feat(ai): support image-guided generation (#37998)

Co-authored-by: Aiden Cline <rekram1-node@users.noreply.github.com>

packages/ai/src/protocols/utils/image-input.ts

@@ -0,0 +1,34 @@
+import { Effect, Encoding } from "effect"
+import type { ImageInput } from "../../image"
+import { InvalidRequestReason, LLMError } from "../../schema"
+
+const invalid = (module: string, message: string) =>
+  new LLMError({
+    module,
+    method: "generate",
+    reason: new InvalidRequestReason({ message }),
+  })
+
+export const dataUrl = (input: Extract<ImageInput, { readonly type: "bytes" }>) =>
+  `data:${input.mediaType};base64,${Encoding.encodeBase64(input.data)}`
+
+export const decodeDataUrl = (
+  url: string,
+  module: string,
+): Effect.Effect<{ readonly mediaType: string; readonly data: Uint8Array } | undefined, LLMError> => {
+  if (!url.startsWith("data:")) return Effect.succeed(undefined)
+  const match = /^data:([^;,]+);base64,(.*)$/s.exec(url)
+  if (!match) return Effect.fail(invalid(module, "Image data URLs must contain a MIME type and base64 data"))
+  return Effect.fromResult(Encoding.decodeBase64(match[2])).pipe(
+    Effect.mapError(() => invalid(module, "Image data URL contains invalid base64 data")),
+    Effect.map((data) => ({ mediaType: match[1], data })),
+  )
+}
+
+export const invalidImageInput = invalid
+
+export const ImageInputs = {
+  dataUrl,
+  decodeDataUrl,
+  invalid: invalidImageInput,
+} as const