import { PDFDocument, StandardFonts, rgb } from 'pdf-lib'

export type IncidentReportData = {
  referenceNo: string | null
  incidentType: string
  reportedAt: string
  siteName: string
  zoneName: string | null
  reporterName: string
  severity: number | null
  medicalStatus: string | null
  description: string
  injuryInvolved: boolean
  assetInvolved: boolean
  isFatality: boolean
  isSeriousBodilyInjury: boolean
  isDangerousOccurrence: boolean
  isOccupationalDisease: boolean
  lostDays: number | null
  triagedBy: string | null
  triagedAt: string | null
  triageNotes: string | null
  investigation: {
    method: string
    findingsText: string | null
    rootCauseSummary: string | null
    alcoholTestResult: string | null
    urineTestResult: string | null
  } | null
  capas: Array<{
    description: string
    ownerName: string
    department: string
    dueDate: string
    priority: string
    status: string
    completedAt: string | null
    ownerNotes: string | null
  }>
  addenda: Array<{
    authorName: string
    createdAt: string
    body: string
  }>
  closedAt: string | null
}

type EmbeddedFont = Awaited<ReturnType<PDFDocument['embedFont']>>
type Page = ReturnType<PDFDocument['addPage']>

const MARGIN = 50
const PAGE_WIDTH = 595
const PAGE_HEIGHT = 842
const BODY_FONT_SIZE = 10
const LABEL_FONT_SIZE = 9
const SECTION_FONT_SIZE = 11
const LINE_HEIGHT = 16
const SECTION_GAP = 20
const BOTTOM_MARGIN = 60

type State = {
  doc: PDFDocument
  pages: Page[]
  font: EmbeddedFont
  boldFont: EmbeddedFont
  y: number
}

function currentPage(state: State): Page {
  return state.pages[state.pages.length - 1]
}

function newPage(state: State): void {
  const page = state.doc.addPage([PAGE_WIDTH, PAGE_HEIGHT])
  state.pages.push(page)
  state.y = PAGE_HEIGHT - MARGIN
}

function ensureSpace(state: State, needed: number): void {
  if (state.y - needed < BOTTOM_MARGIN) newPage(state)
}

function wrapText(text: string, maxWidth: number, font: EmbeddedFont, size: number): string[] {
  const words = text.split(' ')
  const lines: string[] = []
  let current = ''
  for (const word of words) {
    const test = current ? `${current} ${word}` : word
    if (font.widthOfTextAtSize(test, size) > maxWidth && current) {
      lines.push(current)
      current = word
    } else {
      current = test
    }
  }
  if (current) lines.push(current)
  return lines.length ? lines : ['']
}

function drawSection(state: State, title: string): void {
  const yBefore = state.y
  ensureSpace(state, SECTION_GAP + LINE_HEIGHT + 6)
  // Only add gap if we didn't just start a new page
  if (state.y === yBefore) {
    state.y -= SECTION_GAP
  }
  currentPage(state).drawRectangle({
    x: MARGIN, y: state.y - 4,
    width: PAGE_WIDTH - MARGIN * 2, height: LINE_HEIGHT + 4,
    color: rgb(0.9, 0.95, 0.9),
  })
  currentPage(state).drawText(title.toUpperCase(), {
    x: MARGIN + 4, y: state.y,
    size: SECTION_FONT_SIZE, font: state.boldFont, color: rgb(0.05, 0.4, 0.1),
  })
  state.y -= LINE_HEIGHT + 8
}

function drawField(state: State, label: string, value: string | null): void {
  const v = value ?? '—'
  const maxW = PAGE_WIDTH - MARGIN * 2 - 120
  const lines = wrapText(v, maxW, state.font, BODY_FONT_SIZE)
  ensureSpace(state, (lines.length + 1) * LINE_HEIGHT)
  currentPage(state).drawText(label + ':', {
    x: MARGIN, y: state.y,
    size: LABEL_FONT_SIZE, font: state.boldFont, color: rgb(0.3, 0.3, 0.3),
  })
  for (const line of lines) {
    currentPage(state).drawText(line, {
      x: MARGIN + 120, y: state.y,
      size: BODY_FONT_SIZE, font: state.font, color: rgb(0, 0, 0),
    })
    state.y -= LINE_HEIGHT
  }
  if (lines.length === 0) state.y -= LINE_HEIGHT
}

function fmt(iso: string | null): string {
  if (!iso) return '—'
  return new Date(iso).toLocaleString('en-MY', { timeZone: 'Asia/Kuala_Lumpur', hour12: false })
}

function fmtDate(iso: string | null): string {
  if (!iso) return '—'
  return new Date(iso).toLocaleDateString('en-MY', { timeZone: 'Asia/Kuala_Lumpur' })
}

export async function buildIncidentReportPdf(data: IncidentReportData): Promise<Uint8Array> {
  const doc = await PDFDocument.create()
  const font = await doc.embedFont(StandardFonts.Helvetica)
  const boldFont = await doc.embedFont(StandardFonts.HelveticaBold)

  const firstPage = doc.addPage([PAGE_WIDTH, PAGE_HEIGHT])
  const state: State = { doc, pages: [firstPage], font, boldFont, y: PAGE_HEIGHT - MARGIN }

  // ── Header ──────────────────────────────────────────────────────────────
  currentPage(state).drawText('INCIDENT INVESTIGATION REPORT', {
    x: MARGIN, y: state.y,
    size: 16, font: boldFont, color: rgb(0.05, 0.4, 0.1),
  })
  state.y -= 22
  currentPage(state).drawText(`Reference: ${data.referenceNo ?? '—'}`, {
    x: MARGIN, y: state.y,
    size: 10, font, color: rgb(0.2, 0.2, 0.2),
  })
  currentPage(state).drawText(`Generated: ${fmt(new Date().toISOString())}`, {
    x: PAGE_WIDTH - MARGIN - 160, y: state.y,
    size: 10, font, color: rgb(0.2, 0.2, 0.2),
  })
  state.y -= 6
  currentPage(state).drawLine({
    start: { x: MARGIN, y: state.y },
    end: { x: PAGE_WIDTH - MARGIN, y: state.y },
    thickness: 1.5, color: rgb(0.05, 0.4, 0.1),
  })
  state.y -= 12

  // ── Incident Details ─────────────────────────────────────────────────────
  drawSection(state, 'Incident Details')
  drawField(state, 'Type', data.incidentType.replace(/_/g, ' '))
  drawField(state, 'Reported At', fmt(data.reportedAt))
  drawField(state, 'Site', data.siteName)
  drawField(state, 'Zone', data.zoneName)
  drawField(state, 'Reported By', data.reporterName)
  drawField(state, 'Severity', data.severity !== null ? String(data.severity) + ' / 5' : null)
  drawField(state, 'Medical Status', data.medicalStatus?.replace(/_/g, ' ') ?? null)
  drawField(state, 'Injury Involved', data.injuryInvolved ? 'Yes' : 'No')
  drawField(state, 'Asset Involved', data.assetInvolved ? 'Yes' : 'No')
  drawField(state, 'Fatality', data.isFatality ? 'Yes' : 'No')
  drawField(state, 'Serious Bodily Injury', data.isSeriousBodilyInjury ? 'Yes' : 'No')
  drawField(state, 'Dangerous Occurrence', data.isDangerousOccurrence ? 'Yes' : 'No')
  drawField(state, 'Occupational Disease', data.isOccupationalDisease ? 'Yes' : 'No')
  drawField(state, 'Lost Days', data.lostDays !== null ? String(data.lostDays) : null)
  drawField(state, 'Description', data.description)

  // ── Triage ───────────────────────────────────────────────────────────────
  if (data.triagedBy) {
    drawSection(state, 'Triage')
    drawField(state, 'Triaged By', data.triagedBy)
    drawField(state, 'Triaged At', fmt(data.triagedAt))
    drawField(state, 'Triage Notes', data.triageNotes)
  }

  // ── Investigation ────────────────────────────────────────────────────────
  if (data.investigation) {
    const inv = data.investigation
    drawSection(state, 'Investigation')
    drawField(state, 'Method', inv.method.replace(/_/g, ' '))
    drawField(state, 'Findings', inv.findingsText)
    drawField(state, 'Root Cause', inv.rootCauseSummary)
    drawField(state, 'Alcohol Test', inv.alcoholTestResult)
    drawField(state, 'Urine Test', inv.urineTestResult)
  }

  // ── CAPA Actions ─────────────────────────────────────────────────────────
  if (data.capas.length > 0) {
    drawSection(state, `CAPA Actions (${data.capas.length})`)
    for (let i = 0; i < data.capas.length; i++) {
      const c = data.capas[i]
      ensureSpace(state, LINE_HEIGHT * 4)
      currentPage(state).drawText(`#${i + 1}`, {
        x: MARGIN, y: state.y,
        size: BODY_FONT_SIZE, font: boldFont, color: rgb(0, 0, 0),
      })
      state.y -= LINE_HEIGHT
      drawField(state, 'Action', c.description)
      drawField(state, 'Owner', c.ownerName)
      drawField(state, 'Department', c.department)
      drawField(state, 'Due Date', fmtDate(c.dueDate))
      drawField(state, 'Priority', c.priority.toUpperCase())
      drawField(state, 'Status', c.status.replace(/_/g, ' '))
      if (c.completedAt) drawField(state, 'Completed At', fmt(c.completedAt))
      if (c.ownerNotes) drawField(state, 'Owner Notes', c.ownerNotes)
      state.y -= 8
    }
  }

  // ── Addenda ──────────────────────────────────────────────────────────────
  if (data.addenda.length > 0) {
    drawSection(state, `Addenda (${data.addenda.length})`)
    for (const a of data.addenda) {
      drawField(state, 'Author', a.authorName)
      drawField(state, 'Date', fmt(a.createdAt))
      drawField(state, 'Note', a.body)
      state.y -= 8
    }
  }

  // ── Closure ──────────────────────────────────────────────────────────────
  drawSection(state, 'Closure')
  drawField(state, 'Closed At', fmt(data.closedAt))

  // ── Footer on all pages ──────────────────────────────────────────────────
  for (const page of state.pages) {
    page.drawText('Generated by IMS — Confidential', {
      x: MARGIN, y: 30,
      size: 8, font, color: rgb(0.5, 0.5, 0.5),
    })
    page.drawLine({
      start: { x: MARGIN, y: 42 },
      end: { x: PAGE_WIDTH - MARGIN, y: 42 },
      thickness: 0.5, color: rgb(0.8, 0.8, 0.8),
    })
  }

  return doc.save()
}