import { Readable } from 'node:stream'
import { Timestamp } from '@bufbuild/protobuf'
import { Code, ConnectError } from '@connectrpc/connect'
import express, { RequestHandler, Router } from 'express'
import { AppContext } from '../context.js'
import { httpLogger as log } from '../logger.js'
import { SitemapPageType } from '../proto/bsky_pb.js'

export const createRouter = (ctx: AppContext): Router => {
  const router = Router()
  router.get('/external/sitemap/users.xml.gz', userIndexHandler(ctx))
  router.get(
    '/external/sitemap/users/:date/:bucket.xml.gz',
    userPageHandler(ctx),
  )
  return router
}

const userIndexHandler =
  (ctx: AppContext): RequestHandler =>
  async (_req: express.Request, res: express.Response) => {
    try {
      const result = await ctx.dataplane.getSitemapIndex({
        type: SitemapPageType.USER,
      })
      res.set('Content-Type', 'application/gzip')
      res.set('Content-Encoding', 'gzip')
      Readable.from(Buffer.from(result.sitemap)).pipe(res)
    } catch (err) {
      log.error({ err }, 'failed to get sitemap index')
      return res.status(500).send('Internal Server Error')
    }
  }

const userPageHandler =
  (ctx: AppContext): RequestHandler =>
  async (req: express.Request, res: express.Response) => {
    const { date, bucket } = req.params

    // Parse date (YYYY-MM-DD format)
    const dateParts = date.split('-')
    if (dateParts.length !== 3) {
      return res.status(400).send('Invalid date format. Expected YYYY-MM-DD')
    }

    const year = parseInt(dateParts[0], 10)
    const month = parseInt(dateParts[1], 10)
    const day = parseInt(dateParts[2], 10)

    if (isNaN(year) || isNaN(month) || isNaN(day)) {
      return res.status(400).send('Invalid date format. Expected YYYY-MM-DD')
    }

    // Parse bucket (1-indexed)
    const bucketNum = parseInt(bucket, 10)
    if (isNaN(bucketNum) || bucketNum < 1) {
      return res.status(400).send('Invalid bucket number')
    }

    try {
      const result = await ctx.dataplane.getSitemapPage({
        type: SitemapPageType.USER,
        date: Timestamp.fromDate(new Date(year, month - 1, day)),
        bucket: bucketNum,
      })
      res.set('Content-Type', 'application/gzip')
      res.set('Content-Encoding', 'gzip')
      Readable.from(Buffer.from(result.sitemap)).pipe(res)
    } catch (err) {
      if (err instanceof ConnectError && err.code === Code.NotFound) {
        return res.status(404).send('Sitemap page not found')
      }
      log.error({ err }, 'failed to get sitemap page')
      return res.status(500).send('Internal Server Error')
    }
  }