package user

import (
	"bytes"
	"database/sql"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"
	"golang.org/x/text/cases"
	"golang.org/x/text/language"

	"crussell/db"
	"crussell/handlers/auth"
	"crussell/mw"
)

var titleCaser = cases.Title(language.English)

type UserProfile struct {
	ID               string  `json:"id"`
	Email            string  `json:"email"`
	FirstName        string  `json:"firstName"`
	LastName         string  `json:"lastName"`
	Phone            *string `json:"phone,omitempty"`
	DateOfBirth      *string `json:"dateOfBirth,omitempty"`
	Role             string  `json:"role"`
	LoyaltyStamps    int     `json:"loyaltyStamps"`
	ReferralCode     string  `json:"referralCode"`
	ReferralCodeUses int     `json:"referralCodeUses"`
	ProfilePicURL    *string `json:"profilePicUrl,omitempty"`
}

type UpdateProfileRequest struct {
	FirstName string `json:"firstName"`
	LastName  string `json:"lastName"`
	Phone     string `json:"phone"`
}

type AdminUserDetail struct {
	ID               string  `json:"id"`
	Email            *string `json:"email,omitempty"`
	FirstName        string  `json:"firstName"`
	LastName         string  `json:"lastName"`
	FullName         string  `json:"fullName"`
	Phone            *string `json:"phone,omitempty"`
	DateOfBirth      *string `json:"dateOfBirth,omitempty"`
	ProfilePicURL    *string `json:"profilePicUrl,omitempty"`
	AccountRole      string  `json:"accountRole"`
	AccountType      string  `json:"accountType"`
	LoyaltyStamps    int     `json:"loyaltyStamps"`
	ReferralCode     string  `json:"referralCode"`
	ReferralCodeUses int     `json:"referralCodeUses"`
	LastLoginAt      *string `json:"lastLoginAt,omitempty"`
	CreatedAt        string  `json:"createdAt"`
	UpdatedAt        string  `json:"updatedAt"`
	Notes            *string `json:"notes,omitempty"`

	// GDPR consent fields
	PrivacyPolicyConsent   bool    `json:"privacyPolicyConsent"`
	PolicyConsentUpdatedAt *string `json:"policyConsentUpdatedAt,omitempty"`
	DataRetentionConsent   bool    `json:"dataRetentionConsent"`
	DataConsentUpdatedAt   *string `json:"dataConsentUpdatedAt,omitempty"`

	// Social logins
	SocialLogins []SocialLogin `json:"socialLogins,omitempty"`
}

type SocialLogin struct {
	Provider  string `json:"provider"`
	CreatedAt string `json:"createdAt"`
}

type UserListItem struct {
	ID       string  `json:"id"`
	FullName string  `json:"fullName"`
	Email    *string `json:"email,omitempty"`
	Phone    *string `json:"phone,omitempty"`
}

type UserListResponse struct {
	Users      []UserListItem `json:"users"`
	Total      int            `json:"total"`
	Page       int            `json:"page"`
	PerPage    int            `json:"perPage"`
	TotalPages int            `json:"totalPages"`
}

// GET /api/user/profile
func GetProfileHandler(w http.ResponseWriter, r *http.Request) {
	userID, ok := mw.GetUserID(r.Context())
	if !ok {
		http.Error(w, "unauthorized", http.StatusUnauthorized)
		return
	}

	var user UserProfile
	err := db.DB.QueryRow(r.Context(), `
        SELECT
            id, email, n_first_name, n_last_name, phone,
            date_of_birth::text, account_role, loyalty_stamps,
            referral_code, profile_pic_url,
            (SELECT COUNT(*) FROM user_referrals WHERE referrer_id = users.id AND claimed_booking_id IS NOT NULL) AS referral_code_uses
        FROM users
        WHERE id = $1
    `, userID).Scan(
		&user.ID, &user.Email, &user.FirstName, &user.LastName,
		&user.Phone, &user.DateOfBirth, &user.Role,
		&user.LoyaltyStamps, &user.ReferralCode, &user.ProfilePicURL, &user.ReferralCodeUses,
	)

	if err != nil {
		http.Error(w, "user not found", http.StatusNotFound)
		return
	}

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

// PUT /api/user/profile
// updateCardDAV updates an existing contact in SabreDAV using user ID
func updateCardDAV(userID, firstName, lastName, email, phone, dob string) error {
	// Use user ID as filename - consistent with registration
	filename := fmt.Sprintf("%s.vcf", userID)
	url := fmt.Sprintf("http://nginx/dav/addressbooks/principals/default/default/%s", filename)

	// Create vCard with user ID as UID (no need to fetch existing)
	timestamp := time.Now().UTC().Format("20060102T150405Z")
	uid := fmt.Sprintf("%s@example.com", userID)

	vcard := fmt.Sprintf(`BEGIN:VCARD
VERSION:3.0
UID:%s
FN:%s %s
N:%s;%s;;;
EMAIL;TYPE=INTERNET:%s
TEL;TYPE=CELL:%s
BDAY:%s
REV:%s
END:VCARD`, uid, firstName, lastName, lastName, firstName, email, phone, dob, timestamp)

	// PUT updated vCard
	req, err := http.NewRequest("PUT", url, bytes.NewBufferString(vcard))
	if err != nil {
		return fmt.Errorf("failed to create request: %w", err)
	}

	req.Header.Set("Content-Type", "text/vcard; charset=utf-8")
	req.SetBasicAuth("admin", "admin")

	client := &http.Client{Timeout: 10 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("failed to update CardDAV: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("CardDAV returned status: %d", resp.StatusCode)
	}

	return nil
}

// PUT /api/user/profile
func UpdateProfileHandler(w http.ResponseWriter, r *http.Request) {
	userID, _ := mw.GetUserID(r.Context())

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

	// Normalize input
	req.FirstName = strings.TrimSpace(req.FirstName)
	req.LastName = strings.TrimSpace(req.LastName)
	req.Phone = strings.TrimSpace(req.Phone)

	// Required fields
	if req.FirstName == "" || req.LastName == "" || req.Phone == "" {
		http.Error(w, "first name, last name and phone are required", http.StatusBadRequest)
		return
	}

	// Validate names (unicode letters, spaces, hyphen, apostrophe, dot)
	nameRegex := regexp.MustCompile(`^[\p{L}\p{M}\s\-'\.]+$`)

	if !nameRegex.MatchString(req.FirstName) || !nameRegex.MatchString(req.LastName) {
		http.Error(w, "invalid characters in name", http.StatusBadRequest)
		return
	}

	// Validate lengths
	if len(req.FirstName) < 1 || len(req.FirstName) > 50 {
		http.Error(w, "first name must be 1-50 characters", http.StatusBadRequest)
		return
	}
	if len(req.LastName) < 1 || len(req.LastName) > 50 {
		http.Error(w, "last name must be 1-50 characters", http.StatusBadRequest)
		return
	}

	// Normalize phone (strip spaces, hyphens, brackets)
	req.Phone = strings.Map(func(r rune) rune {
		if (r >= '0' && r <= '9') || r == '+' {
			return r
		}
		return -1
	}, req.Phone)

	// Validate UK phone number
	phone, err := auth.ValidateUKPhoneNumber(req.Phone)
	if err != nil {
		http.Error(w, "invalid phone number format", http.StatusBadRequest)
		return
	}
	req.Phone = strings.TrimSpace(phone)

	// Title case names
	req.FirstName = titleCaser.String(strings.ToLower(req.FirstName))
	req.LastName = titleCaser.String(strings.ToLower(req.LastName))

	// Fetch user's email and DOB for CardDAV update
	var email string
	var dob time.Time
	err = db.DB.QueryRow(r.Context(), `
		SELECT email, date_of_birth FROM users WHERE id = $1
	`, userID).Scan(&email, &dob)

	if err != nil {
		http.Error(w, "failed to fetch user data", http.StatusInternalServerError)
		return
	}

	// Update DB
	_, err = db.DB.Exec(r.Context(), `
		UPDATE users
		SET n_first_name = $1, n_last_name = $2, phone = $3, updated_at = NOW()
		WHERE id = $4
	`, req.FirstName, req.LastName, req.Phone, userID)

	if err != nil {
		http.Error(w, "update failed", http.StatusInternalServerError)
		return
	}

	// Update CardDAV (non-blocking)
	go func() {
		dobStr := dob.Format("2006-01-02")
		if err := updateCardDAV(userID, req.FirstName, req.LastName, email, req.Phone, dobStr); err != nil {
			fmt.Printf("Warning: Failed to update CardDAV contact for user %s: %v\n", userID, err)
		}
	}()

	w.WriteHeader(http.StatusOK)
}

// GET /api/admin/users/{id}
func GetAdminUserHandler(w http.ResponseWriter, r *http.Request) {
	userID := chi.URLParam(r, "id")
	if userID == "" {
		http.Error(w, "User ID is required", http.StatusBadRequest)
		return
	}

	// Fetch user details
	var user AdminUserDetail
	err := db.DB.QueryRow(r.Context(), `
		SELECT
			id, email, n_first_name, n_last_name, fn, phone,
			date_of_birth::text, profile_pic_url,
			account_role, account_type, loyalty_stamps, referral_code,
			last_login_at::text, created_at::text, updated_at::text, notes,
			privacy_policy_and_terms_consent,
			policy_consent_updated_at::text,
			data_retention_consent,
			data_consent_updated_at::text
		FROM users
		WHERE id = $1
	`, userID).Scan(
		&user.ID, &user.Email, &user.FirstName, &user.LastName, &user.FullName,
		&user.Phone, &user.DateOfBirth, &user.ProfilePicURL,
		&user.AccountRole, &user.AccountType, &user.LoyaltyStamps, &user.ReferralCode,
		&user.LastLoginAt, &user.CreatedAt, &user.UpdatedAt, &user.Notes,
		&user.PrivacyPolicyConsent, &user.PolicyConsentUpdatedAt,
		&user.DataRetentionConsent, &user.DataConsentUpdatedAt,
	)

	if err != nil {
		if err == sql.ErrNoRows {
			http.Error(w, "User not found", http.StatusNotFound)
			return
		}
		log.Printf("Failed to fetch user %s: %v", userID, err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Fetch referral code uses count
	err = db.DB.QueryRow(r.Context(), `
		SELECT COUNT(*)
		FROM user_referrals
		WHERE referrer_id = $1 AND claimed_booking_id IS NOT NULL
	`, userID).Scan(&user.ReferralCodeUses)
	if err != nil {
		log.Printf("Failed to fetch referral code uses for user %s: %v", userID, err)
		user.ReferralCodeUses = 0
	}

	// Fetch social logins
	socialRows, err := db.DB.Query(r.Context(), `
		SELECT provider, created_at::text
		FROM user_social_logins
		WHERE user_id = $1
		ORDER BY created_at ASC
	`, userID)
	if err != nil {
		log.Printf("Failed to fetch social logins for user %s: %v", userID, err)
	} else {
		defer socialRows.Close()

		var socialLogins []SocialLogin
		for socialRows.Next() {
			var sl SocialLogin
			if err := socialRows.Scan(&sl.Provider, &sl.CreatedAt); err != nil {
				log.Printf("Failed to scan social login for user %s: %v", userID, err)
				continue
			}
			socialLogins = append(socialLogins, sl)
		}

		if len(socialLogins) > 0 {
			user.SocialLogins = socialLogins
		}
	}

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

// GET /api/admin/users
func ListAdminUsersHandler(w http.ResponseWriter, r *http.Request) {
	// Parse query parameters
	query := r.URL.Query()
	searchTerm := query.Get("q")

	// Pagination parameters
	page := 1
	perPage := 10

	if pageStr := query.Get("page"); pageStr != "" {
		if p, err := strconv.Atoi(pageStr); err == nil && p > 0 {
			page = p
		}
	}

	if perPageStr := query.Get("per_page"); perPageStr != "" {
		if pp, err := strconv.Atoi(perPageStr); err == nil && pp > 0 && pp <= 100 {
			perPage = pp
		}
	}

	offset := (page - 1) * perPage

	// Build query based on whether search is provided
	var countQuery string
	var listQuery string
	var countArgs []interface{}
	var listArgs []interface{}

	if searchTerm != "" {
		// Search in name, email, or phone
		searchPattern := "%" + searchTerm + "%"

		countQuery = `
			SELECT COUNT(*)
			FROM users
			WHERE fn ILIKE $1
			   OR email ILIKE $1
			   OR phone ILIKE $1
		`
		countArgs = []interface{}{searchPattern}

		listQuery = `
			SELECT id, fn, email, phone
			FROM users
			WHERE fn ILIKE $1
			   OR email ILIKE $1
			   OR phone ILIKE $1
			ORDER BY created_at DESC
			LIMIT $2 OFFSET $3
		`
		listArgs = []interface{}{searchPattern, perPage, offset}
	} else {
		// No search - get all users
		countQuery = `SELECT COUNT(*) FROM users`
		countArgs = []interface{}{}

		listQuery = `
			SELECT id, fn, email, phone
			FROM users
			ORDER BY created_at DESC
			LIMIT $1 OFFSET $2
		`
		listArgs = []interface{}{perPage, offset}
	}

	// Get total count
	var total int
	err := db.DB.QueryRow(r.Context(), countQuery, countArgs...).Scan(&total)
	if err != nil {
		log.Printf("Failed to count users: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}

	// Get users list
	rows, err := db.DB.Query(r.Context(), listQuery, listArgs...)
	if err != nil {
		log.Printf("Failed to fetch users: %v", err)
		http.Error(w, "Internal server error", http.StatusInternalServerError)
		return
	}
	defer rows.Close()

	var users []UserListItem
	for rows.Next() {
		var user UserListItem
		err := rows.Scan(&user.ID, &user.FullName, &user.Email, &user.Phone)
		if err != nil {
			log.Printf("Failed to scan user row: %v", err)
			http.Error(w, "Internal server error", http.StatusInternalServerError)
			return
		}
		users = append(users, user)
	}

	// Handle empty results
	if users == nil {
		users = []UserListItem{}
	}

	// Calculate total pages
	totalPages := (total + perPage - 1) / perPage
	if totalPages == 0 {
		totalPages = 1
	}

	response := UserListResponse{
		Users:      users,
		Total:      total,
		Page:       page,
		PerPage:    perPage,
		TotalPages: totalPages,
	}

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