feat(tui): use canonical prompt attachments

packages/core/src/mime.ts

@@ -0,0 +1,88 @@
+export * as Mime from "./mime.js"
+
+import { Effect, FileSystem, Option } from "effect"
+import { fileURLToPath } from "url"
+import { FSUtil } from "./fs-util"
+
+const SAMPLE_BYTES = 8192
+
+export const resolve = Effect.fn("Mime.resolve")(function* (uri: string) {
+  const data = dataSample(uri)
+  if (data) return detect(data)
+
+  const target = yield* Effect.try({
+    try: () => localPath(uri),
+    catch: () => new Error("Invalid file URI"),
+  }).pipe(Effect.catch(() => Effect.succeed(undefined)))
+  if (!target) return "application/octet-stream"
+
+  const fs = yield* FSUtil.Service
+  const local = yield* Effect.scoped(
+    Effect.gen(function* () {
+      const info = yield* fs.stat(target)
+      if (info.type === "Directory") return { type: "directory" as const }
+      if (info.type !== "File") return
+      const file = yield* fs.open(target)
+      return {
+        type: "file" as const,
+        sample: Option.getOrElse(yield* file.readAlloc(FileSystem.Size(SAMPLE_BYTES)), () => new Uint8Array()),
+      }
+    }),
+  ).pipe(Effect.catch(() => Effect.succeed(undefined)))
+
+  if (local?.type === "directory") return "application/x-directory"
+  if (local?.type === "file") return detect(local.sample)
+  return "application/octet-stream"
+})
+
+function detect(bytes: Uint8Array) {
+  if (startsWith(bytes, [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a])) return "image/png"
+  if (startsWith(bytes, [0xff, 0xd8, 0xff])) return "image/jpeg"
+  if (startsWith(bytes, [0x47, 0x49, 0x46, 0x38])) return "image/gif"
+  if (startsWith(bytes, [0x42, 0x4d])) return "image/bmp"
+  if (startsWith(bytes, [0x25, 0x50, 0x44, 0x46, 0x2d])) return "application/pdf"
+  if (startsWith(bytes, [0x52, 0x49, 0x46, 0x46]) && startsWith(bytes.subarray(8), [0x57, 0x45, 0x42, 0x50]))
+    return "image/webp"
+  if (
+    startsWith(bytes.subarray(4), [0x66, 0x74, 0x79, 0x70]) &&
+    (startsWith(bytes.subarray(8), [0x61, 0x76, 0x69, 0x66]) ||
+      startsWith(bytes.subarray(8), [0x61, 0x76, 0x69, 0x73]))
+  )
+    return "image/avif"
+  return isText(bytes) ? "text/plain" : "application/octet-stream"
+}
+
+function dataSample(uri: string) {
+  if (!uri.startsWith("data:")) return
+  const comma = uri.indexOf(",")
+  if (comma === -1) return new Uint8Array()
+  const metadata = uri.slice(5, comma)
+  const payload = uri.slice(comma + 1)
+  if (metadata.split(";").some((part) => part.toLowerCase() === "base64")) {
+    return Buffer.from(payload.slice(0, Math.ceil((SAMPLE_BYTES * 4) / 3) + 4), "base64").subarray(0, SAMPLE_BYTES)
+  }
+  return new TextEncoder().encode(payload.slice(0, SAMPLE_BYTES))
+}
+
+function localPath(uri: string) {
+  if (!URL.canParse(uri)) return
+  const url = new URL(uri)
+  if (url.protocol !== "file:") return
+  return fileURLToPath(url)
+}
+
+function startsWith(bytes: Uint8Array, prefix: number[]) {
+  return prefix.every((value, index) => bytes[index] === value)
+}
+
+function isText(bytes: Uint8Array) {
+  if (bytes.length === 0) return true
+  if (bytes.includes(0)) return false
+  try {
+    new TextDecoder("utf-8", { fatal: true }).decode(bytes, { stream: true })
+  } catch {
+    return false
+  }
+  const controls = bytes.reduce((count, byte) => count + Number(byte < 9 || (byte > 13 && byte < 32)), 0)
+  return controls / bytes.length <= 0.3
+}