const fs = require('fs/promises')
const path = require('path')
const express = require('express')
const multer = require('multer')
const bcrypt = require('bcryptjs')
const { z } = require('zod')
const { nanoid } = require('nanoid')
const {
  findUserById,
  findGameById,
  createGame,
  listGames,
  updateGameThumbnail,
  createGameItem,
  updateGameItemLabel,
  deleteGameItem,
  deleteGame,
  updateGameDisplayOrder,
  listCustomItems,
  findCustomItemById,
  findUnusedCustomItems,
  findCustomItemsByIds,
  deleteCustomItems,
  listUsers,
  listAdminTierLists,
  findTierListById,
  listAdminTemplateRequests,
  findTemplateRequestById,
  updateTemplateRequestStatus,
  adminUpdateUser,
  adminUpdateUserPassword,
  adminDeleteUser,
} = require('../db')
const { requireAdmin } = require('../middleware/auth')

const router = express.Router()

function buildUploadFilename(file) {
  const ext = path.extname(file.originalname || '').toLowerCase()
  const safeExt = ext && /^[.a-z0-9]+$/.test(ext) ? ext : ''
  return `${Date.now()}-${nanoid()}${safeExt}`
}

function buildItemLabelFromFilename(file) {
  const originalName = file?.originalname || ''
  const base = path.basename(originalName, path.extname(originalName))
  const normalized = base
    .replace(/[_-]+/g, ' ')
    .replace(/\s+/g, ' ')
    .trim()
    .slice(0, 60)

  return normalized || 'item'
}

const upload = multer({
  storage: multer.diskStorage({
    destination: (req, file, cb) => cb(null, path.join(__dirname, '..', '..', 'uploads', 'games')),
    filename: (req, file, cb) => cb(null, buildUploadFilename(file)),
  }),
  limits: { fileSize: 6 * 1024 * 1024 },
})

const avatarUpload = multer({
  storage: multer.diskStorage({
    destination: (req, file, cb) => cb(null, path.join(__dirname, '..', '..', 'uploads', 'avatars')),
    filename: (req, file, cb) => cb(null, buildUploadFilename(file)),
  }),
  limits: { fileSize: 3 * 1024 * 1024 },
})

router.post('/games', requireAdmin, async (req, res) => {
  const schema = z.object({ id: z.string().min(1), name: z.string().min(1).max(60) })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })
  const exists = await findGameById(parsed.data.id)
  if (exists) return res.status(409).json({ error: 'game_id_taken' })
  const game = await createGame({ id: parsed.data.id, name: parsed.data.name })
  res.json({ game })
})

router.patch('/games/display-order', requireAdmin, async (req, res) => {
  const schema = z.object({
    gameIds: z.array(z.string().min(1)).max(50),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const games = await listGames()
  const validGameIds = new Set(games.map((game) => game.id))
  const filteredIds = parsed.data.gameIds.filter((gameId) => validGameIds.has(gameId))
  const updatedGames = await updateGameDisplayOrder(filteredIds)
  res.json({ games: updatedGames })
})

router.post('/games/:gameId/thumbnail', requireAdmin, upload.single('thumbnail'), async (req, res) => {
  if (!req.file) return res.status(400).json({ error: 'file_required' })
  const game = await findGameById(req.params.gameId)
  if (!game) return res.status(404).json({ error: 'not_found' })
  const updated = await updateGameThumbnail(req.params.gameId, `/uploads/games/${req.file.filename}`)
  res.json({ game: updated })
})

router.post('/games/:gameId/images', requireAdmin, upload.array('images', 50), async (req, res) => {
  const files = Array.isArray(req.files) ? req.files : []
  if (!files.length) return res.status(400).json({ error: 'file_required' })
  const game = await findGameById(req.params.gameId)
  if (!game) return res.status(404).json({ error: 'not_found' })

  const manualLabel = typeof req.body?.label === 'string' ? req.body.label.trim() : ''
  if (manualLabel && manualLabel.length > 60) return res.status(400).json({ error: 'bad_request' })

  const items = await Promise.all(
    files.map((file, index) =>
      createGameItem({
        id: nanoid(),
        gameId: game.id,
        src: `/uploads/games/${file.filename}`,
        label: index === 0 && manualLabel ? manualLabel : buildItemLabelFromFilename(file),
      })
    )
  )

  res.json({ item: items[0], items })
})

router.delete('/games/:gameId/items/:itemId', requireAdmin, async (req, res) => {
  const game = await findGameById(req.params.gameId)
  if (!game) return res.status(404).json({ error: 'not_found' })
  await deleteGameItem(req.params.itemId)
  res.json({ ok: true })
})

router.patch('/games/:gameId/items/:itemId', requireAdmin, async (req, res) => {
  const schema = z.object({ label: z.string().trim().min(1).max(60) })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const game = await findGameById(req.params.gameId)
  if (!game) return res.status(404).json({ error: 'not_found' })

  const updated = await updateGameItemLabel(req.params.itemId, parsed.data.label)
  if (!updated || updated.gameId !== game.id) return res.status(404).json({ error: 'not_found' })
  res.json({ item: updated })
})

router.delete('/games/:gameId', requireAdmin, async (req, res) => {
  const game = await findGameById(req.params.gameId)
  if (!game) return res.status(404).json({ error: 'not_found' })
  await deleteGame(req.params.gameId)
  res.json({ ok: true })
})

router.get('/custom-items', requireAdmin, async (req, res) => {
  const schema = z.object({
    q: z.string().trim().max(120).optional().default(''),
    page: z.coerce.number().int().min(1).optional().default(1),
    limit: z.coerce.number().int().min(1).max(200).optional().default(50),
    orphanOnly: z
      .union([z.literal('true'), z.literal('false'), z.boolean()])
      .optional()
      .default('false')
      .transform((value) => value === true || value === 'true'),
  })
  const parsed = schema.safeParse(req.query)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const result = await listCustomItems({
    queryText: parsed.data.q,
    page: parsed.data.page,
    limit: parsed.data.limit,
    orphanOnly: parsed.data.orphanOnly,
  })
  res.json(result)
})

router.get('/tierlists', requireAdmin, async (req, res) => {
  const schema = z.object({
    q: z.string().trim().max(120).optional().default(''),
    page: z.coerce.number().int().min(1).optional().default(1),
    limit: z.coerce.number().int().min(1).max(200).optional().default(50),
  })
  const parsed = schema.safeParse(req.query)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const result = await listAdminTierLists({
    queryText: parsed.data.q,
    page: parsed.data.page,
    limit: parsed.data.limit,
    currentUserId: req.session?.userId || '',
  })
  res.json(result)
})

router.get('/template-requests', requireAdmin, async (req, res) => {
  const requests = await listAdminTemplateRequests({ status: 'pending' })
  res.json({ requests })
})

async function removeCustomItemFiles(items) {
  await Promise.all(
    items.map(async (item) => {
      if (!item?.src || !item.src.startsWith('/uploads/custom/')) return
      const absolutePath = path.join(__dirname, '..', '..', item.src.replace(/^\//, ''))
      try {
        await fs.unlink(absolutePath)
      } catch (e) {
        if (e?.code !== 'ENOENT') throw e
      }
    })
  )
}

async function promoteCustomItemToGameItem({ customItem, gameId }) {
  const originalName = path.basename(customItem.src || '')
  const nextFilename = buildUploadFilename({ originalname: originalName })
  const sourcePath = path.join(__dirname, '..', '..', customItem.src.replace(/^\//, ''))
  const targetRelativePath = path.join('uploads', 'games', nextFilename)
  const targetPath = path.join(__dirname, '..', '..', targetRelativePath)

  await fs.copyFile(sourcePath, targetPath)

  return createGameItem({
    id: nanoid(),
    gameId,
    src: `/${targetRelativePath.replace(/\\/g, '/')}`,
    label: customItem.label,
  })
}

async function copyUploadIntoGameAsset(src) {
  if (typeof src !== 'string' || !src.startsWith('/uploads/')) return src || ''

  const originalName = path.basename(src)
  const nextFilename = buildUploadFilename({ originalname: originalName })
  const sourcePath = path.join(__dirname, '..', '..', src.replace(/^\//, ''))
  const targetRelativePath = path.join('uploads', 'games', nextFilename)
  const targetPath = path.join(__dirname, '..', '..', targetRelativePath)

  await fs.copyFile(sourcePath, targetPath)
  return `/${targetRelativePath.replace(/\\/g, '/')}`
}

function uniqueTierListPoolItems(tierList) {
  const seen = new Set()
  return (tierList?.pool || []).filter((item) => {
    if (!item?.id || seen.has(item.id)) return false
    seen.add(item.id)
    return true
  })
}

async function promoteTierListItemsToGame({ tierList, gameId, itemIds = [] }) {
  const allowedIds = new Set((itemIds || []).filter(Boolean))
  const sourceItems = uniqueTierListPoolItems(tierList).filter((item) => item.origin === 'custom')
  const itemsToCopy = allowedIds.size ? sourceItems.filter((item) => allowedIds.has(item.id)) : sourceItems
  const createdItems = []

  for (const item of itemsToCopy) {
    const copiedSrc = await copyUploadIntoGameAsset(item.src)
    createdItems.push(
      await createGameItem({
        id: nanoid(),
        gameId,
        src: copiedSrc,
        label: item.label,
      })
    )
  }

  return createdItems
}

async function promoteSnapshotItemsToGame({ items, gameId }) {
  const createdItems = []

  for (const item of items || []) {
    const copiedSrc = await copyUploadIntoGameAsset(item.src)
    createdItems.push(
      await createGameItem({
        id: nanoid(),
        gameId,
        src: copiedSrc,
        label: item.label,
      })
    )
  }

  return createdItems
}

async function createGameTemplateFromTierList({ tierList, gameId, gameName }) {
  await createGame({ id: gameId, name: gameName })
  if (tierList.thumbnailSrc) {
    const copiedThumb = await copyUploadIntoGameAsset(tierList.thumbnailSrc)
    await updateGameThumbnail(gameId, copiedThumb)
  }

  const createdItems = []
  for (const item of uniqueTierListPoolItems(tierList)) {
    const copiedSrc = await copyUploadIntoGameAsset(item.src)
    createdItems.push(
      await createGameItem({
        id: nanoid(),
        gameId,
        src: copiedSrc,
        label: item.label,
      })
    )
  }

  return { game: await findGameById(gameId), items: createdItems }
}

async function createGameTemplateFromRequest({ templateRequest, gameId, gameName }) {
  await createGame({ id: gameId, name: gameName })

  if (templateRequest.thumbnailSrc) {
    const copiedThumb = await copyUploadIntoGameAsset(templateRequest.thumbnailSrc)
    await updateGameThumbnail(gameId, copiedThumb)
  }

  const items = await promoteSnapshotItemsToGame({
    items: templateRequest.items || [],
    gameId,
  })

  return { game: await findGameById(gameId), items }
}

router.delete('/custom-items/:itemId', requireAdmin, async (req, res) => {
  const result = await listCustomItems({ page: 1, limit: 200, orphanOnly: false })
  const target = result.items.find((item) => item.id === req.params.itemId)
  if (!target) return res.status(404).json({ error: 'not_found' })
  if (target.usageCount > 0) return res.status(409).json({ error: 'item_in_use' })

  const items = await findCustomItemsByIds([target.id])
  await deleteCustomItems([target.id])
  await removeCustomItemFiles(items)
  res.json({ ok: true })
})

router.post('/custom-items/:itemId/promote', requireAdmin, async (req, res) => {
  const schema = z.object({
    gameId: z.string().min(1),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const game = await findGameById(parsed.data.gameId)
  if (!game) return res.status(404).json({ error: 'game_not_found' })

  const customItem = await findCustomItemById(req.params.itemId)
  if (!customItem) return res.status(404).json({ error: 'not_found' })

  const item = await promoteCustomItemToGameItem({ customItem, gameId: game.id })
  res.json({ item })
})

router.post('/tierlists/:tierListId/promote-items', requireAdmin, async (req, res) => {
  const schema = z.object({
    gameId: z.string().min(1),
    itemIds: z.array(z.string().min(1)).optional().default([]),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const game = await findGameById(parsed.data.gameId)
  if (!game) return res.status(404).json({ error: 'game_not_found' })

  const tierList = await findTierListById(req.params.tierListId)
  if (!tierList) return res.status(404).json({ error: 'not_found' })

  const items = await promoteTierListItemsToGame({
    tierList,
    gameId: game.id,
    itemIds: parsed.data.itemIds,
  })
  res.json({ items })
})

router.post('/tierlists/:tierListId/create-game-template', requireAdmin, async (req, res) => {
  const schema = z.object({
    gameId: z.string().trim().min(1).max(120),
    name: z.string().trim().min(1).max(120),
    itemIds: z.array(z.string().min(1)).optional().default([]),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const exists = await findGameById(parsed.data.gameId)
  if (exists) return res.status(409).json({ error: 'game_id_taken' })

  const tierList = await findTierListById(req.params.tierListId)
  if (!tierList) return res.status(404).json({ error: 'not_found' })

  const result = await createGameTemplateFromTierList({
    tierList: {
      ...tierList,
      pool: parsed.data.itemIds.length ? (tierList.pool || []).filter((item) => parsed.data.itemIds.includes(item.id)) : tierList.pool,
    },
    gameId: parsed.data.gameId,
    gameName: parsed.data.name,
  })
  res.json(result)
})

router.post('/template-requests/:requestId/approve', requireAdmin, async (req, res) => {
  const templateRequest = await findTemplateRequestById(req.params.requestId)
  if (!templateRequest) return res.status(404).json({ error: 'not_found' })
  if (templateRequest.status !== 'pending') return res.status(409).json({ error: 'request_already_handled' })

  if (templateRequest.type === 'update') {
    const targetGameId = templateRequest.targetGameId || templateRequest.sourceGameId
    const game = await findGameById(targetGameId)
    if (!game) return res.status(404).json({ error: 'game_not_found' })

    const items = await promoteSnapshotItemsToGame({
      items: templateRequest.items || [],
      gameId: game.id,
    })
    const request = await updateTemplateRequestStatus({ id: templateRequest.id, status: 'approved' })
    return res.json({ request, items })
  }

  const schema = z.object({
    gameId: z.string().trim().min(1).max(120),
    name: z.string().trim().min(1).max(120),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const exists = await findGameById(parsed.data.gameId)
  if (exists) return res.status(409).json({ error: 'game_id_taken' })

  const result = await createGameTemplateFromRequest({
    templateRequest,
    gameId: parsed.data.gameId,
    gameName: parsed.data.name,
  })
  const request = await updateTemplateRequestStatus({ id: templateRequest.id, status: 'approved' })
  res.json({ request, ...result })
})

router.post('/template-requests/:requestId/reject', requireAdmin, async (req, res) => {
  const templateRequest = await findTemplateRequestById(req.params.requestId)
  if (!templateRequest) return res.status(404).json({ error: 'not_found' })
  if (templateRequest.status !== 'pending') return res.status(409).json({ error: 'request_already_handled' })

  const request = await updateTemplateRequestStatus({ id: templateRequest.id, status: 'rejected' })
  res.json({ request })
})

router.delete('/custom-items', requireAdmin, async (req, res) => {
  const schema = z.object({
    q: z.string().trim().max(120).optional().default(''),
  })
  const parsed = schema.safeParse(req.query)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const items = await findUnusedCustomItems({ queryText: parsed.data.q })
  const ids = items.map((item) => item.id)
  await deleteCustomItems(ids)
  await removeCustomItemFiles(items)
  res.json({ ok: true, deletedCount: ids.length })
})

router.get('/users', requireAdmin, async (req, res) => {
  const users = await listUsers()
  res.json({ users })
})

router.patch('/users/:userId', requireAdmin, async (req, res) => {
  const schema = z.object({
    email: z.string().email(),
    nickname: z.string().trim().max(40).default(''),
    isAdmin: z.boolean(),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  if (req.params.userId === req.session.userId && !parsed.data.isAdmin) {
    return res.status(400).json({ error: 'self_admin_required' })
  }

  const user = await findUserById(req.params.userId)
  if (!user) return res.status(404).json({ error: 'not_found' })

  try {
    const updated = await adminUpdateUser({
      id: user.id,
      email: parsed.data.email,
      nickname: parsed.data.nickname,
      isAdmin: parsed.data.isAdmin,
    })
    res.json({ user: updated })
  } catch (e) {
    if (e && e.code === 'ER_DUP_ENTRY') {
      return res.status(409).json({ error: 'email_taken' })
    }
    throw e
  }
})

router.post('/users/:userId/avatar', requireAdmin, avatarUpload.single('avatar'), async (req, res) => {
  const schema = z.object({
    removeAvatar: z.union([z.literal('1'), z.undefined()]).optional(),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const user = await findUserById(req.params.userId)
  if (!user) return res.status(404).json({ error: 'not_found' })

  const shouldRemoveAvatar = parsed.data.removeAvatar === '1'
  const nextAvatarSrc = shouldRemoveAvatar ? '' : req.file ? `/uploads/avatars/${req.file.filename}` : user.avatarSrc || ''
  const updated = await adminUpdateUser({
    id: user.id,
    email: user.email,
    nickname: user.nickname || '',
    isAdmin: !!user.isAdmin,
    avatarSrc: nextAvatarSrc,
  })

  res.json({ user: updated })
})

router.delete('/users/:userId', requireAdmin, async (req, res) => {
  if (req.params.userId === req.session.userId) {
    return res.status(400).json({ error: 'cannot_delete_self' })
  }

  const user = await findUserById(req.params.userId)
  if (!user) return res.status(404).json({ error: 'not_found' })

  await adminDeleteUser(user.id)
  res.json({ ok: true })
})

router.patch('/users/:userId/password', requireAdmin, async (req, res) => {
  const schema = z.object({
    password: z.string().min(6).max(120),
  })
  const parsed = schema.safeParse(req.body)
  if (!parsed.success) return res.status(400).json({ error: 'bad_request' })

  const user = await findUserById(req.params.userId)
  if (!user) return res.status(404).json({ error: 'not_found' })

  const passwordHash = await bcrypt.hash(parsed.data.password, 10)
  await adminUpdateUserPassword({ id: user.id, passwordHash })
  res.json({ ok: true })
})

module.exports = router