import {
  IModelType,
  IModelTypeComposite,
  IStatusMessage,
  IPropertyStatusMessage,
  MessageSeverity,
  Primitive,
  Predicate,
  IClientProps
} from "./model.api";


export interface IModelViewField {
  keypath:string[];   // ["a","b","c"]
  pointer:string;     // "/a/b/c"
  key:string;         // "a.b.c"
  type:IModelType<any>;
  validate(val:any):IPropertyStatusMessage[];
}

export interface IModelViewPage extends IClientProps {
  alias:string;
  index:number;
  type:IModelTypeComposite<any>|IModelType<any>;
  fields:string[];
  pages: IModelViewPage[];
  skipPredicate?: Predicate<any>;
  flagIsTrue(flagName: string, object: any): boolean;
  flagExists(flagName: string): boolean;
  flagNames(): string[];
}

export enum ValidationScope {
  VISITED, PAGE, FULL
}

/**
 * Provides an immutable facade for a model, adding IModelType
 * based validation and support for copy-on-write mutation.
 *
 */
export interface IModelView<T = any> {
  getModelType():IModelType<T>;
  getModel():Readonly<T>; // might actually be a read-only view of underlying data

  withChangedField(keyPath:string|string[], newValue:Primitive|any[]):IModelView<T>;
  withClearedField(keyPath:string|string[]):IModelView<T>;
  withAddedData(obj:any):IModelView<T>;
  withFieldEditableFlag(keyPath:string|string[], flag:boolean):IModelView<T>;
  withFieldEditableFlags(flags:{ [keyPath:string]:boolean; }):IModelView<T>;
  withClearedVisitedFlags(): IModelView<any>;
  withAddedVisitedFlags(fields:string[]): IModelView<any>;

  isFieldEditable(keyPath:string|string[]):boolean;

  getFieldValue(keyPath:string|string[]):any;
  getFieldType(keyPath:string|string[]):IModelType<any>;
  getFieldContainerType(keyPath:string|string[]):IModelTypeComposite<any>;

  getField(keyPath:string|string[]):IModelViewField;
  getFields(fields?:string[]):IModelViewField[];
  getPossibleFieldValues(keyPath:string|string[]):any[];

  getFieldMessages(keyPath:string|string[]):IPropertyStatusMessage[];
  getValidationMessages(): IPropertyStatusMessage[];

  isFieldVisited(field: string | string[]):boolean;
  isFieldValid(keyPath:string|string[]):boolean;
  areFieldsValid(fields:string[]):boolean;

  withFocusedPage(pageOrAliasOrIndex: IModelViewPage|string|number|undefined|null): IModelView<any>;
  withAllPages(): IModelView<any>;
  getFocusedPage(): undefined|IModelViewPage;
  getFocusedPageNo(): undefined|number;
  getFocusedPageUnskippedPageNo(): undefined|number;
  getPages():IModelViewPage[];
  getUnskippedPages(): IModelViewPage[];
  getAllPages():IModelViewPage[];
  getPage(aliasOrIndex?:string|number):IModelViewPage;
  getPageIndex(alias: string):number;
  getPageByUnskippedPageNo(no: number): IModelViewPage;
  getNextUnskippedPage(dir: 1 | -1): IModelViewPage;
  getPageMessages(aliasOrIndex?:string|number):IStatusMessage[];
  isPageVisited(aliasOrIndex: string | number):boolean;
  isPageValid(aliasOrIndex?:string|number):boolean;

  // page flags: properties of the current page ending in If
  // e.g. xxxIf defines the flag 'xxx', prefix 'x-' is removed from name
  isPageFlagTrue(flag: string): boolean;

  isVisitedValid():boolean;
  areVisitedPagesValid():boolean;
  arePagesUpToCurrentValid():boolean;
  isValid(): boolean;

  isFinished(): boolean;

  getStatusMessages():IStatusMessage[];

  currentPageAlias: string;
  currentPageIndex:number; // 0 based
  currentPageNo:number;    // 1 based
  totalPageCount: number;
  currentUnskippedPageNo: number;
  totalUnskippedPageCount: number;

  changePage(step:number):IModelView<T>;
  gotoPage(indexOrAlias:number|string, validationScope?:ValidationScope):IModelView<T>;

  withValidationMessages(messages:IPropertyStatusMessage[]):IModelView<T>;
  withStatusMessages(messages:IStatusMessage[]):IModelView<T>;

  validationScope():ValidationScope;
  validateDefault():Promise<IModelView<T>>;
  validateVisited():Promise<IModelView<T>>;
  validatePage():Promise<IModelView<T>>;
  validateFull():Promise<IModelView<T>>;
}



export interface IValidationResult {
  messages: IPropertyStatusMessage[];
}

export interface IValidator {
    (oldModel:any, newModel:any):Promise<IValidationResult>;
}