package handler

import (
	"encoding/json"
	"net/http"
	"strconv"
	"api_es/internal/dto"
	appMiddleware "api_es/internal/middleware"
	"api_es/internal/service"

	"github.com/go-chi/chi/v5"
	"github.com/go-playground/validator/v10"
)

type UserHandler struct {
	userService service.UserService
	validator   *validator.Validate
}

func NewUserHandler(userService service.UserService) *UserHandler {
	return &UserHandler{
		userService: userService,
		validator:   validator.New(),
	}
}

// Register godoc
// @Summary Register new user
// @Description Create a new user account
// @Tags auth
// @Accept json
// @Produce json
// @Param request body dto.RegisterRequest true "Register request"
// @Success 201 {object} dto.AuthResponse
// @Failure 400 {object} map[string]string
// @Failure 500 {object} map[string]string
// @Router /auth/register [post]
func (h *UserHandler) Register(w http.ResponseWriter, r *http.Request) {
	var req dto.RegisterRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	if err := h.validator.Struct(req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	response, err := h.userService.Register(r.Context(), req)
	if err != nil {
		switch err {
		case service.ErrUserAlreadyExists:
			http.Error(w, "User already exists", http.StatusConflict)
		default:
			http.Error(w, "Internal server error", http.StatusInternalServerError)
		}
		return
	}

	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(response)
}

// Login godoc
// @Summary Login user
// @Description Authenticate user and get token
// @Tags auth
// @Accept json
// @Produce json
// @Param request body dto.LoginRequest true "Login request"
// @Success 200 {object} dto.AuthResponse
// @Failure 400 {object} map[string]string
// @Failure 401 {object} map[string]string
// @Router /auth/login [post]
func (h *UserHandler) Login(w http.ResponseWriter, r *http.Request) {
	var req dto.LoginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	if err := h.validator.Struct(req); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	response, err := h.userService.Login(r.Context(), req)
	if err != nil {
		switch err {
		case service.ErrInvalidCredentials:
			http.Error(w, "Invalid credentials", http.StatusUnauthorized)
		default:
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(response)
}

// GetProfile godoc
// @Summary Get user profile
// @Description Get current user profile
// @Tags users
// @Accept json
// @Produce json
// @Security BearerAuth
// @Success 200 {object} dto.UserResponse
// @Failure 404 {object} map[string]string
// @Router /users/profile [get]
func (h *UserHandler) GetProfile(w http.ResponseWriter, r *http.Request) {
	userID, ok := r.Context().Value(appMiddleware.UserIDKey).(uint)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	user, err := h.userService.GetUserProfile(r.Context(), userID)
	if err != nil {
		http.Error(w, "User not found", http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(user)
}

// UpdateProfile godoc
// @Summary Update user profile
// @Description Update current user profile
// @Tags users
// @Accept json
// @Produce json
// @Security BearerAuth
// @Param request body dto.UpdateUserRequest true "Update request"
// @Success 200 {object} dto.UserResponse
// @Failure 400 {object} map[string]string
// @Router /users/profile [put]
func (h *UserHandler) UpdateProfile(w http.ResponseWriter, r *http.Request) {
	userID, ok := r.Context().Value(appMiddleware.UserIDKey).(uint)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}

	var req dto.UpdateUserRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, "Invalid request body", http.StatusBadRequest)
		return
	}

	user, err := h.userService.UpdateUser(r.Context(), userID, req)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(user)
}

// GetUser godoc
// @Summary Get user by ID
// @Description Get user details by ID (admin only)
// @Tags users
// @Accept json
// @Produce json
// @Security BearerAuth
// @Param id path int true "User ID"
// @Success 200 {object} dto.UserResponse
// @Failure 404 {object} map[string]string
// @Router /users/{id} [get]
func (h *UserHandler) GetUser(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	id, err := strconv.ParseUint(idStr, 10, 32)
	if err != nil {
		http.Error(w, "Invalid user ID", http.StatusBadRequest)
		return
	}

	user, err := h.userService.GetUser(r.Context(), uint(id))
	if err != nil {
		http.Error(w, "User not found", http.StatusNotFound)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(user)
}

// ListUsers godoc
// @Summary List users
// @Description Get paginated list of users (admin only)
// @Tags users
// @Accept json
// @Produce json
// @Security BearerAuth
// @Param limit query int false "Limit" default(10)
// @Param offset query int false "Offset" default(0)
// @Success 200 {array} dto.UserResponse
// @Router /users [get]
func (h *UserHandler) ListUsers(w http.ResponseWriter, r *http.Request) {
	limitStr := r.URL.Query().Get("limit")
	offsetStr := r.URL.Query().Get("offset")

	limit := 10
	offset := 0

	if limitStr != "" {
		if l, err := strconv.Atoi(limitStr); err == nil {
			limit = l
		}
	}

	if offsetStr != "" {
		if o, err := strconv.Atoi(offsetStr); err == nil {
			offset = o
		}
	}

	users, err := h.userService.ListUsers(r.Context(), limit, offset)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(users)
}

func (h *UserHandler) Routes(r chi.Router) chi.Router {

	r.Route("/auth", func(r chi.Router) {
		r.Post("/register", h.Register)
		r.Post("/login", h.Login)
	})

	r.Route("/users", func(r chi.Router) {
		r.Use(appMiddleware.AuthMiddleware)

		r.Get("/profile", h.GetProfile)
		r.Put("/profile", h.UpdateProfile)

		// Admin routes
		r.With(appMiddleware.AdminMiddleware).Get("/", h.ListUsers)
		r.With(appMiddleware.AdminMiddleware).Get("/{id}", h.GetUser)
	})

	return r
}