import crypto from 'crypto';

function filter(value: any) {
  return typeof value === 'string'
    ? value.replace(/[\t\n\r\f]/g, ' ')
    : value.toString();
}

function getCanonicalizedHeaders(headers: { [x: string]: any }) {
  const keys = Object.keys(headers);
  const canonicalizedKeys = [];
  for (let i = 0; i < keys.length; i++) {
    const key = keys[i];
    if (key.startsWith('x-authing-') || key === 'date') {
      canonicalizedKeys.push(key);
    }
  }

  canonicalizedKeys.sort();

  let result = '';
  for (let i = 0; i < canonicalizedKeys.length; i++) {
    const key = canonicalizedKeys[i];
    result += `${key}:${filter(headers[key]).trim()}\n`;
  }

  return result;
}

function getCanonicalizedResource(
  uriPattern: string,
  query: { [x: string]: any }
) {
  const keys = Object.keys(query).sort();

  if (keys.length === 0) {
    return uriPattern;
  }

  const result = [];
  for (let i = 0; i < keys.length; i++) {
    const key = keys[i];
    let value = query[key];
    if (value === undefined) {
      continue;
    }
    value =
      typeof value === 'object' && value !== null
        ? JSON.stringify(value)
        : value;
    result.push(`${key}=${value}`);
  }

  return `${uriPattern}?${result.join('&')}`;
}

/**
 * buildSignature
 * @param accessKeySecret
 * @param stringToSign
 * @returns
 */
export function buildSignature(accessKeySecret: string, stringToSign: string) {
  return crypto
    .createHmac('sha1', accessKeySecret)
    .update(Buffer.from(stringToSign, 'utf8'))
    .digest('base64');
}

export function buildStringToSign(
  method: string,
  uriPattern: string,
  headers: { [x: string]: any },
  query: { [x: string]: any }
) {
  const header = `${method}\n`;
  const canonicalizedHeaders = getCanonicalizedHeaders(headers);
  const canonicalizedResource = getCanonicalizedResource(uriPattern, query);

  return `${header}${canonicalizedHeaders}${canonicalizedResource}`;
}

export function buildAuthorization(
  accessKeyId: string,
  accessKeySecret: string,
  stringToSign: string
) {
  return `${accessKeyId}:${buildSignature(accessKeySecret, stringToSign)}`;
}