import { readBoundedResponseText } from "../lib/bounded-response.mjs";

export const GITHUB_ERROR_BODY_MAX_BYTES = 64 * 1024;
export const GITHUB_RESPONSE_BODY_MAX_BYTES = 4 * 1024 * 1024;
export const GITHUB_API_REQUEST_TIMEOUT_MS = 30_000;

export function guardTrustedActorCandidates({ pullRequest, event, currentHeadSha }) {
  const eventHeadSha = event?.pull_request?.head?.sha;
  const eventAfterSha = event?.after;
  const eventMatchesCurrentHead =
    Boolean(currentHeadSha) &&
    (eventHeadSha === currentHeadSha || eventAfterSha === currentHeadSha);
  if (!eventMatchesCurrentHead) {
    return [];
  }
  const candidates = [];
  const seen = new Set();
  for (const [source, login] of [["pull request author", pullRequest?.user?.login]]) {
    if (typeof login !== "string" || login.length === 0) {
      continue;
    }
    const normalizedLogin = login.toLowerCase();
    if (seen.has(normalizedLogin)) {
      continue;
    }
    seen.add(normalizedLogin);
    candidates.push({ login, source });
  }
  return candidates;
}

export function createGuardApproverChecks({
  api,
  owner,
  repo,
  securityTeamSlug,
  explicitSecurityApprovers,
  warn = console.warn,
}) {
  const membershipCache = new Map();
  const permissionCache = new Map();
  const isSecurityMember = async (login) => {
    const normalizedLogin = login.toLowerCase();
    if (explicitSecurityApprovers.has(normalizedLogin)) {
      return true;
    }
    if (membershipCache.has(normalizedLogin)) {
      return membershipCache.get(normalizedLogin);
    }
    try {
      const membership = await api.request(
        `/orgs/${owner}/teams/${securityTeamSlug}/memberships/${encodeURIComponent(login)}`,
      );
      const allowed = membership?.state === "active";
      membershipCache.set(normalizedLogin, allowed);
      return allowed;
    } catch (error) {
      if (error?.status !== 404) {
        warn(`Could not verify ${login} against ${securityTeamSlug}: ${error.message}`);
      }
      membershipCache.set(normalizedLogin, false);
      return false;
    }
  };
  const isRepositoryAdmin = async (login) => {
    const normalizedLogin = login.toLowerCase();
    if (permissionCache.has(normalizedLogin)) {
      return permissionCache.get(normalizedLogin);
    }
    try {
      const result = await api.request(
        `/repos/${owner}/${repo}/collaborators/${encodeURIComponent(login)}/permission`,
      );
      const allowed = result?.permission === "admin";
      permissionCache.set(normalizedLogin, allowed);
      return allowed;
    } catch (error) {
      if (error?.status !== 404) {
        warn(`Could not verify repository permission for ${login}: ${error.message}`);
      }
      permissionCache.set(normalizedLogin, false);
      return false;
    }
  };
  return { isSecurityMember, isRepositoryAdmin };
}

function githubErrorBodyTooLarge(maxBytes) {
  return new Error(`GitHub error response body exceeded ${maxBytes} bytes`);
}

function githubResponseBodyTooLarge(maxBytes) {
  return new Error(`GitHub response body exceeded ${maxBytes} bytes`);
}

export async function readBoundedGitHubErrorText(
  response,
  maxBytes = GITHUB_ERROR_BODY_MAX_BYTES,
  options = {},
) {
  return await readBoundedResponseText(response, "GitHub error", maxBytes, {
    createTooLargeError: () => githubErrorBodyTooLarge(maxBytes),
    ...options,
  });
}

export async function readBoundedGitHubJson(
  response,
  maxBytes = GITHUB_RESPONSE_BODY_MAX_BYTES,
  options = {},
) {
  const text = await readBoundedResponseText(response, "GitHub", maxBytes, {
    createTooLargeError: () => githubResponseBodyTooLarge(maxBytes),
    ...options,
  });
  return JSON.parse(text);
}

function timeoutError(path, method, timeoutMs) {
  return new Error(`GitHub API ${method} ${path} exceeded timeout ${timeoutMs}ms`);
}

function combineAbortSignals(signals) {
  const activeSignals = signals.filter(Boolean);
  if (activeSignals.length === 0) {
    return undefined;
  }
  if (activeSignals.length === 1) {
    return activeSignals[0];
  }
  return AbortSignal.any(activeSignals);
}

export function createGitHubApi(token, options = {}) {
  const fetchImpl = options.fetchImpl ?? fetch;
  const timeoutMs = options.timeoutMs ?? GITHUB_API_REQUEST_TIMEOUT_MS;
  const responseMaxBodyBytes = options.responseMaxBodyBytes ?? GITHUB_RESPONSE_BODY_MAX_BYTES;
  const baseHeaders = {
    accept: "application/vnd.github+json",
    authorization: `Bearer ${token}`,
    "user-agent": options.userAgent,
    "x-github-api-version": "2022-11-28",
  };
  const request = async (path, requestOptions = {}) => {
    const method = requestOptions.method ?? "GET";
    const timeoutController = new AbortController();
    let timeout;
    const timeoutPromise = new Promise((_, reject) => {
      timeout = setTimeout(() => {
        timeoutController.abort();
        reject(timeoutError(path, method, timeoutMs));
      }, timeoutMs);
      timeout.unref?.();
    });
    const operationPromise = (async () => {
      const response = await fetchImpl(`https://api.github.com${path}`, {
        ...requestOptions,
        signal: combineAbortSignals([requestOptions.signal, timeoutController.signal]),
        headers: { ...baseHeaders, ...requestOptions.headers },
      });
      if (response.status === 204) {
        return null;
      }
      if (!response.ok) {
        let errorText;
        try {
          errorText = await readBoundedGitHubErrorText(response, GITHUB_ERROR_BODY_MAX_BYTES, {
            signal: timeoutController.signal,
            timeoutPromise,
          });
        } catch (bodyError) {
          errorText = bodyError instanceof Error ? bodyError.message : String(bodyError);
        }
        const error = new Error(`${response.status} ${response.statusText}: ${errorText}`);
        error.status = response.status;
        throw error;
      }
      return await readBoundedGitHubJson(response, responseMaxBodyBytes, {
        signal: timeoutController.signal,
        timeoutPromise,
      });
    })();
    operationPromise.catch(() => {});
    try {
      return await Promise.race([operationPromise, timeoutPromise]);
    } finally {
      clearTimeout(timeout);
    }
  };
  return { request };
}