const 
{
  Client,
  Events,
  GatewayIntentBits
} = require("discord.js")

const axios = require("axios")
const fs = require("fs-extra")
const path = require("path")

const config = require("../config/config.json")
const api = require("../config/api.json")

const 
{
  channel_id,
  minecraft_version,
  modrinth_mods
} = config

const 
{
  token
} = api

const cacheFile = path.join(__dirname, "../cache/mod_versions.json")

const client = new Client
({
  intents: [GatewayIntentBits.Guilds]
})

const LoadCache = async () =>
{
  try
  {
    if (await fs.pathExists(cacheFile))
      return JSON.parse(await fs.readFile(cacheFile, "utf8"))
  }
  catch (err)
  {
    console.error("[Cache] Failed to read cache:", err)
  }
  return {}
}

const SaveCache = async cache =>
{
  try
  {
    await fs.ensureDir(path.dirname(cacheFile))
    await fs.writeFile(cacheFile, JSON.stringify(cache, null, 2))
  }
  catch (err)
  {
    console.error("[Cache] Failed to save cache:", err)
  }
}

const GetModrinthData = async slug =>
{
  try
  {
    const r = await axios.get(`https://api.modrinth.com/v2/project/${slug}/version`)
    return r.data
  }
  catch (err)
  {
    console.error(`[Modrinth] Failed for ${slug}:`, err.message)
    return null
  }
}

const CheckMods = async () =>
{
  const cache = await LoadCache()
  const newCache = { ...cache }

  const updatedNotCompatible = []
  const newlyCompatible = []
  const compatibleUpdated = []

  for (const slug of modrinth_mods)
  {
    const versions = await GetModrinthData(slug)
    if (!versions)
      continue

    const fabric = versions.filter(v => v.loaders.includes("fabric"))
    if (!fabric.length)
      continue

    const latest = fabric.sort((a, b) =>
      new Date(b.date_published) - new Date(a.date_published)
    )[0]

    const latestId = latest.id
    const compatible = latest.game_versions.includes(minecraft_version)
    const cachedId = cache[slug]

    if (!cachedId)
      newCache[slug] = latestId

    if (latestId === cachedId)
      continue

    const previouslyCompatible = fabric.some(v =>
      v.id === cachedId && v.game_versions.includes(minecraft_version)
    )

    if (!compatible)
      updatedNotCompatible.push(slug)
    else if (compatible && !previouslyCompatible)
      newlyCompatible.push(slug)
    else if (compatible && previouslyCompatible)
      compatibleUpdated.push(slug)

    newCache[slug] = latestId
  }

  await SaveCache(newCache)
  return { updatedNotCompatible, newlyCompatible, compatibleUpdated }
}

const SendUpdate = async (channel, updatedNotCompatible, newlyCompatible, compatibleUpdated) =>
{
  if (!updatedNotCompatible.length && !newlyCompatible.length && !compatibleUpdated.length)
    return

  let msg = `**Modrinth Update Check — ${minecraft_version}**\n\n`

  if (updatedNotCompatible.length)
  {
    msg += `**❗ Updated but NOT compatible:**\n`
    for (const s of updatedNotCompatible)
      msg += `❗ ${s}\n`
    msg += `\n`
  }

  if (newlyCompatible.length)
  {
    msg += `**🎉 NOW Compatible:**\n`
    for (const s of newlyCompatible)
      msg += `🎉 ${s}\n`
    msg += `\n`
  }

  if (compatibleUpdated.length)
  {
    msg += `**🟢 Updated (still compatible):**\n`
    for (const s of compatibleUpdated)
      msg += `🟢 ${s}\n`
    msg += `\n`
  }

  await channel.send
  ({
    content: msg,
    allowedMentions:
    {
      parse: []
    },
    flags: 4
  })

  console.log("[Discord] Sent update.")
}

client.once(Events.ClientReady, async c =>
{
  console.log(`[OK] Logged in as ${c.user.tag}`)

  const channel = await client.channels.fetch(channel_id).catch(() => null)
  if (!channel)
  {
    console.error("Invalid channel_id:", channel_id)
    return
  }

  const 
  {
    updatedNotCompatible,
    newlyCompatible,
    compatibleUpdated
  } = await CheckMods()

  await SendUpdate(channel, updatedNotCompatible, newlyCompatible, compatibleUpdated)

  setInterval(async () =>
  {
    const 
    {
      updatedNotCompatible,
      newlyCompatible,
      compatibleUpdated
    } = await CheckMods()

    await SendUpdate(channel, updatedNotCompatible, newlyCompatible, compatibleUpdated)
  }, 60 * 60 * 1000)
})

client.login(token)