var AWS = require('./core');

/**
 * @api private
 */
AWS.ParamValidator = AWS.util.inherit({
  /**
   * Create a new validator object.
   *
   * @param validation [Boolean|map] whether input parameters should be
   *     validated against the operation description before sending the
   *     request. Pass a map to enable any of the following specific
   *     validation features:
   *
   *     * **min** [Boolean] &mdash; Validates that a value meets the min
   *       constraint. This is enabled by default when paramValidation is set
   *       to `true`.
   *     * **max** [Boolean] &mdash; Validates that a value meets the max
   *       constraint.
   *     * **pattern** [Boolean] &mdash; Validates that a string value matches a
   *       regular expression.
   *     * **enum** [Boolean] &mdash; Validates that a string value matches one
   *       of the allowable enum values.
   */
  constructor: function ParamValidator(validation) {
    if (validation === true || validation === undefined) {
      validation = {'min': true};
    }
    this.validation = validation;
  },

  validate: function validate(shape, params, context) {
    this.errors = [];
    this.validateMember(shape, params || {}, context || 'params');

    if (this.errors.length > 1) {
      var msg = this.errors.join('\n* ');
      msg = 'There were ' + this.errors.length +
        ' validation errors:\n* ' + msg;
      throw AWS.util.error(new Error(msg),
        {code: 'MultipleValidationErrors', errors: this.errors});
    } else if (this.errors.length === 1) {
      throw this.errors[0];
    } else {
      return true;
    }
  },

  fail: function fail(code, message) {
    this.errors.push(AWS.util.error(new Error(message), {code: code}));
  },

  validateStructure: function validateStructure(shape, params, context) {
    this.validateType(params, context, ['object'], 'structure');

    var paramName;
    for (var i = 0; shape.required && i < shape.required.length; i++) {
      paramName = shape.required[i];
      var value = params[paramName];
      if (value === undefined || value === null) {
        this.fail('MissingRequiredParameter',
          'Missing required key \'' + paramName + '\' in ' + context);
      }
    }

    // validate hash members
    for (paramName in params) {
      if (!Object.prototype.hasOwnProperty.call(params, paramName)) continue;

      var paramValue = params[paramName],
          memberShape = shape.members[paramName];

      if (memberShape !== undefined) {
        var memberContext = [context, paramName].join('.');
        this.validateMember(memberShape, paramValue, memberContext);
      } else {
        this.fail('UnexpectedParameter',
          'Unexpected key \'' + paramName + '\' found in ' + context);
      }
    }

    return true;
  },

  validateMember: function validateMember(shape, param, context) {
    switch (shape.type) {
      case 'structure':
        return this.validateStructure(shape, param, context);
      case 'list':
        return this.validateList(shape, param, context);
      case 'map':
        return this.validateMap(shape, param, context);
      default:
        return this.validateScalar(shape, param, context);
    }
  },

  validateList: function validateList(shape, params, context) {
    if (this.validateType(params, context, [Array])) {
      this.validateRange(shape, params.length, context, 'list member count');
      // validate array members
      for (var i = 0; i < params.length; i++) {
        this.validateMember(shape.member, params[i], context + '[' + i + ']');
      }
    }
  },

  validateMap: function validateMap(shape, params, context) {
    if (this.validateType(params, context, ['object'], 'map')) {
      // Build up a count of map members to validate range traits.
      var mapCount = 0;
      for (var param in params) {
        if (!Object.prototype.hasOwnProperty.call(params, param)) continue;
        // Validate any map key trait constraints
        this.validateMember(shape.key, param,
                            context + '[key=\'' + param + '\']')
        this.validateMember(shape.value, params[param],
                            context + '[\'' + param + '\']');
        mapCount++;
      }
      this.validateRange(shape, mapCount, context, 'map member count');
    }
  },

  validateScalar: function validateScalar(shape, value, context) {
    switch (shape.type) {
      case null:
      case undefined:
      case 'string':
        return this.validateString(shape, value, context);
      case 'base64':
      case 'binary':
        return this.validatePayload(value, context);
      case 'integer':
      case 'float':
        return this.validateNumber(shape, value, context);
      case 'boolean':
        return this.validateType(value, context, ['boolean']);
      case 'timestamp':
        return this.validateType(value, context, [Date,
          /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(\.\d+)?Z$/, 'number'],
          'Date object, ISO-8601 string, or a UNIX timestamp');
      default:
        return this.fail('UnkownType', 'Unhandled type ' +
                         shape.type + ' for ' + context);
    }
  },

  validateString: function validateString(shape, value, context) {
    if (this.validateType(value, context, ['string'])) {
      this.validateEnum(shape, value, context);
      this.validateRange(shape, value.length, context, 'string length');
      this.validatePattern(shape, value, context);
    }
  },

  validatePattern: function validatePattern(shape, value, context) {
    if (this.validation['pattern'] && shape['pattern'] !== undefined) {
      if (!(new RegExp(shape['pattern'])).test(value)) {
        this.fail('PatternMatchError', 'Provided value "' + value + '" '
          + 'does not match regex pattern /' + shape['pattern'] + '/ for '
          + context);
      }
    }
  },

  validateRange: function validateRange(shape, value, context, descriptor) {
    if (this.validation['min']) {
      if (shape['min'] !== undefined && value < shape['min']) {
        this.fail('MinRangeError', 'Expected ' + descriptor + ' >= '
          + shape['min'] + ', but found ' + value + ' for ' + context);
      }
    }
    if (this.validation['max']) {
      if (shape['max'] !== undefined && value > shape['max']) {
        this.fail('MaxRangeError', 'Expected ' + descriptor + ' <= '
          + shape['max'] + ', but found ' + value + ' for ' + context);
      }
    }
  },

  validateEnum: function validateRange(shape, value, context) {
    if (this.validation['enum'] && shape['enum'] !== undefined) {
      // Fail if the string value is not present in the enum list
      if (shape['enum'].indexOf(value) === -1) {
        this.fail('EnumError', 'Found string value of ' + value + ', but '
          + 'expected ' + shape['enum'].join('|') + ' for ' + context);
      }
    }
  },

  validateType: function validateType(value, context, acceptedTypes, type) {
    // We will not log an error for null or undefined, but we will return
    // false so that callers know that the expected type was not strictly met.
    if (value === null || value === undefined) return false;

    var foundInvalidType = false;
    for (var i = 0; i < acceptedTypes.length; i++) {
      if (typeof acceptedTypes[i] === 'string') {
        if (typeof value === acceptedTypes[i]) return true;
      } else if (acceptedTypes[i] instanceof RegExp) {
        if ((value || '').toString().match(acceptedTypes[i])) return true;
      } else {
        if (value instanceof acceptedTypes[i]) return true;
        if (AWS.util.isType(value, acceptedTypes[i])) return true;
        if (!type && !foundInvalidType) acceptedTypes = acceptedTypes.slice();
        acceptedTypes[i] = AWS.util.typeName(acceptedTypes[i]);
      }
      foundInvalidType = true;
    }

    var acceptedType = type;
    if (!acceptedType) {
      acceptedType = acceptedTypes.join(', ').replace(/,([^,]+)$/, ', or$1');
    }

    var vowel = acceptedType.match(/^[aeiou]/i) ? 'n' : '';
    this.fail('InvalidParameterType', 'Expected ' + context + ' to be a' +
              vowel + ' ' + acceptedType);
    return false;
  },

  validateNumber: function validateNumber(shape, value, context) {
    if (value === null || value === undefined) return;
    if (typeof value === 'string') {
      var castedValue = parseFloat(value);
      if (castedValue.toString() === value) value = castedValue;
    }
    if (this.validateType(value, context, ['number'])) {
      this.validateRange(shape, value, context, 'numeric value');
    }
  },

  validatePayload: function validatePayload(value, context) {
    if (value === null || value === undefined) return;
    if (typeof value === 'string') return;
    if (value && typeof value.byteLength === 'number') return; // typed arrays
    if (AWS.util.isNode()) { // special check for buffer/stream in Node.js
      var Stream = AWS.util.stream.Stream;
      if (AWS.util.Buffer.isBuffer(value) || value instanceof Stream) return;
    }

    var types = ['Buffer', 'Stream', 'File', 'Blob', 'ArrayBuffer', 'DataView'];
    if (value) {
      for (var i = 0; i < types.length; i++) {
        if (AWS.util.isType(value, types[i])) return;
        if (AWS.util.typeName(value.constructor) === types[i]) return;
      }
    }

    this.fail('InvalidParameterType', 'Expected ' + context + ' to be a ' +
      'string, Buffer, Stream, Blob, or typed array object');
  }
});
