import {Type, isPresent} from 'angular2/src/facade/lang';
import {List, ListWrapper} from 'angular2/src/facade/collection';
import {GetterFn, SetterFn, MethodFn} from './types';

export class ReflectionCapabilities {
  factory(type:Type):Function {
    switch (type.length) {
      case 0:
        return function(){return new type();};
      case 1:
        return function(a1){return new type(a1);};
      case 2:
        return function(a1, a2){return new type(a1, a2);};
      case 3:
        return function(a1, a2, a3){return new type(a1, a2, a3);};
      case 4:
        return function(a1, a2, a3, a4){return new type(a1, a2, a3, a4);};
      case 5:
        return function(a1, a2, a3, a4, a5){return new type(a1, a2, a3, a4, a5);};
      case 6:
        return function(a1, a2, a3, a4, a5, a6){return new type(a1, a2, a3, a4, a5, a6);};
      case 7:
        return function(a1, a2, a3, a4, a5, a6, a7){return new type(a1, a2, a3, a4, a5, a6, a7);};
      case 8:
        return function(a1, a2, a3, a4, a5, a6, a7, a8){return new type(a1, a2, a3, a4, a5, a6, a7, a8);};
      case 9:
        return function(a1, a2, a3, a4, a5, a6, a7, a8, a9){return new type(a1, a2, a3, a4, a5, a6, a7, a8, a9);};
      case 10:
        return function(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10){return new type(a1, a2, a3, a4, a5, a6, a7, a8, a9, a10);};
    };

    throw new Error("Factory cannot take more than 10 arguments");
  }

  parameters(typeOfFunc):List<List> {
    // Prefer the direct API.
    if (isPresent(typeOfFunc.parameters)) {
      return typeOfFunc.parameters;
    }
    if (isPresent(window.Reflect) && isPresent(window.Reflect.getMetadata)) {
      var paramtypes = window.Reflect.getMetadata('design:paramtypes', typeOfFunc);
      if (isPresent(paramtypes)) {
        // TODO(rado): add parameter annotations here.
        return paramtypes.map((p) => [p]);
      }
    }
    return ListWrapper.createFixedSize(typeOfFunc.length);
  }

  annotations(typeOfFunc):List {
    // Prefer the direct API.
    if (isPresent(typeOfFunc.annotations)) {
      return typeOfFunc.annotations;
    }
    if (isPresent(window.Reflect) && isPresent(window.Reflect.getMetadata)) {
      var annotations = window.Reflect.getMetadata('annotations', typeOfFunc);
      if (isPresent(annotations)) return annotations;
    }
    return [];
  }

  getter(name:string):GetterFn {
    return new Function('o', 'return o.' + name + ';');
  }

  setter(name:string):SetterFn {
    return new Function('o', 'v', 'return o.' + name + ' = v;');
  }

  method(name:string):MethodFn {
    var method = `o.${name}`;
    return new Function('o', 'args',
      `if (!${method}) throw new Error('"${name}" is undefined');` +
      `return ${method}.apply(o, args);`);
  }
}