// preview.js — file preview popup. Reuses shared/preview-lib.js for
// TIFF, ZIP listing, and image-rendering helpers; native iframe for
// PDF and HTML; <pre> for text; download button for everything else.
//
// Lifecycle: a single popup window is reused across multiple file
// clicks (state.previewWindow). Subsequent clicks rewrite its
// contents instead of spawning a new window — same UX as the archive
// tool.
(function () {
    'use strict';

    var state = window.app.state;
    var loader = window.app.modules.loader;
    var preview = window.zddc && window.zddc.preview;
    if (!preview) {
        // shared/preview-lib.js wasn't concatenated in. Bail loudly so
        // the bug shows up in console rather than mysteriously failing.
        console.error('[browse] zddc.preview not loaded — preview popup disabled.');
    }

    function escapeHtml(s) {
        return String(s).replace(/&/g, '&amp;').replace(/</g, '&lt;')
            .replace(/>/g, '&gt;').replace(/"/g, '&quot;');
    }

    var MIME = {
        'pdf': 'application/pdf',
        'html': 'text/html', 'htm': 'text/html',
        'jpg': 'image/jpeg', 'jpeg': 'image/jpeg', 'png': 'image/png',
        'gif': 'image/gif', 'webp': 'image/webp', 'svg': 'image/svg+xml',
        'tif': 'image/tiff', 'tiff': 'image/tiff',
        'zip': 'application/zip',
        'txt': 'text/plain', 'md': 'text/markdown', 'json': 'application/json',
        'xml': 'application/xml', 'csv': 'text/csv', 'log': 'text/plain',
        'js': 'text/javascript', 'css': 'text/css'
    };

    // Pull bytes for a file node. Three sources:
    //   - server URL (zddc-server-backed file, including downloads
    //     of archived files served at real paths)
    //   - FS-API handle (local folder)
    //   - JSZip entry (file inside an expanded zip; reads from
    //     parent's cached JSZip instance)
    async function getArrayBuffer(node) {
        if (node.zipParentId != null) {
            var owner = state.nodes.get(node.zipParentId);
            if (!owner || !owner.zipFile) {
                throw new Error('parent zip not loaded');
            }
            return await owner.zipFile.file(node.zipPath).async('arraybuffer');
        }
        if (state.source === 'server' && node.url) {
            var resp = await fetch(node.url);
            if (!resp.ok) throw new Error('HTTP ' + resp.status);
            return await resp.arrayBuffer();
        }
        if (node.handle) {
            var f = await node.handle.getFile();
            return await f.arrayBuffer();
        }
        throw new Error('no source for file');
    }

    function getMime(ext) {
        return MIME[ext] || 'application/octet-stream';
    }

    // Build a blob URL for the file's bytes. For server-mode regular
    // files (not in a zip), prefer the live URL — relative links and
    // server-side interception (e.g. .archive resolution) work then.
    async function getBlobUrl(node) {
        if (state.source === 'server' && node.url && node.zipParentId == null) {
            return { url: node.url, fromServer: true };
        }
        var buf = await getArrayBuffer(node);
        var blob = new Blob([buf], { type: getMime(node.ext) });
        return { url: URL.createObjectURL(blob), fromServer: false };
    }

    function popupShell(node, primaryUrl) {
        var safeName = escapeHtml(node.name);
        var safeHref = escapeHtml(primaryUrl);
        var ext = (node.ext || '').toLowerCase();
        // Inline PDF and HTML previews load in iframes. HTML uses
        // sandbox="allow-same-origin allow-popups
        // allow-popups-to-escape-sandbox" — same posture as archive's
        // preview: links navigate, scripts blocked, popups allowed.
        var contentHtml;
        if (ext === 'pdf') {
            contentHtml = '<iframe src="' + safeHref + '"></iframe>';
        } else if (ext === 'html' || ext === 'htm') {
            contentHtml = '<iframe src="' + safeHref + '" sandbox="allow-same-origin allow-popups allow-popups-to-escape-sandbox"></iframe>';
        } else if (preview && preview.isImage(ext) && !preview.isTiff(ext)) {
            contentHtml = '<img class="preview-image" src="' + safeHref + '" alt="' + safeName + '">';
        } else {
            contentHtml = '<div id="previewContent"><div class="loading">Loading preview…</div></div>';
        }
        return '<!DOCTYPE html><html><head><meta charset="UTF-8">'
            + '<title>' + safeName + ' — preview</title><style>'
            + '*{margin:0;padding:0;box-sizing:border-box;}'
            + 'body{display:flex;flex-direction:column;height:100vh;'
            + 'font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,sans-serif;}'
            + '.toolbar{display:flex;align-items:center;gap:.5rem;padding:.5rem 1rem;'
            + 'background:#f5f5f5;border-bottom:1px solid #ddd;}'
            + '.toolbar h1{flex:1;font-size:.95rem;font-weight:500;overflow:hidden;'
            + 'text-overflow:ellipsis;white-space:nowrap;}'
            + '.btn{padding:.4rem .8rem;font-size:.85rem;border:1px solid #ccc;'
            + 'border-radius:4px;background:white;cursor:pointer;}'
            + '.btn:hover{background:#e8e8e8;}'
            + 'iframe{flex:1;width:100%;border:none;}'
            + '#previewContent{flex:1;overflow:auto;display:flex;flex-direction:column;}'
            + '.loading{display:flex;align-items:center;justify-content:center;height:100%;'
            + 'color:#666;font-size:1.1rem;}'
            + 'img.preview-image{max-width:100%;max-height:100%;object-fit:contain;'
            + 'margin:auto;display:block;}'
            + 'pre.preview-text{padding:1rem;font-family:Consolas,Monaco,monospace;'
            + 'font-size:.85rem;white-space:pre-wrap;word-wrap:break-word;}'
            + '</style></head><body>'
            + '<div class="toolbar"><h1>' + safeName + '</h1>'
            + '<button class="btn" onclick="downloadFile()">Download</button></div>'
            + contentHtml
            + '<script>'
            + 'var blobUrl=' + JSON.stringify(primaryUrl) + ';'
            + 'var fileName=' + JSON.stringify(node.name) + ';'
            + 'function downloadFile(){var a=document.createElement("a");'
            + 'a.href=blobUrl;a.download=fileName;document.body.appendChild(a);'
            + 'a.click();document.body.removeChild(a);}'
            + '</' + 'script></body></html>';
    }

    async function renderTextInWindow(node, win) {
        var c = win.document.getElementById('previewContent');
        if (!c) return;
        try {
            var buf = await getArrayBuffer(node);
            var text = new TextDecoder('utf-8', { fatal: false }).decode(buf);
            var MAX = 200000;
            if (text.length > MAX) {
                text = text.substring(0, MAX) + '\n\n... (truncated, '
                    + (text.length - MAX) + ' more chars — Download for full file)';
            }
            var pre = win.document.createElement('pre');
            pre.className = 'preview-text';
            pre.textContent = text;
            c.innerHTML = '';
            c.appendChild(pre);
        } catch (e) {
            c.innerHTML = '<div class="loading">Error: ' + escapeHtml(e.message || e) + '</div>';
        }
    }

    async function renderTiffInWindow(node, win) {
        var c = win.document.getElementById('previewContent');
        if (!c || !preview) return;
        try {
            var buf = await getArrayBuffer(node);
            await preview.renderTiff(win.document, c, buf, { fileName: node.name });
        } catch (e) {
            c.innerHTML = '<div class="loading">Error rendering TIFF: '
                + escapeHtml(e.message || e) + '</div>';
        }
    }

    async function renderZipInWindow(node, win) {
        var c = win.document.getElementById('previewContent');
        if (!c || !preview) return;
        try {
            var buf = await getArrayBuffer(node);
            await preview.renderZipListing(win.document, c, buf, { fileName: node.name });
        } catch (e) {
            c.innerHTML = '<div class="loading">Error reading ZIP: '
                + escapeHtml(e.message || e) + '</div>';
        }
    }

    async function showFilePreview(node) {
        if (node.isDir) return;

        var ext = (node.ext || '').toLowerCase();
        var info;
        try {
            info = await getBlobUrl(node);
        } catch (e) {
            window.app.modules.events.statusError('Preview failed: ' + e.message);
            return;
        }
        var html = popupShell(node, info.url);

        var win = state.previewWindow;
        if (win && !win.closed) {
            win.document.open();
            win.document.write(html);
            win.document.close();
            win.focus();
        } else {
            var w = Math.round(screen.width * 0.6);
            var h = Math.round(screen.height * 0.8);
            var left = Math.round((screen.width - w) / 2);
            var top = Math.round((screen.height - h) / 2);
            win = window.open('', 'browseFilePreview',
                'width=' + w + ',height=' + h + ',left=' + left + ',top=' + top
                + ',resizable=yes,scrollbars=yes');
            if (!win) {
                // Popup blocked — fall back to opening the file directly.
                window.open(info.url, '_blank', 'noopener');
                return;
            }
            win.document.write(html);
            win.document.close();
            win.focus();
            state.previewWindow = win;
        }

        // Async content rendering for the non-iframe types.
        if (ext === 'pdf' || ext === 'html' || ext === 'htm') {
            return; // iframe wired in popupShell
        }
        if (preview && preview.isImage(ext) && !preview.isTiff(ext)) {
            return; // <img> wired in popupShell
        }
        if (preview && preview.isTiff(ext)) {
            await renderTiffInWindow(node, win);
        } else if (preview && preview.isZip(ext)) {
            await renderZipInWindow(node, win);
        } else if (preview && preview.isText(ext)) {
            await renderTextInWindow(node, win);
        } else {
            // Unknown type — show a friendly "no preview, click
            // download" placeholder.
            var c = win.document.getElementById('previewContent');
            if (c) {
                c.innerHTML = '<div class="loading">No inline preview for .'
                    + escapeHtml(ext) + ' — click Download.</div>';
            }
        }
    }

    window.app.modules.preview = { showFilePreview: showFilePreview };
})();