package api

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

	"dance-lessons-coach/pkg/user"

	"github.com/go-chi/chi/v5"
	"github.com/rs/zerolog/log"
)

// AuthHandler handles authentication-related HTTP requests
type AuthHandler struct {
	authService          user.AuthService
	userRepo             user.UserRepository
	passwordResetService user.PasswordResetService
}

// NewAuthHandler creates a new authentication handler
func NewAuthHandler(authService user.AuthService, userRepo user.UserRepository) *AuthHandler {
	passwordResetService := user.NewPasswordResetService(userRepo, authService.(*user.AuthServiceImpl))
	return &AuthHandler{
		authService:          authService,
		userRepo:             userRepo,
		passwordResetService: passwordResetService,
	}
}

// RegisterRoutes registers authentication routes
func (h *AuthHandler) RegisterRoutes(router chi.Router) {
	router.Post("/login", h.handleLogin)
	router.Post("/admin/login", h.handleAdminLogin)
	router.Post("/register", h.handleRegister)
	router.Post("/password-reset/request", h.handlePasswordResetRequest)
	router.Post("/password-reset/complete", h.handlePasswordResetComplete)
}

// LoginRequest represents a login request
type LoginRequest struct {
	Username string `json:"username" validate:"required,min=3,max=50"`
	Password string `json:"password" validate:"required,min=6"`
}

// LoginResponse represents a login response
type LoginResponse struct {
	Token string `json:"token"`
}

// handleLogin handles user login requests
func (h *AuthHandler) handleLogin(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req LoginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, `{"error":"invalid_request","message":"Invalid JSON request body"}`, http.StatusBadRequest)
		return
	}

	// Authenticate user
	user, err := h.authService.Authenticate(ctx, req.Username, req.Password)
	if err != nil {
		log.Trace().Ctx(ctx).Err(err).Str("username", req.Username).Msg("Authentication failed")
		http.Error(w, `{"error":"invalid_credentials","message":"Invalid username or password"}`, http.StatusUnauthorized)
		return
	}

	// Generate JWT token
	token, err := h.authService.GenerateJWT(ctx, user)
	if err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to generate JWT token")
		http.Error(w, `{"error":"server_error","message":"Failed to generate authentication token"}`, http.StatusInternalServerError)
		return
	}

	// Return token
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(LoginResponse{Token: token})
}

// handleAdminLogin handles admin login requests
func (h *AuthHandler) handleAdminLogin(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req LoginRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, `{"error":"invalid_request","message":"Invalid JSON request body"}`, http.StatusBadRequest)
		return
	}

	// Authenticate admin
	adminUser, err := h.authService.AdminAuthenticate(ctx, req.Password)
	if err != nil {
		log.Trace().Ctx(ctx).Err(err).Msg("Admin authentication failed")
		http.Error(w, `{"error":"invalid_credentials","message":"Invalid admin credentials"}`, http.StatusUnauthorized)
		return
	}

	// Generate JWT token
	token, err := h.authService.GenerateJWT(ctx, adminUser)
	if err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to generate JWT token for admin")
		http.Error(w, `{"error":"server_error","message":"Failed to generate authentication token"}`, http.StatusInternalServerError)
		return
	}

	// Return token
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(LoginResponse{Token: token})
}

// RegisterRequest represents a user registration request
type RegisterRequest struct {
	Username string `json:"username" validate:"required,min=3,max=50"`
	Password string `json:"password" validate:"required,min=6"`
}

// handleRegister handles user registration requests
func (h *AuthHandler) handleRegister(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req RegisterRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, `{"error":"invalid_request","message":"Invalid JSON request body"}`, http.StatusBadRequest)
		return
	}

	// Check if user already exists
	exists, err := h.userRepo.UserExists(ctx, req.Username)
	if err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to check if user exists")
		http.Error(w, `{"error":"server_error","message":"Failed to process registration"}`, http.StatusInternalServerError)
		return
	}
	if exists {
		http.Error(w, `{"error":"user_exists","message":"Username already taken"}`, http.StatusConflict)
		return
	}

	// Hash password
	hashedPassword, err := h.authService.HashPassword(ctx, req.Password)
	if err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to hash password")
		http.Error(w, `{"error":"server_error","message":"Failed to process registration"}`, http.StatusInternalServerError)
		return
	}

	// Create user
	newUser := &user.User{
		Username:     req.Username,
		PasswordHash: hashedPassword,
		IsAdmin:      false,
	}

	if err := h.userRepo.CreateUser(ctx, newUser); err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to create user")
		http.Error(w, `{"error":"server_error","message":"Failed to create user"}`, http.StatusInternalServerError)
		return
	}

	// Return success
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusCreated)
	json.NewEncoder(w).Encode(map[string]string{"message": "User registered successfully"})
}

// PasswordResetRequest represents a password reset request
type PasswordResetRequest struct {
	Username string `json:"username" validate:"required,min=3,max=50"`
}

// handlePasswordResetRequest handles password reset requests
func (h *AuthHandler) handlePasswordResetRequest(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req PasswordResetRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, `{"error":"invalid_request","message":"Invalid JSON request body"}`, http.StatusBadRequest)
		return
	}

	// Request password reset
	if err := h.passwordResetService.RequestPasswordReset(ctx, req.Username); err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to request password reset")
		http.Error(w, `{"error":"server_error","message":"Failed to process password reset request"}`, http.StatusInternalServerError)
		return
	}

	// Return success
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(map[string]string{"message": "Password reset allowed, user can now reset password"})
}

// PasswordResetCompleteRequest represents a password reset completion request
type PasswordResetCompleteRequest struct {
	Username    string `json:"username" validate:"required,min=3,max=50"`
	NewPassword string `json:"new_password" validate:"required,min=6"`
}

// handlePasswordResetComplete handles password reset completion requests
func (h *AuthHandler) handlePasswordResetComplete(w http.ResponseWriter, r *http.Request) {
	ctx := r.Context()

	var req PasswordResetCompleteRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		http.Error(w, `{"error":"invalid_request","message":"Invalid JSON request body"}`, http.StatusBadRequest)
		return
	}

	// Complete password reset
	if err := h.passwordResetService.CompletePasswordReset(ctx, req.Username, req.NewPassword); err != nil {
		log.Error().Ctx(ctx).Err(err).Msg("Failed to complete password reset")
		http.Error(w, `{"error":"server_error","message":"Failed to complete password reset"}`, http.StatusInternalServerError)
		return
	}

	// Return success
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(http.StatusOK)
	json.NewEncoder(w).Encode(map[string]string{"message": "Password reset completed successfully"})
}