package handlers

import (
	"encoding/json"
	"net/http"
	"strconv"

	"github.com/jmoiron/sqlx"

	"mgit.msbls.de/m/KanzlAI-mGMT/internal/auth"
	"mgit.msbls.de/m/KanzlAI-mGMT/internal/services"
)

// NotificationHandler handles notification API endpoints.
type NotificationHandler struct {
	svc *services.NotificationService
	db  *sqlx.DB
}

// NewNotificationHandler creates a new notification handler.
func NewNotificationHandler(svc *services.NotificationService, db *sqlx.DB) *NotificationHandler {
	return &NotificationHandler{svc: svc, db: db}
}

// List returns paginated notifications for the authenticated user.
func (h *NotificationHandler) List(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	limit, _ := strconv.Atoi(r.URL.Query().Get("limit"))
	offset, _ := strconv.Atoi(r.URL.Query().Get("offset"))

	notifications, total, err := h.svc.ListForUser(r.Context(), tenantID, userID, limit, offset)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to list notifications")
		return
	}

	writeJSON(w, http.StatusOK, map[string]any{
		"data":  notifications,
		"total": total,
	})
}

// UnreadCount returns the count of unread notifications.
func (h *NotificationHandler) UnreadCount(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	count, err := h.svc.UnreadCount(r.Context(), tenantID, userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to count notifications")
		return
	}

	writeJSON(w, http.StatusOK, map[string]int{"unread_count": count})
}

// MarkRead marks a single notification as read.
func (h *NotificationHandler) MarkRead(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	notifID, err := parsePathUUID(r, "id")
	if err != nil {
		writeError(w, http.StatusBadRequest, "invalid notification ID")
		return
	}

	if err := h.svc.MarkRead(r.Context(), tenantID, userID, notifID); err != nil {
		writeError(w, http.StatusNotFound, err.Error())
		return
	}

	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// MarkAllRead marks all notifications as read.
func (h *NotificationHandler) MarkAllRead(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	if err := h.svc.MarkAllRead(r.Context(), tenantID, userID); err != nil {
		writeError(w, http.StatusInternalServerError, "failed to mark all read")
		return
	}

	writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
}

// GetPreferences returns notification preferences for the authenticated user.
func (h *NotificationHandler) GetPreferences(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	pref, err := h.svc.GetPreferences(r.Context(), tenantID, userID)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to get preferences")
		return
	}

	writeJSON(w, http.StatusOK, pref)
}

// UpdatePreferences updates notification preferences for the authenticated user.
func (h *NotificationHandler) UpdatePreferences(w http.ResponseWriter, r *http.Request) {
	tenantID, ok := auth.TenantFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}
	userID, ok := auth.UserFromContext(r.Context())
	if !ok {
		writeError(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	var input services.UpdatePreferencesInput
	if err := json.NewDecoder(r.Body).Decode(&input); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body")
		return
	}

	pref, err := h.svc.UpdatePreferences(r.Context(), tenantID, userID, input)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to update preferences")
		return
	}

	writeJSON(w, http.StatusOK, pref)
}