import { AbstractControl } from '@angular/forms';
import { toPromise } from 'rxjs/operator/toPromise';

/**
 * Validator utility function library:
 *
 * Validator and error utilities:
 *   _executeValidators, _executeAsyncValidators, _mergeObjects, _mergeErrors
 *
 * Individual value checking:
 *   isDefined, hasValue, isEmpty
 *
 * Individual type checking:
 *   isString, isNumber, isInteger, isBoolean, isFunction, isObject, isArray,
 *   isMap, isSet, isPromise
 *
 * Multiple type checking and fixing:
 *   getType, isType, isPrimitive, toJavaScriptType, toSchemaType, _convertToPromise
 *
 * Utility functions:
 *   inArray, xor
 *
 * Typescript types and interfaces:
 *   SchemaPrimitiveType, SchemaType, JavaScriptPrimitiveType, JavaScriptType,
 *   PrimitiveValue, PlainObject, IValidatorFn, AsyncIValidatorFn
 *
 * Note: 'IValidatorFn' is short for 'invertable validator function',
 *   which is a validator functions that accepts an optional second
 *   argument which, if set to TRUE, causes the validator to perform
 *   the opposite of its original function.
 */

export type SchemaPrimitiveType =
  'string' | 'number' | 'integer' | 'boolean' | 'null';
export type SchemaType =
  'string' | 'number' | 'integer' | 'boolean' | 'null' | 'object' | 'array';
export type JavaScriptPrimitiveType =
  'string' | 'number' | 'boolean' | 'null' | 'undefined';
export type JavaScriptType =
  'string' | 'number' | 'boolean' | 'null' | 'undefined' | 'object' | 'array' |
  'map' | 'set' | 'arguments' | 'date' | 'error' | 'function' | 'json' |
  'math' | 'regexp'; // Note: this list is incomplete
export type PrimitiveValue = string | number | boolean | null | undefined;
export type PlainObject = { [k: string]: any };

export interface IValidatorFn { (c: AbstractControl, i?: boolean): PlainObject; }
export interface AsyncIValidatorFn { (c: AbstractControl, i?: boolean): any; }

/**
 * '_executeValidators' utility function
 *
 * Validates a control against an array of validators, and returns
 * an array of the same length containing a combination of error messages
 * (from invalid validators) and null values (from valid validators)
 *
 * @param {AbstractControl} control - control to validate
 * @param {IValidatorFn[]} validators - array of validators
 * @return {any[]} - array of nulls and error message
 */
export function _executeValidators(
  control: AbstractControl, validators: IValidatorFn[], invert: boolean = false
): PlainObject[] {
  return validators.map(validator => validator(control, invert));
}

/**
 * '_executeAsyncValidators' utility function
 *
 * Validates a control against an array of async validators, and returns
 * an array of observabe results of the same length containing a combination of
 * error messages (from invalid validators) and null values (from valid ones)
 *
 * @param {AbstractControl} control - control to validate
 * @param {AsyncIValidatorFn[]} validators - array of async validators
 * @return {any[]} - array of observable nulls and error message
 */
export function _executeAsyncValidators(
  control: AbstractControl, validators: AsyncIValidatorFn[], invert: boolean = false
): any[] {
  return validators.map(v => v(control, invert));
}

/**
 * '_mergeObjects' utility function
 *
 * Recursively Merges one or more objects into a single object with combined keys.
 * Automatically detects and ignores null and undefined inputs.
 * Also detects duplicated boolean 'not' keys and XORs their values.
 *
 * @param {PlainObject[]} object - one or more objects to merge
 * @return {PlainObject} - merged object
 */
export function _mergeObjects(...object: PlainObject[]): PlainObject {
  let mergedObject: PlainObject = { };
  for (let i = 0, l = arguments.length; i < l; i++) {
    const currentObject = arguments[i];
    if (isObject(currentObject)) {
      for (let key of Object.keys(currentObject)) {
        const currentValue = currentObject[key];
        const mergedValue = mergedObject[key];
        if (isDefined(mergedValue)) {
          if ( key === 'not' &&
            isBoolean(mergedValue, 'strict') &&
            isBoolean(currentValue, 'strict')
          ) {
            mergedObject[key] = xor(mergedValue, currentValue);
          } else if (
            getType(mergedValue) === 'object' &&
            getType(currentValue) === 'object'
          ) {
            mergedObject[key] = _mergeObjects(mergedValue, currentValue);
          } else {
            mergedObject[key] = currentValue;
          }
        } else {
          mergedObject[key] = currentValue;
        }
      }
    }
  }
  return mergedObject;
}

/**
 * '_mergeErrors' utility function
 *
 * Merges an array of objects.
 * Used for combining the validator errors returned from 'executeValidators'
 *
 * @param {PlainObject[]} arrayOfErrors - array of objects
 * @return {PlainObject} - merged object, or null if no usable input objectcs
 */
export function _mergeErrors(arrayOfErrors: PlainObject[]): PlainObject {
  let mergedErrors: PlainObject = _mergeObjects.apply(null, arrayOfErrors);
  return isEmpty(mergedErrors) ? null : mergedErrors;
}

/**
 * 'isDefined' utility function
 *
 * Checks if a variable contains a value of any type.
 * Returns true even for otherwise 'falsey' values of 0, '', and false.
 *
 * @param {any} object - the value to check
 * @return {boolean} - false if undefined or null, otherwise true
 */
export function isDefined(value: any): boolean {
  return value !== undefined && value !== null;
}

/**
 * 'hasValue' utility function
 *
 * Checks if a variable contains a value.
 * Returs false for null, undefined, or a zero-length strng, '',
 * otherwise returns true.
 * (Stricter than 'isDefined' because it also returns false for '',
 * though it stil returns true for otherwise 'falsey' values 0 and false.)
 *
 * @param {any} object - the value to check
 * @return {boolean} - false if undefined, null, or '', otherwise true
 */
export function hasValue(value: any): boolean {
  return value !== undefined && value !== null && value !== '';
}

/**
 * 'isEmpty' utility function
 *
 * Similar to !hasValue, but also returns true for empty arrays and objects.
 *
 * @param {any} object - the value to check
 * @return {boolean} - false if undefined, null, or '', otherwise true
 */
export function isEmpty(value: any): boolean {
  if (isArray(value)) { return !value.length; }
  if (isObject(value)) { return !Object.keys(value).length; }
  return value === undefined || value === null || value === '';
}

/**
 * 'isString' utility function
 *
 * Checks if a value is a string.
 *
 * @param {any} object - the value to check
 * @return {boolean} - true if string, false if not
 */
export function isString(value: any): value is string {
  return typeof value === 'string';
}

/**
 * 'isNumber' utility function
 *
 * Checks if a value is a regular number or a numeric string.
 *
 * @param {any} object - the value to check
 * @param {any = false} strict - if truthy, also checks JavaScript tyoe
 * @return {boolean} - true if number, false if not
 */
export function isNumber(value: any, strict: any = false): boolean {
  if (strict && typeof value !== 'number') { return false; }
  return !isNaN(value) && value !== value / 0;
}

/**
 * 'isInteger' utility function
 *
 * Checks if a value is an integer.
 *
 * @param {any} object - the value to check
 * @param {any = false} strict - if truthy, also checks JavaScript tyoe
 * @return {boolean} - true if number, false if not
 */
export function isInteger(value: any, strict: any = false): boolean {
  if (strict && typeof value !== 'number') { return false; }
  return !isNaN(value) &&  value !== value / 0 && value % 1 === 0;
}

/**
 * 'isBoolean' utility function
 *
 * Checks if a value is a boolean.
 *
 * @param {any} object - the value to check
 * @param {any = null} option - if 'strict', also checks JavaScript type
 *                              if TRUE or FALSE, checks only for that value
 * @return {boolean} - true if boolean, false if not
 */
export function isBoolean(value: any, option: any = null): boolean {
  if (option === 'strict') { return value === true || value === false; }
  if (option === true) {
    return value === true || value === 1 || value === 'true' || value === '1';
  }
  if (option === false) {
    return value === false || value === 0 || value === 'false' || value === '0';
  }
  return value === true || value === 1 || value === 'true' || value === '1' ||
    value === false || value === 0 || value === 'false' || value === '0';
}

export function isFunction(item: any): boolean {
  return typeof item === 'function';
}

export function isObject(item: any): boolean {
  return item !== null && typeof item === 'object' &&
    Object.prototype.toString.call(item) === '[object Object]';
}

export function isArray(item: any): boolean {
  return Array.isArray(item) ||
    Object.prototype.toString.call(item) === '[object Array]';
}

export function isMap(item: any): boolean {
  return typeof item === 'object' &&
    Object.prototype.toString.call(item) === '[object Map]';
}

export function isSet(item: any): boolean {
  return typeof item === 'object' &&
    Object.prototype.toString.call(item) === '[object Set]';
}

/**
 * 'getType' function
 *
 * Detects the JSON Schema Type of a value.
 * By default, detects numbers and integers even if formatted as strings.
 * (So all integers are also numbers, and any number may also be a string.)
 * However, it only detects true boolean values (to detect boolean values
 * in non-boolean formats, use isBoolean() instead).
 *
 * If passed a second optional parameter of 'strict', it will only detect
 * numbers and integers if they are JavaScript numbers.
 *
 * Examples:
 * getType('10.5') = 'number'
 * getType(10.5) = 'number'
 * getType('10') = 'integer'
 * getType(10) = 'integer'
 * getType('true') = 'string'
 * getType(true) = 'boolean'
 * getType(null) = 'null'
 * getType({ }) = 'object'
 * getType([]) = 'array'
 *
 * getType('10.5', 'strict') = 'string'
 * getType(10.5, 'strict') = 'number'
 * getType('10', 'strict') = 'string'
 * getType(10, 'strict') = 'integer'
 * getType('true', 'strict') = 'string'
 * getType(true, 'strict') = 'boolean'
 *
 * @param {any} value - value to check
 * @param {any = false} strict - if truthy, also checks JavaScript tyoe
 * @return {boolean}
 */
export function getType(value: any, strict: any = false): SchemaType {
  if (!isDefined(value)) { return 'null'; }
  if (isArray(value)) { return 'array'; }
  if (isObject(value)) { return 'object'; }
  if (isBoolean(value, 'strict')) { return 'boolean'; }
  if (isInteger(value, strict)) { return 'integer'; }
  if (isNumber(value, strict)) { return 'number'; }
  if (isString(value)) { return 'string'; }
  return null;
}

/**
 * 'isType' function
 *
 * Checks wether an input (probably string) value contains data of
 * a specified JSON Schema type
 *
 * @param {PrimitiveValue} value - value to check
 * @param {SchemaPrimitiveType} type - type to check
 * @return {boolean}
 */
export function isType(value: PrimitiveValue, type: SchemaPrimitiveType): boolean {
  switch (type) {
    case 'string':
      return isString(value);
    case 'number':
      return isNumber(value);
    case 'integer':
      return isInteger(value);
    case 'boolean':
      return isBoolean(value);
    case 'null':
      return !hasValue(value);
    default:
      console.error('isType error: "' + type + '" is not a recognized type.');
      return null;
  }
}

/**
 * 'isPrimitive' function
 *
 * Checks wether an input value is a JavaScript primitive type:
 * string, number, boolean, or null.
 *
 * @param {any} value - value to check
 * @return {boolean}
 */
export function isPrimitive(value: any): boolean {
  return (isString(value) || isNumber(value) ||
    isBoolean(value, 'strict') || value === null);
}

/**
 * 'toJavaScriptType' function
 *
 * Converts an input (probably string) value to a JavaScript primitive type -
 * 'string', 'number', 'boolean', or 'null' - before storing in a JSON object.
 *
 * Does not coerce values (other than null), and only converts the types
 * of values that would otherwise be valid.
 *
 * If the optional third parameter 'strictIntegers' is TRUE, and the
 * JSON Schema type 'integer' is specified, it also verifies the input value
 * is an integer and, if it is, returns it as a JaveScript number.
 * If 'strictIntegers' is FALSE (or not set) the type 'integer' is treated
 * exactly the same as 'number', and allows decimals.
 *
 * Examples:
 * toJavaScriptType('10', 'number') = 10
 * toJavaScriptType('10', 'integer') = 10
 * toJavaScriptType('10.5', 'number') = 10.5
 * toJavaScriptType('10.5', 'integer') = null // '10.5' is not an integer
 * toJavaScriptType(10.5, 'integer') = null // 10.5 is still not an integer
 *
 * @param {PrimitiveValue} value - value to convert
 * @param {SchemaPrimitiveType | SchemaPrimitiveType[]} types - types to convert to
 * @param {boolean = false} strictIntegers - if FALSE, treat integers as numbers
 * @return {boolean}
 */
export function toJavaScriptType(
  value: any,
  types: SchemaPrimitiveType | SchemaPrimitiveType[],
  strictIntegers: boolean = true
): PrimitiveValue {
  if (!isDefined(value)) { return null; }
  if (isString(types)) { types = [types]; }
  if (strictIntegers && inArray('integer', types)) {
    if (isInteger(value, 'strict')) { return value; }
    if (isInteger(value)) { return parseInt(value, 10); }
  }
  if (inArray('number', types) || (!strictIntegers && inArray('integer', types))) {
    if (isNumber(value, 'strict')) { return value; }
    if (isNumber(value)) { return parseFloat(value); }
  }
  if (inArray('string', types)) {
    if (isString(value)) { return value; }
  }
  if (inArray('boolean', types)) {
    if (isBoolean(value, true)) { return true; }
    if (isBoolean(value, false)) { return false; }
  }
  return null;
}

/**
 * 'toSchemaType' function
 *
 * Converts an input (probably string) value to the "best" JavaScript
 * equivalent available from an allowed list of JSON Schema types, which may
 * contain 'string', 'number', 'integer', 'boolean', and/or 'null'.
 * If necssary, it does progressively agressive type coersion.
 * It will not return null unless null is in the list of allowed types.
 *
 * Number conversion examples:
 * toSchemaType('10', ['number','integer','string']) = 10 // integer
 * toSchemaType('10', ['number','string']) = 10 // number
 * toSchemaType('10', ['string']) = '10' // string
 * toSchemaType('10.5', ['number','integer','string']) = 10.5 // number
 * toSchemaType('10.5', ['integer','string']) = '10.5' // string
 * toSchemaType('10.5', ['integer']) = 10 // integer
 * toSchemaType(10.5, ['null','boolean','string']) = '10.5' // string
 * toSchemaType(10.5, ['null','boolean']) = true // boolean
 *
 * String conversion examples:
 * toSchemaType('1.5x', ['boolean','number','integer','string']) = '1.5x' // string
 * toSchemaType('1.5x', ['boolean','number','integer']) = '1.5' // number
 * toSchemaType('1.5x', ['boolean','integer']) = '1' // integer
 * toSchemaType('1.5x', ['boolean']) = true // boolean
 * toSchemaType('xyz', ['number','integer','boolean','null']) = true // boolean
 * toSchemaType('xyz', ['number','integer','null']) = null // null
 * toSchemaType('xyz', ['number','integer']) = 0 // number
 *
 * Boolean conversion examples:
 * toSchemaType('1', ['integer','number','string','boolean']) = 1 // integer
 * toSchemaType('1', ['number','string','boolean']) = 1 // number
 * toSchemaType('1', ['string','boolean']) = '1' // string
 * toSchemaType('1', ['boolean']) = true // boolean
 * toSchemaType('true', ['number','string','boolean']) = 'true' // string
 * toSchemaType('true', ['boolean']) = true // boolean
 * toSchemaType('true', ['number']) = 0 // number
 * toSchemaType(true, ['number','string','boolean']) = true // boolean
 * toSchemaType(true, ['number','string']) = 'true' // string
 * toSchemaType(true, ['number']) = 1 // number
 *
 * @param {PrimitiveValue} value - value to convert
 * @param {SchemaPrimitiveType[]} types - allowed types to convert to
 * @return {boolean}
 */
export function toSchemaType(
  value: PrimitiveValue, types: SchemaPrimitiveType | SchemaPrimitiveType[]
): PrimitiveValue {
  if (!isArray(<SchemaPrimitiveType>types)) {
    types = <SchemaPrimitiveType[]>[types];
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('null') !== -1 && !hasValue(value)) {
    return null;
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('boolean') !== -1 && !isBoolean(value, 'strict')) {
    return value;
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('integer') !== -1) {
    let testValue = toJavaScriptType(value, 'integer');
    if (testValue !== null) { return +testValue; }
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('number') !== -1) {
    let testValue = toJavaScriptType(value, 'number');
    if (testValue !== null) { return +testValue; }
  }
  if (
    (isString(value) || isNumber(value, 'strict')) &&
    (<SchemaPrimitiveType[]>types).indexOf('string') !== -1
  ) { // Convert number to string
    return toJavaScriptType(value, 'string');
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('boolean') !== -1 && isBoolean(value)) {
    return toJavaScriptType(value, 'boolean');
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('string') !== -1) { // Convert null & boolean to string
    if (value === null) { return ''; }
    let testValue = toJavaScriptType(value, 'string');
    if (testValue !== null) { return testValue; }
  }
  if ((
    (<SchemaPrimitiveType[]>types).indexOf('number') !== -1 ||
    (<SchemaPrimitiveType[]>types).indexOf('integer') !== -1)
  ) {
    if (value === true) { return 1; } // Convert boolean & null to number
    if (value === false || value === null || value === '') { return 0; }
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('number') !== -1) { // Convert mixed string to number
    let testValue = parseFloat(<string>value);
    if (!!testValue) { return testValue; }
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('integer') !== -1) { // Convert string or number to integer
    let testValue = parseInt(<string>value, 10);
    if (!!testValue) { return testValue; }
  }
  if ((<SchemaPrimitiveType[]>types).indexOf('boolean') !== -1) { // Convert anything to boolean
    return !!value;
  }
  if ((
      (<SchemaPrimitiveType[]>types).indexOf('number') !== -1 ||
      (<SchemaPrimitiveType[]>types).indexOf('integer') !== -1
    ) && (<SchemaPrimitiveType[]>types).indexOf('null') === -1
  ) {
    return 0; // If null not allowed, return 0 for non-convertable values
  }
}

/**
 * 'isPromise' function
 *
 * @param {object} object
 * @return {object}
 */
export function isPromise(object: any): object is Promise<any> {
  return !!object && typeof object.then === 'function';
}

/**
 * '_convertToPromise' function
 *
 * @param {object} object
 * @return {Promise<any>}
 */
export function _convertToPromise(object: any): Promise<any> {
  return isPromise(object) ? object : toPromise.call(object);
}

/**
 * 'inArray' function
 *
 * Searches an array for an item, or one of a list of items, and returns true
 * as soon as a match is found, or false if no match.
 *
 * If the optional third parameter allIn is set to TRUE, and the item to find
 * is an array, then the function returns true only if all elements from item
 * are found in the list, and false if any element is not found. If the item to
 * find is not an array, setting allIn to TRUE has no effect.
 *
 * @param {any|any[]} item - the item to search for
 * @param {any[]} array - the array to search
 * @param {boolean = false} allIn - if TRUE, all items must be in array
 * @return {boolean} - true if item(s) in array, false otherwise
 */
export function inArray(
  item: any|any[], array: any[], allIn: boolean = false
): boolean {
  if (!isDefined(item) || !isArray(array)) { return false; }
  if (isArray(item)) {
    for (let subItem of item) {
      if (xor(array.indexOf(subItem) !== -1, allIn)) { return !allIn; }
    }
    return allIn;
  } else {
    return array.indexOf(item) !== -1;
  }
}

/**
 * 'xor' utility function - exclusive or
 *
 * Returns true if exactly one of two values is truthy.
 *
 * @param {any} value1 - first value to check
 * @param {any} value2 - second value to check
 * @return {boolean} - true if exactly one input value is truthy, false if not
 */
export function xor(value1: any, value2: any): boolean {
  return (!!value1 && !value2) || (!value1 && !!value2);
}