/**
 * @license
 * Copyright Google LLC All Rights Reserved.
 *
 * Use of this source code is governed by an MIT-style license that can be
 * found in the LICENSE file at https://angular.io/license
 */

import chalk from 'chalk';
import {createPromptModule, ListChoiceOptions, prompt} from 'inquirer';
import * as inquirerAutocomplete from 'inquirer-autocomplete-prompt';


/** Reexport of chalk colors for convenient access. */
export const red: typeof chalk = chalk.red;
export const green: typeof chalk = chalk.green;
export const yellow: typeof chalk = chalk.yellow;

/** Prompts the user with a confirmation question and a specified message. */
export async function promptConfirm(message: string, defaultValue = false): Promise<boolean> {
  return (await prompt<{result: boolean}>({
           type: 'confirm',
           name: 'result',
           message: message,
           default: defaultValue,
         }))
      .result;
}

/** Prompts the user to select an option from a filterable autocomplete list. */
export async function promptAutocomplete(
    message: string, choices: (string|ListChoiceOptions)[]): Promise<string>;
/**
 * Prompts the user to select an option from a filterable autocomplete list, with an option to
 * choose no value.
 */
export async function promptAutocomplete(
    message: string, choices: (string|ListChoiceOptions)[],
    noChoiceText?: string): Promise<string|false>;
export async function promptAutocomplete(
    message: string, choices: (string|ListChoiceOptions)[],
    noChoiceText?: string): Promise<string|false> {
  // Creates a local prompt module with an autocomplete prompt type.
  const prompt = createPromptModule({}).registerPrompt('autocomplete', inquirerAutocomplete);
  if (noChoiceText) {
    choices = [noChoiceText, ...choices];
  }
  // `prompt` must be cast as `any` as the autocomplete typings are not available.
  const result = (await (prompt as any)({
                   type: 'autocomplete',
                   name: 'result',
                   message,
                   source: (_: any, input: string) => {
                     if (!input) {
                       return Promise.resolve(choices);
                     }
                     return Promise.resolve(choices.filter(choice => {
                       if (typeof choice === 'string') {
                         return choice.includes(input);
                       }
                       return choice.name!.includes(input);
                     }));
                   }
                 })).result;
  if (result === noChoiceText) {
    return false;
  }
  return result;
}

/** Prompts the user for one line of input. */
export async function promptInput(message: string): Promise<string> {
  return (await prompt<{result: string}>({type: 'input', name: 'result', message})).result;
}

/**
 * Supported levels for logging functions.
 *
 * Levels are mapped to numbers to represent a hierarchy of logging levels.
 */
export enum LOG_LEVELS {
  SILENT = 0,
  ERROR = 1,
  WARN = 2,
  LOG = 3,
  INFO = 4,
  DEBUG = 5,
}

/** Default log level for the tool. */
export const DEFAULT_LOG_LEVEL = LOG_LEVELS.INFO;

/** Write to the console for at INFO logging level */
export const info = buildLogLevelFunction(() => console.info, LOG_LEVELS.INFO);

/** Write to the console for at ERROR logging level */
export const error = buildLogLevelFunction(() => console.error, LOG_LEVELS.ERROR);

/** Write to the console for at DEBUG logging level */
export const debug = buildLogLevelFunction(() => console.debug, LOG_LEVELS.DEBUG);

/** Write to the console for at LOG logging level */
// tslint:disable-next-line: no-console
export const log = buildLogLevelFunction(() => console.log, LOG_LEVELS.LOG);

/** Write to the console for at WARN logging level */
export const warn = buildLogLevelFunction(() => console.warn, LOG_LEVELS.WARN);

/** Build an instance of a logging function for the provided level. */
function buildLogLevelFunction(loadCommand: () => Function, level: LOG_LEVELS) {
  /** Write to stdout for the LOG_LEVEL. */
  const loggingFunction = (...text: string[]) => {
    runConsoleCommand(loadCommand, level, ...text);
  };

  /** Start a group at the LOG_LEVEL, optionally starting it as collapsed. */
  loggingFunction.group = (text: string, collapsed = false) => {
    const command = collapsed ? console.groupCollapsed : console.group;
    runConsoleCommand(() => command, level, text);
  };

  /** End the group at the LOG_LEVEL. */
  loggingFunction.groupEnd = () => {
    runConsoleCommand(() => console.groupEnd, level);
  };

  return loggingFunction;
}

/**
 * Run the console command provided, if the environments logging level greater than the
 * provided logging level.
 *
 * The loadCommand takes in a function which is called to retrieve the console.* function
 * to allow for jasmine spies to still work in testing.  Without this method of retrieval
 * the console.* function, the function is saved into the closure of the created logging
 * function before jasmine can spy.
 */
function runConsoleCommand(loadCommand: () => Function, logLevel: LOG_LEVELS, ...text: string[]) {
  if (getLogLevel() >= logLevel) {
    loadCommand()(...text);
  }
}

/**
 * Retrieve the log level from environment variables, if the value found
 * based on the LOG_LEVEL environment variable is undefined, return the default
 * logging level.
 */
function getLogLevel() {
  const logLevelEnvValue: any = (process.env[`LOG_LEVEL`] || '').toUpperCase();
  const logLevel = LOG_LEVELS[logLevelEnvValue];
  if (logLevel === undefined) {
    return DEFAULT_LOG_LEVEL;
  }
  return logLevel;
}