const fs = require("fs-extra")
const path = require("path")
const { spawn } = require("child_process")

const { LoadConfig } = require("../../lib/config")
const { GetModVersions, GetCompatibleVersion, DownloadFile } = require("../../lib/modrinth")

const config = LoadConfig()

const 
{
    minecraft_version,
    fabric_loader_version,
    loader_meta_version,
    java_path,
    modrinth_mods
} = config

const javaCmd = java_path || "java"

const serverDir = path.join(__dirname, "../../server")
const modsDir = path.join(serverDir, "mods")

const deleteList = 
[
    "audioplayer_uploads",
    "config",
    "cache",
    "world",
    "logs",
    "banned-players.json",
    "server.properties",
    "banned-ips.json",
    "usercache.json",
    "whitelist.json",
    "ops.json",
    "eula.txt"
]

const EnsureDirs = async () =>
{
    await fs.ensureDir(serverDir)
    await fs.ensureDir(modsDir)
}

const DownloadModrinthMods = async (modList, mcVersion) =>
{
    const downloadedFiles = []
    const failedMods = []

    for (const slug of modList)
    {
        try
        {
            const versions = await GetModVersions(slug)
            if (!versions)
            {
                console.log(`  [Modrinth] Could not get versions for ${slug}`)
                failedMods.push(slug)
                continue
            }

            const compatible = GetCompatibleVersion(versions, mcVersion, "fabric")
            if (!compatible)
            {
                console.log(`  [Modrinth] No Fabric version for ${slug} on MC ${mcVersion}`)
                failedMods.push(slug)
                continue
            }

            const fileInfo = compatible.files[0]
            const jarUrl = fileInfo.url
            const filename = fileInfo.filename
            const destPath = path.join(modsDir, filename)

            console.log(`  [Modrinth] Downloading ${slug} -> ${filename} ...`)

            const success = await DownloadFile(jarUrl, destPath)
            if (!success)
            {
                console.log(`  [Modrinth] Couldn't download jar for ${slug}`)
                failedMods.push(slug)
                continue
            }

            downloadedFiles.push(destPath)
            console.log(`  [Modrinth] Downloaded: ${filename}`)
        }
        catch (err)
        {
            console.error(`  [Modrinth] Error downloading ${slug}:`, err.message)
            failedMods.push(slug)
        }
    }

    return { downloadedFiles, failedMods }
}

const DownloadFabricServer = async (mcVersion, loaderVersion, metaVersion) =>
{
    const url = `https://meta.fabricmc.net/v2/versions/loader/${mcVersion}/${loaderVersion}/${metaVersion}/server/jar`
    const filename = "server.jar"
    const destPath = path.join(serverDir, filename)

    console.log(`  [Fabric] Downloading Fabric server for MC ${mcVersion} ...`)

    const success = await DownloadFile(url, destPath)
    if (!success)
    {
        console.log(`  [Fabric] Failed to download Fabric server JAR`)
        return null
    }

    console.log(`  [Fabric] Downloaded: ${filename}`)
    return destPath
}

const RunServerAutoStop = (rl) =>
{
    return new Promise((resolve) =>
    {
        const jarPath = path.join(serverDir, "server.jar")

        if (!fs.existsSync(jarPath))
        {
            console.log("  Server JAR not found.")
            resolve(false)
            return
        }

        const eulaPath = path.join(serverDir, "eula.txt")
        if (!fs.existsSync(eulaPath))
        {
            console.log("  Accepting EULA...")
            fs.writeFileSync(eulaPath, "eula=true\n")
        }

        console.log("  Starting server (will auto-stop after loading)...\n")

        rl.pause()

        let hadError = false

        const serverProcess = spawn(javaCmd, ["-jar", "server.jar", "nogui"],
        {
            cwd: serverDir,
            stdio: ["pipe", "pipe", "pipe"]
        })

        serverProcess.stdout.on("data", (data) =>
        {
            const line = data.toString()
            process.stdout.write(line)

            if (line.includes("Done"))
            {
                console.log("\n  Server loaded, stopping...")
                serverProcess.stdin.write("stop\n")
            }
        })

        serverProcess.stderr.on("data", (data) =>
        {
            process.stderr.write(data.toString())
        })

        serverProcess.on("error", err =>
        {
            hadError = true
            console.error("  Failed to start server:", err.message)
            rl.resume()
            resolve(false)
        })

        serverProcess.on("close", () =>
        {
            if (!hadError)
            {
                console.log("\n  Server stopped.")
                rl.resume()
                resolve(true)
            }
        })
    })
}

const DeletePostGenerate = async () =>
{
    console.log("  Cleaning up server-generated files...")

    let removed = 0
    for (const item of deleteList)
    {
        const itemPath = path.join(serverDir, item)

        try
        {
            if (await fs.pathExists(itemPath))
            {
                await fs.remove(itemPath)
                removed++
            }
        }
        catch (err)
        {
            console.error(`  Failed to remove ${item}:`, err.message)
        }
    }

    console.log(`  Removed ${removed} items.`)
}

const Generate = async (rl) =>
{
    await EnsureDirs()

    console.log(`\n  Generating server for MC ${minecraft_version}...\n`)

    const { downloadedFiles, failedMods } = await DownloadModrinthMods(modrinth_mods, minecraft_version)
    console.log(`\n  [OK] Downloaded ${downloadedFiles.length} mods`)
    if (failedMods.length)
        console.log(`  [FAIL] Failed: ${failedMods.join(", ")}`)

    const serverFile = await DownloadFabricServer(minecraft_version, fabric_loader_version, loader_meta_version)

    if (serverFile)
    {
        console.log("")
        await RunServerAutoStop(rl)
        await DeletePostGenerate()
    }

    console.log("")
}

module.exports = { Generate, serverDir }