/**
 * Utilities - 工具函式
 * 包含 XSS 防護、表單欄位工具、UI 回饋工具
 */

import { TOAST_DURATION } from './config.js';

// ==================== XSS 防護工具 ====================

/**
 * 消毒 HTML 字串，防止 XSS 攻擊
 * @param {string} str - 需要消毒的字串
 * @returns {string} - 安全的字串
 */
export function sanitizeHTML(str) {
    if (str === null || str === undefined) return '';
    const temp = document.createElement('div');
    temp.textContent = str;
    return temp.innerHTML;
}

/**
 * 安全設定元素文字內容
 * @param {HTMLElement} element - 目標元素
 * @param {string} text - 文字內容
 */
export function safeSetText(element, text) {
    if (element) {
        element.textContent = text;
    }
}

// ==================== 表單欄位工具 ====================

/**
 * 只在欄位為空時填入值
 * @param {string} elementId - DOM 元素 ID
 * @param {string} value - 要填入的值
 * @returns {boolean} - 是否有填入值
 */
export function fillIfEmpty(elementId, value) {
    const el = document.getElementById(elementId);
    if (el && !el.value.trim() && value) {
        el.value = value;
        return true;
    }
    return false;
}

/**
 * 獲取欄位當前值
 * @param {string} elementId - DOM 元素 ID
 * @returns {string} - 欄位值（已 trim）
 */
export function getFieldValue(elementId) {
    const el = document.getElementById(elementId);
    return el ? el.value.trim() : '';
}

/**
 * 獲取空白欄位列表
 * @param {string[]} fieldIds - 欄位 ID 陣列
 * @returns {string[]} - 空白欄位 ID 陣列
 */
export function getEmptyFields(fieldIds) {
    return fieldIds.filter(id => !getFieldValue(id));
}

// ==================== UI 回饋工具 ====================

/**
 * 顯示 Toast 提示訊息
 * @param {string} message - 訊息內容
 * @param {number} duration - 顯示時長（毫秒），預設 3000
 */
export function showToast(message, duration = TOAST_DURATION) {
    const existingToast = document.querySelector('.toast');
    if (existingToast) {
        existingToast.remove();
    }

    const toast = document.createElement('div');
    toast.className = 'toast';
    toast.innerHTML = `
        <svg viewBox="0 0 24 24">
            <path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2zm-2 15l-5-5 1.41-1.41L10 14.17l7.59-7.59L19 8l-9 9z"/>
        </svg>
        <span>${sanitizeHTML(message)}</span>
    `;
    document.body.appendChild(toast);

    setTimeout(() => toast.classList.add('show'), 10);
    setTimeout(() => {
        toast.classList.remove('show');
        setTimeout(() => toast.remove(), 300);
    }, duration);
}

/**
 * 設定按鈕載入狀態
 * @param {HTMLElement} btn - 按鈕元素
 * @param {boolean} loading - 是否載入中
 */
export function setButtonLoading(btn, loading) {
    if (loading) {
        btn.disabled = true;
        btn.innerHTML = '<div class="spinner"></div><span>AI 生成中...</span>';
    } else {
        btn.disabled = false;
        btn.innerHTML = '<svg viewBox="0 0 24 24"><path d="M12 2C6.48 2 2 6.48 2 12s4.48 10 10 10 10-4.48 10-10S17.52 2 12 2zm-2 15l-5-5 1.41-1.41L10 14.17l7.59-7.59L19 8l-9 9z"/></svg><span>✨ I\'m feeling lucky</span>';
    }
}

// ==================== 錯誤處理工具 ====================

/**
 * 顯示可複製的錯誤對話框
 * @param {Object} options - 錯誤選項
 * @param {string} options.title - 錯誤標題
 * @param {string} options.message - 錯誤訊息
 * @param {string} options.details - 錯誤詳情
 * @param {string[]} options.suggestions - 建議列表
 */
export function showCopyableError(options) {
    const { title, message, details, suggestions } = options;

    // 移除舊的錯誤對話框
    const existingModal = document.getElementById('errorModal');
    if (existingModal) {
        existingModal.remove();
    }

    const modalHTML = `
        <div id="errorModal" class="modal-overlay show">
            <div class="modal" style="max-width: min(90vw, 500px); max-height: 85vh; display: flex; flex-direction: column;">
                <div class="modal-header" style="background: linear-gradient(135deg, #e74c3c 0%, #c0392b 100%); color: white; flex-shrink: 0;">
                    <h3 style="font-size: 1rem;">🚨 ${sanitizeHTML(title)}</h3>
                    <button class="modal-close" onclick="closeErrorModal(this)" style="color: white;">✕</button>
                </div>
                <div class="modal-body" style="overflow-y: auto; flex: 1; padding: 16px;">
                    <div style="margin-bottom: 12px;">
                        <strong style="font-size: 0.9rem;">錯誤訊息：</strong>
                        <p style="color: #e74c3c; font-weight: 500; font-size: 0.85rem; word-break: break-word;">${sanitizeHTML(message)}</p>
                    </div>
                    ${details ? `
                    <div style="margin-bottom: 12px;">
                        <strong style="font-size: 0.9rem;">詳細資訊：</strong>
                        <pre style="background: #f8f9fa; padding: 10px; border-radius: 6px; overflow-x: auto; font-size: 0.75rem; max-height: 120px; white-space: pre-wrap; word-break: break-all;">${sanitizeHTML(details)}</pre>
                    </div>
                    ` : ''}
                    ${suggestions && suggestions.length > 0 ? `
                    <div>
                        <strong style="font-size: 0.9rem;">請檢查以下項目：</strong>
                        <ul style="margin: 6px 0; padding-left: 18px; font-size: 0.85rem;">
                            ${suggestions.map(s => `<li style="margin: 3px 0;">${sanitizeHTML(s)}</li>`).join('')}
                        </ul>
                    </div>
                    ` : ''}
                </div>
                <div class="modal-footer" style="flex-shrink: 0; padding: 12px 16px;">
                    <button class="btn btn-secondary" onclick="copyErrorDetails()" style="font-size: 0.85rem; padding: 8px 12px;">
                        <svg viewBox="0 0 24 24" style="width: 14px; height: 14px;">
                            <path fill="currentColor" d="M16 1H4c-1.1 0-2 .9-2 2v14h2V3h12V1zm3 4H8c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h11c1.1 0 2-.9 2-2V7c0-1.1-.9-2-2-2zm0 16H8V7h11v14z"/>
                        </svg>
                        複製
                    </button>
                    <button class="btn btn-primary" onclick="closeErrorModal(this)" style="font-size: 0.85rem; padding: 8px 16px;">關閉</button>
                </div>
            </div>
        </div>
    `;

    document.body.insertAdjacentHTML('beforeend', modalHTML);
}

/**
 * 關閉錯誤對話框
 * @param {HTMLElement} button - 按鈕元素
 */
export function closeErrorModal(button) {
    const modal = button.closest('.modal-overlay');
    if (modal) {
        modal.remove();
    }
}

/**
 * 複製錯誤詳情到剪貼板
 */
export function copyErrorDetails() {
    const modal = document.getElementById('errorModal');
    if (!modal) return;

    const errorText = modal.querySelector('.modal-body').textContent;
    navigator.clipboard.writeText(errorText).then(() => {
        showToast('錯誤詳情已複製到剪貼板');
    }).catch(err => {
        console.error('複製失敗:', err);
    });
}

// 將函式掛載到 window 上以便內聯事件處理器使用
if (typeof window !== 'undefined') {
    window.closeErrorModal = closeErrorModal;
    window.copyErrorDetails = copyErrorDetails;
}