import qs from 'qs';
import glob from 'glob';
import compose from 'koa-compose';
import Action, { ActionName } from './action';
import Resource, { ResourceOptions } from './resource';
import { parseRequest, getNameByParams, ParaseParams, requireModule } from './utils';
import { pathToRegexp } from 'path-to-regexp';

export interface ResourcerContext {
  resourcer?: Resourcer;
  action?: Action;
  params?: ParaseParams;
  [key: string]: any;
}

export interface KoaMiddlewareOptions {

  /**
   * 前缀
   */
  prefix?: string;

  /**
   * 自定义 resource name 的获取规则
   * 
   * 默认规则 relatedTable ? relatedTable.table : table
   */
  nameRule?: (params: ParaseParams) => string;

  /**
   * 上下文中的 key - ctx[paramsKey]
   * 
   * 可以单独配置 paramsKey，默认为 params
   */
  paramsKey?: string;

  /**
   * 自定义 action name
   * 
   * 默认为
   * 
   * - list 查看列表
   * - create 新增数据
   * - get 查看数据详情
   * - update 更新数据
   * - delete 删除数据
   */
  accessors?: {

    /**
     * 查看列表
     */
    list?: string;

    /**
     * 新增数据
     */
    create?: string;

    /**
     * 查看数据详情
     */
    get?: string;

    /**
     * 更新数据
     */
    update?: string;

    /**
     * 删除数据
     */
    delete?: string;
  };
}

export interface ExecuteOptions {

  /**
   * 资源名称
   */
  resource: string;

  /**
   * 自定义 action name
   * 
   * 默认
   * - list 查看列表
   * - create 新增数据
   * - get 查看数据详情
   * - update 更新数据
   * - delete 删除数据
   */
  action: ActionName;
}

export type HandlerType = (ctx: ResourcerContext, next: () => Promise<any>) => any;

export interface Handlers {
  [key: string]: HandlerType;
}

export interface ImportOptions {

  /**
   * 指定配置所在路径
   */
  directory: string;

  /**
   * 文件后缀，默认值 ['js', 'ts', 'json']
   */
  extensions?: string[];
}

export class Resourcer {

  protected resources = new Map<string, Resource>();

  /**
   * 全局定义的 action handlers
   */
  protected handlers = new Map<ActionName, any>();

  protected paramsKey = 'params';

  protected middlewares = [];

  /**
   * 载入指定目录下的 resource 配置（配置的文件驱动）
   * 
   * TODO: 配置的文件驱动现在会全部初始化，大数据时可能存在性能瓶颈，后续可以加入动态加载
   * 
   * @param {object}   [options]
   * @param {string}   [options.directory] 指定配置所在路径
   * @param {array}    [options.extensions = ['js', 'ts', 'json']] 文件后缀
   */
  public import(options: ImportOptions): Map<string, Resource> {
    const { extensions = ['js', 'ts', 'json'], directory } = options;
    const patten = `${directory}/*.{${extensions.join(',')}}`;
    const files = glob.sync(patten);
    const resources = new Map<string, Resource>();
    files.forEach((file: string) => {
      if (file.endsWith('.d.ts')) {
        return;
      }
      const options = requireModule(file);
      const table = this.define(typeof options === 'function' ? options(this) : options);
      resources.set(table.getName(), table);
    });
    return resources;
  }

  /**
   * resource 配置
   * 
   * @param name 
   * @param options 
   */
  define(options: ResourceOptions) {
    const { name } = options;
    const resource = new Resource(options, this);
    this.resources.set(name, resource);
    return resource;
  }

  /**
   * 注册全局的 action handlers
   * 
   * @param handlers 
   */
  registerHandlers(handlers: Handlers) {
    this.handlers = new Map(Object.entries(handlers));
  }

  getRegisteredHandler(name: ActionName) {
    return this.handlers.get(name);
  }

  getRegisteredHandlers() {
    return this.handlers;
  }

  getResource(name: string): Resource {
    if (!this.resources.has(name)) {
      throw new Error(`${name} resource does not exist`);
    }
    return this.resources.get(name);
  }

  getAction(name: string, action: ActionName): Action {
    return this.getResource(name).getAction(action);
  }

  getParamsKey() {
    return this.paramsKey;
  }

  getMiddlewares() {
    return this.middlewares;
  }

  use(middlewares: HandlerType | HandlerType[]) {
    if (typeof middlewares === 'function') {
      this.middlewares.push(middlewares);
    } else if (Array.isArray(middlewares)) {
      this.middlewares.push(...middlewares);
    }
  }

  middleware(options: KoaMiddlewareOptions = {}) {
    const { prefix, accessors, paramsKey = 'params', nameRule = getNameByParams } = options;
    return async (ctx: ResourcerContext, next: () => Promise<any>) => {
      ctx.resourcer = this;
      let params = parseRequest({
        path: ctx.request.path,
        method: ctx.request.method,
      }, {
        prefix,
        accessors,
      });
      if (!params) {
        return next();
      }
      try {
        const resource = this.getResource(nameRule(params));
        // 为关系资源时，暂时需要再执行一遍 parseRequest
        if (resource.options.type !== 'single') {
          params = parseRequest({
            path: ctx.request.path,
            method: ctx.request.method,
            type: resource.options.type,
          }, {
            prefix,
            accessors,
          });
          if (!params) {
            return next();
          }
        }
        // action 需要 clone 之后再赋给 ctx
        ctx.action = this.getAction(nameRule(params), params.actionName).clone();
        ctx.action.setContext(ctx);
        // 自带 query 处理的不太给力，需要用 qs 转一下
        const query = qs.parse(qs.stringify(ctx.query));
        // filter 支持 json string
        if (typeof query.filter === 'string') {
          query.filter = JSON.parse(query.filter);
        }
        // 兼容 ctx.params 的处理，之后的版本里会去掉
        ctx[paramsKey] = {
          table: params.resourceName,
          tableKey: params.resourceKey,
          relatedTable: params.associatedName,
          relatedKey: params.resourceKey,
          action: params.actionName,
        };
        if (pathToRegexp('/resourcer/{:associatedName.}?:resourceName{\\::actionName}').test(ctx.request.path)) {
          await ctx.action.mergeParams({
            ...query,
            ...params,
            ...ctx.request.body,
          });
        } else {
          await ctx.action.mergeParams({
            ...query,
            ...params,
            values: ctx.request.body,
          });
        }
        return compose(ctx.action.getHandlers())(ctx, next);
      } catch (error) {
        return next();
      }
    }
  }

  /**
   * 实验性 API
   * 
   * @param options 
   * @param context 
   * @param next 
   */
  async execute(options: ExecuteOptions, context: ResourcerContext = {}, next?: any) {
    const { resource, action } = options;
    context.resourcer = this;
    context.action = this.getAction(resource, action);
    return await context.action.execute(context, next);
  }
}

export default Resourcer;