package bookings

import (
	"crussell/db"
	"crussell/handlers/notifications"
	"crussell/mw"
	"database/sql"
	"encoding/json"
	"log"
	"net/http"
	"time"

	"github.com/go-chi/chi/v5"
)

// UserCancelBookingHandler allows an authenticated user to cancel a booking they own.
// The update is performed in a transaction with notification handling.
func UserCancelBookingHandler(w http.ResponseWriter, r *http.Request) {
	bookingID := chi.URLParam(r, "id")

	userID, ok := r.Context().Value(mw.UserIDKey).(string)
	if !ok || userID == "" {
		http.Error(w, "Authentication required", http.StatusUnauthorized)
		return
	}

	tx, err := db.DB.Begin(r.Context())
	if err != nil {
		log.Printf("Failed to start transaction: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	defer tx.Rollback(r.Context())

	// Get current status before updating
	var originalStatus string
	err = tx.QueryRow(r.Context(), "SELECT status FROM bookings WHERE id = $1 AND user_id = $2", bookingID, userID).Scan(&originalStatus)
	if err != nil {
		if err == sql.ErrNoRows {
			http.Error(w, "Booking not cancellable", http.StatusNotFound)
			return
		}
		log.Printf("Failed to get booking status %s: %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	res, err := tx.Exec(r.Context(), `
		UPDATE bookings
		SET status = 'client_cancelled', updated_at = $1
		WHERE id = $2 AND user_id = $3 AND status IN ('pending', 'confirmed', 'in_progress')
	`, time.Now(), bookingID, userID)
	if err != nil {
		log.Printf("Failed to cancel booking %s: %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	rowsAffected := res.RowsAffected()
	if rowsAffected == 0 {
		http.Error(w, "Booking not cancellable", http.StatusNotFound)
		return
	}

	// Acknowledge pending notification if exists
	if err := notifications.AcknowledgePendingBookingNotification(tx, r.Context(), bookingID); err != nil {
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Only notify on cancellation if booking was not pending (e.g. confirmed, in_progress)
	if originalStatus != "pending" {
		notificationQuery := `
			INSERT INTO admin_notifications (reason, booking_id, user_id)
			VALUES ($1, $2, $3)
		`
		_, err = tx.Exec(r.Context(), notificationQuery, "cancelled_booking", bookingID, userID)
		if err != nil {
			log.Printf("Failed to create admin notification for booking %s: %v", bookingID, err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
			return
		}
	}

	if err := tx.Commit(r.Context()); err != nil {
		log.Printf("Failed to commit user cancel: %v, %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// AdminCancelBookingHandler allows an admin to cancel any booking.
// The update uses a status filter and checks RowsAffected for existence.
func AdminCancelBookingHandler(w http.ResponseWriter, r *http.Request) {
	bookingID := chi.URLParam(r, "id")

	tx, err := db.DB.Begin(r.Context())
	if err != nil {
		log.Printf("Failed to start transaction: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	defer tx.Rollback(r.Context())

	// Get current status before updating
	var originalStatus string
	err = tx.QueryRow(r.Context(), "SELECT status FROM bookings WHERE id = $1", bookingID).Scan(&originalStatus)
	if err != nil {
		if err == sql.ErrNoRows {
			http.Error(w, "Booking not cancellable", http.StatusNotFound)
			return
		}
		log.Printf("Failed to get booking status %s: %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	res, err := tx.Exec(r.Context(), `
		UPDATE bookings
		SET status = 'we_cancelled', updated_at = $1
		WHERE id = $2 AND status IN ('pending', 'confirmed', 'in_progress')
	`, time.Now(), bookingID)
	if err != nil {
		log.Printf("Failed to admin cancel booking %s: %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	rowsAffected := res.RowsAffected()
	if rowsAffected == 0 {
		http.Error(w, "Booking not cancellable", http.StatusNotFound)
		return
	}

	// Acknowledge pending notification if exists
	if err := notifications.AcknowledgePendingBookingNotification(tx, r.Context(), bookingID); err != nil {
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Only notify on cancellation if booking was not pending (e.g. confirmed, in_progress)
	if originalStatus != "pending" {
		notificationQuery := `
			INSERT INTO admin_notifications (reason, booking_id, user_id)
			SELECT 'cancelled_booking', $1, user_id FROM bookings WHERE id = $1
		`
		_, err = tx.Exec(r.Context(), notificationQuery, bookingID)
		if err != nil {
			log.Printf("Failed to create admin notification for booking %s: %v", bookingID, err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
			return
		}
	}

	if err := tx.Commit(r.Context()); err != nil {
		log.Printf("Failed to commit admin cancel: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// AdminListPendingBookingsHandler returns all bookings with status `pending` by delegating to the existing admin list handler.
func AdminListPendingBookingsHandler(w http.ResponseWriter, r *http.Request) {
	r = r.Clone(r.Context())
	q := r.URL.Query()
	q.Set("status", "pending")
	r.URL.RawQuery = q.Encode()

	GetAllAdminBookingsHandler(w, r)
}

// AdminGetInProgressBookingHandler returns the booking that is currently in progress.
// It joins the bookings table with users to populate the UserSummary in the returned Booking.
func AdminGetInProgressBookingHandler(w http.ResponseWriter, r *http.Request) {
	var b Booking
	var userID, fullName string

	err := db.DB.QueryRow(r.Context(), `
		SELECT
			b.id,
			b.start_time,
			b.status,
			b.notes,
			b.created_at,
			b.updated_at,
			b.created_by,
			u.id,
			u.fn
		FROM bookings b
		LEFT JOIN users u ON b.user_id = u.id
		WHERE b.status = 'in_progress'
		ORDER BY b.start_time
		LIMIT 1
	`).Scan(
		&b.ID,
		&b.StartTime,
		&b.Status,
		&b.Notes,
		&b.CreatedAt,
		&b.UpdatedAt,
		&b.CreatedBy,
		&userID,
		&fullName,
	)
	if err != nil {
		if err == sql.ErrNoRows {
			http.Error(w, "No in-progress booking found", http.StatusNotFound)
			return
		}
		log.Printf("Failed to fetch in-progress booking: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Populate the UserSummary field
	b.User = &UserSummary{
		ID:        userID,
		FullName:  fullName,
		FirstName: "", // not available here
		LastName:  "", // not available here
	}

	w.Header().Set("Content-Type", "application/json")
	if err := json.NewEncoder(w).Encode(b); err != nil {
		log.Printf("Failed to encode booking response: %v", err)
	}
}

// AdminEditBookingHandler allows an admin to modify the start time of any booking.
// It validates the new start time and returns 404 if the booking does not exist.
func AdminEditBookingHandler(w http.ResponseWriter, r *http.Request) {
	bookingID := chi.URLParam(r, "id")
	var req EditBookingRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	// Basic validation: ensure the new time is not in the past
	if time.Now().After(req.StartTime) {
		http.Error(w, "Start time must be in the future", http.StatusBadRequest)
		return
	}

	res, err := db.DB.Exec(r.Context(), `
		UPDATE bookings
		SET start_time = $1, updated_at = $2
		WHERE id = $3
	`, req.StartTime, time.Now(), bookingID)
	if err != nil {
		log.Printf("Failed to edit booking %s: %v", bookingID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	rowsAffected := res.RowsAffected()
	if rowsAffected == 0 {
		http.Error(w, "Booking not found", http.StatusNotFound)
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

type AdminCreateBookingForUserRequest struct {
	UserID           string            `json:"user_id" validate:"required"`
	StartTime        time.Time         `json:"start_time" validate:"required"`
	ServiceIDs       []string          `json:"service_ids" validate:"required,min=1"`
	ServiceOverrides []ServiceOverride `json:"service_overrides,omitempty"`
	Notes            *string           `json:"notes,omitempty"` // appointment notes, visible to customers and staff
}

func AdminCreateBookingForUserHandler(w http.ResponseWriter, r *http.Request) {
	// Admin identity (creator)
	adminID, ok := r.Context().Value(mw.UserIDKey).(string)
	if !ok || adminID == "" {
		http.Error(w, "Authentication required", http.StatusUnauthorized)
		return
	}

	var req AdminCreateBookingForUserRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		log.Printf("Failed to decode request: %v", err)
		http.Error(w, "Invalid request", http.StatusBadRequest)
		return
	}

	// Basic validation
	if req.UserID == "" {
		http.Error(w, "User ID is required", http.StatusBadRequest)
		return
	}
	if req.StartTime.IsZero() {
		http.Error(w, "Start time is required", http.StatusBadRequest)
		return
	}
	if len(req.ServiceIDs) == 0 {
		http.Error(w, "At least one service is required", http.StatusBadRequest)
		return
	}

	// Validate overrides
	for _, override := range req.ServiceOverrides {
		if override.ServiceID == "" {
			http.Error(w, "Service ID is required for overrides", http.StatusBadRequest)
			return
		}
		if override.OverridePrice != nil && *override.OverridePrice < 0 {
			http.Error(w, "Override price cannot be negative", http.StatusBadRequest)
			return
		}
		if override.OverrideDurationMinutes != nil && *override.OverrideDurationMinutes <= 0 {
			http.Error(w, "Override duration must be positive", http.StatusBadRequest)
			return
		}
	}

	tx, err := db.DB.Begin(r.Context())
	if err != nil {
		log.Printf("Failed to start transaction: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	defer tx.Rollback(r.Context())

	// Create booking directly as confirmed
	bookingQuery := `
		INSERT INTO bookings (
			user_id,
			start_time,
			status,
			notes,
			created_by
		)
		VALUES ($1, $2, 'confirmed', $3, $4)
		RETURNING id, user_id, start_time, status, notes, created_at, updated_at, created_by
	`

	var booking Booking
	booking.User = &UserSummary{}

	err = tx.QueryRow(
		r.Context(),
		bookingQuery,
		req.UserID,
		req.StartTime,
		req.Notes,
		adminID,
	).Scan(
		&booking.ID,
		&booking.User.ID,
		&booking.StartTime,
		&booking.Status,
		&booking.Notes,
		&booking.CreatedAt,
		&booking.UpdatedAt,
		&booking.CreatedBy,
	)

	if err != nil {
		log.Printf("Failed to create admin booking: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Insert booking services
	serviceInsertQuery := `
		INSERT INTO booking_services (booking_id, service_id)
		VALUES ($1, $2)
	`

	for _, serviceID := range req.ServiceIDs {
		_, err := tx.Exec(r.Context(), serviceInsertQuery, booking.ID, serviceID)
		if err != nil {
			log.Printf("Failed to insert booking service %s: %v", serviceID, err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
			return
		}
	}

	// Apply overrides (optional)
	if len(req.ServiceOverrides) > 0 {
		// Ensure overrides only reference services in this booking
		serviceCheckQuery := `
			SELECT COUNT(*) FROM booking_services
			WHERE booking_id = $1 AND service_id = ANY($2)
		`

		overrideServiceIDs := make([]string, len(req.ServiceOverrides))
		for i, o := range req.ServiceOverrides {
			overrideServiceIDs[i] = o.ServiceID
		}

		var count int
		err = tx.QueryRow(
			r.Context(),
			serviceCheckQuery,
			booking.ID,
			overrideServiceIDs,
		).Scan(&count)

		if err != nil {
			log.Printf("Failed to verify service overrides: %v", err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
			return
		}

		if count != len(req.ServiceOverrides) {
			http.Error(w, "One or more service overrides do not belong to this booking", http.StatusBadRequest)
			return
		}

		overrideUpdateQuery := `
			UPDATE booking_services
			SET override_price = $1,
			    override_duration_minutes = $2
			WHERE booking_id = $3 AND service_id = $4
		`

		for _, override := range req.ServiceOverrides {
			_, err := tx.Exec(
				r.Context(),
				overrideUpdateQuery,
				override.OverridePrice,
				override.OverrideDurationMinutes,
				booking.ID,
				override.ServiceID,
			)
			if err != nil {
				log.Printf(
					"Failed to apply override (booking %s, service %s): %v",
					booking.ID,
					override.ServiceID,
					err,
				)
				http.Error(w, "Internal server error", http.StatusInternalServerError)
				return
			}
		}
	}

	if err := tx.Commit(r.Context()); err != nil {
		log.Printf("Failed to commit admin booking creation: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	if err := json.NewEncoder(w).Encode(booking); err != nil {
		log.Printf("Failed to encode response: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
	}
}