import { assign, MergeStrategies, requireModule } from '@nocobase/utils';
import compose from 'koa-compose';
import _ from 'lodash';
import Middleware, { MiddlewareType } from './middleware';
import Resource from './resource';
import { HandlerType } from './resourcer';

export type ActionType = string | HandlerType | ActionOptions;

export type DefaultActionType = 'list' | 'create' | 'get' | 'update' | 'destroy' | 'set' | 'add' | 'remove';

export type ActionName = DefaultActionType | Omit<String, DefaultActionType>;

export interface ActionContext {
  action?: Action;
  [key: string]: any;
}

export type FieldsOptions =
  | string[]
  | {
      only?: string[];
      appends?: string[];
    }
  | {
      except?: string[];
      appends?: string[];
    };

export type FieldsOptionsFn = (ctx: ActionContext) => FieldsOptions | Promise<FieldsOptions>;

/**
 * 过滤参数
 *
 * TODO：细节待定
 */
export interface FilterOptions {
  [key: string]: any;
}

export type FilterOptionsFn = (ctx: ActionContext) => FilterOptions | Promise<FieldsOptions>;

export type ParamsCallback = (ctx: ActionContext) => ActionParams | Promise<ActionParams>;

export interface ActionOptions {
  /**
   * 默认数据
   */
  values?: any;
  /**
   * 字段
   *
   * 示例一：
   * ['col1', 'col2', 'relation.col1'];
   *
   * 示例二：
   * {
   *  only: ['col1'],
   * }
   *
   * 示例三：
   * {
   *  except: ['col1'],
   * }
   */
  fields?: string[];

  appends?: string[];

  except?: string[];

  whitelist?: string[];

  blacklist?: string[];

  /**
   * 过滤
   */
  filter?: FilterOptions;
  /**
   * 排序
   */
  sort?: string[];
  /**
   * 当前页码
   */
  page?: number;
  /**
   * 每页显示数量
   */
  pageSize?: number;
  /**
   * 最大每页显示数量
   */
  maxPageSize?: number;
  /**
   * 中间件
   */
  middleware?: MiddlewareType;
  /**
   * 中间件
   *
   * 与 middleware 用法相同
   */
  middlewares?: MiddlewareType;
  /**
   * 当前 Action 待执行的方法
   *
   * 支持 Function 和 require 调用
   */
  handler?: HandlerType;
  /**
   * 其他扩展配置
   */
  [key: string]: any;
}

/**
 * action params 与 action options 略有不同
 * - options 的参数更灵活，主要用于开发配置
 * - params 是开发配置参数 + 客户端参数的结合体
 */
export interface ActionParams {
  filterByTk?: any;
  /**
   * 输出哪些字段
   *
   * 与 ActionOptions 的不同，这里的 fields 是 object，提供 only，except，appends 三种情况
   */
  fields?: string[];

  appends?: string[];

  except?: string[];

  whitelist?: string[];

  blacklist?: string[];

  /**
   * 过滤
   */
  filter?: FilterOptions;
  /**
   * 排序
   *
   * 与 ActionOptions 的不同，这里的 sort 只有一种 array 类型
   */
  sort?: string[];
  /**
   * 当前页码
   */
  page?: number;
  /**
   * 每页显示数量
   */
  pageSize?: number;
  /**
   * 数据，默认为 options.defaultValues + request.body
   */
  values?: any;
  /**
   * 当前资源的主体，对应的表名或 Model 名称
   */
  resourceName?: string;
  /**
   * 资源标识符
   */
  resourceIndex?: string;
  /**
   * 资源的从属关系
   */
  associatedName?: string;
  /**
   * 从属关系的标识符
   */
  associatedIndex?: string;
  /**
   * 从属关系的当前实例
   */
  associated?: any;
  /**
   * 资源提供哪些行为或方法
   */
  actionName?: string;
  /**
   * 其他扩展配置
   */
  [key: string]: any;
}

export class Action {
  protected handler: any;

  protected resource: Resource;

  protected name: ActionName;

  protected options: ActionOptions;

  protected context: ActionContext = {};

  public params: ActionParams = {};

  public actionName: string;
  public resourceName: string;
  public resourceOf: any;

  public readonly middlewares: Array<Middleware> = [];

  constructor(options: ActionOptions) {
    options = requireModule(options);
    if (typeof options === 'function') {
      options = { handler: options };
    }
    const { middleware, middlewares = [], handler, ...params } = options;
    this.middlewares = Middleware.toInstanceArray(middleware || middlewares);
    this.handler = handler;
    this.options = options;
    this.mergeParams(params);
  }

  toJSON() {
    return {
      actionName: this.actionName,
      resourceName: this.resourceName,
      resourceOf: this.resourceOf,
      params: this.params,
    };
  }

  clone() {
    const options = _.cloneDeep(this.options);
    delete options.middleware;
    delete options.middlewares;
    const action = new Action(options);
    action.setName(this.name);
    action.setResource(this.resource);
    action.middlewares.push(...this.middlewares);
    return action;
  }

  setContext(context: any) {
    this.context = context;
  }

  mergeParams(params: ActionParams, strategies: MergeStrategies = {}) {
    if (!this.params) {
      this.params = {};
    }

    if (!params) {
      return;
    }

    assign(this.params, params, {
      filter: 'andMerge',
      fields: 'intersect',
      appends: 'union',
      except: 'union',
      whitelist: 'intersect',
      blacklist: 'intersect',
      sort: 'overwrite',
      ...strategies,
    });
  }

  setResource(resource: Resource) {
    this.resource = resource;
    return this;
  }

  getResource() {
    return this.resource;
  }

  getOptions(): ActionOptions {
    return this.options;
  }

  setName(name: ActionName) {
    this.name = name;
    return this;
  }

  getName() {
    return this.name;
  }

  getMiddlewareHandlers() {
    return this.middlewares
      .filter((middleware) => middleware.canAccess(this.name))
      .map((middleware) => middleware.getHandler());
  }

  getHandler() {
    const handler = requireModule(this.handler || this.resource.resourcer.getRegisteredHandler(this.name));
    if (typeof handler !== 'function') {
      throw new Error('Handler must be a function!');
    }

    return handler;
  }

  getHandlers() {
    const handlers = [
      ...this.resource.resourcer.getMiddlewares(),
      ...this.getMiddlewareHandlers(),
      this.getHandler(),
    ].filter(Boolean);

    return handlers;
  }

  async execute(context: any, next?: any) {
    return await compose(this.getHandlers())(context, next);
  }

  static toInstanceMap(actions: object, resource?: Resource) {
    return new Map(
      Object.entries(actions).map(([key, options]) => {
        let action: Action;
        if (options instanceof Action) {
          action = options;
        } else {
          action = new Action(options);
        }
        action.setName(key);
        action.setResource(resource);
        resource && action.middlewares.unshift(...resource.middlewares);
        return [key, action];
      }),
    );
  }
}

export default Action;