export const ATTACHMENT_MAX_BYTES = 10 * 1024 * 1024;
export const ATTACHMENT_MAX_COUNT = 4;
/** Base64 expands payload by 4/3; cap before decode to reject oversize uploads cheaply. */
export const ATTACHMENT_MAX_BASE64_LENGTH = Math.ceil(ATTACHMENT_MAX_BYTES / 3) * 4;

export const ATTACHMENT_IMAGE_MIME_TYPES = [
  "image/jpeg",
  "image/png",
  "image/webp",
  "image/gif",
] as const;

export const ATTACHMENT_VIDEO_MIME_TYPES = ["video/mp4", "video/webm", "video/quicktime"] as const;

export const ATTACHMENT_AUDIO_MIME_TYPES = [
  "audio/mpeg",
  "audio/mp4",
  "audio/wav",
  "audio/webm",
  "audio/ogg",
] as const;

export const ATTACHMENT_FILE_MIME_TYPES = [
  "application/pdf",
  "text/plain",
  "text/markdown",
  "text/csv",
  "application/json",
  "text/vtt",
  "application/x-subrip",
] as const;

export const ATTACHMENT_ALLOWED_MIME_TYPES = [
  ...ATTACHMENT_IMAGE_MIME_TYPES,
  ...ATTACHMENT_VIDEO_MIME_TYPES,
  ...ATTACHMENT_AUDIO_MIME_TYPES,
  ...ATTACHMENT_FILE_MIME_TYPES,
] as const;

export type AttachmentKind = "image" | "video" | "audio" | "file";

/**
 * Size caps for artifacts that do not travel inline as base64 (streamed uploads, generated and
 * edited media). Inline RPC uploads stay capped by ATTACHMENT_MAX_BYTES.
 */
export const ARTIFACT_MAX_BYTES_BY_KIND: Record<AttachmentKind, number> = {
  image: 25 * 1024 * 1024,
  video: 500 * 1024 * 1024,
  audio: 200 * 1024 * 1024,
  file: 25 * 1024 * 1024,
};

export type AttachmentMimeType = (typeof ATTACHMENT_ALLOWED_MIME_TYPES)[number];

export function isAttachmentImageMimeType(mimeType: string): boolean {
  return (ATTACHMENT_IMAGE_MIME_TYPES as readonly string[]).includes(mimeType);
}

export function isAttachmentVideoMimeType(mimeType: string): boolean {
  return (ATTACHMENT_VIDEO_MIME_TYPES as readonly string[]).includes(mimeType);
}

export function isAttachmentAudioMimeType(mimeType: string): boolean {
  return (ATTACHMENT_AUDIO_MIME_TYPES as readonly string[]).includes(mimeType);
}

export function attachmentKindOf(mimeType: string): AttachmentKind {
  if (isAttachmentImageMimeType(mimeType)) return "image";
  if (isAttachmentVideoMimeType(mimeType)) return "video";
  if (isAttachmentAudioMimeType(mimeType)) return "audio";
  return "file";
}

export function isAllowedAttachmentMimeType(mimeType: string): mimeType is AttachmentMimeType {
  return (ATTACHMENT_ALLOWED_MIME_TYPES as readonly string[]).includes(mimeType);
}

export function validateThreadsSendInput(input: {
  text?: string;
  artifactIds?: string[];
}): boolean {
  const text = input.text?.trim() ?? "";
  const artifactIds = input.artifactIds ?? [];
  return Boolean(text || artifactIds.length);
}