/*
 * Copyright 2020 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

export interface GrpcUri {
  scheme?: string;
  authority?: string;
  path: string;
}

/*
 * The groups correspond to URI parts as follows:
 * 1. scheme
 * 2. authority
 * 3. path
 */
const URI_REGEX = /^(?:([A-Za-z0-9+.-]+):)?(?:\/\/([^/]*)\/)?(.+)$/;

export function parseUri(uriString: string): GrpcUri | null {
  const parsedUri = URI_REGEX.exec(uriString);
  if (parsedUri === null) {
    return null;
  }
  return {
    scheme: parsedUri[1],
    authority: parsedUri[2],
    path: parsedUri[3],
  };
}

export interface HostPort {
  host: string;
  port?: number;
}

const NUMBER_REGEX = /^\d+$/;

export function splitHostPort(path: string): HostPort | null {
  if (path.startsWith('[')) {
    const hostEnd = path.indexOf(']');
    if (hostEnd === -1) {
      return null;
    }
    const host = path.substring(1, hostEnd);
    /* Only an IPv6 address should be in bracketed notation, and an IPv6
     * address should have at least one colon */
    if (host.indexOf(':') === -1) {
      return null;
    }
    if (path.length > hostEnd + 1) {
      if (path[hostEnd + 1] === ':') {
        const portString = path.substring(hostEnd + 2);
        if (NUMBER_REGEX.test(portString)) {
          return {
            host: host,
            port: +portString,
          };
        } else {
          return null;
        }
      } else {
        return null;
      }
    } else {
      return {
        host,
      };
    }
  } else {
    const splitPath = path.split(':');
    /* Exactly one colon means that this is host:port. Zero colons means that
     * there is no port. And multiple colons means that this is a bare IPv6
     * address with no port */
    if (splitPath.length === 2) {
      if (NUMBER_REGEX.test(splitPath[1])) {
        return {
          host: splitPath[0],
          port: +splitPath[1],
        };
      } else {
        return null;
      }
    } else {
      return {
        host: path,
      };
    }
  }
}

export function combineHostPort(hostPort: HostPort): string {
  if (hostPort.port === undefined) {
    return hostPort.host;
  } else {
    // Only an IPv6 host should include a colon
    if (hostPort.host.includes(':')) {
      return `[${hostPort.host}]:${hostPort.port}`;
    } else {
      return `${hostPort.host}:${hostPort.port}`;
    }
  }
}

export function uriToString(uri: GrpcUri): string {
  let result = '';
  if (uri.scheme !== undefined) {
    result += uri.scheme + ':';
  }
  if (uri.authority !== undefined) {
    result += '//' + uri.authority + '/';
  }
  result += uri.path;
  return result;
}