'use strict';

/**
 * Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 *
 */

const MOCK_CONSTRUCTOR_NAME = 'mockConstructor';

/**
 * Represents the result of a single call to a mock function.
 */

const FUNCTION_NAME_RESERVED_PATTERN = /[\s!-\/:-@\[-`{-~]/;
const FUNCTION_NAME_RESERVED_REPLACE = new RegExp(
  FUNCTION_NAME_RESERVED_PATTERN.source,
  'g'
);

const RESERVED_KEYWORDS = Object.assign(Object.create(null), {
  arguments: true,
  await: true,
  break: true,
  case: true,
  catch: true,
  class: true,
  const: true,
  continue: true,
  debugger: true,
  default: true,
  delete: true,
  do: true,
  else: true,
  enum: true,
  eval: true,
  export: true,
  extends: true,
  false: true,
  finally: true,
  for: true,
  function: true,
  if: true,
  implements: true,
  import: true,
  in: true,
  instanceof: true,
  interface: true,
  let: true,
  new: true,
  null: true,
  package: true,
  private: true,
  protected: true,
  public: true,
  return: true,
  static: true,
  super: true,
  switch: true,
  this: true,
  throw: true,
  true: true,
  try: true,
  typeof: true,
  var: true,
  void: true,
  while: true,
  with: true,
  yield: true
});

function matchArity(fn, length) {
  let mockConstructor;

  switch (length) {
    case 1:
      mockConstructor = function(a) {
        return fn.apply(this, arguments);
      };
      break;
    case 2:
      mockConstructor = function(a, b) {
        return fn.apply(this, arguments);
      };
      break;
    case 3:
      mockConstructor = function(a, b, c) {
        return fn.apply(this, arguments);
      };
      break;
    case 4:
      mockConstructor = function(a, b, c, d) {
        return fn.apply(this, arguments);
      };
      break;
    case 5:
      mockConstructor = function(a, b, c, d, e) {
        return fn.apply(this, arguments);
      };
      break;
    case 6:
      mockConstructor = function(a, b, c, d, e, f) {
        return fn.apply(this, arguments);
      };
      break;
    case 7:
      mockConstructor = function(a, b, c, d, e, f, g) {
        return fn.apply(this, arguments);
      };
      break;
    case 8:
      mockConstructor = function(a, b, c, d, e, f, g, h) {
        return fn.apply(this, arguments);
      };
      break;
    case 9:
      mockConstructor = function(a, b, c, d, e, f, g, h, i) {
        return fn.apply(this, arguments);
      };
      break;
    default:
      mockConstructor = function() {
        return fn.apply(this, arguments);
      };
      break;
  }

  return mockConstructor;
}

function isA(typeName, value) {
  return Object.prototype.toString.apply(value) === '[object ' + typeName + ']';
}

function getType(ref) {
  if (
    isA('Function', ref) ||
    isA('AsyncFunction', ref) ||
    isA('GeneratorFunction', ref)
  ) {
    return 'function';
  } else if (Array.isArray(ref)) {
    return 'array';
  } else if (isA('Object', ref)) {
    return 'object';
  } else if (
    isA('Number', ref) ||
    isA('String', ref) ||
    isA('Boolean', ref) ||
    isA('Symbol', ref)
  ) {
    return 'constant';
  } else if (isA('Map', ref) || isA('WeakMap', ref) || isA('Set', ref)) {
    return 'collection';
  } else if (isA('RegExp', ref)) {
    return 'regexp';
  } else if (ref === undefined) {
    return 'undefined';
  } else if (ref === null) {
    return 'null';
  } else {
    return null;
  }
}

function isReadonlyProp(object, prop) {
  return (
    ((prop === 'arguments' ||
      prop === 'caller' ||
      prop === 'callee' ||
      prop === 'name' ||
      prop === 'length') &&
      (isA('Function', object) ||
        isA('AsyncFunction', object) ||
        isA('GeneratorFunction', object))) ||
    ((prop === 'source' ||
      prop === 'global' ||
      prop === 'ignoreCase' ||
      prop === 'multiline') &&
      isA('RegExp', object))
  );
}

function getSlots(object) {
  const slots = {};
  if (!object) {
    return [];
  }

  let parent = Object.getPrototypeOf(object);
  do {
    if (object === Object.getPrototypeOf(Function)) {
      break;
    }
    const ownNames = Object.getOwnPropertyNames(object);
    for (let i = 0; i < ownNames.length; i++) {
      const prop = ownNames[i];
      if (!isReadonlyProp(object, prop)) {
        const propDesc = Object.getOwnPropertyDescriptor(object, prop);
        if ((propDesc !== undefined && !propDesc.get) || object.__esModule) {
          slots[prop] = true;
        }
      }
    }
    object = parent;
  } while (object && (parent = Object.getPrototypeOf(object)) !== null);
  return Object.keys(slots);
}

class ModuleMockerClass {
  /**
   * @see README.md
   * @param global Global object of the test environment, used to create
   * mocks
   */
  constructor(global) {
    this._environmentGlobal = global;
    this._mockState = new WeakMap();
    this._mockConfigRegistry = new WeakMap();
    this._spyState = new Set();
    this.ModuleMocker = ModuleMockerClass;
    this._invocationCallCounter = 1;
  }

  _ensureMockConfig(f) {
    let config = this._mockConfigRegistry.get(f);
    if (!config) {
      config = this._defaultMockConfig();
      this._mockConfigRegistry.set(f, config);
    }
    return config;
  }

  _ensureMockState(f) {
    let state = this._mockState.get(f);
    if (!state) {
      state = this._defaultMockState();
      this._mockState.set(f, state);
    }
    return state;
  }

  _defaultMockConfig() {
    return {
      defaultReturnValue: undefined,
      isReturnValueLastSet: false,
      mockImpl: undefined,
      mockName: 'jest.fn()',
      specificMockImpls: [],
      specificReturnValues: []
    };
  }

  _defaultMockState() {
    return {
      calls: [],
      instances: [],
      invocationCallOrder: [],
      results: []
    };
  }

  _makeComponent(metadata, restore) {
    if (metadata.type === 'object') {
      return new this._environmentGlobal.Object();
    } else if (metadata.type === 'array') {
      return new this._environmentGlobal.Array();
    } else if (metadata.type === 'regexp') {
      return new this._environmentGlobal.RegExp('');
    } else if (
      metadata.type === 'constant' ||
      metadata.type === 'collection' ||
      metadata.type === 'null' ||
      metadata.type === 'undefined'
    ) {
      return metadata.value;
    } else if (metadata.type === 'function') {
      /* eslint-disable prefer-const */
      let f;
      /* eslint-enable prefer-const */

      const prototype =
        (metadata.members &&
          metadata.members.prototype &&
          metadata.members.prototype.members) ||
        {};
      const prototypeSlots = getSlots(prototype);
      const mocker = this;
      const mockConstructor = matchArity(function() {
        const mockState = mocker._ensureMockState(f);
        const mockConfig = mocker._ensureMockConfig(f);
        mockState.instances.push(this);
        mockState.calls.push(Array.prototype.slice.call(arguments));
        mockState.invocationCallOrder.push(mocker._invocationCallCounter++);

        // Will be set to the return value of the mock if an error is not thrown
        let finalReturnValue;
        // Will be set to the error that is thrown by the mock (if it throws)
        let thrownError;
        // Will be set to true if the mock throws an error. The presence of a
        // value in `thrownError` is not a 100% reliable indicator because a
        // function could throw a value of undefined.
        let callDidThrowError = false;

        try {
          // The bulk of the implementation is wrapped in an immediately
          // executed arrow function so the return value of the mock function
          // can be easily captured and recorded, despite the many separate
          // return points within the logic.
          finalReturnValue = (() => {
            if (this instanceof f) {
              // This is probably being called as a constructor
              prototypeSlots.forEach(slot => {
                // Copy prototype methods to the instance to make
                // it easier to interact with mock instance call and
                // return values
                if (prototype[slot].type === 'function') {
                  const protoImpl = this[slot];
                  this[slot] = mocker.generateFromMetadata(prototype[slot]);
                  this[slot]._protoImpl = protoImpl;
                }
              });

              // Run the mock constructor implementation
              const mockImpl = mockConfig.specificMockImpls.length
                ? mockConfig.specificMockImpls.shift()
                : mockConfig.mockImpl;
              return mockImpl && mockImpl.apply(this, arguments);
            }

            const returnValue = mockConfig.defaultReturnValue;
            // If return value is last set, either specific or default, i.e.
            // mockReturnValueOnce()/mockReturnValue() is called and no
            // mockImplementationOnce()/mockImplementation() is called after
            // that.
            // use the set return value.
            if (mockConfig.specificReturnValues.length) {
              return mockConfig.specificReturnValues.shift();
            }

            if (mockConfig.isReturnValueLastSet) {
              return mockConfig.defaultReturnValue;
            }

            // If mockImplementationOnce()/mockImplementation() is last set,
            // or specific return values are used up, use the mock
            // implementation.
            let specificMockImpl;
            if (returnValue === undefined) {
              specificMockImpl = mockConfig.specificMockImpls.shift();
              if (specificMockImpl === undefined) {
                specificMockImpl = mockConfig.mockImpl;
              }
              if (specificMockImpl) {
                return specificMockImpl.apply(this, arguments);
              }
            }

            // Otherwise use prototype implementation
            if (returnValue === undefined && f._protoImpl) {
              return f._protoImpl.apply(this, arguments);
            }

            return returnValue;
          })();
        } catch (error) {
          // Store the thrown error so we can record it, then re-throw it.
          thrownError = error;
          callDidThrowError = true;
          throw error;
        } finally {
          // Record the result of the function
          mockState.results.push({
            isThrow: callDidThrowError,
            value: callDidThrowError ? thrownError : finalReturnValue
          });
        }

        return finalReturnValue;
      }, metadata.length || 0);

      f = this._createMockFunction(metadata, mockConstructor);
      f._isMockFunction = true;
      f.getMockImplementation = () => this._ensureMockConfig(f).mockImpl;

      if (typeof restore === 'function') {
        this._spyState.add(restore);
      }

      this._mockState.set(f, this._defaultMockState());
      this._mockConfigRegistry.set(f, this._defaultMockConfig());

      // $FlowFixMe - defineProperty getters not supported
      Object.defineProperty(f, 'mock', {
        configurable: false,
        enumerable: true,
        get: () => this._ensureMockState(f),
        set: val => this._mockState.set(f, val)
      });

      f.mockClear = () => {
        this._mockState.delete(f);
        return f;
      };

      f.mockReset = () => {
        f.mockClear();
        this._mockConfigRegistry.delete(f);
        return f;
      };

      f.mockRestore = () => {
        f.mockReset();
        return restore ? restore() : undefined;
      };

      f.mockReturnValueOnce = value => {
        // next function call will return this value or default return value
        const mockConfig = this._ensureMockConfig(f);
        mockConfig.specificReturnValues.push(value);
        return f;
      };

      f.mockResolvedValueOnce = value =>
        f.mockImplementationOnce(() => Promise.resolve(value));

      f.mockRejectedValueOnce = value =>
        f.mockImplementationOnce(() => Promise.reject(value));

      f.mockReturnValue = value => {
        // next function call will return specified return value or this one
        const mockConfig = this._ensureMockConfig(f);
        mockConfig.isReturnValueLastSet = true;
        mockConfig.defaultReturnValue = value;
        return f;
      };

      f.mockResolvedValue = value =>
        f.mockImplementation(() => Promise.resolve(value));

      f.mockRejectedValue = value =>
        f.mockImplementation(() => Promise.reject(value));

      f.mockImplementationOnce = fn => {
        // next function call will use this mock implementation return value
        // or default mock implementation return value
        const mockConfig = this._ensureMockConfig(f);
        mockConfig.isReturnValueLastSet = false;
        mockConfig.specificMockImpls.push(fn);
        return f;
      };

      f.mockImplementation = fn => {
        // next function call will use mock implementation return value
        const mockConfig = this._ensureMockConfig(f);
        mockConfig.isReturnValueLastSet = false;
        mockConfig.defaultReturnValue = undefined;
        mockConfig.mockImpl = fn;
        return f;
      };

      f.mockReturnThis = () =>
        f.mockImplementation(function() {
          return this;
        });

      f.mockName = name => {
        if (name) {
          const mockConfig = this._ensureMockConfig(f);
          mockConfig.mockName = name;
        }
        return f;
      };

      f.getMockName = () => {
        const mockConfig = this._ensureMockConfig(f);
        return mockConfig.mockName || 'jest.fn()';
      };

      if (metadata.mockImpl) {
        f.mockImplementation(metadata.mockImpl);
      }

      return f;
    } else {
      const unknownType = metadata.type || 'undefined type';
      throw new Error('Unrecognized type ' + unknownType);
    }
  }

  _createMockFunction(metadata, mockConstructor) {
    let name = metadata.name;
    if (!name) {
      return mockConstructor;
    }

    // Preserve `name` property of mocked function.
    const boundFunctionPrefix = 'bound ';
    let bindCall = '';
    // if-do-while for perf reasons. The common case is for the if to fail.
    if (name && name.startsWith(boundFunctionPrefix)) {
      do {
        name = name.substring(boundFunctionPrefix.length);
        // Call bind() just to alter the function name.
        bindCall = '.bind(null)';
      } while (name && name.startsWith(boundFunctionPrefix));
    }

    // Special case functions named `mockConstructor` to guard for infinite
    // loops.
    if (name === MOCK_CONSTRUCTOR_NAME) {
      return mockConstructor;
    }

    // It's a syntax error to define functions with a reserved keyword
    // as name.
    if (RESERVED_KEYWORDS[name]) {
      name = '$' + name;
    }

    // It's also a syntax error to define a function with a reserved character
    // as part of it's name.
    if (FUNCTION_NAME_RESERVED_PATTERN.test(name)) {
      name = name.replace(FUNCTION_NAME_RESERVED_REPLACE, '$');
    }

    const body =
      'return function ' +
      name +
      '() {' +
      'return ' +
      MOCK_CONSTRUCTOR_NAME +
      '.apply(this,arguments);' +
      '}' +
      bindCall;
    const createConstructor = new this._environmentGlobal.Function(
      MOCK_CONSTRUCTOR_NAME,
      body
    );

    return createConstructor(mockConstructor);
  }

  _generateMock(metadata, callbacks, refs) {
    const mock = this._makeComponent(metadata);
    if (metadata.refID != null) {
      refs[metadata.refID] = mock;
    }

    getSlots(metadata.members).forEach(slot => {
      const slotMetadata = (metadata.members && metadata.members[slot]) || {};
      if (slotMetadata.ref != null) {
        callbacks.push(() => (mock[slot] = refs[slotMetadata.ref]));
      } else {
        mock[slot] = this._generateMock(slotMetadata, callbacks, refs);
      }
    });

    if (
      metadata.type !== 'undefined' &&
      metadata.type !== 'null' &&
      mock.prototype
    ) {
      mock.prototype.constructor = mock;
    }

    return mock;
  }

  /**
   * @see README.md
   * @param metadata Metadata for the mock in the schema returned by the
   * getMetadata method of this module.
   */
  generateFromMetadata(_metadata) {
    const callbacks = [];
    const refs = {};
    const mock = this._generateMock(_metadata, callbacks, refs);
    callbacks.forEach(setter => setter());
    return mock;
  }

  /**
   * @see README.md
   * @param component The component for which to retrieve metadata.
   */
  getMetadata(component, _refs) {
    const refs = _refs || new Map();
    const ref = refs.get(component);
    if (ref != null) {
      return {ref};
    }

    const type = getType(component);
    if (!type) {
      return null;
    }

    const metadata = {type};
    if (
      type === 'constant' ||
      type === 'collection' ||
      type === 'undefined' ||
      type === 'null'
    ) {
      metadata.value = component;
      return metadata;
    } else if (type === 'function') {
      metadata.name = component.name;
      if (component._isMockFunction) {
        metadata.mockImpl = component.getMockImplementation();
      }
    }

    metadata.refID = refs.size;
    refs.set(component, metadata.refID);

    let members = null;
    // Leave arrays alone
    if (type !== 'array') {
      if (type !== 'undefined') {
        getSlots(component).forEach(slot => {
          if (
            type === 'function' &&
            component._isMockFunction &&
            slot.match(/^mock/)
          ) {
            return;
          }

          if (
            (!component.hasOwnProperty && component[slot] !== undefined) ||
            (component.hasOwnProperty && component.hasOwnProperty(slot)) ||
            (type === 'object' && component[slot] != Object.prototype[slot])
          ) {
            const slotMetadata = this.getMetadata(component[slot], refs);
            if (slotMetadata) {
              if (!members) {
                members = {};
              }
              members[slot] = slotMetadata;
            }
          }
        });
      }

      // If component is native code function, prototype might be undefined
      if (type === 'function' && component.prototype) {
        const prototype = this.getMetadata(component.prototype, refs);
        if (prototype && prototype.members) {
          if (!members) {
            members = {};
          }
          members.prototype = prototype;
        }
      }
    }

    if (members) {
      metadata.members = members;
    }

    return metadata;
  }

  isMockFunction(fn) {
    return !!(fn && fn._isMockFunction);
  }

  fn(implementation) {
    const length = implementation ? implementation.length : 0;
    const fn = this._makeComponent({length, type: 'function'});
    if (implementation) {
      fn.mockImplementation(implementation);
    }
    return fn;
  }

  spyOn(object, methodName, accessType) {
    if (accessType) {
      return this._spyOnProperty(object, methodName, accessType);
    }

    if (typeof object !== 'object' && typeof object !== 'function') {
      throw new Error(
        'Cannot spyOn on a primitive value; ' + this._typeOf(object) + ' given'
      );
    }

    const original = object[methodName];

    if (!this.isMockFunction(original)) {
      if (typeof original !== 'function') {
        throw new Error(
          'Cannot spy the ' +
            methodName +
            ' property because it is not a function; ' +
            this._typeOf(original) +
            ' given instead'
        );
      }

      object[methodName] = this._makeComponent({type: 'function'}, () => {
        object[methodName] = original;
      });

      object[methodName].mockImplementation(function() {
        return original.apply(this, arguments);
      });
    }

    return object[methodName];
  }

  _spyOnProperty(obj, propertyName) {
    let accessType =
      arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : 'get';

    if (typeof obj !== 'object' && typeof obj !== 'function') {
      throw new Error(
        'Cannot spyOn on a primitive value; ' + this._typeOf(obj) + ' given'
      );
    }

    if (!obj) {
      throw new Error(
        'spyOn could not find an object to spy upon for ' + propertyName + ''
      );
    }

    if (!propertyName) {
      throw new Error('No property name supplied');
    }

    let descriptor = Object.getOwnPropertyDescriptor(obj, propertyName);
    let proto = Object.getPrototypeOf(obj);

    while (!descriptor && proto !== null) {
      descriptor = Object.getOwnPropertyDescriptor(proto, propertyName);
      proto = Object.getPrototypeOf(proto);
    }

    if (!descriptor) {
      throw new Error(propertyName + ' property does not exist');
    }

    if (!descriptor.configurable) {
      throw new Error(propertyName + ' is not declared configurable');
    }

    if (!descriptor[accessType]) {
      throw new Error(
        'Property ' + propertyName + ' does not have access type ' + accessType
      );
    }

    const original = descriptor[accessType];

    if (!this.isMockFunction(original)) {
      if (typeof original !== 'function') {
        throw new Error(
          'Cannot spy the ' +
            propertyName +
            ' property because it is not a function; ' +
            this._typeOf(original) +
            ' given instead'
        );
      }

      descriptor[accessType] = this._makeComponent({type: 'function'}, () => {
        // $FlowFixMe
        descriptor[accessType] = original;
        // $FlowFixMe
        Object.defineProperty(obj, propertyName, descriptor);
      });

      descriptor[accessType].mockImplementation(function() {
        return original.apply(this, arguments);
      });
    }

    Object.defineProperty(obj, propertyName, descriptor);
    return descriptor[accessType];
  }

  clearAllMocks() {
    this._mockState = new WeakMap();
  }

  resetAllMocks() {
    this._mockConfigRegistry = new WeakMap();
    this._mockState = new WeakMap();
  }

  restoreAllMocks() {
    this._spyState.forEach(restore => restore());
    this._spyState = new Set();
  }

  _typeOf(value) {
    return value == null ? '' + value : typeof value;
  }
}

module.exports = new ModuleMockerClass(global);