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packages/api/src/adapter-aws/zipArchive.ts

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+/**
+ * Minimal ZIP writer for Lambda deployment packages.
+ *
+ * `CreateFunction`'s `Code.ZipFile` must be a real ZIP archive — passing raw
+ * source text makes the runtime reject the call with "Handler file not found in
+ * deployment package". Nothing in the dependency tree can build one, and the
+ * archives here are a single small source file, so entries are written with the
+ * STORED method (no compression): that needs only a CRC-32 and keeps this to a
+ * format-exact, dependency-free implementation.
+ *
+ * Spec: PKWARE APPNOTE 6.3.x, sections 4.3.7 (local header), 4.3.12 (central
+ * directory) and 4.3.16 (end of central directory).
+ */
+
+const CRC32_TABLE = buildCrc32Table()
+
+function buildCrc32Table(): Uint32Array {
+    const table = new Uint32Array(256)
+    for (let i = 0; i < 256; i += 1) {
+        let value = i
+        for (let bit = 0; bit < 8; bit += 1) {
+            value = value & 1 ? 0xedb88320 ^ (value >>> 1) : value >>> 1
+        }
+        table[i] = value >>> 0
+    }
+    return table
+}
+
+export function crc32(bytes: Uint8Array): number {
+    let crc = 0xffffffff
+    for (const byte of bytes) {
+        crc = CRC32_TABLE[(crc ^ byte) & 0xff]! ^ (crc >>> 8)
+    }
+    return (crc ^ 0xffffffff) >>> 0
+}
+
+export interface ZipEntry {
+    name: string
+    content: string | Uint8Array
+}
+
+/** Build a ZIP archive containing the given files, stored uncompressed. */
+export function createZipArchive(entries: ZipEntry[]): Uint8Array {
+    const encoder = new TextEncoder()
+    const localParts: Uint8Array[] = []
+    const centralParts: Uint8Array[] = []
+    let offset = 0
+    let localSize = 0
+
+    for (const entry of entries) {
+        const nameBytes = encoder.encode(entry.name)
+        const data = typeof entry.content === 'string' ? encoder.encode(entry.content) : entry.content
+        const checksum = crc32(data)
+
+        const localHeader = new Uint8Array(30 + nameBytes.length)
+        const localView = new DataView(localHeader.buffer)
+        localView.setUint32(0, 0x04034b50, true) // local file header signature
+        localView.setUint16(4, 20, true) // version needed to extract (2.0)
+        localView.setUint16(6, 0, true) // general purpose bit flag
+        localView.setUint16(8, 0, true) // compression method: STORED
+        localView.setUint16(10, 0, true) // last mod time — fixed for reproducibility
+        localView.setUint16(12, 0x0021, true) // last mod date: 1980-01-01, the epoch ZIP allows
+        localView.setUint32(14, checksum, true)
+        localView.setUint32(18, data.length, true) // compressed size
+        localView.setUint32(22, data.length, true) // uncompressed size
+        localView.setUint16(26, nameBytes.length, true)
+        localView.setUint16(28, 0, true) // extra field length
+        localHeader.set(nameBytes, 30)
+
+        const centralHeader = new Uint8Array(46 + nameBytes.length)
+        const centralView = new DataView(centralHeader.buffer)
+        centralView.setUint32(0, 0x02014b50, true) // central directory signature
+        centralView.setUint16(4, 20, true) // version made by
+        centralView.setUint16(6, 20, true) // version needed to extract
+        centralView.setUint16(8, 0, true)
+        centralView.setUint16(10, 0, true) // STORED
+        centralView.setUint16(12, 0, true)
+        centralView.setUint16(14, 0x0021, true)
+        centralView.setUint32(16, checksum, true)
+        centralView.setUint32(20, data.length, true)
+        centralView.setUint32(24, data.length, true)
+        centralView.setUint16(28, nameBytes.length, true)
+        centralView.setUint16(30, 0, true) // extra field length
+        centralView.setUint16(32, 0, true) // file comment length
+        centralView.setUint16(34, 0, true) // disk number start
+        centralView.setUint16(36, 0, true) // internal file attributes
+        centralView.setUint32(38, 0o100644 << 16, true) // external attrs: regular file, rw-r--r--
+        centralView.setUint32(42, offset, true) // relative offset of local header
+        centralHeader.set(nameBytes, 46)
+
+        localParts.push(localHeader, data)
+        centralParts.push(centralHeader)
+        offset += localHeader.length + data.length
+        localSize += localHeader.length + data.length
+    }
+
+    const centralSize = centralParts.reduce((total, part) => total + part.length, 0)
+    const endRecord = new Uint8Array(22)
+    const endView = new DataView(endRecord.buffer)
+    endView.setUint32(0, 0x06054b50, true) // end of central directory signature
+    endView.setUint16(4, 0, true) // this disk number
+    endView.setUint16(6, 0, true) // disk with central directory
+    endView.setUint16(8, entries.length, true)
+    endView.setUint16(10, entries.length, true)
+    endView.setUint32(12, centralSize, true)
+    endView.setUint32(16, localSize, true) // central directory offset
+    endView.setUint16(20, 0, true) // comment length
+
+    return concat([...localParts, ...centralParts, endRecord])
+}
+
+function concat(parts: Uint8Array[]): Uint8Array {
+    const total = parts.reduce((sum, part) => sum + part.length, 0)
+    const out = new Uint8Array(total)
+    let cursor = 0
+    for (const part of parts) {
+        out.set(part, cursor)
+        cursor += part.length
+    }
+    return out
+}
+
+/**
+ * Derive the deployment-package filename Lambda will look for from a handler
+ * string. `index.handler` means the exported `handler` lives in `index.js`;
+ * `src/app.run` means `run` lives in `src/app.js`.
+ */
+export function handlerFileName(handler: string, runtime: string): string {
+    const modulePath = handler.split('.').slice(0, -1).join('.') || 'index'
+    const extension = runtime.startsWith('python') ? 'py' : runtime.startsWith('ruby') ? 'rb' : 'js'
+    return `${modulePath}.${extension}`
+}