import type { UIMessage } from "ai";
import { MODEL_INPUTS, type ModelConfiguration } from "./model-providers.ts";

export const MAX_ATTACHMENT_BYTES = 20 * 1024 * 1024;
export const MAX_IMAGE_BYTES = 3.5 * 1024 * 1024;
export const MAX_ATTACHMENTS = 4;
export const ATTACHMENT_ACCEPT =
  "image/png,image/jpeg,image/webp,application/pdf";
export const attachmentId =
  /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/;
export interface Attachment {
  id: string;
  name: string;
  mediaType: "image/png" | "image/jpeg" | "image/webp" | "application/pdf";
  size: number;
}
export function attachmentUrl(conversation: string, id: string) {
  return `/api/conversations/${conversation}/attachments/${id}`;
}
export function messageAttachments(message: UIMessage): Attachment[] {
  const value = (message.metadata as { attachments?: unknown } | undefined)
    ?.attachments;
  if (!Array.isArray(value)) return [];
  return value
    .slice(0, MAX_ATTACHMENTS)
    .filter(
      (file): file is Attachment =>
        file &&
        attachmentId.test(file.id) &&
        typeof file.name === "string" &&
        file.name.length <= 180 &&
        ATTACHMENT_ACCEPT.split(",").includes(file.mediaType) &&
        Number.isSafeInteger(file.size) &&
        file.size > 0 &&
        file.size <= MAX_ATTACHMENT_BYTES,
    );
}

export function attachmentCapabilities(configuration: ModelConfiguration) {
  const models: Record<string, readonly string[]> =
    MODEL_INPUTS[configuration.provider];
  const inputs = models[configuration.model] ?? [];
  return {
    images: inputs.includes("image"),
    pdf: inputs.includes("pdf"),
  };
}

export function requestedAttachmentReader(
  messages: readonly UIMessage[],
  continuation = false,
) {
  if (continuation) return false;
  const latest = messages.findLast((m) => m.role === "user");
  if (!latest) return false;
  if (messageAttachments(latest).length) return true;
  if (!messages.some((m) => m.role === "user" && messageAttachments(m).length))
    return false;
  const text = latest.parts
    .filter((p) => p.type === "text")
    .map((p) => p.text)
    .join(" ");
  return (
    /\b(?:the|this|that|attached|uploaded)\s+(?:(?:attached|uploaded)\s+)?(?:image|picture|photo|pdf|document|thumbnail|attachment)s?\b/i.test(
      text,
    ) ||
    messages.some((m) =>
      messageAttachments(m).some((file) => text.includes(file.name)),
    )
  );
}