package api

import (
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"strconv"
	"sync"
	"time"

	authpkg "fuego/internal/auth"
	"fuego/internal/database"
	"fuego/internal/storage"
	"fuego/pkg/types"

	"github.com/go-chi/chi/v5"
	"github.com/go-chi/chi/v5/middleware"
	"github.com/go-chi/cors"
	"github.com/gorilla/websocket"
)

// Server represents the API server
type Server struct {
	db      *database.DB
	auth    *authpkg.Auth
	secrets *authpkg.Secrets
	storage *storage.Storage
	router  *chi.Mux

	// WebSocket connections
	wsUpgrader      websocket.Upgrader
	runnerConns     map[int64]*websocket.Conn
	runnerConnsMu   sync.RWMutex
	frontendConns   map[string]*websocket.Conn // key: "jobId:taskId"
	frontendConnsMu sync.RWMutex
}

// NewServer creates a new API server
func NewServer(db *database.DB, auth *authpkg.Auth, storage *storage.Storage) (*Server, error) {
	secrets, err := authpkg.NewSecrets(db.DB)
	if err != nil {
		return nil, fmt.Errorf("failed to initialize secrets: %w", err)
	}

	s := &Server{
		db:      db,
		auth:    auth,
		secrets: secrets,
		storage: storage,
		router:  chi.NewRouter(),
		wsUpgrader: websocket.Upgrader{
			CheckOrigin: func(r *http.Request) bool {
				return true // Allow all origins for now
			},
			ReadBufferSize:  1024,
			WriteBufferSize: 1024,
		},
		runnerConns:   make(map[int64]*websocket.Conn),
		frontendConns: make(map[string]*websocket.Conn),
	}

	s.setupMiddleware()
	s.setupRoutes()
	s.StartBackgroundTasks()

	return s, nil
}

// setupMiddleware configures middleware
func (s *Server) setupMiddleware() {
	s.router.Use(middleware.Logger)
	s.router.Use(middleware.Recoverer)
	s.router.Use(middleware.Timeout(60 * time.Second))

	s.router.Use(cors.Handler(cors.Options{
		AllowedOrigins:   []string{"*"},
		AllowedMethods:   []string{"GET", "POST", "PUT", "DELETE", "OPTIONS"},
		AllowedHeaders:   []string{"Accept", "Authorization", "Content-Type"},
		ExposedHeaders:   []string{"Link"},
		AllowCredentials: true,
		MaxAge:           300,
	}))
}

// setupRoutes configures routes
func (s *Server) setupRoutes() {
	// Public routes
	s.router.Route("/api/auth", func(r chi.Router) {
		r.Get("/google/login", s.handleGoogleLogin)
		r.Get("/google/callback", s.handleGoogleCallback)
		r.Get("/discord/login", s.handleDiscordLogin)
		r.Get("/discord/callback", s.handleDiscordCallback)
		r.Post("/logout", s.handleLogout)
		r.Get("/me", s.handleGetMe)
	})

	// Protected routes
	s.router.Route("/api/jobs", func(r chi.Router) {
		r.Use(func(next http.Handler) http.Handler {
			return http.HandlerFunc(s.auth.Middleware(next.ServeHTTP))
		})
		r.Post("/", s.handleCreateJob)
		r.Get("/", s.handleListJobs)
		r.Get("/{id}", s.handleGetJob)
		r.Delete("/{id}", s.handleCancelJob)
		r.Post("/{id}/upload", s.handleUploadJobFile)
		r.Get("/{id}/files", s.handleListJobFiles)
		r.Get("/{id}/files/{fileId}/download", s.handleDownloadJobFile)
		r.Get("/{id}/video", s.handleStreamVideo)
		r.Get("/{id}/metadata", s.handleGetJobMetadata)
		r.Get("/{id}/tasks", s.handleListJobTasks)
		r.Get("/{id}/tasks/{taskId}/logs", s.handleGetTaskLogs)
		r.Get("/{id}/tasks/{taskId}/logs/ws", s.handleStreamTaskLogsWebSocket)
		r.Get("/{id}/tasks/{taskId}/steps", s.handleGetTaskSteps)
		r.Post("/{id}/tasks/{taskId}/retry", s.handleRetryTask)
	})

	s.router.Route("/api/runners", func(r chi.Router) {
		r.Use(func(next http.Handler) http.Handler {
			return http.HandlerFunc(s.auth.Middleware(next.ServeHTTP))
		})
		r.Get("/", s.handleListRunners)
	})

	// Admin routes
	s.router.Route("/api/admin", func(r chi.Router) {
		r.Use(func(next http.Handler) http.Handler {
			return http.HandlerFunc(s.auth.AdminMiddleware(next.ServeHTTP))
		})
		r.Route("/runners", func(r chi.Router) {
			r.Route("/tokens", func(r chi.Router) {
				r.Post("/", s.handleGenerateRegistrationToken)
				r.Get("/", s.handleListRegistrationTokens)
				r.Delete("/{id}", s.handleRevokeRegistrationToken)
			})
			r.Get("/", s.handleListRunnersAdmin)
			r.Post("/{id}/verify", s.handleVerifyRunner)
			r.Delete("/{id}", s.handleDeleteRunner)
		})
	})

	// Runner API
	s.router.Route("/api/runner", func(r chi.Router) {
		// Registration doesn't require auth (uses token)
		r.Post("/register", s.handleRegisterRunner)

		// WebSocket endpoint (auth handled in handler)
		r.Get("/ws", s.handleRunnerWebSocket)

		// File operations still use HTTP (WebSocket not suitable for large files)
		r.Group(func(r chi.Router) {
			r.Use(func(next http.Handler) http.Handler {
				return http.HandlerFunc(s.runnerAuthMiddleware(next.ServeHTTP))
			})
			r.Post("/tasks/{id}/progress", s.handleUpdateTaskProgress)
			r.Post("/tasks/{id}/steps", s.handleUpdateTaskStep)
			r.Get("/files/{jobId}/{fileName}", s.handleDownloadFileForRunner)
			r.Post("/files/{jobId}/upload", s.handleUploadFileFromRunner)
			r.Get("/jobs/{jobId}/status", s.handleGetJobStatusForRunner)
			r.Get("/jobs/{jobId}/files", s.handleGetJobFilesForRunner)
			r.Post("/jobs/{jobId}/metadata", s.handleSubmitMetadata)
		})
	})

	// Serve static files (built React app)
	s.router.Handle("/*", http.FileServer(http.Dir("./web/dist")))
}

// ServeHTTP implements http.Handler
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	s.router.ServeHTTP(w, r)
}

// JSON response helpers
func (s *Server) respondJSON(w http.ResponseWriter, status int, data interface{}) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	if err := json.NewEncoder(w).Encode(data); err != nil {
		log.Printf("Failed to encode JSON response: %v", err)
	}
}

func (s *Server) respondError(w http.ResponseWriter, status int, message string) {
	s.respondJSON(w, status, map[string]string{"error": message})
}

// Auth handlers
func (s *Server) handleGoogleLogin(w http.ResponseWriter, r *http.Request) {
	url, err := s.auth.GoogleLoginURL()
	if err != nil {
		s.respondError(w, http.StatusInternalServerError, err.Error())
		return
	}
	http.Redirect(w, r, url, http.StatusFound)
}

func (s *Server) handleGoogleCallback(w http.ResponseWriter, r *http.Request) {
	code := r.URL.Query().Get("code")
	if code == "" {
		s.respondError(w, http.StatusBadRequest, "Missing code parameter")
		return
	}

	session, err := s.auth.GoogleCallback(r.Context(), code)
	if err != nil {
		s.respondError(w, http.StatusInternalServerError, err.Error())
		return
	}

	sessionID := s.auth.CreateSession(session)
	http.SetCookie(w, &http.Cookie{
		Name:     "session_id",
		Value:    sessionID,
		Path:     "/",
		MaxAge:   86400,
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
	})

	http.Redirect(w, r, "/", http.StatusFound)
}

func (s *Server) handleDiscordLogin(w http.ResponseWriter, r *http.Request) {
	url, err := s.auth.DiscordLoginURL()
	if err != nil {
		s.respondError(w, http.StatusInternalServerError, err.Error())
		return
	}
	http.Redirect(w, r, url, http.StatusFound)
}

func (s *Server) handleDiscordCallback(w http.ResponseWriter, r *http.Request) {
	code := r.URL.Query().Get("code")
	if code == "" {
		s.respondError(w, http.StatusBadRequest, "Missing code parameter")
		return
	}

	session, err := s.auth.DiscordCallback(r.Context(), code)
	if err != nil {
		s.respondError(w, http.StatusInternalServerError, err.Error())
		return
	}

	sessionID := s.auth.CreateSession(session)
	http.SetCookie(w, &http.Cookie{
		Name:     "session_id",
		Value:    sessionID,
		Path:     "/",
		MaxAge:   86400,
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
	})

	http.Redirect(w, r, "/", http.StatusFound)
}

func (s *Server) handleLogout(w http.ResponseWriter, r *http.Request) {
	cookie, err := r.Cookie("session_id")
	if err == nil {
		s.auth.DeleteSession(cookie.Value)
	}
	http.SetCookie(w, &http.Cookie{
		Name:     "session_id",
		Value:    "",
		Path:     "/",
		MaxAge:   -1,
		HttpOnly: true,
	})
	s.respondJSON(w, http.StatusOK, map[string]string{"message": "Logged out"})
}

func (s *Server) handleGetMe(w http.ResponseWriter, r *http.Request) {
	cookie, err := r.Cookie("session_id")
	if err != nil {
		s.respondError(w, http.StatusUnauthorized, "Not authenticated")
		return
	}

	session, ok := s.auth.GetSession(cookie.Value)
	if !ok {
		s.respondError(w, http.StatusUnauthorized, "Invalid session")
		return
	}

	s.respondJSON(w, http.StatusOK, map[string]interface{}{
		"id":       session.UserID,
		"email":    session.Email,
		"name":     session.Name,
		"is_admin": session.IsAdmin,
	})
}

// Helper to get user ID from context
func getUserID(r *http.Request) (int64, error) {
	userID, ok := authpkg.GetUserID(r.Context())
	if !ok {
		return 0, fmt.Errorf("user ID not found in context")
	}
	return userID, nil
}

// Helper to parse ID from URL
func parseID(r *http.Request, param string) (int64, error) {
	idStr := chi.URLParam(r, param)
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil {
		return 0, fmt.Errorf("invalid ID: %s", idStr)
	}
	return id, nil
}

// StartBackgroundTasks starts background goroutines for error recovery
func (s *Server) StartBackgroundTasks() {
	go s.recoverStuckTasks()
}

// recoverStuckTasks periodically checks for dead runners and stuck tasks
func (s *Server) recoverStuckTasks() {
	ticker := time.NewTicker(10 * time.Second)
	defer ticker.Stop()

	// Also distribute tasks every 5 seconds
	distributeTicker := time.NewTicker(5 * time.Second)
	defer distributeTicker.Stop()

	go func() {
		for range distributeTicker.C {
			s.distributeTasksToRunners()
		}
	}()

	for range ticker.C {
		func() {
			defer func() {
				if r := recover(); r != nil {
					log.Printf("Panic in recoverStuckTasks: %v", r)
				}
			}()

			// Find dead runners (no heartbeat for 90 seconds)
			rows, err := s.db.Query(
				`SELECT id FROM runners 
				 WHERE last_heartbeat < datetime('now', '-90 seconds')
				   AND status = ?`,
				types.RunnerStatusOnline,
			)
			if err != nil {
				log.Printf("Failed to query dead runners: %v", err)
				return
			}
			defer rows.Close()

			var deadRunnerIDs []int64
			for rows.Next() {
				var runnerID int64
				if err := rows.Scan(&runnerID); err == nil {
					deadRunnerIDs = append(deadRunnerIDs, runnerID)
				}
			}
			rows.Close()

			if len(deadRunnerIDs) == 0 {
				// Check for task timeouts
				s.recoverTaskTimeouts()
				return
			}

			// Reset tasks assigned to dead runners
			for _, runnerID := range deadRunnerIDs {
				// Get tasks assigned to this runner
				taskRows, err := s.db.Query(
					`SELECT id, retry_count, max_retries FROM tasks 
					 WHERE runner_id = ? AND status = ?`,
					runnerID, types.TaskStatusRunning,
				)
				if err != nil {
					log.Printf("Failed to query tasks for runner %d: %v", runnerID, err)
					continue
				}

				var tasksToReset []struct {
					ID         int64
					RetryCount int
					MaxRetries int
				}

				for taskRows.Next() {
					var t struct {
						ID         int64
						RetryCount int
						MaxRetries int
					}
					if err := taskRows.Scan(&t.ID, &t.RetryCount, &t.MaxRetries); err == nil {
						tasksToReset = append(tasksToReset, t)
					}
				}
				taskRows.Close()

				// Reset or fail tasks
				for _, task := range tasksToReset {
					if task.RetryCount >= task.MaxRetries {
						// Mark as failed
						_, err = s.db.Exec(
							`UPDATE tasks SET status = ?, error_message = ?, runner_id = NULL 
							 WHERE id = ?`,
							types.TaskStatusFailed, "Runner died, max retries exceeded", task.ID,
						)
						if err != nil {
							log.Printf("Failed to mark task %d as failed: %v", task.ID, err)
						}
					} else {
						// Reset to pending
						_, err = s.db.Exec(
							`UPDATE tasks SET status = ?, runner_id = NULL, current_step = NULL,
							 retry_count = retry_count + 1 WHERE id = ?`,
							types.TaskStatusPending, task.ID,
						)
						if err != nil {
							log.Printf("Failed to reset task %d: %v", task.ID, err)
						} else {
							// Add log entry
							_, _ = s.db.Exec(
								`INSERT INTO task_logs (task_id, log_level, message, step_name, created_at)
								 VALUES (?, ?, ?, ?, ?)`,
								task.ID, types.LogLevelWarn, fmt.Sprintf("Runner died, task reset (retry %d/%d)", task.RetryCount+1, task.MaxRetries),
								"", time.Now(),
							)
						}
					}
				}

				// Mark runner as offline
				_, _ = s.db.Exec(
					`UPDATE runners SET status = ? WHERE id = ?`,
					types.RunnerStatusOffline, runnerID,
				)
			}

			// Check for task timeouts
			s.recoverTaskTimeouts()

			// Distribute newly recovered tasks
			s.distributeTasksToRunners()
		}()
	}
}

// recoverTaskTimeouts handles tasks that have exceeded their timeout
func (s *Server) recoverTaskTimeouts() {
	// Find tasks running longer than their timeout
	rows, err := s.db.Query(
		`SELECT t.id, t.runner_id, t.retry_count, t.max_retries, t.timeout_seconds, t.started_at
		 FROM tasks t
		 WHERE t.status = ?
		   AND t.started_at IS NOT NULL
		   AND (t.timeout_seconds IS NULL OR 
		        datetime(t.started_at, '+' || t.timeout_seconds || ' seconds') < datetime('now'))`,
		types.TaskStatusRunning,
	)
	if err != nil {
		log.Printf("Failed to query timed out tasks: %v", err)
		return
	}
	defer rows.Close()

	for rows.Next() {
		var taskID int64
		var runnerID sql.NullInt64
		var retryCount, maxRetries int
		var timeoutSeconds sql.NullInt64
		var startedAt time.Time

		err := rows.Scan(&taskID, &runnerID, &retryCount, &maxRetries, &timeoutSeconds, &startedAt)
		if err != nil {
			continue
		}

		// Use default timeout if not set (5 minutes for frame tasks, 24 hours for FFmpeg)
		timeout := 300 // 5 minutes default
		if timeoutSeconds.Valid {
			timeout = int(timeoutSeconds.Int64)
		}

		// Check if actually timed out
		if time.Since(startedAt).Seconds() < float64(timeout) {
			continue
		}

		if retryCount >= maxRetries {
			// Mark as failed
			_, err = s.db.Exec(
				`UPDATE tasks SET status = ?, error_message = ?, runner_id = NULL 
				 WHERE id = ?`,
				types.TaskStatusFailed, "Task timeout exceeded, max retries reached", taskID,
			)
		} else {
			// Reset to pending
			_, err = s.db.Exec(
				`UPDATE tasks SET status = ?, runner_id = NULL, current_step = NULL,
				 retry_count = retry_count + 1 WHERE id = ?`,
				types.TaskStatusPending, taskID,
			)
			if err == nil {
				// Add log entry
				_, _ = s.db.Exec(
					`INSERT INTO task_logs (task_id, log_level, message, step_name, created_at)
					 VALUES (?, ?, ?, ?, ?)`,
					taskID, types.LogLevelWarn, fmt.Sprintf("Task timeout exceeded, resetting (retry %d/%d)", retryCount+1, maxRetries),
					"", time.Now(),
				)
			}
		}
	}
}