// utils.js - Shared utility functions

/**
 * Escape HTML to prevent XSS attacks
 * @param {string} text - The text to escape
 * @returns {string} - HTML-escaped text
 */
function escapeHtml(text) {
    const div = document.createElement("div");
    div.textContent = text;
    return div.innerHTML;
}

/**
 * Wrap tables in a scrollable container for mobile responsiveness
 * @param {HTMLElement} element - The element containing tables to wrap
 */
function wrapTablesForScroll(element) {
    const tables = element.querySelectorAll("table");
    tables.forEach(table => {
        if (!table.parentElement.classList.contains("table-wrapper")) {
            const wrapper = document.createElement("div");
            wrapper.className = "table-wrapper";
            table.parentNode.insertBefore(wrapper, table);
            wrapper.appendChild(table);
        }
    });
}

/**
 * Download a file with the given content
 * @param {string} content - The file content
 * @param {string} filename - The filename to use
 * @param {string} mimeType - The MIME type of the file
 */
function downloadFile(content, filename, mimeType) {
    const blob = new Blob([content], { type: mimeType });
    const url = URL.createObjectURL(blob);
    const a = document.createElement("a");
    a.href = url;
    a.download = filename;
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
}

/**
 * Sanitize a filename by removing invalid characters
 * @param {string} name - The filename to sanitize
 * @returns {string} - Sanitized filename
 */
function sanitizeFilename(name) {
    return name.replace(/[^a-z0-9]/gi, "_").substring(0, 50);
}

/**
 * Show export format selection modal and return chosen format
 * @param {string} conversationTitle - Title of the conversation for display
 * @returns {Promise<string|null>} - 'json', 'markdown', or null if cancelled
 */
function showExportFormatModal(conversationTitle) {
    return new Promise(resolve => {
        // Create modal
        const modal = document.createElement("div");
        modal.className = "modal";
        modal.id = "exportFormatModal";
        modal.innerHTML = `
            <div class="modal-content modal-content-sm">
                <div class="modal-header">
                    <h2 class="modal-title">Export Conversation</h2>
                    <button class="icon-btn close-btn">
                        <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2">
                            <line x1="18" y1="6" x2="6" y2="18"></line>
                            <line x1="6" y1="6" x2="18" y2="18"></line>
                        </svg>
                    </button>
                </div>
                <div class="modal-body">
                    <p style="margin-bottom: 16px; color: var(--color-text-secondary);">
                        Choose export format for "<strong>${escapeHtml(conversationTitle)}</strong>"
                    </p>
                    <div style="display: flex; gap: 12px;">
                        <button class="btn-primary" style="flex: 1;" data-format="json">
                            📄 JSON
                            <span style="display: block; font-size: 11px; opacity: 0.8;">Full data, re-importable</span>
                        </button>
                        <button class="btn-secondary" style="flex: 1;" data-format="markdown">
                            📝 Markdown
                            <span style="display: block; font-size: 11px; opacity: 0.8;">Human-readable</span>
                        </button>
                    </div>
                </div>
            </div>
        `;

        document.body.appendChild(modal);

        // Event handlers
        const closeModal = () => {
            modal.remove();
            resolve(null);
        };

        modal.querySelector(".close-btn").addEventListener("click", closeModal);
        modal.addEventListener("click", e => {
            if (e.target === modal) closeModal();
        });

        modal.querySelectorAll("[data-format]").forEach(btn => {
            btn.addEventListener("click", () => {
                const format = btn.dataset.format;
                modal.remove();
                resolve(format);
            });
        });

        // ESC to close
        const handleEsc = e => {
            if (e.key === "Escape") {
                document.removeEventListener("keydown", handleEsc);
                closeModal();
            }
        };
        document.addEventListener("keydown", handleEsc);
    });
}

/**
 * Show import file picker and handle the import
 * @returns {Promise<{conversation: Object, messages: Array}|null>} - Imported data or null
 */
function showImportFilePicker() {
    return new Promise(resolve => {
        const input = document.createElement("input");
        input.type = "file";
        input.accept = ".json";

        input.addEventListener("change", async e => {
            const file = e.target.files[0];
            if (!file) {
                resolve(null);
                return;
            }

            try {
                const text = await file.text();
                const data = JSON.parse(text);

                // Validate basic structure
                if (!data.conversation || !data.messages || !Array.isArray(data.messages)) {
                    throw new Error("Invalid file format: missing conversation or messages");
                }

                // Validate conversation object
                if (!data.conversation.title || typeof data.conversation.title !== "string") {
                    throw new Error("Invalid file format: missing or invalid conversation title");
                }

                // Validate messages structure
                for (let i = 0; i < data.messages.length; i++) {
                    const msg = data.messages[i];
                    if (!msg.role || !msg.content) {
                        throw new Error(`Invalid message at index ${i}: missing role or content`);
                    }
                    if (msg.role !== "user" && msg.role !== "assistant") {
                        throw new Error(`Invalid message role at index ${i}: must be 'user' or 'assistant'`);
                    }
                }

                resolve(data);
            } catch (error) {
                showNotification("Invalid JSON file: " + error.message, "error");
                resolve(null);
            }
        });

        input.click();
    });
}

// Export for use in other scripts
if (typeof window !== "undefined") {
    window.escapeHtml = escapeHtml;
    window.wrapTablesForScroll = wrapTablesForScroll;
    window.downloadFile = downloadFile;
    window.sanitizeFilename = sanitizeFilename;
    window.showExportFormatModal = showExportFormatModal;
    window.showImportFilePicker = showImportFilePicker;
}