import dayjs from "dayjs"
import { type NextRequest, NextResponse } from "next/server"

import { env } from "@/env/server"

import {
  getEntries,
  getSyncToken,
  saveEntries,
  saveLastUpdatedDate,
  saveSitemapData,
  saveSyncToken,
} from "@/utils/sitemap"

import { contentstackSync } from "./sync"
import {
  generateSitemapCounter,
  generateSitemapFailCounter,
  generateSitemapSuccessCounter,
  saveEntriesCounter,
  saveSitemapDataCounter,
  saveSyncTokenCounter,
} from "./telemetry"
import { mapEntriesToSitemapData, mergeEntries } from "./utils"

export const dynamic = "force-dynamic"

export async function GET(request: NextRequest) {
  try {
    generateSitemapCounter.add(1)
    console.info("sitemap.generate start")
    const headersList = request.headers
    const secret = headersList.get("x-sitemap-sync-secret")

    if (secret !== env.SITEMAP_SYNC_SECRET) {
      throw Error(
        `Can't sync and generate sitemap, invalid secret, received secret: ${secret}`
      )
    }

    const syncToken = await getSyncToken()
    const currentEntries = await getEntries()

    const responseData = await contentstackSync(syncToken)
    const mergedEntries = mergeEntries(currentEntries, responseData.entries)

    saveEntriesCounter.add(1, { entriesCount: mergedEntries.length })
    console.info(
      "sitemap.entries.save",
      JSON.stringify({ entriesCount: mergedEntries.length })
    )
    await saveEntries(mergedEntries)

    const sitemapData = mapEntriesToSitemapData(mergedEntries)
    const lastUpdated = dayjs.utc().format()
    saveSitemapDataCounter.add(1, {
      sitemapEntriesCount: sitemapData.length,
    })
    console.info(
      "sitemap.data.save",
      JSON.stringify({
        sitemapEntriesCount: sitemapData.length,
        lastUpdated,
      })
    )
    await saveSitemapData(sitemapData)
    await saveLastUpdatedDate(lastUpdated)

    if (syncToken !== responseData.syncToken) {
      saveSyncTokenCounter.add(1, {
        syncToken: responseData.syncToken,
      })
      console.info(
        "sitemap.synctoken.save",
        JSON.stringify({ syncToken: responseData.syncToken })
      )
      await saveSyncToken(responseData.syncToken)
    }

    generateSitemapSuccessCounter.add(1)
    return NextResponse.json({
      message: "Sitemap data generated and stored successfully!",
      now: dayjs.utc().format(),
    })
  } catch (error) {
    const errorMessage =
      error instanceof Error ? error.message : JSON.stringify(error)
    generateSitemapFailCounter.add(1, { error: errorMessage })
    console.error("sitemap.generate.fail", errorMessage)

    return NextResponse.json(
      {
        error: "Failed to generate sitemap",
        now: dayjs.utc().format(),
      },
      { status: 500, statusText: "Internal Server Error" }
    )
  }
}