Repository navigation
Expand file tree
/
Copy pathfetch.ts
More file actions
186 lines (165 loc) · 5.38 KB
/
Copy pathfetch.ts
File metadata and controls
186 lines (165 loc) · 5.38 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
import path from "node:path";
import { detectMime, extensionForMime } from "./mime.js";
type FetchMediaResult = {
buffer: Buffer;
contentType?: string;
fileName?: string;
};
export type MediaFetchErrorCode = "max_bytes" | "http_error" | "fetch_failed";
export class MediaFetchError extends Error {
readonly code: MediaFetchErrorCode;
constructor(code: MediaFetchErrorCode, message: string) {
super(message);
this.code = code;
this.name = "MediaFetchError";
}
}
export type FetchLike = (input: RequestInfo | URL, init?: RequestInit) => Promise<Response>;
type FetchMediaOptions = {
url: string;
fetchImpl?: FetchLike;
filePathHint?: string;
maxBytes?: number;
};
function stripQuotes(value: string): string {
return value.replace(/^["']|["']$/g, "");
}
function parseContentDispositionFileName(header?: string | null): string | undefined {
if (!header) return undefined;
const starMatch = /filename\*\s*=\s*([^;]+)/i.exec(header);
if (starMatch?.[1]) {
const cleaned = stripQuotes(starMatch[1].trim());
const encoded = cleaned.split("''").slice(1).join("''") || cleaned;
try {
return path.basename(decodeURIComponent(encoded));
} catch {
return path.basename(encoded);
}
}
const match = /filename\s*=\s*([^;]+)/i.exec(header);
if (match?.[1]) return path.basename(stripQuotes(match[1].trim()));
return undefined;
}
async function readErrorBodySnippet(res: Response, maxChars = 200): Promise<string | undefined> {
try {
const text = await res.text();
if (!text) return undefined;
const collapsed = text.replace(/\s+/g, " ").trim();
if (!collapsed) return undefined;
if (collapsed.length <= maxChars) return collapsed;
return `${collapsed.slice(0, maxChars)}…`;
} catch {
return undefined;
}
}
export async function fetchRemoteMedia(options: FetchMediaOptions): Promise<FetchMediaResult> {
const { url, fetchImpl, filePathHint, maxBytes } = options;
const fetcher: FetchLike | undefined = fetchImpl ?? globalThis.fetch;
if (!fetcher) {
throw new Error("fetch is not available");
}
let res: Response;
try {
res = await fetcher(url);
} catch (err) {
throw new MediaFetchError("fetch_failed", `Failed to fetch media from ${url}: ${String(err)}`);
}
if (!res.ok) {
const statusText = res.statusText ? ` ${res.statusText}` : "";
const redirected = res.url && res.url !== url ? ` (redirected to ${res.url})` : "";
let detail = `HTTP ${res.status}${statusText}`;
if (!res.body) {
detail = `HTTP ${res.status}${statusText}; empty response body`;
} else {
const snippet = await readErrorBodySnippet(res);
if (snippet) detail += `; body: ${snippet}`;
}
throw new MediaFetchError(
"http_error",
`Failed to fetch media from ${url}${redirected}: ${detail}`,
);
}
const contentLength = res.headers.get("content-length");
if (maxBytes && contentLength) {
const length = Number(contentLength);
if (Number.isFinite(length) && length > maxBytes) {
throw new MediaFetchError(
"max_bytes",
`Failed to fetch media from ${url}: content length ${length} exceeds maxBytes ${maxBytes}`,
);
}
}
const buffer = maxBytes
? await readResponseWithLimit(res, maxBytes)
: Buffer.from(await res.arrayBuffer());
let fileNameFromUrl: string | undefined;
try {
const parsed = new URL(url);
const base = path.basename(parsed.pathname);
fileNameFromUrl = base || undefined;
} catch {
// ignore parse errors; leave undefined
}
const headerFileName = parseContentDispositionFileName(res.headers.get("content-disposition"));
let fileName =
headerFileName || fileNameFromUrl || (filePathHint ? path.basename(filePathHint) : undefined);
const filePathForMime =
headerFileName && path.extname(headerFileName) ? headerFileName : (filePathHint ?? url);
const contentType = await detectMime({
buffer,
headerMime: res.headers.get("content-type"),
filePath: filePathForMime,
});
if (fileName && !path.extname(fileName) && contentType) {
const ext = extensionForMime(contentType);
if (ext) fileName = `${fileName}${ext}`;
}
return {
buffer,
contentType: contentType ?? undefined,
fileName,
};
}
async function readResponseWithLimit(res: Response, maxBytes: number): Promise<Buffer> {
const body = res.body;
if (!body || typeof body.getReader !== "function") {
const fallback = Buffer.from(await res.arrayBuffer());
if (fallback.length > maxBytes) {
throw new MediaFetchError(
"max_bytes",
`Failed to fetch media from ${res.url || "response"}: payload exceeds maxBytes ${maxBytes}`,
);
}
return fallback;
}
const reader = body.getReader();
const chunks: Uint8Array[] = [];
let total = 0;
try {
while (true) {
const { done, value } = await reader.read();
if (done) break;
if (value?.length) {
total += value.length;
if (total > maxBytes) {
try {
await reader.cancel();
} catch {}
throw new MediaFetchError(
"max_bytes",
`Failed to fetch media from ${res.url || "response"}: payload exceeds maxBytes ${maxBytes}`,
);
}
chunks.push(value);
}
}
} finally {
try {
reader.releaseLock();
} catch {}
}
return Buffer.concat(
chunks.map((chunk) => Buffer.from(chunk)),
total,
);
}