import type { IncomingMessage, ServerResponse } from 'node:http';
import {
  isAgentSystemDocumentKind,
  readAgentSystemDocuments,
  resetAgentSystemDocument,
  saveAgentSystemDocument,
} from '../../utils/agent-system-documents';
import type { HostApiContext } from '../context';
import { parseJsonBody, sendJson } from '../route-utils';

function scheduleGatewayReload(ctx: HostApiContext): void {
  if (ctx.gatewayManager.getStatus().state !== 'stopped') {
    ctx.gatewayManager.debouncedReload();
  }
}

function parseDocumentPath(url: URL): { kind: string; reset: boolean } | null {
  const prefix = '/api/agent-system-documents/';
  if (!url.pathname.startsWith(prefix)) return null;

  const parts = url.pathname.slice(prefix.length).split('/').filter(Boolean);
  if (parts.length === 1) {
    return { kind: decodeURIComponent(parts[0]), reset: false };
  }
  if (parts.length === 2 && parts[1] === 'reset') {
    return { kind: decodeURIComponent(parts[0]), reset: true };
  }
  return null;
}

export async function handleAgentSystemDocumentRoutes(
  req: IncomingMessage,
  res: ServerResponse,
  url: URL,
  ctx: HostApiContext,
): Promise<boolean> {
  if (url.pathname === '/api/agent-system-documents' && req.method === 'GET') {
    try {
      sendJson(res, 200, await readAgentSystemDocuments(url.searchParams.get('agentId') ?? undefined));
    } catch (error) {
      sendJson(res, 500, { success: false, error: String(error) });
    }
    return true;
  }

  const parsed = parseDocumentPath(url);
  if (!parsed) return false;

  if (!isAgentSystemDocumentKind(parsed.kind)) {
    sendJson(res, 404, { success: false, error: `Unsupported system document kind "${parsed.kind}"` });
    return true;
  }

  if (!parsed.reset && req.method === 'PUT') {
    try {
      const body = await parseJsonBody<{ agentId?: string; content?: string }>(req);
      const snapshot = await saveAgentSystemDocument(body.agentId, parsed.kind, body.content ?? '');
      scheduleGatewayReload(ctx);
      sendJson(res, 200, snapshot);
    } catch (error) {
      sendJson(res, 500, { success: false, error: String(error) });
    }
    return true;
  }

  if (parsed.reset && req.method === 'POST') {
    try {
      const body = await parseJsonBody<{ agentId?: string }>(req);
      const snapshot = await resetAgentSystemDocument(body.agentId, parsed.kind);
      scheduleGatewayReload(ctx);
      sendJson(res, 200, snapshot);
    } catch (error) {
      sendJson(res, 500, { success: false, error: String(error) });
    }
    return true;
  }

  return false;
}