1/*
2 * Copyright (c) 2026 DataPond D-Library Pty Ltd. ("The Sanctuary")
3 * Non-Profit Public Library — The World Library
4 * 
5 * D-SAFE Certification issued by POND Enterprise.
6 * Published under the D-Open Code Sovereign Licence v1.0 framework
7 * DataPond D-Library All exclusive Right reserved on modifiying the code - CC Attribution to data pond, Non modifiable, Non Commercial.
8 * https://registry.world.bibliotech.com/licence
9 * Source code donated to DataPond D-Library by it's author: data pond.
10 * 
11 * Technical Guardian ("The Shield"): Pond Enterprise Pty Ltd. (ACN 694 747 987)
12 * All liability claims about D-SAFE certification issues coming from the published D-Safe direction must be addressed with Pond Enterprise Pty Ltd.
13 * Code Modification automatically voids the certified liability protection provided by Pond Enterprise.
14 */
15// File download worker (Phase A: dedicated). Handles GetFile + CancelDownload.
16import { fetchFromGateways, DEFAULT_GATEWAYS } from '../fetcher';
17import { putPdf, putPreview } from '../cache-store';
18import { putDownloadRecord } from '../meta-db';
19import { runLruPruneAndEmit } from '../lru';
20import type { WorkerCommand, WorkerMessage } from '../worker-protocol';
21
22// Gateways can be overridden via an init message (future extension).
23let gateways = DEFAULT_GATEWAYS;
24
25function post(msg: WorkerMessage): void {
26    (self as unknown as Worker).postMessage(msg);
27}
28
29async function handleGetFile(txId: string, mime: 'pdf' | 'preview'): Promise<void> {
30    try {
31        const response = await fetchFromGateways(txId, gateways, (loaded, total) => {
32            post({ type: 'DownloadProgress', txId, loaded, total });
33        });
34
35        // Determine correct Content-Type.
36        const ct = mime === 'pdf'
37            ? 'application/pdf'
38            : (response.headers.get('content-type') || 'application/octet-stream');
39
40        // Content-Length can't be trusted here: fetcher.ts strips it (it would
41        // otherwise describe the pre-decompression byte count for gzipped
42        // payloads), so the real size is measured from the decoded body itself.
43        const buffer = await response.arrayBuffer();
44        const sizeBytes = buffer.byteLength;
45
46        // Store in the correct named cache.
47        const headers = new Headers(response.headers);
48        headers.set('Content-Type', ct);
49        headers.set('Content-Length', String(sizeBytes));
50        headers.set('X-DL2-Stored', new Date().toISOString());
51        const cloned = new Response(buffer, { status: response.status, headers });
52
53        if (mime === 'pdf') {
54            await putPdf(txId, cloned);
55        } else {
56            await putPreview(txId, cloned);
57        }
58
59        // Bookkeeping.
60        await putDownloadRecord({
61            txId,
62            fileType:       mime,
63            sizeBytes,
64            downloadedAt:   Date.now(),
65            lastAccessedAt: Date.now(),
66        });
67
68        post({ type: 'DownloadFinished', txId, key: txId, mime });
69        // Resolve the orchestrator's rpc() — keyed by `${txId}:${mime}`, matching
70        // rpcRequestKey() in client/worker-client.ts, so a concurrent pdf + preview
71        // rpc() for the same book each resolve with their own result instead of
72        // whichever one happens to post its FileRpcResponse first (§5.5 / §13.3).
73        post({ type: 'FileRpcResponse', ok: true, key: `${txId}:${mime}` });
74
75        // Self-prune after every successful write.
76        await runLruPruneAndEmit(post);
77    } catch (err: unknown) {
78        const msg = err instanceof Error ? err.message : String(err);
79        post({ type: 'DownloadError', txId, error: msg, retryable: true });
80        post({ type: 'FileRpcResponse', ok: false, key: `${txId}:${mime}`, error: msg });
81    }
82}
83
84(self as unknown as Worker).onmessage = (e: MessageEvent<WorkerCommand>) => {
85    const cmd = e.data;
86    if (cmd.type === 'GetFile') {
87        handleGetFile(cmd.txId, cmd.mime);
88    } else if (cmd.type === 'CancelDownload') {
89        // Phase A stub — full cancellation via AbortController in Phase B.
90    }
91    // ProcessPages is handled by the mu-worker, not here.
92};
93