/**
 * GoingsOn - External File Import Module
 * Handles importing contacts from vCard (.vcf) and events from iCalendar (.ics) files.
 */

(function() {
    'use strict';
    const esc = GoingsOn.utils.escapeHtml;

    // ============ Import Type Selection ============

    /**
     * Opens the external import dialog with type selection.
     */
    function openImportDialog() {
        const content = `
            <div class="import-external-types">
                <button class="import-type-card" onclick="GoingsOn.importExternal.startContactImport()">
                    <span class="import-type-icon">&#128101;</span>
                    <span class="import-type-label">Import Contacts</span>
                    <span class="import-type-desc">Import from a vCard (.vcf) file</span>
                </button>
                <button class="import-type-card" onclick="GoingsOn.importExternal.startCalendarImport()">
                    <span class="import-type-icon">&#128197;</span>
                    <span class="import-type-label">Import Calendar</span>
                    <span class="import-type-desc">Import from an iCalendar (.ics) file</span>
                </button>
            </div>
            <div class="form-actions">
                <button type="button" class="btn btn-secondary" onclick="GoingsOn.ui.closeModal()">Cancel</button>
            </div>
        `;

        GoingsOn.ui.openModal('Import External Data', content);
    }

    // ============ Contact Import ============

    /**
     * Opens file picker for vCard import, then shows preview.
     */
    async function startContactImport() {
        const filePath = await pickFile('vCard Files', ['vcf']);
        if (!filePath) return;

        GoingsOn.ui.openModal('Import Contacts', `
            <div class="import-preview-container">
                <div class="loading">Parsing ${esc(getFileName(filePath))}...</div>
            </div>
        `);

        try {
            const preview = await GoingsOn.api.import.previewVcf(filePath);

            if (preview.length === 0) {
                updatePreviewContent('<p class="import-empty">No contacts found in file.</p>', null);
                return;
            }

            const maxPreview = 25;
            const display = preview.slice(0, maxPreview);

            const html = `
                <p class="import-summary"><strong>${preview.length}</strong> contact${preview.length !== 1 ? 's' : ''} found</p>
                <div class="import-preview-table-wrapper">
                    <table class="data-table import-preview-table">
                        <thead>
                            <tr><th>Name</th><th>Company</th><th>Emails</th><th>Phones</th></tr>
                        </thead>
                        <tbody>
                            ${display.map(c => `
                                <tr>
                                    <td>${esc(c.displayName)}</td>
                                    <td>${esc(c.company || '')}</td>
                                    <td>${c.emailCount}</td>
                                    <td>${c.phoneCount}</td>
                                </tr>
                            `).join('')}
                        </tbody>
                    </table>
                </div>
                ${preview.length > maxPreview ? `<p class="import-more">...and ${preview.length - maxPreview} more</p>` : ''}
            `;

            updatePreviewContent(html, async () => {
                await executeContactImport(filePath, preview.length);
            });
        } catch (err) {
            updatePreviewContent(`<p class="import-error">Failed to parse file: ${esc(GoingsOn.utils.getErrorMessage(err))}</p>`, null);
        }
    }

    /**
     * Executes the vCard import.
     */
    async function executeContactImport(filePath, expectedCount) {
        const btn = document.getElementById('import-external-confirm');
        if (btn) {
            btn.disabled = true;
            btn.textContent = 'Importing...';
        }

        try {
            const result = await GoingsOn.api.import.importVcf(filePath);
            GoingsOn.ui.closeModal();

            const parts = [];
            if (result.imported > 0) parts.push(`${result.imported} imported`);
            if (result.skipped > 0) parts.push(`${result.skipped} skipped (duplicates)`);
            if (result.errors.length > 0) parts.push(`${result.errors.length} failed`);

            const hasErrors = result.errors.length > 0;
            GoingsOn.ui.showToast(
                `Contacts: ${parts.join(', ')}`,
                hasErrors ? 'warning' : 'success'
            );

            if (GoingsOn.navigation && GoingsOn.navigation.reloadCurrentView) {
                GoingsOn.navigation.reloadCurrentView();
            }
        } catch (err) {
            GoingsOn.ui.showToast('Import failed: ' + GoingsOn.utils.getErrorMessage(err), 'error');
            if (btn) {
                btn.disabled = false;
                btn.textContent = 'Import';
            }
        }
    }

    // ============ Calendar Import ============

    /**
     * Opens file picker for ICS import, then shows preview.
     */
    async function startCalendarImport() {
        const filePath = await pickFile('iCalendar Files', ['ics']);
        if (!filePath) return;

        GoingsOn.ui.openModal('Import Calendar', `
            <div class="import-preview-container">
                <div class="loading">Parsing ${esc(getFileName(filePath))}...</div>
            </div>
        `);

        try {
            const preview = await GoingsOn.api.import.previewIcs(filePath);

            if (preview.length === 0) {
                updatePreviewContent('<p class="import-empty">No events found in file.</p>', null);
                return;
            }

            const maxPreview = 25;
            const display = preview.slice(0, maxPreview);

            const html = `
                <p class="import-summary"><strong>${preview.length}</strong> event${preview.length !== 1 ? 's' : ''} found</p>
                <div class="import-preview-table-wrapper">
                    <table class="data-table import-preview-table">
                        <thead>
                            <tr><th>Title</th><th>Start</th><th>Location</th><th>Recurrence</th></tr>
                        </thead>
                        <tbody>
                            ${display.map(e => `
                                <tr>
                                    <td>${esc(e.title)}</td>
                                    <td>${esc(formatImportDate(e.startTime))}</td>
                                    <td>${esc(e.location || '')}</td>
                                    <td>${esc(e.recurrence)}</td>
                                </tr>
                            `).join('')}
                        </tbody>
                    </table>
                </div>
                ${preview.length > maxPreview ? `<p class="import-more">...and ${preview.length - maxPreview} more</p>` : ''}
            `;

            updatePreviewContent(html, async () => {
                await executeCalendarImport(filePath, preview.length);
            });
        } catch (err) {
            updatePreviewContent(`<p class="import-error">Failed to parse file: ${esc(GoingsOn.utils.getErrorMessage(err))}</p>`, null);
        }
    }

    /**
     * Executes the ICS import.
     */
    async function executeCalendarImport(filePath, expectedCount) {
        const btn = document.getElementById('import-external-confirm');
        if (btn) {
            btn.disabled = true;
            btn.textContent = 'Importing...';
        }

        try {
            const result = await GoingsOn.api.import.importIcs(filePath);
            GoingsOn.ui.closeModal();

            const parts = [];
            if (result.imported > 0) parts.push(`${result.imported} imported`);
            if (result.skipped > 0) parts.push(`${result.skipped} skipped (duplicates)`);
            if (result.errors.length > 0) parts.push(`${result.errors.length} failed`);

            const hasErrors = result.errors.length > 0;
            GoingsOn.ui.showToast(
                `Events: ${parts.join(', ')}`,
                hasErrors ? 'warning' : 'success'
            );

            if (GoingsOn.navigation && GoingsOn.navigation.reloadCurrentView) {
                GoingsOn.navigation.reloadCurrentView();
            }
        } catch (err) {
            GoingsOn.ui.showToast('Import failed: ' + GoingsOn.utils.getErrorMessage(err), 'error');
            if (btn) {
                btn.disabled = false;
                btn.textContent = 'Import';
            }
        }
    }

    // ============ Helpers ============

    /**
     * Opens native file picker with given filter.
     * @param {string} filterName - Display name for the file filter
     * @param {string[]} extensions - Allowed file extensions
     * @returns {Promise<string|null>} Selected file path, or null if cancelled
     */
    async function pickFile(filterName, extensions) {
        try {
            const { open } = window.__TAURI__.dialog;
            return await open({
                multiple: false,
                filters: [{ name: filterName, extensions }],
            });
        } catch (err) {
            GoingsOn.ui.showToast('Failed to open file picker: ' + GoingsOn.utils.getErrorMessage(err), 'error');
            return null;
        }
    }

    /**
     * Gets the filename from a full path.
     * @param {string} path - Full file path
     * @returns {string} Filename component
     */
    function getFileName(path) {
        return path.split(/[/\\]/).pop() || path;
    }

    /**
     * Formats an ISO date string for display in preview table.
     * @param {string} isoString - ISO 8601 date string
     * @returns {string} Locale-formatted date string
     */
    function formatImportDate(isoString) {
        if (!isoString) return '';
        try {
            const d = new Date(isoString);
            return d.toLocaleDateString(undefined, { year: 'numeric', month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' });
        } catch {
            return isoString;
        }
    }

    /**
     * Updates the modal content with preview HTML and optional confirm button.
     * @param {string} previewHtml - HTML to insert into the preview container
     * @param {Function|null} onConfirm - Callback for the Import button, or null for close-only
     */
    function updatePreviewContent(previewHtml, onConfirm) {
        const container = document.querySelector('.import-preview-container');
        if (!container) return;

        container.innerHTML = previewHtml;

        // Update or create form actions
        const modal = container.closest('.modal-body') || container.parentElement;
        let actions = modal.querySelector('.form-actions');
        if (!actions) {
            actions = document.createElement('div');
            actions.className = 'form-actions';
            modal.appendChild(actions);
        }

        if (onConfirm) {
            actions.innerHTML = `
                <button type="button" class="btn btn-secondary" onclick="GoingsOn.ui.closeModal()">Cancel</button>
                <button type="button" class="btn btn-primary" id="import-external-confirm">Import</button>
            `;
            document.getElementById('import-external-confirm').addEventListener('click', onConfirm);
        } else {
            actions.innerHTML = `
                <button type="button" class="btn btn-secondary" onclick="GoingsOn.ui.closeModal()">Close</button>
            `;
        }
    }

    // ============ Populate Namespace ============

    GoingsOn.importExternal = {
        openDialog: openImportDialog,
        startContactImport,
        startCalendarImport,
    };

})();