// Network + IO wrapper around the pure logic in ./core.mjs. `run()` takes an
// injectable IO bag (fetch/env/stdout/stderr) so it can be exercised offline in
// tests, and returns a numeric exit code:
//   0 success · 1 request/transport error · 2 usage error
import {
  API_KEY_HEADER,
  AUTH_HINT,
  DEFAULT_SPEC_URL,
  HELP,
  MCP_AUTH_ERROR_CODE,
  USER_AGENT,
  UsageError,
  VERSION,
  formatOutput,
  parseArgs,
  planRequest,
  renderListing,
  resolveConfig,
  summarizeSpec,
} from './core.mjs';

const DEFAULT_TIMEOUT_MS = 30000;

// MCP responses may arrive as Server-Sent Events (Streamable HTTP). Pull the
// last `data:` payload; otherwise parse the whole body as JSON, falling back to
// the raw text when it is not JSON at all.
function parseBody(text, headers) {
  const contentType = (headers && headers.get && headers.get('content-type')) || '';
  let payload = text;
  if (contentType.includes('text/event-stream') || /^(event|data):/m.test(text)) {
    const dataLines = text
      .split(/\r?\n/)
      .filter((line) => line.startsWith('data:'))
      .map((line) => line.slice(5).trim());
    payload = dataLines[dataLines.length - 1] || '';
  }
  if (!payload) return text;
  try {
    return JSON.parse(payload);
  } catch {
    return text;
  }
}

async function withTimeout(timeoutOpt, fn) {
  const ms = Number(timeoutOpt) > 0 ? Number(timeoutOpt) : DEFAULT_TIMEOUT_MS;
  const controller = new AbortController();
  const timer = setTimeout(() => controller.abort(new Error(`request timed out after ${ms}ms`)), ms);
  try {
    return await fn(controller.signal);
  } finally {
    clearTimeout(timer);
  }
}

export async function run(argv, io = {}) {
  const fetchImpl = io.fetch || globalThis.fetch;
  const env = io.env || (typeof process !== 'undefined' ? process.env : {});
  const stdout = io.stdout || ((s) => process.stdout.write(s));
  const stderr = io.stderr || ((s) => process.stderr.write(s));

  const parsed = parseArgs(argv);
  const { command, options } = parsed;

  if (options.version) {
    stdout(`${VERSION}\n`);
    return 0;
  }
  if (options.help || !command || command === 'help') {
    stdout(`${HELP}\n`);
    return 0;
  }

  try {
    if (!fetchImpl) {
      throw new Error('global fetch is unavailable — Node 18+ is required');
    }

    const config = resolveConfig(env);
    const plan = planRequest(parsed, config);

    if (plan.kind === 'list') {
      const specUrl = plan.specUrl || DEFAULT_SPEC_URL;
      const headers = { 'user-agent': USER_AGENT, accept: 'application/json' };
      const apiKey = options.apiKey || config.apiKey;
      if (apiKey) headers[API_KEY_HEADER] = apiKey;
      const res = await withTimeout(options.timeout, (signal) =>
        fetchImpl(specUrl, { headers, signal }),
      );
      const spec = parseBody(await res.text(), res.headers);
      if (!res.ok) {
        stderr(`${formatOutput(spec, options)}\n`);
        if (res.status === 401) stderr(`${AUTH_HINT}\n`);
        return 1;
      }
      stdout(`${renderListing(summarizeSpec(spec, plan.service))}\n`);
      return 0;
    }

    const res = await withTimeout(options.timeout, (signal) =>
      fetchImpl(plan.url, { method: plan.method, headers: plan.headers, body: plan.body, signal }),
    );
    const value = parseBody(await res.text(), res.headers);

    if (plan.kind === 'mcp') {
      if (value && typeof value === 'object' && value.error && typeof value.error === 'object') {
        stderr(`${formatOutput(value.error, options)}\n`);
        if (value.error.code === MCP_AUTH_ERROR_CODE) {
          stderr(`${AUTH_HINT}\n`);
        }
        return 1;
      }
      if (!res.ok) {
        stderr(`${formatOutput(value, options)}\n`);
        if (res.status === 401) stderr(`${AUTH_HINT}\n`);
        return 1;
      }
      const result = value && typeof value === 'object' && 'result' in value ? value.result : value;
      stdout(`${formatOutput(result, options)}\n`);
      return 0;
    }

    // plan.kind === 'rest'
    if (!res.ok) {
      stderr(`${formatOutput(value, options)}\n`);
      if (res.status === 401) stderr(`${AUTH_HINT}\n`);
      return 1;
    }
    stdout(`${formatOutput(value, options)}\n`);
    return 0;
  } catch (err) {
    if (err instanceof UsageError) {
      stderr(`Error: ${err.message}\n`);
      return 2;
    }
    stderr(`Error: ${err && err.message ? err.message : String(err)}\n`);
    return 1;
  }
}

export default run;