package main

// update.go 客户端软件自动更新：每 30 分钟检查服务端最新版，下载 NSIS 后拉起安装。

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"time"

	"view/platform"
)

type appLatestInfo struct {
	Version   string `json:"version"`
	Channel   string `json:"channel"`
	SHA256    string `json:"sha256"`
	SizeBytes int64  `json:"sizeBytes"`
	Changelog string `json:"changelog"`
	CreatedAt string `json:"createdAt"`
}

// CheckAppUpdate 手动/定时检查更新；force=true 忽略“已忽略版本”。
func (a *App) CheckAppUpdate(force bool) (map[string]any, error) {
	if e := a.ready(); e != nil {
		return nil, e
	}
	info, e := a.fetchLatestRelease()
	if e != nil {
		if e.Error() == "NO_RELEASE" {
			return map[string]any{"upToDate": true, "current": appVersion}, nil
		}
		return nil, e
	}
	if !versionNewer(info.Version, appVersion) {
		return map[string]any{"upToDate": true, "current": appVersion, "latest": info.Version}, nil
	}
	if !force {
		if skipped := strings.TrimSpace(a.store.Meta("app_update_skipped")); skipped == info.Version {
			return map[string]any{"upToDate": false, "skipped": true, "current": appVersion, "latest": info.Version}, nil
		}
	}
	payload := map[string]any{
		"upToDate":  false,
		"current":   appVersion,
		"latest":    info.Version,
		"changelog": info.Changelog,
		"sizeBytes": info.SizeBytes,
		"sha256":    info.SHA256,
		"channel":   info.Channel,
	}
	a.emit("app:update-available", payload)
	return payload, nil
}

// SkipAppUpdate 本次跳过该版本提示。
func (a *App) SkipAppUpdate(version string) error {
	if e := a.ready(); e != nil {
		return e
	}
	return a.store.SetMeta("app_update_skipped", strings.TrimSpace(version))
}

// DownloadAndInstallUpdate 下载最新安装包、校验后退出应用并由独立脚本拉起安装器。
func (a *App) DownloadAndInstallUpdate() error {
	if e := a.ready(); e != nil {
		return e
	}
	info, e := a.fetchLatestRelease()
	if e != nil {
		return e
	}
	if !versionNewer(info.Version, appVersion) {
		return errors.New("ALREADY_LATEST")
	}
	path, e := a.downloadRelease(info)
	if e != nil {
		return e
	}
	if e := launchDownloadedInstaller(path); e != nil {
		return e
	}
	a.store.Log("info", "系统", "开始安装更新", info.Version)
	// 安装脚本会等本进程退出后再 start 安装器，避免占用 exe / 作业对象杀掉子进程。
	a.QuitApp()
	return nil
}

func (a *App) runAppUpdateLoop() {
	time.Sleep(60 * time.Second)
	a.checkAppUpdateQuiet()
	t := time.NewTicker(30 * time.Minute)
	defer t.Stop()
	for {
		select {
		case <-a.ctx.Done():
			return
		case <-t.C:
			a.checkAppUpdateQuiet()
		}
	}
}

func (a *App) checkAppUpdateQuiet() {
	if a.store == nil || a.bootstrap.State != BootstrapReady {
		return
	}
	if a.syncUserID() <= 0 || a.store.Meta("sync_access_token") == "" {
		return
	}
	_, _ = a.CheckAppUpdate(false)
}

func (a *App) fetchLatestRelease() (*appLatestInfo, error) {
	if a.apiBaseURL() == "" {
		return nil, errors.New("SYNC_NOT_CONFIGURED")
	}
	var info appLatestInfo
	if e := a.apiDecode(http.MethodGet, "/api/v1/app/latest?channel=stable", nil, &info, false); e != nil {
		return nil, e
	}
	if strings.TrimSpace(info.Version) == "" {
		return nil, errors.New("NO_RELEASE")
	}
	return &info, nil
}

func (a *App) downloadRelease(info *appLatestInfo) (string, error) {
	base := a.apiBaseURL()
	if base == "" {
		return "", errors.New("SYNC_NOT_CONFIGURED")
	}
	url := base + "/api/v1/app/download/" + pathEscape(info.Version) + "?channel=stable"
	req, e := http.NewRequest(http.MethodGet, url, nil)
	if e != nil {
		return "", errors.New("SYNC_OFFLINE")
	}
	// 公开接口不带过期 JWT，避免网关/反代因 Authorization 直接 401。
	req.Header.Set("Accept-Encoding", "identity")
	client := &http.Client{Timeout: 30 * time.Minute}
	resp, e := client.Do(req)
	if e != nil {
		return "", errors.New("SYNC_OFFLINE")
	}
	defer resp.Body.Close()
	if resp.StatusCode >= 400 {
		raw, _ := io.ReadAll(io.LimitReader(resp.Body, 4096))
		var er struct {
			Error string `json:"error"`
		}
		if json.Unmarshal(raw, &er) == nil && er.Error != "" {
			return "", errors.New(er.Error)
		}
		return "", errors.New("SYNC_HTTP_" + strconv.Itoa(resp.StatusCode))
	}
	total := info.SizeBytes
	if resp.ContentLength > 0 {
		total = resp.ContentLength
	}
	a.emit("app:update-progress", map[string]any{"received": int64(0), "total": total})
	dir := filepath.Join(os.TempDir(), "code-count-updates")
	if e := os.MkdirAll(dir, 0755); e != nil {
		return "", errors.New("SAVE_FAILED")
	}
	outPath := filepath.Join(dir, fmt.Sprintf("%s-installer-%d.exe", info.Version, os.Getpid()))
	f, e := os.Create(outPath)
	if e != nil {
		return "", errors.New("SAVE_FAILED")
	}
	h := sha256.New()
	prog := &updateProgressWriter{a: a, total: total}
	n, e := io.Copy(io.MultiWriter(f, h, prog), resp.Body)
	_ = f.Close()
	if e != nil {
		_ = os.Remove(outPath)
		return "", errors.New("DOWNLOAD_FAILED")
	}
	sum := hex.EncodeToString(h.Sum(nil))
	if info.SHA256 != "" && !strings.EqualFold(sum, info.SHA256) {
		_ = os.Remove(outPath)
		return "", errors.New("SHA256_MISMATCH")
	}
	if info.SizeBytes > 0 && n != info.SizeBytes {
		_ = os.Remove(outPath)
		return "", errors.New("SIZE_MISMATCH")
	}
	if !isWindowsPE(outPath) {
		_ = os.Remove(outPath)
		return "", errors.New("NOT_INSTALLER")
	}
	a.emit("app:update-progress", map[string]any{"received": n, "total": total})
	return outPath, nil
}

type updateProgressWriter struct {
	a        *App
	total    int64
	written  int64
	lastEmit time.Time
}

func (w *updateProgressWriter) Write(p []byte) (int, error) {
	n := len(p)
	w.written += int64(n)
	now := time.Now()
	if w.lastEmit.IsZero() || now.Sub(w.lastEmit) >= 200*time.Millisecond || (w.total > 0 && w.written >= w.total) {
		w.lastEmit = now
		if w.a != nil {
			w.a.emit("app:update-progress", map[string]any{"received": w.written, "total": w.total})
		}
	}
	return n, nil
}

func isWindowsPE(path string) bool {
	f, err := os.Open(path)
	if err != nil {
		return false
	}
	defer f.Close()
	var hdr [2]byte
	if _, err := io.ReadFull(f, hdr[:]); err != nil {
		return false
	}
	return hdr[0] == 'M' && hdr[1] == 'Z'
}

// launchDownloadedInstaller 用独立脚本等本进程退出后再打开安装器。
// 不能对安装器本身用 CREATE_NO_WINDOW + /S：需要 UAC 的 NSIS 会静默失败，且文件仍被占用。
func launchDownloadedInstaller(path string) error {
	path = strings.TrimPrefix(filepath.Clean(path), `\\?\`)
	if runtime.GOOS != "windows" {
		cmd := exec.Command(path)
		if e := cmd.Start(); e != nil {
			return errors.New("INSTALLER_START_FAILED")
		}
		return nil
	}
	bat := filepath.Join(os.TempDir(), fmt.Sprintf("cc-update-%d.bat", os.Getpid()))
	if e := os.WriteFile(bat, []byte(updateLaunchScript(os.Getpid(), path)), 0644); e != nil {
		return errors.New("SAVE_FAILED")
	}
	cmd := exec.Command("cmd", "/C", bat)
	platform.ConfigureUpdaterHelper(cmd)
	if e := cmd.Start(); e != nil {
		cmd = exec.Command("cmd", "/C", bat)
		platform.ConfigureHidden(cmd)
		if e2 := cmd.Start(); e2 != nil {
			return errors.New("INSTALLER_START_FAILED")
		}
	}
	return nil
}

func updateLaunchScript(pid int, installer string) string {
	return fmt.Sprintf(""+
		"@echo off\r\n"+
		"set \"PID=%d\"\r\n"+
		"set /a N=0\r\n"+
		":wait\r\n"+
		"set /a N+=1\r\n"+
		"if %%N%% GEQ 90 goto launch\r\n"+
		"ping -n 2 127.0.0.1 >nul\r\n"+
		"tasklist /FI \"PID eq %%PID%%\" /NH 2>nul | find \"%%PID%%\" >nul\r\n"+
		"if not errorlevel 1 goto wait\r\n"+
		":launch\r\n"+
		"ping -n 3 127.0.0.1 >nul\r\n"+
		"start \"\" \"%s\"\r\n"+
		"del \"%%~f0\"\r\n", pid, installer)
}

// versionNewer 判断 remote 是否比 local 新（简单 x.y.z 比较）。
func versionNewer(remote, local string) bool {
	rp := parseSemver(remote)
	lp := parseSemver(local)
	for i := 0; i < 3; i++ {
		if rp[i] > lp[i] {
			return true
		}
		if rp[i] < lp[i] {
			return false
		}
	}
	return false
}

func parseSemver(v string) [3]int {
	v = strings.TrimPrefix(strings.TrimSpace(v), "v")
	if i := strings.IndexAny(v, "-+"); i >= 0 {
		v = v[:i]
	}
	parts := strings.Split(v, ".")
	var out [3]int
	for i := 0; i < 3 && i < len(parts); i++ {
		n, _ := strconv.Atoi(parts[i])
		out[i] = n
	}
	return out
}