package app

import (
	"context"
	"embed"
	"encoding/json"
	"errors"
	"io"
	"io/fs"
	"log"
	"net/http"
	"os"
	"strings"
	"sync"
	"time"

	"codex-helper/internal/cliproxy"
	"codex-helper/internal/security"
	"codex-helper/internal/store"
	webassets "codex-helper/internal/web"
)

// Version is overridden at build time for release images.
var Version = "0.3.0"

type App struct {
	dataDir       string
	store         *store.Store
	vault         *security.Vault
	cpa           cpaClient
	server        *http.Server
	ctx           context.Context
	cancel        context.CancelFunc
	mu            sync.RWMutex
	syncAllMu     sync.Mutex
	runtimes      map[int64]*accountRuntime
	loginAttempts sync.Map
	reminderMu    sync.Mutex
	telegramMu    sync.Mutex
}

type accountRuntime struct {
	dash    Dashboard
	syncing sync.Mutex
}

type cpaClient interface {
	Configured() bool
	Snapshot(context.Context, string) (cliproxy.Snapshot, error)
}

const automaticSyncInterval = time.Duration(automaticSyncMinutes) * time.Minute

func New() (*App, error) {
	dir := env("DATA_DIR", "/data")
	s, err := store.Open(dir)
	if err != nil {
		return nil, err
	}
	v, err := security.OpenVault(dir)
	if err != nil {
		_ = s.DB.Close()
		return nil, err
	}
	ctx, cancel := context.WithCancel(context.Background())
	a := &App{
		dataDir:  dir,
		store:    s,
		vault:    v,
		cpa:      cliproxy.New(os.Getenv("CLIPROXY_API_BASE_URL"), os.Getenv("CLIPROXY_API_MANAGEMENT_KEY")),
		ctx:      ctx,
		cancel:   cancel,
		runtimes: map[int64]*accountRuntime{},
	}
	accounts, _ := s.Accounts()
	for _, account := range accounts {
		a.addRuntime(account.ID)
	}
	a.server = &http.Server{Addr: env("LISTEN_ADDR", ":8080"), Handler: a.routes(), ReadHeaderTimeout: 10 * time.Second, IdleTimeout: 60 * time.Second}
	return a, nil
}

func env(k, d string) string {
	if v := os.Getenv(k); v != "" {
		return v
	}
	return d
}

func (a *App) Run() error {
	go a.syncScheduler()
	go a.maintenanceScheduler()
	go a.telegramLoop()
	log.Printf("codex-helper listening on %s", a.server.Addr)
	err := a.server.ListenAndServe()
	if errors.Is(err, http.ErrServerClosed) {
		return nil
	}
	return err
}

func (a *App) Close() {
	a.cancel()
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	if a.server != nil {
		_ = a.server.Shutdown(ctx)
	}
	a.syncAllMu.Lock()
	a.syncAllMu.Unlock()
	_ = a.store.DB.Close()
}

func (a *App) addRuntime(id int64) {
	dashboard := Dashboard{AccountID: id, Limits: []LimitBucket{}, Usage: []UsagePoint{}, Stale: true}
	if account, err := a.store.Account(id); err == nil {
		dashboard.DisplayName = account.DisplayName
		dashboard.Account = AccountView{Email: account.Email, PlanType: account.PlanType, Connected: account.Connected}
	}
	a.mu.Lock()
	a.runtimes[id] = &accountRuntime{dash: dashboard}
	a.mu.Unlock()
}

func (a *App) runtime(id int64) *accountRuntime {
	a.mu.RLock()
	defer a.mu.RUnlock()
	return a.runtimes[id]
}

func (a *App) syncAll(ctx context.Context) {
	if !a.syncAllMu.TryLock() {
		return
	}
	defer a.syncAllMu.Unlock()
	if ctx.Err() != nil {
		return
	}
	a.mu.RLock()
	ids := make([]int64, 0, len(a.runtimes))
	for id := range a.runtimes {
		ids = append(ids, id)
	}
	a.mu.RUnlock()

	const maxConcurrentAccountSyncs = 4
	sem := make(chan struct{}, maxConcurrentAccountSyncs)
	var wg sync.WaitGroup
	for _, id := range ids {
		wg.Add(1)
		go func(accountID int64) {
			defer wg.Done()
			select {
			case sem <- struct{}{}:
				defer func() { <-sem }()
			case <-ctx.Done():
				return
			}
			_ = a.syncAccount(ctx, accountID)
		}(id)
	}
	wg.Wait()
}

func (a *App) syncScheduler() {
	a.syncAll(a.ctx)
	ticker := time.NewTicker(automaticSyncInterval)
	defer ticker.Stop()
	for {
		select {
		case <-a.ctx.Done():
			return
		case <-ticker.C:
			a.syncAll(a.ctx)
		}
	}
}

func (a *App) maintenanceScheduler() {
	ticker := time.NewTicker(time.Minute)
	defer ticker.Stop()
	for {
		select {
		case <-a.ctx.Done():
			return
		case <-ticker.C:
			g := a.general()
			_, _ = a.store.Cleanup(g.RetentionDays)
			go a.processReminders()
		}
	}
}

func (a *App) cpaConfigured() bool {
	return a.cpa != nil && a.cpa.Configured()
}

func (a *App) routes() http.Handler {
	m := http.NewServeMux()
	m.HandleFunc("/health/live", func(w http.ResponseWriter, r *http.Request) {
		jsonOut(w, http.StatusOK, map[string]any{"status": "ok"})
	})
	m.HandleFunc("/health/ready", func(w http.ResponseWriter, r *http.Request) {
		if err := a.store.Health(r.Context()); err != nil {
			jsonOut(w, http.StatusServiceUnavailable, map[string]string{"error": err.Error()})
			return
		}
		jsonOut(w, http.StatusOK, map[string]any{"status": "ok", "cpa": a.cpaConfigured()})
	})
	m.HandleFunc("/api/v1/", a.api)
	sub, _ := fs.Sub(webassets.Assets, "dist")
	files := http.FileServer(http.FS(sub))
	m.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
		if r.URL.Path != "/" {
			if _, err := fs.Stat(sub, strings.TrimPrefix(r.URL.Path, "/")); err == nil {
				files.ServeHTTP(w, r)
				return
			}
		}
		b, _ := fs.ReadFile(sub, "index.html")
		w.Header().Set("Content-Type", "text/html; charset=utf-8")
		_, _ = w.Write(b)
	})
	return securityHeaders(m)
}

func securityHeaders(next http.Handler) http.Handler {
	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("X-Content-Type-Options", "nosniff")
		w.Header().Set("X-Frame-Options", "DENY")
		w.Header().Set("Referrer-Policy", "same-origin")
		w.Header().Set("Content-Security-Policy", "default-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; connect-src 'self'")
		next.ServeHTTP(w, r)
	})
}

func jsonOut(w http.ResponseWriter, status int, v any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(v)
}

func decode(r *http.Request, v any) error {
	defer r.Body.Close()
	d := json.NewDecoder(io.LimitReader(r.Body, 1<<20))
	d.DisallowUnknownFields()
	return d.Decode(v)
}

func (a *App) authed(r *http.Request) bool {
	c, err := r.Cookie("session")
	if err != nil {
		return false
	}
	var x int
	return a.store.DB.QueryRow("SELECT 1 FROM sessions WHERE token_hash=? AND expires_at>?", security.HashToken(c.Value), time.Now().Unix()).Scan(&x) == nil
}

func (a *App) require(w http.ResponseWriter, r *http.Request) bool {
	if !a.authed(r) {
		jsonOut(w, http.StatusUnauthorized, map[string]string{"error": "未登录"})
		return false
	}
	if r.Method != http.MethodGet && r.Method != http.MethodHead && r.Header.Get("X-Requested-With") != "codex-helper" {
		jsonOut(w, http.StatusForbidden, map[string]string{"error": "请求来源校验失败"})
		return false
	}
	return true
}

// Keep an explicit embed reference visible to tooling.
var _ embed.FS