module formsjs {

  /**
   * A collection of validatable data.
   *
   * <p>Despite its name, this is not an HTMLFormElement nor does it directly interact with one.
   * This object is responsible for tracking fields/inputs and ensuring their validity before allowing a submit action.
   */
  export class Form {

    private disabled_:boolean;
    private fieldNameToAttributeMetadata_:{[fieldName:string]:AttributeMetadata};
    private formData_:any;
    private strings_:Strings;
    private validationSchema_:ValidationSchema;
    private validationService_:ValidationService;

    /**
     * Constructor.
     */
    constructor() {
      this.fieldNameToAttributeMetadata_ = {};
      this.formData_ = {};
      this.strings_ = new Strings();
      this.validationService_ = new ValidationService(this.strings_);
    }

    /**
     * This form (and all child input elements) is disabled.
     */
    public get disabled():boolean { return this.disabled_; }
    public set disabled(value:boolean) {
      this.disabled_ = value;

      Object.keys(this.fieldNameToAttributeMetadata_).forEach(
        (fieldName:string) => {
          var attributeMetadata:AttributeMetadata = this.fieldNameToAttributeMetadata_[fieldName];
          attributeMetadata.disabled = value;
        });
    }

    /**
     * The POJO being edited by this form.
     */
    public get formData():any { return this.formData_; }
    public set formData(value:any) { this.formData_ = value; }

    /**
     * Set the strings for this specific form.
     * See {@link Strings}.
     */
    public get strings():Strings { return this.strings_; }
    public set strings(value:Strings) {
      this.strings_ = value;
      this.validationService_.strings = value;
    }

    /**
     * This form's validations schema.
     */
    public get validationSchema():ValidationSchema { return this.validationSchema_; }
    public set validationSchema(value:ValidationSchema) { this.validationSchema_ = value; }

    /**
     * Returns a ValidationService configured for the current Form.
     */
    get validationService():ValidationService { return this.validationService_; }

    /**
     * Register a field with the form.
     *
     * <p>All registered form-fields must be valid before the form will enable submission.
     */
    public registerAttribute(fieldName:string):AttributeMetadata {
      if (this.fieldNameToAttributeMetadata_[fieldName]) {
        throw Error(`Attribute "${fieldName}" has already been registered`);
      }

      var attributeMetadata:AttributeMetadata = new AttributeMetadata(this, fieldName);

      this.fieldNameToAttributeMetadata_[fieldName] = attributeMetadata;

      return attributeMetadata;
    }

    /**
     * Unregister a form field.
     */
    public unregisterAttribute(fieldName:string):void {
      delete this.fieldNameToAttributeMetadata_[fieldName];
    }

    /**
     * Validate all registered form-fields in preparation for submission.
     *
     * <p>This method returns a Promise that will resolve if all fields are found valid or reject if any field isn't.
     * This validation process will also update all {@link AttributeMetadata}s.
     * This in turn may cause view/binding updates.
     */
    public validate():Promise<any> {
      var promises:Array<Promise<any>> = [];


      Object.keys(this.fieldNameToAttributeMetadata_).forEach(
        (fieldName:string) => {
          var attributeMetadata:AttributeMetadata = this.fieldNameToAttributeMetadata_[fieldName];

          promises.push(attributeMetadata.validate());
        });

      return Promise.all(promises);
    }

    // TODO Decide how to handle:
    // 1) Disabling fields while submit is pending or in progress.
    // 2) Re-enable fields once a submit has completed.
    // 3) Showing/processing any server-side validation errors in the event of a failed submission.
  }
}