// ============================================================
// app.attachments.js — ENCRYPTED ATTACHMENTS module (extracted from app.js, §3.1)
// ============================================================
//
// Per-entry file crypto + upload/download/slideover UI. Pure declarations
// (no top-level side effects) → loads BEFORE app.js. Uses state, api,
// authHeaders, Bridge, toast — all resolved via the shared global scope at
// call time.

// Per-entry files (PDFs, backup-code images, recovery sheets, …)
// encrypted client-side with the vault key, base64-shipped to the server
// for opaque storage. Listing returns metadata only — the ciphertext is
// fetched on demand when the user clicks Download.

const ATTACHMENT_MAX_BYTES = 5 * 1024 * 1024;  // raw file size cap (5 MB)

async function encryptBlobBytes(bytes) {
    const iv = crypto.getRandomValues(new Uint8Array(12));
    const ct = await crypto.subtle.encrypt(
        { name: 'AES-GCM', iv }, state.cryptoKey, bytes);
    return { encrypted: bytesToBase64(ct), iv: bytesToBase64(iv) };
}
async function decryptBlobBytes(encB64, ivB64) {
    const ct = base64ToBytes(encB64);
    const iv = base64ToBytes(ivB64);
    const dec = await crypto.subtle.decrypt(
        { name: 'AES-GCM', iv }, state.cryptoKey, ct);
    return new Uint8Array(dec);
}

function humanFileSize(n) {
    if (n < 1024) return n + ' B';
    if (n < 1024 * 1024) return (n / 1024).toFixed(1) + ' KB';
    return (n / 1024 / 1024).toFixed(2) + ' MB';
}

async function uploadAttachment(entryId, file) {
    if (!file) return null;
    if (file.size > ATTACHMENT_MAX_BYTES) {
        toast('File too large (max 5 MB raw)', 'error');
        return null;
    }
    const bytes = new Uint8Array(await file.arrayBuffer());
    const { encrypted, iv } = await encryptBlobBytes(bytes);
    const meta = await api('/entries/' + entryId + '/attachments', {
        method: 'POST',
        headers: authHeaders({ 'Content-Type': 'application/json' }),
        body: JSON.stringify({
            filename:       file.name,
            mime:           file.type || 'application/octet-stream',
            encrypted_blob: encrypted,
            iv,
            size_bytes:     file.size,
        }),
    });
    return meta;
}

async function downloadAttachment(att) {
    // Spinner for large attachments — fetch + decrypt + chunked transfer
    // of a multi-MB file takes a moment before the Save dialog appears.
    const big = (att.size_bytes || 0) > 512 * 1024;
    try {
        if (big) showBusy('Preparing download…');
        const full = await api('/attachments/' + att.id, { headers: authHeaders() });
        const bytes = await decryptBlobBytes(full.encrypted_blob, full.iv);
        if (Bridge.active && typeof Bridge.saveFile === 'function') {
            const res = await Bridge.saveFile(att.filename, bytes, pct => {
                if (big) updateBusy('Preparing download… ' + pct + '%');
            });
            if (big) hideBusy();
            if (res.ok) toast('Saved to ' + res.path);
            else if (res.error) toast('Save failed: ' + res.error, 'error');
        } else {
            if (big) hideBusy();
            // Web fallback: trigger a browser download.
            const blob = new Blob([bytes], { type: att.mime || 'application/octet-stream' });
            const url = URL.createObjectURL(blob);
            const a = el('a', { href: url, download: att.filename });
            document.body.appendChild(a);
            a.click();
            setTimeout(() => { URL.revokeObjectURL(url); a.remove(); }, 100);
        }
    } catch (e) {
        if (big) hideBusy();
        toast('Download failed: ' + (e && e.message ? e.message : e), 'error');
    }
}

// Slideover field: header + upload button + list of attachments.
// Re-renders the list in place when the contents change (upload/delete).
function soAttachmentsField(entryId) {
    const isStaging = (entryId === null || entryId === undefined);
    const wrap = el('div', { class: 'slideover-field' });
    wrap.appendChild(el('div', { class: 'slideover-field-label' }, 'Attachments'));

    const addBtn = el('button', {
        class: 'btn btn-ghost btn-sm', type: 'button',
        title: 'Attach a file (encrypted before upload, max 5 MB)',
    });
    addBtn.appendChild(icon('i-paperclip'));
    addBtn.appendChild(document.createTextNode(' Attach file'));
    wrap.appendChild(addBtn);

    const fileInput = el('input', { type: 'file', style: 'display:none' });
    wrap.appendChild(fileInput);

    const list = el('div', { class: 'so-attach-list', id: 'soAttachList' });
    wrap.appendChild(list);

    addBtn.addEventListener('click', ev => {
        ev.stopPropagation();
        fileInput.click();
    });
    fileInput.addEventListener('change', async ev => {
        ev.stopPropagation();
        const file = fileInput.files && fileInput.files[0];
        if (!file) return;
        fileInput.value = '';   // allow re-uploading the same name later
        if (file.size > ATTACHMENT_MAX_BYTES) {
            toast('File too large (max 5 MB raw)', 'error');
            return;
        }
        addBtn.disabled = true;
        try {
            if (isStaging) {
                // Stage in memory — uploaded by soSave after the new
                // entry's id is known.
                const bytes = new Uint8Array(await file.arrayBuffer());
                soState.pendingAttachments.push({
                    filename:   file.name,
                    mime:       file.type || 'application/octet-stream',
                    size_bytes: file.size,
                    bytes,
                });
                soDirtyCheck();
                renderStagedAttachments(list);
            } else {
                await uploadAttachment(entryId, file);
                toast('Attachment uploaded');
                await refreshAttachments(entryId, list);
            }
        } catch (e) {
            toast('Upload failed: ' + e.message, 'error');
        } finally {
            addBtn.disabled = false;
        }
    });

    if (isStaging) renderStagedAttachments(list);
    else           refreshAttachments(entryId, list);
    return wrap;
}

// Renders the pendingAttachments array (new-entry mode). Mirrors the
// existing-entry layout so users can't tell the difference until they
// hit Save.
function renderStagedAttachments(container) {
    container.innerHTML = '';
    const list = soState.pendingAttachments || [];
    if (list.length === 0) {
        container.appendChild(el('div', { class: 'so-attach-empty' },
            'No attachments yet. Files will upload after you save.'));
        return;
    }
    list.forEach((att, idx) => {
        const row = el('div', { class: 'so-attach-row' });
        const info = el('div', { class: 'so-attach-info' });
        info.appendChild(el('div', { class: 'so-attach-name', title: att.filename }, att.filename));
        info.appendChild(el('div', { class: 'so-attach-meta' },
            humanFileSize(att.size_bytes) + ' · ' + (att.mime || '?') +
            ' · pending'));
        row.appendChild(info);

        const del = el('button',
            { class: 'icon-btn icon-btn-sm', type: 'button', title: 'Remove' });
        del.appendChild(icon('i-trash'));
        del.addEventListener('click', ev => {
            ev.stopPropagation();
            soState.pendingAttachments.splice(idx, 1);
            soDirtyCheck();
            renderStagedAttachments(container);
        });
        row.appendChild(del);
        container.appendChild(row);
    });
}

async function refreshAttachments(entryId, container) {
    container.innerHTML = '';
    let items = [];
    try {
        items = await api('/entries/' + entryId + '/attachments',
                          { headers: authHeaders() });
    } catch (e) {
        container.appendChild(el('div', { class: 'so-attach-empty' },
            'Failed to load attachments'));
        return;
    }
    if (!items || items.length === 0) {
        container.appendChild(el('div', { class: 'so-attach-empty' },
            'No attachments yet.'));
        return;
    }
    items.forEach(att => container.appendChild(buildAttachmentRow(att, entryId, container)));
}

function buildAttachmentRow(att, entryId, listContainer) {
    const row = el('div', { class: 'so-attach-row' });
    const name = el('div', { class: 'so-attach-name', title: att.filename }, att.filename);
    const meta = el('div', { class: 'so-attach-meta' },
        humanFileSize(att.size_bytes) + ' · ' + (att.mime || '?'));
    const info = el('div', { class: 'so-attach-info' });
    info.appendChild(name);
    info.appendChild(meta);
    row.appendChild(info);

    const dl = el('button', { class: 'icon-btn icon-btn-sm', type: 'button', title: 'Download' });
    dl.appendChild(icon('i-download'));
    dl.addEventListener('click', ev => {
        ev.stopPropagation();
        downloadAttachment(att);
    });
    row.appendChild(dl);

    const del = el('button', { class: 'icon-btn icon-btn-sm', type: 'button', title: 'Delete' });
    del.appendChild(icon('i-trash'));
    del.addEventListener('click', async ev => {
        ev.stopPropagation();
        const ok = await confirmDialog({
            title: 'Delete attachment?',
            message: 'This will permanently remove <b>' + att.filename + '</b>. There is no trash for attachments.',
            okText: 'Delete',
            danger: true,
        });
        if (!ok) return;
        try {
            await api('/attachments/' + att.id, {
                method: 'DELETE', headers: authHeaders(),
            });
            toast('Attachment deleted');
            await refreshAttachments(entryId, listContainer);
        } catch (e) {
            toast('Delete failed: ' + e.message, 'error');
        }
    });
    row.appendChild(del);
    return row;
}