// Copyright 2018-2020 Google LLC
//
// 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.
import { readFileSync } from 'fs';
import { Transform, TransformOptions } from 'stream';

/** get the server address from host, port, and schema (defaults to 'http'). */
export function getAddress({
  host,
  port,
  namespace,
  schema = 'http',
}: {
  host: string;
  port?: string | number;
  namespace?: string;
  schema?: string;
}) {
  namespace = namespace ? `.${namespace}` : '';
  port = port ? `:${port}` : '';
  return `${schema}://${host}${namespace}${port}`;
}

export function equalArrays(a1: any[], a2: any[]): boolean {
  if (!Array.isArray(a1) || !Array.isArray(a2) || a1.length !== a2.length) {
    return false;
  }
  return JSON.stringify(a1) === JSON.stringify(a2);
}

export function generateRandomString(length: number): string {
  let d = new Date().getTime();
  function randomChar(): string {
    const r = Math.trunc((d + Math.random() * 16) % 16);
    d = Math.floor(d / 16);
    return r.toString(16);
  }
  let str = '';
  for (let i = 0; i < length; ++i) {
    str += randomChar();
  }
  return str;
}

export function loadJSON<T>(filepath?: string, defaultValue?: T): T | undefined {
  if (!filepath) {
    return defaultValue;
  }
  try {
    return JSON.parse(readFileSync(filepath, 'utf-8'));
  } catch (error) {
    console.error(`Failed reading json data from '${filepath}':`);
    console.error(error);
    return defaultValue;
  }
}

export interface PreviewStreamOptions extends TransformOptions {
  peek: number;
}

/**
 * Transform stream that only stream the first X number of bytes.
 */
export class PreviewStream extends Transform {
  constructor({ peek, ...opts }: PreviewStreamOptions) {
    // acts like passthrough
    let transform: TransformOptions['transform'] = (chunk, _encoding, callback) =>
      callback(undefined, chunk);
    // implements preview - peek must be positive number
    if (peek && peek > 0) {
      let size = 0;
      transform = (chunk, _encoding, callback) => {
        const delta = peek - size;
        size += chunk.length;
        if (size >= peek) {
          callback(undefined, chunk.slice(0, delta));
          this.resume(); // do not handle any subsequent data
          return;
        }
        callback(undefined, chunk);
      };
    }
    super({ ...opts, transform });
  }
}

export interface ErrorDetails {
  message: string;
  additionalInfo: any;
}
const UNKOWN_ERROR = 'Unknown error';
export async function parseError(error: any): Promise<ErrorDetails> {
  return (
    parseK8sError(error) ||
    (await parseKfpApiError(error)) ||
    parseGenericError(error) || { message: UNKOWN_ERROR, additionalInfo: error }
  );
}

function parseGenericError(error: any): ErrorDetails | undefined {
  if (!error) {
    return undefined;
  } else if (typeof error === 'string') {
    return {
      message: error,
      additionalInfo: error,
    };
  } else if (error instanceof Error) {
    return { message: error.message, additionalInfo: error };
  } else if (error.message && typeof error.message === 'string') {
    return { message: error.message, additionalInfo: error };
  } else if (
    error.url &&
    typeof error.url === 'string' &&
    error.status &&
    typeof error.status === 'number' &&
    error.statusText &&
    typeof error.statusText === 'string'
  ) {
    const { url, status, statusText } = error;
    return {
      message: `Fetching ${url} failed with status code ${status} and message: ${statusText}`,
      additionalInfo: { url, status, statusText },
    };
  }
  // Cannot understand error type
  return undefined;
}
async function parseKfpApiError(error: any): Promise<ErrorDetails | undefined> {
  if (!error || !error.json || typeof error.json !== 'function') {
    return undefined;
  }
  try {
    const json = await error.json();
    const { error: message, details } = json;
    if (message && details && typeof message === 'string' && typeof details === 'object') {
      return {
        message,
        additionalInfo: details,
      };
    } else {
      return undefined;
    }
  } catch (err) {
    return undefined;
  }
}
function parseK8sError(error: any): ErrorDetails | undefined {
  if (!error || !error.body || typeof error.body !== 'object') {
    return undefined;
  }

  if (typeof error.body.message !== 'string') {
    return undefined;
  }

  // Kubernetes client http error has body with all the info.
  // Example error.body
  // {
  //   kind: 'Status',
  //   apiVersion: 'v1',
  //   metadata: {},
  //   status: 'Failure',
  //   message: 'pods "test-pod" not found',
  //   reason: 'NotFound',
  //   details: { name: 'test-pod', kind: 'pods' },
  //   code: 404
  // }
  return {
    message: error.body.message,
    additionalInfo: error.body,
  };
}