#!/usr/bin/env node
import fs from 'node:fs'
import path from 'node:path'
import { fileURLToPath } from 'node:url'

const root = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..')
const bad = []

/**
 * @param {string} dir
 * @returns {string[]}
 */
function walkMarkdown(dir) {
  /** @type {string[]} */
  const out = []
  for (const name of fs.readdirSync(dir)) {
    const p = path.join(dir, name)
    const st = fs.statSync(p)
    if (st.isDirectory()) out.push(...walkMarkdown(p))
    else if (name.endsWith('.md')) out.push(p)
  }
  return out
}

/**
 * @param {string} text
 */
function validateMermaidBlocks(text) {
  /** @type {{ body: string, startLine: number }[]} */
  const blocks = []
  const lines = text.split(/\r?\n/)
  for (let i = 0; i < lines.length; i++) {
    if (String(lines[i]).trim() !== '```mermaid') continue
    const startLine = i + 1
    let j = i + 1
    while (j < lines.length && String(lines[j]).trim() !== '```') j++
    if (j >= lines.length) {
      bad.push(`unclosed mermaid code fence at line ${startLine}`)
      break
    }
    const body = lines.slice(i + 1, j).join('\n').trim()
    blocks.push({ body, startLine })
    i = j
  }
  for (const b of blocks) {
    if (!b.body) {
      bad.push(`empty mermaid block at line ${b.startLine}`)
      continue
    }
    const first = b.body.split(/\r?\n/, 1)[0].trim()
    if (
      !/^(graph|flowchart|sequenceDiagram|classDiagram|stateDiagram|erDiagram|journey|gantt|pie|mindmap|timeline)\b/.test(
        first
      )
    ) {
      bad.push(
        `invalid mermaid first line at ${b.startLine}: expected diagram type, got "${first}"`
      )
    }
  }
}

const mdFiles = [
  ...walkMarkdown(path.join(root, 'docs')),
  ...walkMarkdown(path.join(root, 'developer-guide')),
  ...walkMarkdown(path.join(root, 'handbook')),
  ...walkMarkdown(path.join(root, 'users-manual'))
]

for (const file of mdFiles) {
  const raw = fs.readFileSync(file, 'utf8')
  const before = bad.length
  validateMermaidBlocks(raw)
  if (bad.length > before) {
    for (let i = before; i < bad.length; i++) {
      bad[i] = `${path.relative(root, file)}: ${bad[i]}`
    }
  }
}

if (bad.length) {
  console.error('validate-mermaid-syntax: failed')
  for (const b of bad) console.error(' ', b)
  process.exit(1)
}
console.log('validate-mermaid-syntax: OK')