import { readFile, readdir, writeFile } from 'node:fs/promises'
import path from 'node:path'

const [mode, inputPath, workDir, outputPath] = process.argv.slice(2)

if (!['prepare', 'render'].includes(mode) || !inputPath || !workDir) {
  console.error('Usage: render-markdown-pdf.mjs <prepare|render> <input.md> <work-dir> [output.html]')
  process.exit(1)
}

const markdown = await readFile(inputPath, 'utf8')

function escapeHtml(value) {
  return value
    .replaceAll('&', '&amp;')
    .replaceAll('<', '&lt;')
    .replaceAll('>', '&gt;')
    .replaceAll('"', '&quot;')
    .replaceAll("'", '&#39;')
}

function inline(text) {
  const tokens = []
  let value = escapeHtml(text)

  value = value.replace(/`([^`]+)`/g, (_, code) => {
    tokens.push(`<code>${code}</code>`)
    return `\u0000${tokens.length - 1}\u0000`
  })
  value = value.replace(/\*\*(.+?)\*\*/g, '<strong>$1</strong>')
  value = value.replace(/\[(.+?)\]\((https?:[^)]+)\)/g, '<a href="$2">$1</a>')

  return value.replace(/\u0000(\d+)\u0000/g, (_, index) => tokens[Number(index)])
}

function isTableDivider(line) {
  return /^\s*\|?\s*:?-{3,}:?\s*(\|\s*:?-{3,}:?\s*)+\|?\s*$/.test(line)
}

function cells(line) {
  return line
    .trim()
    .replace(/^\|/, '')
    .replace(/\|$/, '')
    .split('|')
    .map((cell) => inline(cell.trim()))
}

function renderMarkdown(source, diagrams) {
  const diagramPattern = /```mermaid\n[\s\S]*?\n```/g
  let index = 0
  const prepared = source.replace(diagramPattern, () => `@@MERMAID_${index++}@@`)
  const lines = prepared.replace(/\r\n/g, '\n').split('\n')
  const output = []

  for (let i = 0; i < lines.length;) {
    const line = lines[i]

    if (!line.trim()) {
      i += 1
      continue
    }

    const diagram = line.match(/^@@MERMAID_(\d+)@@$/)
    if (diagram) {
      const svg = diagrams[Number(diagram[1])] || ''
      output.push(`<div class="mermaid-diagram">${svg}</div>`)
      i += 1
      continue
    }

    const fence = line.match(/^```([^`]*)$/)
    if (fence) {
      const language = fence[1].trim()
      const code = []
      i += 1
      while (i < lines.length && !/^```\s*$/.test(lines[i])) {
        code.push(lines[i])
        i += 1
      }
      if (i < lines.length) i += 1
      output.push(`<pre><code class="language-${escapeHtml(language)}">${escapeHtml(code.join('\n'))}</code></pre>`)
      continue
    }

    const heading = line.match(/^(#{1,6})\s+(.+)$/)
    if (heading) {
      const level = heading[1].length
      output.push(`<h${level}>${inline(heading[2])}</h${level}>`)
      i += 1
      continue
    }

    if (line.startsWith('> ')) {
      const quote = []
      while (i < lines.length && lines[i].startsWith('> ')) {
        quote.push(lines[i].slice(2))
        i += 1
      }
      output.push(`<blockquote>${inline(quote.join('<br>'))}</blockquote>`)
      continue
    }

    if (line.includes('|') && i + 1 < lines.length && isTableDivider(lines[i + 1])) {
      const header = cells(line)
      const rows = []
      i += 2
      while (i < lines.length && lines[i].includes('|') && lines[i].trim()) {
        rows.push(cells(lines[i]))
        i += 1
      }
      output.push(`<table><thead><tr>${header.map((cell) => `<th>${cell}</th>`).join('')}</tr></thead><tbody>${rows.map((row) => `<tr>${row.map((cell) => `<td>${cell}</td>`).join('')}</tr>`).join('')}</tbody></table>`)
      continue
    }

    const unordered = line.match(/^[-*]\s+(.*)$/)
    const ordered = line.match(/^\d+\.\s+(.*)$/)
    if (unordered || ordered) {
      const tag = ordered ? 'ol' : 'ul'
      const items = []
      while (i < lines.length) {
        const match = tag === 'ol'
          ? lines[i].match(/^\d+\.\s+(.*)$/)
          : lines[i].match(/^[-*]\s+(.*)$/)
        if (!match) break
        const task = match[1].match(/^\[([ xX])\]\s+(.*)$/)
        const content = task
          ? `<span class="checkbox">${task[1].trim() ? '☑' : '☐'}</span> ${inline(task[2])}`
          : inline(match[1])
        items.push(`<li>${content}</li>`)
        i += 1
      }
      output.push(`<${tag}>${items.join('')}</${tag}>`)
      continue
    }

    const paragraph = [line.trim()]
    i += 1
    while (
      i < lines.length &&
      lines[i].trim() &&
      !/^(#{1,6})\s+/.test(lines[i]) &&
      !/^```/.test(lines[i]) &&
      !/^@@MERMAID_\d+@@$/.test(lines[i]) &&
      !/^[-*]\s+/.test(lines[i]) &&
      !/^\d+\.\s+/.test(lines[i]) &&
      !lines[i].startsWith('> ') &&
      !(lines[i].includes('|') && i + 1 < lines.length && isTableDivider(lines[i + 1]))
    ) {
      paragraph.push(lines[i].trim())
      i += 1
    }
    output.push(`<p>${inline(paragraph.join(' '))}</p>`)
  }

  return output.join('\n')
}

if (mode === 'prepare') {
  const diagrams = [...markdown.matchAll(/```mermaid\n([\s\S]*?)\n```/g)].map((match) => match[1])
  await Promise.all(diagrams.map((diagram, index) => writeFile(path.join(workDir, `diagram-${index}.mmd`), diagram)))
  process.exit(0)
}

if (!outputPath) {
  console.error('An HTML output path is required for render mode.')
  process.exit(1)
}

const svgFiles = (await readdir(workDir))
  .filter((file) => /^diagram-\d+\.svg$/.test(file))
  .sort((a, b) => Number(a.match(/\d+/)[0]) - Number(b.match(/\d+/)[0]))
const diagrams = await Promise.all(svgFiles.map((file) => readFile(path.join(workDir, file), 'utf8')))
const body = renderMarkdown(markdown, diagrams)

const html = `<!doctype html>
<html lang="zh-CN">
<head>
  <meta charset="utf-8">
  <title>Markdown PDF</title>
  <style>
    @page { size: A4; margin: 18mm 15mm; }
    * { box-sizing: border-box; }
    body { color: #1f2937; font: 10.5pt/1.6 -apple-system, BlinkMacSystemFont, "Segoe UI", "Microsoft YaHei", sans-serif; }
    h1 { margin: 0 0 8px; color: #0f4c81; font-size: 24pt; }
    h2 { margin-top: 26px; border-bottom: 1px solid #dbe4ef; padding-bottom: 5px; color: #123b62; font-size: 16pt; }
    h3 { margin-top: 18px; color: #174f84; font-size: 12pt; }
    p, li, table, .mermaid-diagram { break-inside: avoid; }
    table { width: 100%; margin: 12px 0; border-collapse: collapse; font-size: 9.5pt; }
    th { background: #eaf3fb; color: #123b62; font-weight: 600; }
    th, td { border: 1px solid #cbd5e1; padding: 7px 8px; text-align: left; vertical-align: top; }
    code { border-radius: 3px; background: #f1f5f9; padding: 1px 4px; color: #a33d10; font-family: "SFMono-Regular", Consolas, monospace; }
    pre { overflow-wrap: anywhere; border: 1px solid #dbe4ef; border-radius: 4px; background: #f8fafc; padding: 10px; white-space: pre-wrap; font-size: 8.8pt; }
    pre code { background: transparent; padding: 0; color: #1f2937; }
    blockquote { margin: 10px 0; border-left: 3px solid #67a6d8; padding-left: 12px; color: #475569; }
    .mermaid-diagram { margin: 14px 0; text-align: center; }
    .mermaid-diagram svg { max-width: 100%; height: auto; }
    .checkbox { color: #0f4c81; }
    a { color: #0f4c81; }
  </style>
</head>
<body>${body}</body>
</html>`

await writeFile(outputPath, html)