/**
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @flow strict
 * @format
 */

'use strict';

const Systrace = require('../Performance/Systrace');

const infoLog = require('./infoLog');
const performanceNow =
  global.nativeQPLTimestamp ?? global.performance.now.bind(global.performance);

type Timespan = {
  description?: string,
  totalTime?: number,
  startTime?: number,
  endTime?: number,
  ...
};

export interface IPerformanceLogger {
  addTimeAnnotation(
    key: string,
    durationInMs: number,
    description?: string,
  ): void;
  addTimespan(
    key: string,
    startTime: number,
    endTime: number,
    description?: string,
  ): void;
  startTimespan(key: string, description?: string): void;
  stopTimespan(key: string, options?: {update?: boolean}): void;
  clear(): void;
  clearCompleted(): void;
  currentTimestamp(): number;
  getTimespans(): {[key: string]: Timespan, ...};
  hasTimespan(key: string): boolean;
  setExtra(key: string, value: mixed): void;
  getExtras(): {[key: string]: mixed, ...};
  removeExtra(key: string): ?mixed;
  markPoint(key: string, timestamp?: number): void;
  getPoints(): {[key: string]: number, ...};
  logEverything(): void;
}

const _cookies: {[key: string]: number, ...} = {};

const PRINT_TO_CONSOLE: false = false; // Type as false to prevent accidentally committing `true`;

/**
 * This function creates performance loggers that can be used to collect and log
 * various performance data such as timespans, points and extras.
 * The loggers need to have minimal overhead since they're used in production.
 */
function createPerformanceLogger(): IPerformanceLogger {
  const result: IPerformanceLogger & {
    _timespans: {[key: string]: Timespan, ...},
    _extras: {[key: string]: mixed, ...},
    _points: {[key: string]: number, ...},
    ...
  } = {
    _timespans: {},
    _extras: {},
    _points: {},

    addTimeAnnotation(key: string, durationInMs: number, description?: string) {
      if (this._timespans[key]) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to add a timespan that already exists ',
            key,
          );
        }
        return;
      }

      this._timespans[key] = {
        description: description,
        totalTime: durationInMs,
      };
    },

    addTimespan(
      key: string,
      startTime: number,
      endTime: number,
      description?: string,
    ) {
      if (this._timespans[key]) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to add a timespan that already exists ',
            key,
          );
        }
        return;
      }

      this._timespans[key] = {
        description,
        startTime,
        endTime,
        totalTime: endTime - (startTime || 0),
      };
    },

    startTimespan(key: string, description?: string) {
      if (this._timespans[key]) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to start a timespan that already exists ',
            key,
          );
        }
        return;
      }

      this._timespans[key] = {
        description: description,
        startTime: performanceNow(),
      };
      _cookies[key] = Systrace.beginAsyncEvent(key);
      if (PRINT_TO_CONSOLE) {
        infoLog('PerformanceLogger.js', 'start: ' + key);
      }
    },

    stopTimespan(key: string, options?: {update?: boolean}) {
      const timespan = this._timespans[key];
      if (!timespan || !timespan.startTime) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to end a timespan that has not started ',
            key,
          );
        }
        return;
      }
      if (timespan.endTime && !options?.update) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to end a timespan that has already ended ',
            key,
          );
        }
        return;
      }

      timespan.endTime = performanceNow();
      timespan.totalTime = timespan.endTime - (timespan.startTime || 0);
      if (PRINT_TO_CONSOLE) {
        infoLog('PerformanceLogger.js', 'end: ' + key);
      }

      if (_cookies[key] != null) {
        Systrace.endAsyncEvent(key, _cookies[key]);
        delete _cookies[key];
      }
    },

    clear() {
      this._timespans = {};
      this._extras = {};
      this._points = {};
      if (PRINT_TO_CONSOLE) {
        infoLog('PerformanceLogger.js', 'clear');
      }
    },

    clearCompleted() {
      for (const key in this._timespans) {
        if (this._timespans[key].totalTime) {
          delete this._timespans[key];
        }
      }
      this._extras = {};
      this._points = {};
      if (PRINT_TO_CONSOLE) {
        infoLog('PerformanceLogger.js', 'clearCompleted');
      }
    },

    currentTimestamp() {
      return performanceNow();
    },

    getTimespans() {
      return this._timespans;
    },

    hasTimespan(key: string) {
      return !!this._timespans[key];
    },

    setExtra(key: string, value: mixed) {
      if (this._extras[key]) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to set an extra that already exists ',
            {key, currentValue: this._extras[key], attemptedValue: value},
          );
        }
        return;
      }
      this._extras[key] = value;
    },

    getExtras() {
      return this._extras;
    },

    removeExtra(key: string): ?mixed {
      const value = this._extras[key];
      delete this._extras[key];
      return value;
    },

    markPoint(key: string, timestamp?: number) {
      if (this._points[key]) {
        if (PRINT_TO_CONSOLE && __DEV__) {
          infoLog(
            'PerformanceLogger: Attempting to mark a point that has been already logged ',
            key,
          );
        }
        return;
      }
      this._points[key] = timestamp ?? performanceNow();
    },

    getPoints() {
      return this._points;
    },

    logEverything() {
      if (PRINT_TO_CONSOLE) {
        // log timespans
        for (const key in this._timespans) {
          if (this._timespans[key].totalTime) {
            infoLog(key + ': ' + this._timespans[key].totalTime + 'ms');
          }
        }

        // log extras
        infoLog(this._extras);

        // log points
        for (const key in this._points) {
          infoLog(key + ': ' + this._points[key] + 'ms');
        }
      }
    },
  };
  return result;
}

module.exports = createPerformanceLogger;