const fs = require('fs')
const path = require('path')

const root = path.resolve(__dirname, '..')
const fixtureDir = path.join(root, 'scripts', 'fixtures')
const reportDir = path.join(root, 'reports')
const sourceFile = process.env.MIGRATION_SOURCE || path.join(fixtureDir, 'opendb-news-articles.json')
const outputFile = path.join(reportDir, 'cms-migration-dry-run.json')

function readRows(file) {
  if (!fs.existsSync(file)) return []
  const value = JSON.parse(fs.readFileSync(file, 'utf8'))
  if (!Array.isArray(value)) throw new Error(`fixture must be an array: ${file}`)
  return value
}

function toDelta(content) {
  if (content && typeof content === 'object' && Array.isArray(content.ops)) return content
  if (typeof content !== 'string' || !content) return { ops: [] }
  return { ops: [{ insert: content }, { insert: '\n' }] }
}

function mapArticle(row) {
  const thumbnail = Array.isArray(row.thumbnail)
    ? row.thumbnail
    : row.avatar ? [row.avatar] : []
  return {
    _id: row._id,
    title: row.title || '',
    excerpt: row.excerpt || '',
    content: toDelta(row.content),
    category_id: row.category_id || '',
    user_id: row.user_id || '',
    thumbnail,
    article_status: Number.isInteger(row.article_status) ? row.article_status : 0,
    view_count: Number(row.view_count || 0),
    like_count: Number(row.like_count || 0),
    comment_status: Number(row.comment_status || 0),
    comment_count: Number(row.comment_count || 0),
    publish_date: row.publish_date || row.create_date || null,
    source_id: row._id,
    migration_source: 'opendb-news-articles'
  }
}

function main() {
  const source = readRows(sourceFile)
  const seen = new Set()
  const rows = []
  const conflicts = []
  for (const row of source) {
    if (!row || !row._id) {
      conflicts.push({ reason: 'missing _id', row })
      continue
    }
    if (seen.has(row._id)) {
      conflicts.push({ reason: 'duplicate _id', id: row._id })
      continue
    }
    seen.add(row._id)
    rows.push(mapArticle(row))
  }
  const report = {
    mode: 'dry-run',
    source: path.relative(root, sourceFile).replace(/\\/g, '/'),
    target: 'uni-cms-articles',
    generatedAt: new Date().toISOString(),
    summary: { source: source.length, mapped: rows.length, conflicts: conflicts.length },
    conflicts,
    rows
  }
  fs.mkdirSync(reportDir, { recursive: true })
  fs.writeFileSync(outputFile, JSON.stringify(report, null, 2) + '\n')
  console.log(JSON.stringify(report.summary))
}

main()