package user

import (
	"bytes"
	"encoding/json"
	"fmt"
	"net/http"
	"regexp"
	"strings"
	"time"

	"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"`
	ProfilePicURL *string `json:"profilePicUrl,omitempty"`
}

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

// 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
		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,
	)

	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)
}