/**
 * YS Project - Authentication JavaScript
 * Handles registration form validation and login form
 */

(function () {
    'use strict';

    // ============================================================
    // Utility
    // ============================================================
    const $ = (sel) => document.querySelector(sel);

    let debounceTimers = {};

    function debounce(key, fn, delay = 400) {
        if (debounceTimers[key]) clearTimeout(debounceTimers[key]);
        debounceTimers[key] = setTimeout(fn, delay);
    }

    function setFeedback(el, message, type) {
        if (!el) return;
        el.textContent = message;
        el.className = 'auth-form__feedback';
        if (type === 'error') el.classList.add('auth-form__feedback--error');
        else if (type === 'success') el.classList.add('auth-form__feedback--success');
    }

    function setInputState(input, state) {
        if (!input) return;
        input.classList.remove('auth-form__input--error', 'auth-form__input--success');
        if (state === 'error') input.classList.add('auth-form__input--error');
        else if (state === 'success') input.classList.add('auth-form__input--success');
    }

    // ============================================================
    // Registration Form
    // ============================================================
    const registerForm = $('#registerForm');

    if (registerForm) {
        const fields = {
            loginId: $('#regLoginId'),
            nickname: $('#regNickname'),
            password: $('#regPassword'),
            passwordConfirm: $('#regPasswordConfirm'),
        };

        const feedbacks = {
            loginId: $('#loginIdFeedback'),
            nickname: $('#nicknameFeedback'),
            password: $('#passwordFeedback'),
            passwordConfirm: $('#passwordConfirmFeedback'),
        };

        const checkBtns = {
            loginId: $('#checkLoginIdBtn'),
            nickname: $('#checkNicknameBtn'),
        };

        const submitBtn = $('#registerSubmitBtn');
        const errorBox = $('#registerError');

        // Validation state tracking
        const validState = {
            loginId: false,
            loginIdChecked: false,
            nickname: false,
            nicknameChecked: false,
            password: false,
            passwordConfirm: false,
        };

        function updateSubmitBtn() {
            const allValid = validState.loginId && validState.loginIdChecked
                && validState.nickname && validState.nicknameChecked
                && validState.password && validState.passwordConfirm;
            submitBtn.disabled = !allValid;
        }

        // --- Login ID validation ---
        function validateLoginId(value) {
            if (value.length === 0) return { valid: false, message: '' };
            if (value.length < 4) return { valid: false, message: '4자 이상 입력해주세요.' };
            if (value.length > 20) return { valid: false, message: '20자 이하로 입력해주세요.' };
            if (!/^[a-zA-Z0-9_]+$/.test(value)) return { valid: false, message: '영문, 숫자, 언더바(_)만 사용 가능합니다.' };
            return { valid: true, message: '중복확인을 해주세요.' };
        }

        fields.loginId.addEventListener('input', function () {
            const val = this.value.trim();
            const result = validateLoginId(val);

            validState.loginId = result.valid;
            validState.loginIdChecked = false;
            checkBtns.loginId.disabled = !result.valid;

            if (val.length === 0) {
                setFeedback(feedbacks.loginId, '', '');
                setInputState(this, '');
            } else if (result.valid) {
                setFeedback(feedbacks.loginId, result.message, '');
                setInputState(this, '');
            } else {
                setFeedback(feedbacks.loginId, result.message, 'error');
                setInputState(this, 'error');
            }

            updateSubmitBtn();
        });

        checkBtns.loginId.addEventListener('click', function () {
            const val = fields.loginId.value.trim();
            if (!validState.loginId) return;
            checkDuplicate('login_id', val, fields.loginId, feedbacks.loginId, 'loginIdChecked');
        });

        // --- Nickname validation ---
        function validateNickname(value) {
            if (value.length === 0) return { valid: false, message: '' };
            if (value.length < 2) return { valid: false, message: '2자 이상 입력해주세요.' };
            if (value.length > 12) return { valid: false, message: '12자 이하로 입력해주세요.' };
            return { valid: true, message: '중복확인을 해주세요.' };
        }

        fields.nickname.addEventListener('input', function () {
            const val = this.value.trim();
            const result = validateNickname(val);

            validState.nickname = result.valid;
            validState.nicknameChecked = false;
            checkBtns.nickname.disabled = !result.valid;

            if (val.length === 0) {
                setFeedback(feedbacks.nickname, '', '');
                setInputState(this, '');
            } else if (result.valid) {
                setFeedback(feedbacks.nickname, result.message, '');
                setInputState(this, '');
            } else {
                setFeedback(feedbacks.nickname, result.message, 'error');
                setInputState(this, 'error');
            }

            updateSubmitBtn();
        });

        checkBtns.nickname.addEventListener('click', function () {
            const val = fields.nickname.value.trim();
            if (!validState.nickname) return;
            checkDuplicate('nickname', val, fields.nickname, feedbacks.nickname, 'nicknameChecked');
        });

        // --- Password validation ---
        fields.password.addEventListener('input', function () {
            const val = this.value;

            if (val.length === 0) {
                validState.password = false;
                setFeedback(feedbacks.password, '', '');
                setInputState(this, '');
            } else if (val.length < 8) {
                validState.password = false;
                setFeedback(feedbacks.password, '8자 이상 입력해주세요.', 'error');
                setInputState(this, 'error');
            } else {
                validState.password = true;
                setFeedback(feedbacks.password, '사용 가능한 비밀번호입니다.', 'success');
                setInputState(this, 'success');
            }

            // Re-check password confirm
            checkPasswordConfirm();
            updateSubmitBtn();
        });

        // --- Password confirm ---
        fields.passwordConfirm.addEventListener('input', function () {
            checkPasswordConfirm();
            updateSubmitBtn();
        });

        function checkPasswordConfirm() {
            const pw = fields.password.value;
            const pwc = fields.passwordConfirm.value;

            if (pwc.length === 0) {
                validState.passwordConfirm = false;
                setFeedback(feedbacks.passwordConfirm, '', '');
                setInputState(fields.passwordConfirm, '');
                return;
            }

            if (pw !== pwc) {
                validState.passwordConfirm = false;
                setFeedback(feedbacks.passwordConfirm, '비밀번호가 일치하지 않습니다.', 'error');
                setInputState(fields.passwordConfirm, 'error');
            } else {
                validState.passwordConfirm = true;
                setFeedback(feedbacks.passwordConfirm, '비밀번호가 일치합니다.', 'success');
                setInputState(fields.passwordConfirm, 'success');
            }
        }

        // --- Duplicate check API ---
        async function checkDuplicate(type, value, inputEl, feedbackEl, stateKey) {
            try {
                const params = new URLSearchParams({ type, value });
                const resp = await fetch(`/api/check_duplicate.php?${params}`);
                const data = await resp.json();

                if (data.success && data.available) {
                    validState[stateKey] = true;
                    setFeedback(feedbackEl, data.message, 'success');
                    setInputState(inputEl, 'success');
                } else {
                    validState[stateKey] = false;
                    setFeedback(feedbackEl, data.message || data.error, 'error');
                    setInputState(inputEl, 'error');
                }
            } catch (err) {
                validState[stateKey] = false;
                setFeedback(feedbackEl, '확인 중 오류가 발생했습니다.', 'error');
                setInputState(inputEl, 'error');
            }

            updateSubmitBtn();
        }

        // --- Form submit ---
        registerForm.addEventListener('submit', async function (e) {
            e.preventDefault();

            if (submitBtn.disabled) return;

            // Disable button, show loading
            submitBtn.disabled = true;
            submitBtn.classList.add('auth-form__submit--loading');
            errorBox.style.display = 'none';

            try {
                const formData = new FormData(registerForm);
                const resp = await fetch('/api/register.php', {
                    method: 'POST',
                    body: formData,
                });

                const data = await resp.json();

                if (data.success) {
                    window.location.href = data.redirect_url || '/';
                } else {
                    errorBox.textContent = data.error || '회원가입에 실패했습니다.';
                    errorBox.style.display = 'block';
                    submitBtn.disabled = false;
                    submitBtn.classList.remove('auth-form__submit--loading');
                }
            } catch (err) {
                errorBox.textContent = '서버와 통신 중 오류가 발생했습니다.';
                errorBox.style.display = 'block';
                submitBtn.disabled = false;
                submitBtn.classList.remove('auth-form__submit--loading');
            }
        });
    }

    // ============================================================
    // Login Form
    // ============================================================
    const loginForm = $('#loginForm');

    if (loginForm) {
        const loginTypeInput = $('#loginType');
        const tabBtns = document.querySelectorAll('.auth-tabs__btn');
        const submitBtn = $('#loginSubmitBtn');
        const errorBox = $('#loginError');
        const loginFooter = $('#loginFooter');

        // Tab switching
        tabBtns.forEach(function (btn) {
            btn.addEventListener('click', function () {
                tabBtns.forEach(function (b) { b.classList.remove('auth-tabs__btn--active'); });
                btn.classList.add('auth-tabs__btn--active');

                const type = btn.dataset.loginType;
                loginTypeInput.value = type;

                // Show/hide register link based on login type
                if (type === 'owner') {
                    loginFooter.innerHTML = '<p>사장님 계정은 관리자에게 문의해주세요.</p>';
                } else {
                    loginFooter.innerHTML = '<p>계정이 없으신가요? <a href="/register.php" class="auth__footer-link">회원가입</a></p>';
                }

                // Clear error
                errorBox.style.display = 'none';
            });
        });

        // Form submit
        loginForm.addEventListener('submit', async function (e) {
            e.preventDefault();

            const loginId = $('#loginId').value.trim();
            const password = $('#loginPassword').value;

            if (!loginId || !password) {
                errorBox.textContent = 'ID와 비밀번호를 입력해주세요.';
                errorBox.style.display = 'block';
                return;
            }

            submitBtn.disabled = true;
            submitBtn.classList.add('auth-form__submit--loading');
            errorBox.style.display = 'none';

            try {
                const formData = new FormData(loginForm);
                const resp = await fetch('/api/login.php', {
                    method: 'POST',
                    body: formData,
                });

                const data = await resp.json();

                if (data.success) {
                    window.location.href = data.redirect_url || '/';
                } else {
                    errorBox.textContent = data.error || '로그인에 실패했습니다.';
                    errorBox.style.display = 'block';
                    submitBtn.disabled = false;
                    submitBtn.classList.remove('auth-form__submit--loading');
                }
            } catch (err) {
                errorBox.textContent = '서버와 통신 중 오류가 발생했습니다.';
                errorBox.style.display = 'block';
                submitBtn.disabled = false;
                submitBtn.classList.remove('auth-form__submit--loading');
            }
        });
    }

})();