(heading2('C. Orthodontic Band / Copper Band Technique (Historical)'))
story.append(para(
    'A preformed orthodontic band or copper band was adapted around the tooth and filled with '
    'zinc phosphate cement or amalgam to provide a temporary circumferential wall. '
    'Now largely replaced by matrix band + composite build-up.'
))
story.append(space(4))

story.append(heading2('D. Access Through Existing Crown (Crown-Through Technique)'))
story.append(para(
    'When a tooth already has an adequate full-coverage crown, access is drilled through the '
    'crown without removing it. The crown itself serves as the pre-endodontic build-up - '
    'providing walls, clamp retention, and a coronal seal. '
    'The access through crown is sealed with composite or RMGIC at the end of each appointment.'
))
story.append(space(4))

# Image 2 - Access cavity + matrix band
img2_items = img_block(BASE + 'img2.jpg', 12,
    'Fig. 2 - Matrix band (Tofflemire retainer) placed around a molar during endodontic access. '
    'The band provides a wall for pre-endodontic composite build-up and prevents salivary contamination. '
    'Canal orifices (mesio-buccal, disto-buccal, palatal) are visible at the pulp chamber floor.')
for item in img2_items:
    story.append(item)
story.append(space(4))

# ── 7. REQUIREMENTS OF IDEAL PRE-ENDO RESTORATION ───────────────────────────
story.append(heading1('7. Requirements of an Ideal Pre-Endodontic Restoration'))
story.append(boxpara(
    '1. <b>Adequate marginal seal</b> - prevent salivary/bacterial microleakage into canal system<br/>'
    '2. <b>Structural support</b> - withstand condensation forces during obturation and between-visit loads<br/>'
    '3. <b>Rubber dam retention</b> - provide enough tooth/build-up height for a clamp to engage<br/>'
    '4. <b>Compatibility with endodontic irrigants</b> - must not dissolve in NaOCl (2.5-5.25%) or EDTA<br/>'
    '5. <b>Easily identifiable access cavity walls</b> - does not obscure pulp chamber anatomy<br/>'
    '6. <b>Biocompatibility</b> - non-toxic to pulp remnants and periapical tissues<br/>'
    '7. <b>Ease of removal</b> when final restoration is placed post-RCT<br/>'
    '8. <b>Radiopaque</b> - visible on working length radiographs'
))
story.append(space(4))

# ── 8. ROLE OF RUBBER DAM ────────────────────────────────────────────────────
story.append(heading1('8. Relationship to Rubber Dam Isolation'))
story.append(para(
    'The rubber dam is mandatory for RCT (AAE standard of care). Pre-endodontic restorations '
    'directly enable rubber dam placement by:'
))
story.append(bul('Restoring coronal height sufficient for clamp engagement (at least 2 mm above the gingival margin)'))
story.append(bul('Providing a smooth, sealed chamber to prevent NaOCl from flooding under the dam'))
story.append(bul('Supporting the walls of the pulp chamber so irrigants do not leak between appointments'))
story.append(para(
    'Without an adequate build-up, a clamp cannot be placed safely on a grossly broken-down '
    'tooth, making proper isolation - and hence aseptic technique - impossible.'
))
story.append(space(4))

# ── 9. CORONAL LEAKAGE AND SIGNIFICANCE ─────────────────────────────────────
story.append(heading1('9. Coronal Leakage - Why Pre-Endodontic Restoration Matters'))
story.append(para(
    '<b>Coronal leakage</b> is the penetration of oral bacteria and their by-products through '
    'the coronal aspect of a completed root canal filling, causing recontamination of the '
    'obturated canal system and eventual periapical failure.'
))
story.append(para(
    'Ray and Trope (1995) demonstrated that <b>the quality of the coronal restoration had a '
    'greater impact on periapical status than the quality of the root canal filling itself.</b> '
    'A well-obturated canal with a poor coronal seal fails more often than a poorly obturated '
    'canal with an excellent coronal seal.'
))
story.append(para('Therefore, the pre-endodontic build-up serves as the first line of defense against coronal leakage by:'))
story.append(bul('Sealing the pulp chamber between appointments'))
story.append(bul('Preventing bacterial ingress if the temporary dressing is lost'))
story.append(bul('Protecting the canal system from oral fluids during rubber dam removal and placement'))
story.append(space(4))

# ── 10. POST-ENDODONTIC IMPLICATIONS ─────────────────────────────────────────
story.append(heading1('10. Post-Endodontic Restoration Planning'))
story.append(para(
    'The pre-endodontic build-up also informs the <b>post-endodontic restoration plan</b>. '
    'Assessing restorability before RCT avoids the situation of completing a technically '
    'excellent root canal treatment on a non-restorable tooth.'
))
story.append(para('<b>Ferrule Effect:</b> A minimum 2 mm of sound circumferential tooth structure above the alveolar crest is required for a predictable post-endodontic crown. '
    'This must be confirmed <i>before</i> initiating RCT. If ferrule is absent:'))
story.append(bul('Crown lengthening surgery may be required (delay RCT by 6-8 weeks for healing)'))
story.append(bul('Orthodontic extrusion (forced eruption) may bring the margin supragingivally'))
story.append(bul('If neither is feasible, extraction and implant should be considered'))
story.append(space(4))

# Image 3 - Temporized molar
img3_items = img_block(BASE + 'img3.jpg', 10,
    'Fig. 3 - Extensively carious molar with access cavity temporized with RMGIC/Cavit. '
    'Remaining thin walls highlight the need for pre-endodontic build-up before continuing treatment.')
for item in img3_items:
    story.append(item)
story.append(space(4))

# ── 11. CLINICAL STEPS SUMMARY TABLE ─────────────────────────────────────────
story.append(heading1('11. Step-by-Step Clinical Protocol'))
story.append(make_table(
    ['Step', 'Action', 'Material / Instrument'],
    [
        ['1', 'Examine and assess restorability; confirm ferrule', 'Periapical radiograph, CBCT if needed'],
        ['2', 'Administer local anesthesia', '2% Lignocaine 1:80,000 adrenaline'],
        ['3', 'Remove all caries completely', 'Round bur, caries detector dye'],
        ['4', 'Place rubber dam if possible; or isolate with cotton rolls', 'Rubber dam, Ivory clamp, Young frame'],
        ['5', 'Place matrix band around tooth', 'Tofflemire / Sectional matrix (Palodent)'],
        ['6', 'Etch dentin and enamel (if composite planned)', '37% phosphoric acid / self-etch primer'],
        ['7', 'Apply bonding agent; light cure', 'Total-etch or self-etch adhesive'],
        ['8a (Simple build-up)', 'Incrementally place and cure composite resin', 'Bulk-fill or universal composite, LED curing light'],
        ['8b (Doughnut technique)', 'Insert GP points in orifices; apply composite; cure; remove GP points', 'GP cones (size 20-25), composite, LED light'],
        ['9', 'Remove matrix; check occlusion; adjust if needed', 'Articulating paper, finishing burs'],
        ['10', 'Prepare access cavity through build-up', 'Endo access bur, DG-16 explorer'],
        ['11', 'Seal between appointments', 'Cavit / RMGIC / Fuji IX in access cavity'],
    ],
    col_widths=[0.8*cm, 7.5*cm, 8.2*cm]
))
story.append(space(8))

# ── 12. SUMMARY TABLE ────────────────────────────────────────────────────────
story.append(heading1('12. Summary - Pre-Endodontic Restoration at a Glance'))
story.append(make_table(
    ['Parameter', 'Key Points'],
    [
        ['Definition', 'Build-up placed before/during RCT to restore structural integrity and enable treatment'],
        ['When needed', 'Extensive caries, missing walls, subgingival caries, broken cusp, deep canal orifices'],
        ['Best material', 'Composite resin (bonded) or RMGIC - both provide good seal and support'],
        ['Best technique', 'Doughnut technique for molars with deep orifices; simple build-up for 1-2 missing walls'],
        ['Key advantage', 'Enables rubber dam placement; prevents coronal leakage; maintains clean surgical field'],
        ['Critical concept', 'Assess restorability (ferrule effect) BEFORE starting RCT to avoid treating non-restorable teeth'],
        ['Failure consequence', 'Without pre-endo restoration: NaOCl overflow, poor isolation, contamination, RCT failure'],
    ],
    col_widths=[4*cm, 12.5*cm]
))
story.append(space(8))

# ── FOOTER ───────────────────────────────────────────────────────────────────
story.append(hr())
story.append(Paragraph(
    'Orris Medical Notes | Endodontics | Pre-Endodontic Restorations (10 Marks)',
    ParagraphStyle('footer', parent=styles['Normal'], fontSize=8,
        textColor=MID, alignment=TA_CENTER, fontName='Helvetica-Oblique')
))

# ── BUILD ─────────────────────────────────────────────────────────────────────
doc.build(story)
print(f'PDF saved to: {OUTPUT}')