package main

import (
	"context"
	"errors"
	"fmt"
	"os"

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

	"cdrop-desktop/platform"
)

// loginResultFromToken decodes the identity out of the exchanged tokens and
// assembles the payload the WebView store consumes. Shared by login + refresh.
func loginResultFromToken(tok *platform.TokenResult) (*platform.LoginResult, error) {
	user, err := platform.UserFromToken(tok.IDToken, tok.AccessToken)
	if err != nil {
		return nil, err
	}
	return &platform.LoginResult{
		AccessToken:  tok.AccessToken,
		RefreshToken: tok.RefreshToken,
		ExpiresIn:    tok.ExpiresIn,
		User:         user,
	}, nil
}

// 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)
	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
}

// 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,
		}
	}
	// 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)
	}
	a.startClipboardSync(ctx)
	platform.InstallStatusBar(
		platform.StatusBarMenu{
			Title:    "cdrop",
			Show:     "显示主窗口",
			Settings: "设置…",
			Quit:     "退出 cdrop",
		},
		// 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 cdrop", keys.CmdOrCtrl("q"), func(*menu.CallbackData) {
		a.requestQuit()
	}))
	m.Append(menu.SubMenu("cdrop", 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())
}

// 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)
		})
		tok, err := flow.Login(a.ctx)
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		res, err := loginResultFromToken(tok)
		if err != nil {
			runtime.EventsEmit(a.ctx, "oauth:error", map[string]string{"detail": err.Error()})
			return
		}
		a.token = tok
		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
	}
	res, err := loginResultFromToken(tok)
	if err != nil {
		return nil, err
	}
	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
	}
	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)
}

// 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 client);
// otherwise it fetches /api/auth/config from the backend and reuses the web
// app's client_id for the desktop's loopback PKCE flow (see desktop/PLAN.md §3).
func (a *App) resolveOAuthConfig() (platform.OAuthConfig, error) {
	if env := oauthConfigFromEnv(); env.ClientID != "" {
		return env, nil
	}
	return platform.FetchOAuthConfig(a.ctx, a.apiBase)
}

func oauthConfigFromEnv() platform.OAuthConfig {
	return platform.OAuthConfig{
		AuthorizeURL: os.Getenv("CDROP_OAUTH_AUTHORIZE_URL"),
		TokenURL:     os.Getenv("CDROP_OAUTH_TOKEN_URL"),
		ClientID:     os.Getenv("CDROP_OAUTH_CLIENT_ID"),
		Scopes:       os.Getenv("CDROP_OAUTH_SCOPES"),
	}
}

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)
}