import http from 'node:http'
import { createHash } from 'node:crypto'

/**
 * Nachgebautes Gitea 1.25 fuer Tests: nur der REST-Ausschnitt unter `/api/v1`, den das
 * Kundenportal nutzt (Repos, Transfer, Hooks, Aktivitaeten-Feed, Contents, Orgs, Teams).
 * Laeuft auf 127.0.0.1 mit einem vom Betriebssystem vergebenen Port.
 *
 * Besitzer-/Repo-Namen werden ueberall ohne Ruecksicht auf Gross-/Kleinschreibung
 * nachgeschlagen, aber in der zuletzt gesetzten Schreibweise gespeichert - wie Gitea es
 * auch haelt.
 *
 * @param {object} [options]
 * @param {Array<{full_name: string, archived?: boolean, private?: boolean, description?: string, default_branch?: string}>} [options.repos]
 *   Anfangsbestand an Repos.
 * @param {Record<string, Array<{id: number|string, url: string, events?: string[], active?: boolean, type?: string}>>} [options.hooks]
 *   Repo-Webhooks je `"owner/repo"`.
 * @param {Record<string, object[]>} [options.feeds]
 *   Aktivitaeten-Feed je `"owner/repo"`, neueste zuerst (wie `GET .../activities/feeds` sie liefert).
 * @param {Record<string, string>} [options.contents]
 *   Dateiinhalt (Klartext, keine Kodierung) je `"owner/repo:pfad"`, z. B. `"knso/x:.webklar-preview.json"`.
 * @param {string[]} [options.orgs]
 *   Organisationen, die von Anfang an existieren (mit leerer Owners-Mitgliedschaft).
 * @param {string} [options.user] Login, das `GET /user` meldet. Voreinstellung `'webklar-system'`.
 * @returns {Promise<{
 *   baseUrl: string,
 *   calls: Array<{method: string, path: string, query: Record<string, string>, headers: Record<string, string>, body: any}>,
 *   repo: (fullName: string) => (object|undefined),
 *   addRepo: (repo: object) => object,
 *   hooksOf: (fullName: string) => object[],
 *   setDown: (down: boolean) => void,
 *   setTransferDelay: (ms: number) => void,
 *   close: () => Promise<void>,
 * }>} `calls` waechst live, in der Reihenfolge, in der die Anfragen eintreffen - VOR einer
 *   etwaigen `setTransferDelay`-Verzoegerung der Antwort. `repo()`/`hooksOf()` lesen den
 *   aktuellen Stand direkt (ohne Weiterleitung ueber einen umgezogenen alten Namen).
 */
export async function startFakeGitea(options = {}) {
  const calls = []
  let isDown = false
  let transferDelayMs = 0

  let nextRepoId = 1
  let nextHookId = 1
  let nextOrgId = 1
  let nextTeamId = 1

  /** @type {Map<string, object>} Schluessel: `"owner/repo"` klein geschrieben. */
  const repos = new Map()
  /** @type {Map<string, string>} alter Schluessel -> neuer full_name (kanonische Schreibweise) nach Transfer. */
  const redirects = new Map()
  /** @type {Map<string, object[]>} Schluessel: `"owner/repo"` klein geschrieben. */
  const hooksByRepo = new Map()
  /** @type {Map<string, object[]>} Schluessel: `"owner/repo"` klein geschrieben. */
  const feedsByRepo = new Map()
  /** @type {Map<string, string>} Schluessel: `"owner/repo"` klein geschrieben + `:` + Pfad (Original-Gross-/Kleinschreibung). */
  const contents = new Map()
  /** @type {Map<string, {id: number, username: string, full_name: string, visibility: string, ownersTeamId: number}>} Schluessel: Login klein geschrieben. */
  const orgs = new Map()
  /** @type {Map<number, {id: number, name: string, org: string, members: string[]}>} */
  const teams = new Map()
  /** @type {Map<string, object[]>} Schluessel: Org-Login klein geschrieben. */
  const orgHooks = new Map()

  const userLogin = options.user || 'webklar-system'

  function keyFrom(a, b) {
    return (b === undefined ? a : `${a}/${b}`).toLowerCase()
  }

  function sleep(ms) {
    return new Promise((resolve) => {
      const t = setTimeout(resolve, ms)
      t.unref?.()
    })
  }

  function send(res, status, body) {
    if (body === undefined) {
      res.writeHead(status)
      res.end()
      return
    }
    const text = JSON.stringify(body)
    res.writeHead(status, {
      'Content-Type': 'application/json',
      'Content-Length': Buffer.byteLength(text),
    })
    res.end(text)
  }

  function serializeRepo(record) {
    return { ...record, owner: { ...record.owner } }
  }

  function addRepoInternal(def) {
    const fullName = def?.full_name || ''
    const slash = fullName.indexOf('/')
    if (slash < 1) {
      throw new Error(`fakeGitea: repo full_name muss "owner/repo" sein, bekam "${fullName}"`)
    }
    const owner = fullName.slice(0, slash)
    const name = fullName.slice(slash + 1)
    const record = {
      id: nextRepoId++,
      name,
      full_name: fullName,
      owner: { login: owner },
      html_url: `${baseUrl}/${fullName}`,
      default_branch: def.default_branch || 'main',
      archived: Boolean(def.archived),
      private: Boolean(def.private),
      description: def.description || '',
      empty: false,
    }
    repos.set(keyFrom(fullName), record)
    return record
  }

  function normalizeHook(h) {
    return {
      id: h.id,
      url: h.url,
      events: h.events || ['push'],
      active: h.active !== undefined ? h.active : true,
      type: h.type || 'gitea',
      config: { url: h.url, content_type: 'json', ...(h.config || {}) },
    }
  }

  function createOrgRecord(username, full_name, visibility) {
    const org = {
      id: nextOrgId++,
      username,
      full_name: full_name || username,
      visibility: visibility || 'public',
      ownersTeamId: nextTeamId++,
    }
    orgs.set(username.toLowerCase(), org)
    teams.set(org.ownersTeamId, { id: org.ownersTeamId, name: 'Owners', org: username, members: [] })
    return org
  }

  function moveMapKey(map, oldKey, newKey) {
    if (map.has(oldKey)) {
      map.set(newKey, map.get(oldKey))
      map.delete(oldKey)
    }
  }

  function moveContentKeys(oldKey, newKey) {
    const prefix = `${oldKey}:`
    for (const [k, v] of [...contents.entries()]) {
      if (k.startsWith(prefix)) {
        contents.delete(k)
        contents.set(`${newKey}${k.slice(oldKey.length)}`, v)
      }
    }
  }

  function findRepoOrRedirect(owner, name) {
    const key = keyFrom(owner, name)
    if (repos.has(key)) return { key, record: repos.get(key) }
    const redirectTo = redirects.get(key)
    if (redirectTo) return { key, redirectTo }
    return null
  }

  /* ------------------------------------------------------------- Routen --- */

  function handleGetUser(match, searchParams, body, headers, res) {
    send(res, 200, { login: userLogin, is_admin: true })
  }

  function handleSearchRepos(match, searchParams, body, headers, res) {
    const all = [...repos.values()]
    const limit = Number(searchParams.get('limit')) || 50
    const page = Number(searchParams.get('page')) || 1
    const start = (page - 1) * limit
    send(res, 200, { ok: true, data: all.slice(start, start + limit).map(serializeRepo) })
  }

  function handleGetRepo(match, searchParams, body, headers, res) {
    const found = findRepoOrRedirect(match[1], match[2])
    if (!found) return send(res, 404, { message: 'Not Found' })
    if (found.redirectTo) {
      return send304(res, found.redirectTo)
    }
    send(res, 200, serializeRepo(found.record))
  }

  function send304(res, newFullName) {
    res.writeHead(307, { Location: `${baseUrl}/api/v1/repos/${newFullName}` })
    res.end()
  }

  function handlePatchRepo(match, searchParams, body, headers, res) {
    const found = findRepoOrRedirect(match[1], match[2])
    if (!found) return send(res, 404, { message: 'Not Found' })
    if (found.redirectTo) {
      return send304(res, found.redirectTo)
    }
    Object.assign(found.record, body || {})
    send(res, 200, serializeRepo(found.record))
  }

  async function handleTransfer(match, searchParams, body, headers, res) {
    if (transferDelayMs > 0) await sleep(transferDelayMs)

    const key = keyFrom(match[1], match[2])
    const record = repos.get(key)
    if (!record) return send(res, 404, { message: 'Not Found' })

    const newOwner = body?.new_owner
    if (!newOwner) return send(res, 422, { message: 'new_owner erforderlich' })

    const newFullName = `${newOwner}/${record.name}`
    const newKey = keyFrom(newOwner, record.name)
    if (repos.has(newKey)) {
      return send(res, 422, {
        message: `repository already exists [uname: ${newOwner}, name: ${record.name}]`,
      })
    }

    repos.delete(key)
    record.owner = { login: newOwner }
    record.full_name = newFullName
    repos.set(newKey, record)
    redirects.set(key, newFullName)
    moveMapKey(hooksByRepo, key, newKey)
    moveMapKey(feedsByRepo, key, newKey)
    moveContentKeys(key, newKey)

    send(res, 202, serializeRepo(record))
  }

  function handleGetRepoHooks(match, searchParams, body, headers, res) {
    const key = keyFrom(match[1], match[2])
    if (!repos.has(key)) return send(res, 404, { message: 'Not Found' })
    send(res, 200, hooksByRepo.get(key) || [])
  }

  function handleDeleteRepoHook(match, searchParams, body, headers, res) {
    const key = keyFrom(match[1], match[2])
    const list = hooksByRepo.get(key)
    if (!repos.has(key) || !list) return send(res, 404, { message: 'Not Found' })
    const idx = list.findIndex((h) => String(h.id) === match[3])
    if (idx === -1) return send(res, 404, { message: 'Not Found' })
    list.splice(idx, 1)
    send(res, 204)
  }

  function handleFeeds(match, searchParams, body, headers, res) {
    const key = keyFrom(match[1], match[2])
    if (!repos.has(key)) return send(res, 404, { message: 'Not Found' })
    const all = feedsByRepo.get(key) || []
    const limit = Number(searchParams.get('limit')) || 1000
    const page = Number(searchParams.get('page')) || 1
    const start = (page - 1) * limit
    send(res, 200, all.slice(start, start + limit))
  }

  function handleGetContents(match, searchParams, body, headers, res) {
    const key = keyFrom(match[1], match[2])
    const record = repos.get(key)
    if (!record) return send(res, 404, { message: 'Not Found' })
    const filePath = decodeURIComponent(match[3])
    const text = contents.get(`${key}:${filePath}`)
    if (text === undefined) return send(res, 404, { message: 'Not Found' })
    const sha = createHash('sha1').update(text).digest('hex')
    send(res, 200, {
      name: filePath.split('/').pop(),
      path: filePath,
      sha,
      encoding: 'base64',
      content: Buffer.from(text, 'utf8').toString('base64'),
      html_url: `${baseUrl}/${record.full_name}/src/branch/${record.default_branch}/${filePath}`,
    })
  }

  function handleWriteContents(match, searchParams, body, headers, res) {
    const key = keyFrom(match[1], match[2])
    const record = repos.get(key)
    if (!record) return send(res, 404, { message: 'Not Found' })
    const filePath = decodeURIComponent(match[3])
    const contentKey = `${key}:${filePath}`
    const existed = contents.has(contentKey)
    const decoded = Buffer.from(body?.content || '', 'base64').toString('utf8')
    contents.set(contentKey, decoded)
    const sha = createHash('sha1').update(decoded).digest('hex')
    send(res, existed ? 200 : 201, {
      content: {
        name: filePath.split('/').pop(),
        path: filePath,
        sha,
        encoding: 'base64',
        content: body?.content || '',
      },
      commit: { sha, html_url: `${baseUrl}/${record.full_name}/commit/${sha}` },
    })
  }

  function handleGetOrg(match, searchParams, body, headers, res) {
    const org = orgs.get(match[1].toLowerCase())
    if (!org) return send(res, 404, { message: 'Not Found' })
    send(res, 200, { id: org.id, username: org.username, full_name: org.full_name, visibility: org.visibility })
  }

  function handleCreateOrg(match, searchParams, body, headers, res) {
    const username = body?.username
    if (!username) return send(res, 422, { message: 'username erforderlich' })
    if (orgs.has(username.toLowerCase())) {
      return send(res, 422, { message: `user already exists [name: ${username}]` })
    }
    const org = createOrgRecord(username, body?.full_name, body?.visibility)
    send(res, 201, { id: org.id, username: org.username, full_name: org.full_name, visibility: org.visibility })
  }

  function handleOrgTeams(match, searchParams, body, headers, res) {
    const org = orgs.get(match[1].toLowerCase())
    if (!org) return send(res, 404, { message: 'Not Found' })
    const team = teams.get(org.ownersTeamId)
    send(res, 200, [{ id: team.id, name: team.name }])
  }

  function handleTeamMembers(match, searchParams, body, headers, res) {
    const team = teams.get(Number(match[1]))
    if (!team) return send(res, 404, { message: 'Not Found' })
    send(res, 200, team.members.map((login) => ({ login })))
  }

  function handlePutTeamMember(match, searchParams, body, headers, res) {
    const team = teams.get(Number(match[1]))
    if (!team) return send(res, 404, { message: 'Not Found' })
    const user = match[2]
    if (!team.members.some((m) => m.toLowerCase() === user.toLowerCase())) {
      team.members.push(user)
    }
    send(res, 204)
  }

  function handleGetOrgHooks(match, searchParams, body, headers, res) {
    const org = orgs.get(match[1].toLowerCase())
    if (!org) return send(res, 404, { message: 'Not Found' })
    send(res, 200, orgHooks.get(org.username.toLowerCase()) || [])
  }

  function handlePostOrgHooks(match, searchParams, body, headers, res) {
    const org = orgs.get(match[1].toLowerCase())
    if (!org) return send(res, 404, { message: 'Not Found' })
    const key = org.username.toLowerCase()
    const list = orgHooks.get(key) || []
    const hook = { id: nextHookId++, ...body }
    list.push(hook)
    orgHooks.set(key, list)
    send(res, 201, hook)
  }

  const ROUTES = [
    { method: 'GET', re: /^\/api\/v1\/user$/, handler: handleGetUser },
    { method: 'GET', re: /^\/api\/v1\/repos\/search$/, handler: handleSearchRepos },
    { method: 'POST', re: /^\/api\/v1\/orgs$/, handler: handleCreateOrg },
    { method: 'GET', re: /^\/api\/v1\/orgs\/([^/]+)\/teams$/, handler: handleOrgTeams },
    { method: 'GET', re: /^\/api\/v1\/orgs\/([^/]+)\/hooks$/, handler: handleGetOrgHooks },
    { method: 'POST', re: /^\/api\/v1\/orgs\/([^/]+)\/hooks$/, handler: handlePostOrgHooks },
    { method: 'GET', re: /^\/api\/v1\/orgs\/([^/]+)$/, handler: handleGetOrg },
    { method: 'GET', re: /^\/api\/v1\/teams\/([^/]+)\/members$/, handler: handleTeamMembers },
    { method: 'PUT', re: /^\/api\/v1\/teams\/([^/]+)\/members\/([^/]+)$/, handler: handlePutTeamMember },
    { method: 'POST', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/transfer$/, handler: handleTransfer },
    { method: 'GET', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/hooks$/, handler: handleGetRepoHooks },
    { method: 'DELETE', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/hooks\/([^/]+)$/, handler: handleDeleteRepoHook },
    { method: 'GET', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/activities\/feeds$/, handler: handleFeeds },
    { method: 'GET', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/contents\/(.+)$/, handler: handleGetContents },
    { method: 'POST', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/contents\/(.+)$/, handler: handleWriteContents },
    { method: 'PUT', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)\/contents\/(.+)$/, handler: handleWriteContents },
    { method: 'GET', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)$/, handler: handleGetRepo },
    { method: 'PATCH', re: /^\/api\/v1\/repos\/([^/]+)\/([^/]+)$/, handler: handlePatchRepo },
  ]

  /* --------------------------------------------------------- Server --- */

  const sockets = new Set()
  const server = http.createServer((req, res) => {
    const chunks = []
    req.on('data', (c) => chunks.push(c))
    req.on('end', async () => {
      const raw = Buffer.concat(chunks).toString('utf8')
      const url = new URL(req.url, 'http://fake-gitea.local')
      let parsedBody = null
      if (raw) {
        try {
          parsedBody = JSON.parse(raw)
        } catch {
          parsedBody = null
        }
      }
      calls.push({
        method: req.method,
        path: url.pathname,
        query: Object.fromEntries(url.searchParams),
        headers: { ...req.headers },
        body: parsedBody,
      })

      const route = ROUTES.find((r) => r.method === req.method && r.re.test(url.pathname))
      if (!route) return send(res, 404, { message: 'Not Found' })
      const match = route.re.exec(url.pathname)
      try {
        await route.handler(match, url.searchParams, parsedBody, req.headers, res)
      } catch (err) {
        send(res, 500, { message: err?.message || 'fakeGitea: interner Fehler' })
      }
    })
  })

  server.on('connection', (socket) => {
    sockets.add(socket)
    socket.on('close', () => sockets.delete(socket))
    if (isDown) socket.destroy()
  })

  await new Promise((resolve) => server.listen(0, '127.0.0.1', resolve))
  const { port } = server.address()
  const baseUrl = `http://127.0.0.1:${port}`

  /* --------------------------------------------------------- Seeding --- */

  for (const def of options.repos || []) addRepoInternal(def)
  for (const [fullName, list] of Object.entries(options.hooks || {})) {
    hooksByRepo.set(keyFrom(fullName), (list || []).map(normalizeHook))
  }
  for (const [fullName, feed] of Object.entries(options.feeds || {})) {
    feedsByRepo.set(keyFrom(fullName), feed || [])
  }
  for (const [seedKey, text] of Object.entries(options.contents || {})) {
    const idx = seedKey.indexOf(':')
    const fullName = idx === -1 ? seedKey : seedKey.slice(0, idx)
    const filePath = idx === -1 ? '' : seedKey.slice(idx + 1)
    contents.set(`${keyFrom(fullName)}:${filePath}`, text)
  }
  for (const name of options.orgs || []) createOrgRecord(name)

  /* ------------------------------------------------------ oeffentlich --- */

  function repo(fullName) {
    const record = repos.get(keyFrom(fullName))
    return record ? serializeRepo(record) : undefined
  }

  function addRepo(def) {
    return serializeRepo(addRepoInternal(def))
  }

  function hooksOf(fullName) {
    return (hooksByRepo.get(keyFrom(fullName)) || []).map((h) => ({ ...h, config: { ...h.config } }))
  }

  function setDown(down) {
    isDown = Boolean(down)
    if (isDown) {
      for (const socket of sockets) socket.destroy()
    }
  }

  function setTransferDelay(ms) {
    transferDelayMs = Number(ms) || 0
  }

  function close() {
    for (const socket of sockets) socket.destroy()
    return new Promise((resolve) => server.close(() => resolve()))
  }

  return { baseUrl, calls, repo, addRepo, hooksOf, setDown, setTransferDelay, close }
}