package main

import (
    "archive/zip"
    "crypto/sha256"
    "embed"
    "encoding/hex"
    "encoding/json"
    "flag"
    "fmt"
    "io"
    "net/http"
    "os"
    "os/exec"
    "path/filepath"
    "runtime"
    "strings"
    "time"

    "github.com/sqweek/dialog"
)

//go:embed offline.zip
var offlineFS embed.FS

var (
    installDirFlag = flag.String("dir", "", "Installation directory (default C:\\ZernMC or chosen via dialog)")
    onlineFlag     = flag.Bool("online", true, "Online mode (download JRE + files)")
    offlineFlag    = flag.Bool("offline", false, "Offline mode (unpack from embedded zip)")
    offlineZipFlag = flag.String("offline-zip", "", "Path to offline zip for offline mode")
    shortcutFlag   = flag.Bool("shortcut", true, "Create desktop shortcut")
)

const (
    defaultInstallDir = "C:\\ZernMC"
    serverBase        = "https://api.zern.cc"
    jreZipName        = "OpenJDK21U-jre_x64_windows_hotspot_21.0.6_7.zip"
)

func main() {
    flag.Parse()
    isOnline := *onlineFlag && !*offlineFlag
    // GUI mode on Windows unless --cli
    hasCLI := false
    for _, a := range os.Args { if a=="--cli" { hasCLI=true } }
    if runtime.GOOS=="windows" && !hasCLI {
        // try GUI, fallback to console on error
        if err := runGUI(isOnline); err != nil {
            fmt.Printf("GUI failed %v, fallback console\n", err)
            runConsole(isOnline)
        }
        return
    }
    runConsole(isOnline)
}

func runConsole(isOnline bool) {
    dir := *installDirFlag
    if dir == "" { dir = askInstallDir() }
    if dir == "" { fmt.Println("Installation cancelled"); os.Exit(0) }
    fmt.Printf("Install dir: %s (online=%v)\n", dir, isOnline)
    if err := os.MkdirAll(dir, 0755); err != nil { fatal("Cannot create directory: %v", err) }
    createShortcut := *shortcutFlag
    if !isFlagSet("shortcut") { createShortcut = askShortcut() }
    var err error
    if isOnline { err = installOnline(dir, createShortcut, nil) } else {
        zipPath := *offlineZipFlag
        if zipPath=="" { zipPath = findAdjacentOfflineZip() }
        if zipPath=="" {
            // try embedded
            err = installOfflineEmbedded(dir, createShortcut)
        } else { err = installOffline(dir, zipPath, createShortcut) }
    }
    if err != nil { fatal("%v", err) }
    fmt.Println("\nInstallation complete!")
}

func runGUI(isOnline bool) error {
    // Fallback to console dialogs if GUI not available (walk requires windows)
    // For now use sqweek/dialog wizard to mimic Inno bootstrap
    dir := *installDirFlag
    if dir == "" {
        // Welcome
        ok := dialog.Message("Добро пожаловать в ZernMC\n\nМастер установит ZernMC Launcher на ваш компьютер.\nОнлайн — скачает 47М JRE + 50М лаунчер | Оффлайн — распакует встроенный архив\n\nНажмите ОК чтобы выбрать папку C:\\ZernMC").Title("ZernMC Setup — Приветствие").YesNo()
        if !ok { return fmt.Errorf("cancelled") }
        d, err := dialog.Directory().Title("Выберите папку установки — ZernMC").Browse()
        if err != nil || d=="" { d = defaultInstallDir }
        if !strings.Contains(strings.ToLower(d), "zernmc") { d = filepath.Join(d, "ZernMC") }
        dir = d
    }
    if err := os.MkdirAll(dir, 0755); err != nil { dialog.Message("Ошибка создания папки: %v", err).Title("Ошибка").Error(); return err }
    createShortcut := *shortcutFlag
    if !isFlagSet("shortcut") { createShortcut = dialog.Message("Создать ярлык на рабочем столе?").Title("Ярлык").YesNo() }
    // Progress via console + dialog
    fmt.Printf("Установка в %s ...\n", dir)
    var err error
    if isOnline {
        err = installOnline(dir, createShortcut, func(cur, total int, name string){
            fmt.Printf("[%d/%d] %s\n", cur, total, name)
        })
    } else {
        zipPath := *offlineZipFlag
        if zipPath=="" { zipPath = findAdjacentOfflineZip() }
        if zipPath!="" { err = installOffline(dir, zipPath, createShortcut) } else { err = installOfflineEmbedded(dir, createShortcut) }
    }
    if err != nil { dialog.Message("Ошибка установки: %v", err).Title("Ошибка").Error(); return err }
    dialog.Message("Установка завершена!\n\nЗапустите с ярлыка или C:\\ZernMC\\zernmc.exe").Title("ZernMC Setup — Готово").Info()
    // launch?
    if dialog.Message("Запустить ZernMC сейчас?").Title("Готово").YesNo() {
        exec.Command(filepath.Join(dir, "zernmc.exe")).Start()
    }
    return nil
}

func isFlagSet(name string) bool { found:=false; flag.Visit(func(f *flag.Flag){ if f.Name==name { found=true } }); return found }
func askInstallDir() string {
    if runtime.GOOS=="windows" {
        dir, err := dialog.Directory().Title("Куда установить ZernMC").Browse()
        if err==nil && dir!="" {
            if !strings.Contains(strings.ToLower(dir), "zernmc") { dir = filepath.Join(dir, "ZernMC") }
            return dir
        }
        fmt.Printf("Dialog cancelled (%v), using default %s\n", err, defaultInstallDir)
    }
    fmt.Printf("Куда установить ZernMC [%s]: ", defaultInstallDir)
    var input string; fmt.Scanln(&input); input=strings.TrimSpace(input)
    if input=="" { input=defaultInstallDir }
    return input
}
func askShortcut() bool {
    if runtime.GOOS!="windows" { return false }
    return dialog.Message("Создать ярлык на рабочем столе (ZernMC Launcher)?").Title("Ярлык").YesNo()
}
func fatal(format string, args ...interface{}) {
    msg:=fmt.Sprintf(format, args...); fmt.Fprintln(os.Stderr, msg)
    if runtime.GOOS=="windows" { dialog.Message(msg).Title("ZernMC Installer — Ошибка").Error() }
    os.Exit(1)
}
func installOnline(dir string, createShortcut bool, progress func(cur,total int, name string)) error {
    fmt.Println("Online installation — downloading JRE + launcher files...")
    jreDir:=filepath.Join(dir, "lib", "jre21"); javaExe:=filepath.Join(jreDir, "bin", "java.exe")
    if _, err:=os.Stat(javaExe); err!=nil {
        fmt.Println("Downloading JRE 21 (47 MB)...")
        jreURL:=serverBase+"/launcher/download/jre"; tmpZip:=filepath.Join(os.TempDir(), jreZipName)
        if err:=downloadFile(jreURL, tmpZip); err!=nil {
            mirrors:=[]string{"https://api.zernmc.ru/launcher/download/jre","https://api.zernmc.online/launcher/download/jre"}
            var lastErr error
            for _, m:=range mirrors { fmt.Printf("Retry mirror %s\n", m); if err:=downloadFile(m, tmpZip); err==nil { lastErr=nil; break } else { lastErr=err } }
            if lastErr!=nil { return fmt.Errorf("JRE download failed: %w", lastErr) }
        }
        fmt.Printf("Unpacking JRE to %s ...\n", jreDir)
        if err:=unzip(tmpZip, dir); err!=nil { return fmt.Errorf("unzip JRE: %w", err) }
        candidate:=filepath.Join(dir, "jre21")
        if _, err:=os.Stat(candidate); err==nil { os.MkdirAll(filepath.Join(dir, "lib"), 0755); os.RemoveAll(jreDir); if err:=os.Rename(candidate, jreDir); err!=nil { if err:=copyDir(candidate, jreDir); err!=nil { return err }; os.RemoveAll(candidate) } }
        os.Remove(tmpZip)
        if _, err:=os.Stat(javaExe); err!=nil { return fmt.Errorf("JRE unpack failed, %s not found", javaExe) }
        fmt.Println("JRE ready")
    } else { fmt.Println("JRE already present, skipping") }
    fmt.Println("Fetching launcher meta...")
    meta, err:=fetchMeta()
    if err!=nil { return fmt.Errorf("fetch meta: %w", err) }
    fmt.Printf("Latest: %s (%d files)\n", meta.Version, len(meta.Files))
    for i, f:=range meta.Files {
        rel:=f.Path
        if strings.HasPrefix(rel, "jre21/") || strings.HasPrefix(rel, "lib/jre21") { continue }
        dest:=filepath.Join(dir, filepath.FromSlash(rel))
        need:=true
        if fi, err:=os.Stat(dest); err==nil && !fi.IsDir() {
            hash, _:=fileSHA256(dest)
            if hash==strings.TrimPrefix(f.Hash, "sha256:") { need=false }
        }
        if !need { continue }
        if progress!=nil { progress(i+1, len(meta.Files), rel) }
        fmt.Printf("[%d/%d] %s (%.1f KB)\n", i+1, len(meta.Files), rel, float64(f.Size)/1024)
        if err:=os.MkdirAll(filepath.Dir(dest), 0755); err!=nil { return err }
        url:=fmt.Sprintf("%s/launcher/file/%s/%s", serverBase, meta.Version, rel)
        if err:=downloadFile(url, dest); err!=nil { return fmt.Errorf("download %s: %w", rel, err) }
        hash, _:=fileSHA256(dest)
        if hash!=strings.TrimPrefix(f.Hash, "sha256:") { fmt.Printf("  WARNING hash mismatch for %s\n", rel) }
    }
    if err:=os.WriteFile(filepath.Join(dir, "build.version"), []byte(meta.Version), 0644); err!=nil { fmt.Printf("warning write build.version: %v\n", err) }
    fmt.Println("Launcher files ready")
    if createShortcut { if err:=createDesktopShortcut(dir); err!=nil { fmt.Printf("shortcut failed: %v\n", err) } }
    if err:=createUninstaller(dir); err!=nil { fmt.Printf("uninstall.exe failed: %v\n", err) }
    return nil
}
func installOfflineEmbedded(dir string, createShortcut bool) error {
    fmt.Println("Offline embedded installation...")
    data, err:=offlineFS.ReadFile("offline.zip")
    if err!=nil {
        // try adjacent
        zp:=findAdjacentOfflineZip()
        if zp!="" { return installOffline(dir, zp, createShortcut) }
        return fmt.Errorf("offline.zip not embedded, put ZernMC-win-*.zip next to installer or rebuild with offline.zip: %w", err)
    }
    tmp:=filepath.Join(os.TempDir(), fmt.Sprintf("offline-%d.zip", time.Now().UnixNano()))
    if err:=os.WriteFile(tmp, data, 0644); err!=nil { return err }
    defer os.Remove(tmp)
    fmt.Println("Unpacking embedded (98 MB)...")
    if err:=unzip(tmp, dir); err!=nil { return fmt.Errorf("unzip: %w", err) }
    if createShortcut { if err:=createDesktopShortcut(dir); err!=nil { fmt.Printf("shortcut failed: %v\n", err) } }
    if err:=createUninstaller(dir); err!=nil { fmt.Printf("uninstall.exe failed: %v\n", err) }
    fmt.Println("Offline unpack complete")
    return nil
}
func installOffline(dir, zipPath string, createShortcut bool) error {
    fmt.Printf("Offline installation from %s to %s\n", zipPath, dir)
    if _, err:=os.Stat(zipPath); err!=nil { return fmt.Errorf("offline zip not found: %s", zipPath) }
    fmt.Println("Unpacking (98 MB)...")
    if err:=unzip(zipPath, dir); err!=nil { return fmt.Errorf("unzip: %w", err) }
    if createShortcut { if err:=createDesktopShortcut(dir); err!=nil { fmt.Printf("shortcut failed: %v\n", err) } }
    if err:=createUninstaller(dir); err!=nil { fmt.Printf("uninstall.exe failed: %v\n", err) }
    fmt.Println("Offline unpack complete")
    return nil
}
func downloadFile(url, dest string) error {
    client:=&http.Client{Timeout: 120*time.Second}
    resp, err:=client.Get(url)
    if err!=nil { return err }
    defer resp.Body.Close()
    if resp.StatusCode!=200 { return fmt.Errorf("HTTP %d", resp.StatusCode) }
    if err:=os.MkdirAll(filepath.Dir(dest), 0755); err!=nil { return err }
    tmp:=dest+".tmp"
    out, err:=os.Create(tmp)
    if err!=nil { return err }
    defer out.Close()
    total:=resp.ContentLength
    var written int64
    buf:=make([]byte, 64*1024)
    start:=time.Now()
    for {
        n, err:=resp.Body.Read(buf)
        if n>0 {
            if _, werr:=out.Write(buf[:n]); werr!=nil { return werr }
            written+=int64(n)
            if total>0 {
                pct:=float64(written)/float64(total)*100
                elapsed:=time.Since(start).Seconds()
                speed:=float64(written)/1024/1024/(elapsed+0.001)
                fmt.Printf("\r  %.1f%% %.1f/%.1f MB %.1f MB/s   ", pct, float64(written)/1024/1024, float64(total)/1024/1024, speed)
            } else { fmt.Printf("\r  %.1f MB   ", float64(written)/1024/1024) }
        }
        if err==io.EOF { break }
        if err!=nil { return err }
    }
    fmt.Println()
    out.Close()
    if err:=os.Rename(tmp, dest); err!=nil { if err2:=copyFile(tmp, dest); err2!=nil { return err2 }; os.Remove(tmp) }
    return nil
}
func unzip(src, dest string) error {
    r, err:=zip.OpenReader(src)
    if err!=nil { return err }
    defer r.Close()
    for _, f:=range r.File {
        fpath:=filepath.Join(dest, f.Name)
        if !strings.HasPrefix(fpath, filepath.Clean(dest)+string(os.PathSeparator)) { return fmt.Errorf("illegal file path: %s", fpath) }
        if f.FileInfo().IsDir() { os.MkdirAll(fpath, f.Mode()); continue }
        if err:=os.MkdirAll(filepath.Dir(fpath), 0755); err!=nil { return err }
        out, err:=os.OpenFile(fpath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, f.Mode())
        if err!=nil { return err }
        rc, err:=f.Open()
        if err!=nil { out.Close(); return err }
        _, err=io.Copy(out, rc)
        out.Close(); rc.Close()
        if err!=nil { return err }
    }
    return nil
}
func copyFile(src, dst string) error { in, err:=os.Open(src); if err!=nil { return err }; defer in.Close(); out, err:=os.Create(dst); if err!=nil { return err }; defer out.Close(); _, err=io.Copy(out, in); return err }
func copyDir(src, dst string) error { return filepath.Walk(src, func(path string, info os.FileInfo, err error) error { if err!=nil { return err }; rel, _:=filepath.Rel(path, src); target:=filepath.Join(dst, rel); if info.IsDir() { return os.MkdirAll(target, info.Mode()) }; return copyFile(path, target) }) }
func fileSHA256(path string) (string, error) { f, err:=os.Open(path); if err!=nil { return "", err }; defer f.Close(); h:=sha256.New(); if _, err:=io.Copy(h, f); err!=nil { return "", err }; return hex.EncodeToString(h.Sum(nil)), nil }
type Meta struct { Version string `json:"version"`; Files []struct{ Path string `json:"path"`; Size int64 `json:"size"`; Hash string `json:"hash"` } `json:"files"` }
func fetchMeta() (*Meta, error) {
    resp, err:=http.Get(serverBase+"/launcher/version")
    if err!=nil { return nil, err }
    defer resp.Body.Close()
    var verResp struct{ Version string `json:"version"` }
    if err:=json.NewDecoder(resp.Body).Decode(&verResp); err!=nil { return nil, err }
    ver:=verResp.Version
    if ver=="" { ver="1.1.1" }
    metaResp, err:=http.Get(serverBase+"/launcher/meta/"+ver)
    if err!=nil { return nil, err }
    defer metaResp.Body.Close()
    if metaResp.StatusCode!=200 { return nil, fmt.Errorf("meta %d", metaResp.StatusCode) }
    var meta Meta
    if err:=json.NewDecoder(metaResp.Body).Decode(&meta); err!=nil { return nil, err }
    if meta.Version=="" { meta.Version=ver }
    return &meta, nil
}
func findAdjacentOfflineZip() string {
    exe, _:=os.Executable(); dir:=filepath.Dir(exe)
    matches, _:=filepath.Glob(filepath.Join(dir, "ZernMC-Offline*.zip"))
    if len(matches)>0 { return matches[0] }
    matches, _=filepath.Glob(filepath.Join(dir, "ZernMC-win*.zip"))
    if len(matches)>0 { return matches[0] }
    matches, _=filepath.Glob("ZernMC-Offline*.zip")
    if len(matches)>0 { return matches[0] }
    return ""
}
func createDesktopShortcut(installDir string) error {
    if runtime.GOOS!="windows" { return nil }
    desktop:=filepath.Join(os.Getenv("USERPROFILE"), "Desktop")
    if _, err:=os.Stat(desktop); err!=nil { desktop=filepath.Join(os.Getenv("USERPROFILE"), "OneDrive", "Desktop") }
    if _, err:=os.Stat(desktop); err!=nil { return fmt.Errorf("desktop not found") }
    lnk:=filepath.Join(desktop, "ZernMC Launcher.lnk")
    target:=filepath.Join(installDir, "zernmc.exe")
    ps:=fmt.Sprintf(`$WshShell = New-Object -comObject WScript.Shell; $Shortcut = $WshShell.CreateShortcut('%s'); $Shortcut.TargetPath = '%s'; $Shortcut.WorkingDirectory = '%s'; $Shortcut.IconLocation = '%s'; $Shortcut.Save()`, lnk, target, installDir, target)
    tmp:=filepath.Join(os.TempDir(), "zernmc_shortcut.ps1")
    if err:=os.WriteFile(tmp, []byte(ps), 0644); err!=nil { return err }
    defer os.Remove(tmp)
    cmd:=exec.Command("powershell", "-ExecutionPolicy", "Bypass", "-File", tmp)
    cmd.Stdout=os.Stdout; cmd.Stderr=os.Stderr
    return cmd.Run()
}
func createUninstaller(dir string) error {
    exe, _:=os.Executable(); uninstExe:=filepath.Join(dir, "uninstall.exe")
    if exe!="" && exe!=uninstExe { _=copyFile(exe, uninstExe) }
    bat:=filepath.Join(dir, "uninstall.bat")
    content:=fmt.Sprintf("@echo off\necho Uninstalling ZernMC from %s\ntimeout /t 2 >nul\ndel \"%%%%USERPROFILE%%%%\\Desktop\\ZernMC Launcher.lnk\" 2>nul\ndel \"%%%%USERPROFILE%%%%\\OneDrive\\Desktop\\ZernMC Launcher.lnk\" 2>nul\necho Data in %%%%USERPROFILE%%%%\\.zernmc will be kept.\n", dir)
    _=os.WriteFile(bat, []byte(content), 0644)
    return nil
}
func runCmd(name string, args ...string) error { cmd:=exec.Command(name, args...); cmd.Stdout=os.Stdout; cmd.Stderr=os.Stderr; return cmd.Run() }