package main

import (
	"context"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"os"
	"path/filepath"

	"github.com/wailsapp/wails/v2/pkg/menu"
	"github.com/wailsapp/wails/v2/pkg/menu/keys"
	"github.com/wailsapp/wails/v2/pkg/runtime"

	"cdrop-desktop/engine"
	"cdrop-desktop/platform"
)

// App is the Wails application context bound to the WebView.
type App struct {
	ctx         context.Context
	apiBase     string
	token       *platform.TokenResult // in-memory copy; refresh_token persists in the OS secret store (see session.go)
	user        platform.UserInfo     // display identity from 代铸; preserved across refresh (machine tokens are nameless)
	quitting    bool                  // set by the menu bar "Quit" so beforeClose allows the real exit
	startHidden bool                  // set by main when launched via autostart: come up to the menu bar, no window

	clipSource  platform.Source
	clipMonitor *platform.Monitor

	// transfer 是原生 P2P 数据面（pion）：取代 WebView 内 JS WebRTC，逃离 WebKit/WebView2
	// 的 256KB rwnd 与渲染器节流。HTTP（信令 / 状态机）仍由 WebView 侧 JS 经事件桥发起，
	// 引擎只做纯 WebRTC + 文件 I/O。见 desktop/NATIVE-TRANSFER.md。
	transfer *engine.Engine
}

// NewApp creates a new App application struct.
func NewApp() *App {
	return &App{apiBase: envOr("CDROP_API_BASE", "https://drop.commilitia.net")}
}

// startup is called when the app starts. The context is saved so we can call
// the runtime methods, and the menu bar item is installed (macOS; no-op
// elsewhere). The app launches as a regular Dock app with the window visible.
func (a *App) startup(ctx context.Context) {
	a.ctx = ctx
	// Load the persisted refresh_token into the Go process so refresh works after
	// a restart. The refresh_token stays here — it's never handed to the WebView.
	if s, err := platform.LoadSession(); err == nil && s != nil {
		a.token = &platform.TokenResult{
			AccessToken:  s.AccessToken,
			RefreshToken: s.RefreshToken,
			ExpiresIn:    s.ExpiresIn,
		}
		a.user = s.User
	}
	// Keep the autostart entry in sync with this binary: when it's enabled,
	// re-apply so an entry written by an older build (no --hidden flag) or one
	// pointing at a since-moved bundle is refreshed to the current path + flags.
	// Idempotent and cheap — a single plist / registry write.
	if platform.IsLaunchAtLoginEnabled() {
		_ = platform.SetLaunchAtLogin(true)
	}
	// Migrate native notification metadata at startup so an old internal-name
	// entry does not remain visible until the first incoming notification.
	platform.InitializeNotifications()
	// 原生传输引擎：落地目录取当前配置（设置页改目录时经 SaveSettings 同步到引擎）。
	a.transfer = engine.New(engine.Config{DownloadDir: platform.ResolveDownloadDir()}, &transferEvents{app: a})
	a.startClipboardSync(ctx)
	// 触发 macOS 本地网络权限（macOS 15+ 隐私门）：使本进程 WKWebView 的 WebRTC 能收集 host /
	// mDNS 候选、同内网走直连而非 prflx↔prflx 慢路径（见 platform.TriggerLocalNetwork）。其他平台空实现。
	platform.TriggerLocalNetwork()
	platform.InstallStatusBar(
		platform.StatusBarMenu{
			Title:    "Commilitia Drop",
			Show:     "显示主窗口",
			Settings: "设置…",
			Quit:     "退出 Commilitia Drop",
		},
		// The native menu-action callbacks fire on the AppKit main thread; calling
		// Wails runtime methods synchronously there can re-enter the main run loop
		// and crash. Hand off to a goroutine — Wails then dispatches to the main
		// thread safely.
		platform.StatusBarHandler{
			OnShowWindow:   func() { go a.revealWindow() },
			OnOpenSettings: func() { go a.openSettings() },
			OnQuit:         func() { go a.requestQuit() },
		},
	)
	// Autostart launch: the window already came up hidden (options.StartHidden).
	// On macOS also drop the Dock icon to accessory so only the menu bar item
	// remains — the same resting state as close-to-menu-bar. (Windows: this is a
	// no-op; the tray is installed above and the hidden window keeps the taskbar
	// clear. The menu bar item / tray is the way back in.)
	if a.startHidden {
		platform.SetDockVisible(false)
	}
}

// buildMenu returns the macOS application menu. Without it the standard
// shortcuts (⌘C/⌘V/⌘X/⌘A/⌘Z and ⌘W/⌘M) don't work.
//
// Quit is a custom ⌘Q item rather than the role AppMenu's, because Wails routes
// both the window close button and ⌘Q through the same OnBeforeClose("Q")
// channel — indistinguishable there. The custom item sets the quitting flag
// first, so OnBeforeClose lets ⌘Q quit while the close button hides. ⌘W likewise
// hides (close-to-menu-bar), matching the lifecycle.
func (a *App) buildMenu() *menu.Menu {
	m := menu.NewMenu()

	appSub := menu.NewMenu()
	appSub.Append(menu.Text("退出 Commilitia Drop", keys.CmdOrCtrl("q"), func(*menu.CallbackData) {
		a.requestQuit()
	}))
	m.Append(menu.SubMenu("Commilitia Drop", appSub)) // macOS renders the first menu as the app menu

	m.Append(menu.EditMenu()) // Undo/Redo/Cut/Copy/Paste/SelectAll

	window := menu.NewMenu()
	window.Append(menu.Text("最小化", keys.CmdOrCtrl("m"), func(*menu.CallbackData) {
		runtime.WindowMinimise(a.ctx)
	}))
	window.Append(menu.Text("关闭窗口", keys.CmdOrCtrl("w"), func(*menu.CallbackData) {
		a.hideWindow()
	}))
	m.Append(menu.SubMenu("窗口", window))
	return m
}

// hideWindow tucks the window away to the menu bar (window hidden, Dock icon
// gone). Shared by ⌘W and the window's close button (via beforeClose).
func (a *App) hideWindow() {
	runtime.WindowHide(a.ctx)
	platform.SetDockVisible(false)
}

// beforeClose intercepts the window close. Instead of quitting, it hides the
// window and drops to accessory (Dock icon gone, menu bar item remains the way
// back in). The real exit only happens after the menu bar "Quit" sets quitting.
func (a *App) beforeClose(_ context.Context) bool {
	if a.quitting {
		return false // allow the quit to proceed
	}
	a.hideWindow()
	return true // prevent the close
}

// revealWindow brings the main window back and restores the Dock icon. Bound to
// the menu bar "Show" item.
func (a *App) revealWindow() {
	if a.ctx == nil {
		return
	}
	platform.SetDockVisible(true)
	runtime.WindowShow(a.ctx)
	runtime.WindowUnminimise(a.ctx)
}

// openSettings reveals the window and asks the WebView to route to settings.
func (a *App) openSettings() {
	a.revealWindow()
	runtime.EventsEmit(a.ctx, "menu:settings")
}

// requestQuit flags an intentional quit so beforeClose lets it through, then
// asks Wails to terminate.
func (a *App) requestQuit() {
	a.quitting = true
	runtime.Quit(a.ctx)
}

// startClipboardSync starts the native pasteboard watcher. Local copies are
// emitted to the WebView as "clipboard:native"; the JS layer owns the upload
// decision (auth + the user's sync toggle) and reuses the web app's existing
// upload + dedup path. The download direction is driven by the WebView calling
// ApplyRemoteClipboard. The shared Monitor enforces the loop guard across both
// directions.
func (a *App) startClipboardSync(ctx context.Context) {
	a.clipSource = platform.NewClipboardSource()
	a.clipMonitor = platform.NewMonitor(func(text string) {
		runtime.EventsEmit(a.ctx, "clipboard:native", text)
	})
	go platform.Run(ctx, a.clipSource, a.clipMonitor)
}

// ApplyRemoteClipboard is bound to the WebView. It writes a remote clipboard
// update to the local pasteboard (download direction). The Monitor arms its loop
// guard before the write so the resulting change isn't re-uploaded, and skips
// this device's own echoes. content is plain text at this stage.
func (a *App) ApplyRemoteClipboard(content, sourceDevice string) {
	if a.clipMonitor == nil || a.clipSource == nil {
		return
	}
	a.clipMonitor.ApplyRemote(a.clipSource, platform.ClipboardContent{
		Content:      content,
		ContentType:  "text/plain",
		SourceDevice: sourceDevice,
	}, a.DeviceName())
}

// ShowNotification is bound to the WebView. The JS hub calls it when a
// notify-worthy event (incoming file / message / transfer done|failed) arrives
// while the window is NOT in the foreground — so the user gets a native system
// notification instead of an in-app cue they'd miss. Foreground events stay
// in-app: the JS gates on document focus/visibility, so this is only ever
// invoked for the background case. Title/body arrive already localized by the
// WebView (client-side i18n). macOS display additionally needs a signed bundle
// (D6) — until then platform.Notify no-ops safely there; Windows shows now.
func (a *App) ShowNotification(title, body string) {
	platform.Notify(title, body)
}

// StartLogin is bound to the WebView. It runs the loopback PKCE flow in the
// background and reports the outcome via Wails events ("oauth:success" /
// "oauth:error"). On success it persists the full session (with refresh_token)
// Go-side and emits only the refresh-free SessionView to JS — the refresh_token
// never enters the WebView (see the credential policy in session.go).
func (a *App) StartLogin() {
	go func() {
		cfg, err := a.resolveOAuthConfig()
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		flow := platform.NewFlow(cfg, func(u string) {
			runtime.BrowserOpenURL(a.ctx, u)
		})
		// Step 1: device-authorize → a bootstrap machine token (proves identity, no meta).
		boot, err := flow.Login(a.ctx)
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		// Step 2: 代铸 the bootstrap token into a cdrop-managed device session bound to this
		// device's stable device_id, so the desktop is managed exactly like a browser. The
		// device session's tokens supersede the bootstrap (which is discarded, left to expire).
		deviceID, err := platform.ResolveDeviceID()
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		ds, err := platform.MintDeviceSession(a.ctx, a.apiBase, boot.AccessToken, deviceID, platform.ResolveDeviceName(), platform.DeviceType())
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		// Identity from the verified 代铸 response (X-Auth-Subject / X-Auth-Name / X-Auth-Avatar),
		// so the real display name and picture show rather than the subject UUID a nameless
		// machine token yields.
		user := platform.UserInfo{ID: ds.UserID, Name: ds.Name, Avatar: ds.Avatar}
		if user.Name == "" {
			user.Name = user.ID
		}
		res := &platform.LoginResult{
			AccessToken:  ds.AccessToken,
			RefreshToken: ds.RefreshToken,
			ExpiresIn:    ds.ExpiresIn,
			User:         user,
		}
		a.token = &platform.TokenResult{AccessToken: ds.AccessToken, RefreshToken: ds.RefreshToken, ExpiresIn: ds.ExpiresIn}
		a.user = user
		if err := platform.SaveSession(*res); err != nil {
			runtime.LogWarningf(a.ctx, "persist session failed: %v", err)
		}
		view := res.View()
		runtime.EventsEmit(a.ctx, "oauth:success", &view)
	}()
}

// Refresh is bound to the WebView and takes NO argument: the refresh_token never
// crosses into JS, so Go uses its own in-memory copy. It mints a fresh
// access_token (public-client loopback flow, no client_secret), persists the
// rotated session, and returns only the refresh-free SessionView. The WebView
// calls this when an API request comes back 401.
func (a *App) Refresh() (*platform.SessionView, error) {
	if a.token == nil || a.token.RefreshToken == "" {
		return nil, errors.New("no refresh token")
	}
	cfg, err := a.resolveOAuthConfig()
	if err != nil {
		return nil, err
	}
	flow := platform.NewFlow(cfg, func(string) {})
	tok, err := flow.Refresh(a.ctx, a.token.RefreshToken)
	if err != nil {
		return nil, err
	}
	if tok.RefreshToken == "" {
		tok.RefreshToken = a.token.RefreshToken // providers that don't rotate: keep the old one
	}
	// Preserve the identity established at login: the refreshed access token is a nameless
	// machine token (it carries meta, not the display name), so re-deriving identity from it
	// would regress the name to the subject UUID. The device session keeps its meta across
	// rotation, so the device stays the same managed device.
	res := &platform.LoginResult{
		AccessToken:  tok.AccessToken,
		RefreshToken: tok.RefreshToken,
		ExpiresIn:    tok.ExpiresIn,
		User:         a.user,
	}
	a.token = tok
	if err := platform.SaveSession(*res); err != nil {
		runtime.LogWarningf(a.ctx, "persist refreshed session failed: %v", err)
	}
	view := res.View()
	return &view, nil
}

// ClearSession is bound to the WebView; called on logout to drop the persisted
// session file (and the Go-side token copy) so the next launch starts logged out.
func (a *App) ClearSession() error {
	a.token = nil
	return platform.ClearSession()
}

// GetSettings is bound to the WebView. It returns the persisted desktop config,
// with LaunchAtLogin reflecting the actual LaunchAgent state (the plist is the
// source of truth — the user may have toggled it elsewhere).
func (a *App) GetSettings() platform.DesktopConfig {
	cfg, _ := platform.LoadConfig()
	cfg.LaunchAtLogin = platform.IsLaunchAtLoginEnabled()
	return cfg
}

// SaveSettings is bound to the WebView. It persists the settings the page owns
// and applies the launch-at-login side effect (install / remove the LaunchAgent).
//
// The page's DesktopConfig has no device_name field, so the incoming cfg always
// carries DeviceName="". We merge onto the current config (preserving DeviceName,
// which is owned by SetDeviceName) instead of overwriting — otherwise saving any
// setting would wipe the persisted device name. Config is written before the
// launch-agent side effect so its failure doesn't lose the other preferences.
func (a *App) SaveSettings(cfg platform.DesktopConfig) error {
	cur, _ := platform.LoadConfig()
	cur.ClipboardSyncEnabled = cfg.ClipboardSyncEnabled
	cur.LaunchAtLogin = cfg.LaunchAtLogin
	cur.DownloadDir = cfg.DownloadDir
	if err := platform.SaveConfig(cur); err != nil {
		return err
	}
	// 让引擎的落地目录跟随设置变化（接收端直接写盘）。
	if a.transfer != nil {
		a.transfer.SetDownloadDir(platform.ResolveDownloadDir())
	}
	return platform.SetLaunchAtLogin(cur.LaunchAtLogin)
}

// DeviceName is bound to the WebView. Returns the persisted device name, or the
// hostname when the user hasn't renamed it — so the desktop skips the per-device
// naming step the browser shows.
func (a *App) DeviceName() string {
	return platform.ResolveDeviceName()
}

// SetDeviceName is bound to the WebView; called when the user renames this device
// so the name survives restart (the WebView's localStorage doesn't, on wails://).
func (a *App) SetDeviceName(name string) error {
	cfg, _ := platform.LoadConfig()
	cfg.DeviceName = name
	return platform.SaveConfig(cfg)
}

// SaveDownload is bound to the WebView. The transfer pipeline hands a received
// file's bytes (base64 over the bridge) to Go, which writes them into the user's
// configured download directory (default ~/Downloads) without overwriting. The
// absolute path is returned so the page can tell the user where it landed.
func (a *App) SaveDownload(name string, data []byte) (string, error) {
	return platform.SaveDownload(platform.ResolveDownloadDir(), name, data)
}

// BeginDownload / AppendDownload / FinalizeDownload / AbortDownload are the
// streaming counterpart of SaveDownload, bound to the WebView. The receiver's
// hybrid sink keeps a file in memory until it crosses a cap, then spills the
// overflow here so large files don't sit in the WebView heap (the wails:// no-OPFS
// deadlock). Begin opens a temp file in the download dir, Append streams batches
// (base64 over the bridge), Finalize renames it into place and returns the path,
// Abort discards it on cancel / failure.
func (a *App) BeginDownload(sessionId string) error {
	return platform.BeginStreamingDownload(platform.ResolveDownloadDir(), sessionId)
}

func (a *App) AppendDownload(sessionId string, data []byte) error {
	return platform.AppendStreamingDownload(sessionId, data)
}

func (a *App) FinalizeDownload(sessionId, name string) (string, error) {
	return platform.FinalizeStreamingDownload(sessionId, name)
}

func (a *App) AbortDownload(sessionId string) {
	platform.AbortStreamingDownload(sessionId)
}

// ChooseDownloadDir opens a native directory picker (title localised by the
// caller) and returns the chosen path, or "" when the user cancels. The page
// persists the result via SaveSettings.
func (a *App) ChooseDownloadDir(title string) (string, error) {
	return runtime.OpenDirectoryDialog(a.ctx, runtime.OpenDialogOptions{Title: title})
}

// EffectiveDownloadDir returns the directory downloads currently land in — the
// configured override or the system default — for display in the settings page.
func (a *App) EffectiveDownloadDir() string {
	return platform.ResolveDownloadDir()
}

// resolveOAuthConfig prefers explicit env overrides (dev / a pinned broker);
// otherwise it fetches /api/auth/config from the backend for the broker's public URL,
// then runs the broker device-authorization flow against it.
func (a *App) resolveOAuthConfig() (platform.OAuthConfig, error) {
	if env := oauthConfigFromEnv(); env.BrokerURL != "" {
		return env, nil
	}
	return platform.FetchOAuthConfig(a.ctx, a.apiBase)
}

func oauthConfigFromEnv() platform.OAuthConfig {
	return platform.OAuthConfig{
		BrokerURL: os.Getenv("CDROP_BROKER_URL"),
		App:       envOr("CDROP_BROKER_APP", "commilitia-drop"),
	}
}

func envOr(key, def string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return def
}

// LoggedIn reports whether a token is currently held; bound so the WebView can
// query auth state on startup.
func (a *App) LoggedIn() bool {
	return a.token != nil
}

// Greet returns a greeting for the given name (scaffold demo, kept until the
// shared web UI replaces the default frontend).
func (a *App) Greet(name string) string {
	return fmt.Sprintf("Hello %s, It's show time!", name)
}

// --- 原生 P2P 数据面桥（绑定到 WebView） ---
//
// WebView 侧的 p2pBackend（Go-bridge 后端）调用这四个方法发起 / 接收 / 喂信令 / 取消；
// 引擎经 transferEvents 反向 EventsEmit 进度 / 状态 / 出站信令 / 落盘路径。HTTP 全留 JS：
// 出站信令由 JS POST /api/hub/signal，入站信令由 JS hub 转发进 P2PHandleSignal，状态机
// POST（/p2p、/done、/fail）由 JS 据 p2p:state 事件发起。iceServersJSON 由 JS 透传
// （与 web 同源，来自 /api/calls/credentials）。

// P2PStartOutgoing 作为发送端发起：filePath 为本机绝对路径（经 PickFileForSend 获得）。
func (a *App) P2PStartOutgoing(sessionID, peerName, filePath, iceServersJSON string) error {
	return a.transfer.StartOutgoing(sessionID, peerName, filePath, iceServersJSON)
}

// P2PStartIncoming 预备接收端，等对端 offer。
func (a *App) P2PStartIncoming(sessionID, peerName, iceServersJSON string) error {
	return a.transfer.StartIncoming(sessionID, peerName, iceServersJSON)
}

// P2PHandleSignal 把 JS hub 从 SSE 收到的入站信令喂给引擎（按对端设备名路由）。
func (a *App) P2PHandleSignal(fromPeer, payloadJSON string) error {
	return a.transfer.HandleSignal(fromPeer, payloadJSON)
}

// P2PCancel 拆除会话（取消 / 中继回退）。
func (a *App) P2PCancel(sessionID string) {
	a.transfer.Cancel(sessionID)
}

// PickedFile 是原生文件选择的结果，供发送端走原生数据面（Go 直接按路径读盘，不经浏览器
// File 的沙箱无路径 + 内存约束）。
type PickedFile struct {
	Path string `json:"path"`
	Name string `json:"name"`
	Size int64  `json:"size"`
}

// ReadFileSlice 读 path 的 [start,end) 字节并 base64 返回。仅供中继回退时 WebView 侧的
// FileSource.slice 用（原生 P2P 由引擎直接按路径读盘、不走此桥）；故 base64 开销只在罕见
// 的 relay 路径上，不影响 P2P 主路径。镜像 iOS 的 readOutgoingSlice。
func (a *App) ReadFileSlice(path string, start, end int64) (string, error) {
	if start < 0 || end < start {
		return "", fmt.Errorf("bad range [%d,%d)", start, end)
	}
	f, err := os.Open(path)
	if err != nil {
		return "", err
	}
	defer f.Close()
	buf := make([]byte, end-start)
	n, err := f.ReadAt(buf, start)
	if err != nil && err != io.EOF {
		return "", err
	}
	return base64.StdEncoding.EncodeToString(buf[:n]), nil
}

// PickFileForSend 打开原生文件对话框，返回选中文件的绝对路径 + 名 + 大小；用户取消返回 nil。
func (a *App) PickFileForSend(title string) (*PickedFile, error) {
	path, err := runtime.OpenFileDialog(a.ctx, runtime.OpenDialogOptions{Title: title})
	if err != nil {
		return nil, err
	}
	if path == "" {
		return nil, nil // 用户取消
	}
	fi, err := os.Stat(path)
	if err != nil {
		return nil, err
	}
	return &PickedFile{Path: path, Name: filepath.Base(path), Size: fi.Size()}, nil
}

// transferEvents 把引擎回调转成 Wails 事件，供 WebView 侧 p2pBackend 监听。回调可能在 pion
// 任意 goroutine 触发；Wails 的 EventsEmit / Log* 可跨线程安全调用。
type transferEvents struct{ app *App }

func (e *transferEvents) OnProgress(sessionID string, bytes int64) {
	runtime.EventsEmit(e.app.ctx, "p2p:progress", map[string]any{"sessionId": sessionID, "bytes": bytes})
}

func (e *transferEvents) OnState(sessionID, state string) {
	runtime.EventsEmit(e.app.ctx, "p2p:state", map[string]any{"sessionId": sessionID, "state": state})
}

func (e *transferEvents) OnSignal(sessionID, toPeer, payloadJSON string) {
	runtime.EventsEmit(e.app.ctx, "p2p:signal", map[string]any{"sessionId": sessionID, "to": toPeer, "payload": payloadJSON})
}

func (e *transferEvents) OnSaved(sessionID, path string) {
	runtime.EventsEmit(e.app.ctx, "p2p:saved", map[string]any{"sessionId": sessionID, "path": path})
}

func (e *transferEvents) OnIcePair(sessionID, local, remote string) {
	runtime.EventsEmit(e.app.ctx, "p2p:icepair", map[string]any{"sessionId": sessionID, "local": local, "remote": remote})
}

func (e *transferEvents) OnLog(line string) {
	runtime.LogInfof(e.app.ctx, "p2p: %s", line)
}