/*
 * Copyright (c) 2010, 2024 BSI Business Systems Integration AG
 *
 * This program and the accompanying materials are made
 * available under the terms of the Eclipse Public License 2.0
 * which is available at https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 */
import {arrays, numbers, objects, scout} from '../index';
import $ from 'jquery';

export interface AppendToTarget {
  id?: string;
  root?: boolean;
}

export interface InsertTarget {
  id?: string;
  root?: boolean;
  property?: string;
  before?: string;
  after?: string;
  index?: number;
  groupWithTarget?: boolean;
}

export interface AppendToAction {
  operation: 'appendTo';
  target: AppendToTarget;
  extension: object;
}

export interface InsertAction {
  operation: 'insert';
  target: InsertTarget;
  extension: object;
}

export type ExtensionAction = AppendToAction | InsertAction;

export interface ExtensionModel {
  id?: string;
  type?: 'extension';
  extensions: ExtensionAction[];
}

function get<T>(modelFunc: () => T): T;
function get<T, P>(modelFunc: () => T, parent: P): T & { parent: P };

/**
 * Returns a new instance of a model supplied by the given model func
 *
 * @param modelFunc A function that returns the model instance.
 * @param parent Optional parent that is set on the returned object.
 */
function get<T, P>(modelFunc: () => T, parent?: P): T & { parent?: P } {
  let model = modelFunc();
  if (parent) {
    (model as T & { parent?: P }).parent = parent;
  }
  return model;
}

export const models = {

  modelMap: {},

  init(data: any) {
    models.modelMap = data;
  },

  get,

  /**
   * Returns a new instance of an extension from the global modelMap.
   *
   * @param extensionId The id of the extension.
   */
  getExtension(extensionId: string): ExtensionModel {
    return models._get(extensionId, 'extension');
  },

  /**
   * Returns a copy of the object in the global modelMap.
   *
   * @internal
   * @param id ID of the requested object (model or extension)
   * @param type Expected type of the requested object ('model' or 'extension')
   */
  _get(id: string, type: string): ExtensionModel {
    let model = models.modelMap[id];
    if (!model) {
      throw new Error('No model map entry found for id \'' + id + '\'');
    }
    if (scout.nvl(model.type, 'model') !== type) {
      throw new Error('Model \'' + id + '\' is not of type \'' + type + '\'');
    }
    return $.extend(true, {}, model);
  },

  /**
   * Extends 'parentModel' with the contents of 'extension'.
   *
   * Parent model
   * ------------
   * The 'parentModel' argument (mandatory) will be changed and returned.
   *
   * Extension
   * ---------
   * Needs a property id on the parentModel to find the extension point.
   * Syntax of the extension:
   *
   * [appendTo]
   * Adding or overriding a property:
   * ```
   *   {
   *     "id": "..."
   *     "type": "extension"
   *     "extensions": [
   *       {
   *         "operation": "appendTo"
   *         "target": {
   *           "id": "someObjectID"
   *         }
   *         "extension": {
   *           "propertyX": "xyz"
   *         }
   *       }
   *     ]
   *   }
   * ```
   *
   * [insert]
   * Adding new object to the tree:
   * ```
   *   {
   *     "id": "..."
   *     "type": "extension"
   *     "extensions": [
   *       {
   *         "operation": "insert",
   *         "target": {
   *           "id": "someObjectID",
   *           "property": "collectionOfSomeObject",
   *           "before": "somObjectIDInPropertyArray"    // (alternative "index": 0)
   *         },
   *         "extension": {
   *            "id": "newObjectID",
   *            "propertyX": "someThing",
   *            "collectionY": [...]
   *         }
   *       }
   *     ]
   *   }
   * ```
   *
   * To extend the root object directly, "target.root: true" can be used instead of "target.id".
   *
   * To group inserted elements positions with its target use:
   * ```
   *   "target": {
   *     "id": "someObjectID",
   *     "property": "collectionOfSomeObject",
   *     "before": "somObjectIDInPropertyArray",
   *     "groupWithTarget": true
   *   }
   * ```
   * This will group the properties together. Future extensions which use "before": "somObjectIDInPropertyArray"
   * will insert new elements before the grouped items. (Works the same with "after".)
   *
   * The extension property can be an object or an array of objects.
   *
   * @param extension extension to the parentModel.
   * @param parentModel object which contains id's as properties
   * @returns parentModel extended by extension
   */
  extend(extension: ExtensionModel | string | (() => ExtensionModel), parentModel: object): object {
    let extensionObject: ExtensionModel;
    if (typeof extension === 'string') {
      extensionObject = models.getExtension(extension);
    } else if (typeof extension === 'function') {
      extensionObject = extension();
    } else {
      extensionObject = extension;
    }

    scout.assertParameter('extensions', extensionObject.extensions);
    extensionObject.extensions.forEach(extensionConfig => {
      let operation = scout.assertParameter('operation', extensionConfig.operation);
      let target = scout.assertParameter('target', extensionConfig.target);

      let targetObject;
      if (target.root) {
        targetObject = parentModel;
      } else {
        targetObject = objects.findChildObjectByKey(parentModel, 'id', target.id);
      }
      if (!targetObject) {
        throw new Error('Extension target not found: [extension: ' + extensionObject.id + ', target: ' + target.id + ']');
      }

      if (operation === 'appendTo') {
        $.extend(targetObject, extensionConfig.extension);
      } else if (operation === 'insert') {
        let insertTarget = target as InsertTarget;
        targetObject[insertTarget.property] = targetObject[insertTarget.property] || [];
        let targetArray = targetObject[insertTarget.property];
        let extensionArray = arrays.ensure(extensionConfig.extension);
        models._bindExtensionsToBeforeOrAfter(insertTarget, extensionArray);
        let insertAt = models._findExtensionIndex(insertTarget, targetArray);
        arrays.insertAll(targetArray, extensionArray, insertAt);
      }
    });

    return parentModel;
  },

  /**
   * Finds the index in the target array which is given through the target.
   *
   * @internal
   * @param target
   *          target information to search the index (either fixed index or a "before" or "after" tag).
   * @param targetArray
   *          array to search the extension index in.
   * @returns extension index between 0 and targetArray.length or targetArray.length if no index is found.
   */
  _findExtensionIndex(target: InsertTarget, targetArray: { id?: string; groupedWith?: string }[]): number {
    let insertAt = targetArray.length;
    if (target.before) {
      insertAt = arrays.findIndex(targetArray, element => {
        return element.id === target.before || element.groupedWith === target.before;
      });
      if (insertAt === -1) {
        insertAt = targetArray.length;
      }
    } else if (target.after) {
      insertAt = arrays.findIndex(targetArray, element => {
        return element.id === target.after || element.groupedWith === target.after;
      });
      if (insertAt === -1) {
        insertAt = targetArray.length;
      } else {
        insertAt++;
      }
    }
    if (numbers.isNumber(target.index)) {
      insertAt = target.index;
    }
    return insertAt;
  },

  /**
   * Adds the groupedWith tag to all given extensions.
   *
   * @internal
   * @param target
   *          target to bind the extensions to.
   * @param extensionsArray
   *          extensions to bind
   */
  _bindExtensionsToBeforeOrAfter(target: InsertTarget, extensionsArray: { groupedWith?: string }[]) {
    let beforeOrAfter = target.before || target.after;
    if (beforeOrAfter && target.groupWithTarget) {
      extensionsArray.forEach(element => {
        element.groupedWith = beforeOrAfter;
      });
    }
  }
};