// What the AGENTS.md editor sends and reads. The routes are
// `GET` and `PUT /api/agents/{name}/agents-md` (swarm-controller-api's
// `AgentsMdView`, `AgentsMdEdit` and `AgentsMdSaved`).
import { unifiedDiff } from "./unified-diff.js";

/** What `GET` answers: the text as the agent last published it, and its id. */
export interface Instructions {
  content: string;
  /** The git blob id of `content`, which an edit names as its base. */
  revision: string;
}

/** The body of a `PUT`. */
export interface InstructionsEdit {
  base_revision: string;
  diff: string;
}

export function instructionsUrl(agent: string): string {
  return `/api/agents/${encodeURIComponent(agent)}/agents-md`;
}

/** An answer of the wrong shape is no answer: the editor shows an error. */
export function parseInstructions(json: unknown): Instructions | null {
  if (typeof json !== "object" || json === null) return null;
  const { content, revision } = json as Record<string, unknown>;
  if (typeof content !== "string" || typeof revision !== "string") return null;
  return { content, revision };
}

/**
 * The `PUT` body that turns `base` into `draft`, or `null` when they are the
 * same text and there is nothing to save.
 */
export function editBody(
  base: Instructions,
  draft: string,
): InstructionsEdit | null {
  const diff = unifiedDiff(base.content, draft);
  return diff === "" ? null : { base_revision: base.revision, diff };
}

/** The status the swarm answers a `PUT` with when the file moved on. */
export const STALE_STATUS = 409;