/*
 * Copyright 2017 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.javascript.jscomp;

import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link RemoveUnusedCode} that cover removal of instance properties and properties
 * defined directly on constructors.
 */
@RunWith(JUnit4.class)
public final class RemoveUnusedCodeClassPropertiesTest extends CompilerTestCase {

  private static final String EXTERNS =
      lines(
          "/**",
          " * @constructor",
          " * @param {*=} opt_value",
          " * @return {!Object}",
          " */",
          "function Object(opt_value) {}",
          "/**",
          " * @constructor",
          " * @param {...*} var_args",
          " */",
          "function Function(var_args) {}",
          "/**",
          " * @constructor",
          " * @param {*=} arg",
          " * @return {string}",
          " */",
          "function String(arg) {}",
          "/**",
          " * @record",
          " * @template VALUE",
          " */",
          "/**",
          " * @template T",
          " * @constructor ",
          " * @param {...*} var_args",
          " * @return {!Array<?>}",
          " */",
          "function Array(var_args) {}",
          "var window;",
          "function alert(a) {}",
          "function use(x) {}",
          "var EXT = {};",
          "EXT.ext;",
          "var externVar;",
          "function externFunction() {}",
          "/** @type {Function} */",
          "Object.defineProperties = function() {};",
          "/** @type {Function} */",
          "Object.prototype.constructor = function() {};",
          // NOTE: The following are needed to prevent NTI inexistent property warnings.
          "var $jscomp = {};",
          "$jscomp.global = {}",
          "/** @type {?} */",
          "$jscomp.global.Object",
          "function JSCompiler_renameProperty(p) {}",
          "var goog = {};",
          "goog.reflect = {};",
          "goog.reflect.object = function(a, b) {};");

  public RemoveUnusedCodeClassPropertiesTest() {
    super(EXTERNS);
  }

  @Override
  protected CompilerPass getProcessor(Compiler compiler) {
    return new RemoveUnusedCode.Builder(compiler)
        .removeUnusedPrototypeProperties(true)
        .removeUnusedThisProperties(true)
        .removeUnusedConstructorProperties(true)
        .removeUnusedObjectDefinePropertiesDefinitions(true)
        .build();
  }

  @Override
  @Before
  public void setUp() throws Exception {
    super.setUp();
    enableNormalize();
    enableGatherExternProperties();
    setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
    disableTypeCheck();
  }

  @Test
  public void testSimple1() {
    // A property defined on "this" can be removed
    test("this.a = 2", "");
    test("let x = (this.a = 2)", "let x = 2");
    testSame("this.a = 2; let x = this.a;");
  }

  @Test
  public void testSimple2() {
    // A property defined on "this" can be removed, even when defined
    // as part of an expression
    test("this.a = 2, alert(1);", "alert(1);");
    test("const x = (this.a = 2, alert(1));", "const x = alert(1);");
    test("const x = (alert(1), this.a = 2);", "const x = (alert(1), 2);");
  }

  @Test
  public void testSimple3() {
    // A property defined on an object other than "this" can not be removed.
    testSame("var y = {}; y.a = 2");
    // and prevents the removal of the definition on 'this'.
    testSame("var y = {}; y.a = 2; this.a = 2");
    // Some use of the property "a" prevents the removal.
    testSame("var x; var y = {}; y.a = 2; this.a = 1; alert(x.a)");
  }

  @Test
  public void testObjLit() {
    // A property defined on an object other than "this" can not be removed.
    testSame("({a:2})");
    // and prevent the removal of the definition on 'this'.
    testSame("({a:0}); this.a = 1;");
    // ... even if it's quoted
    testSame("({'a':0}); this.a = 1;");
    // Some use of the property "a" prevents the removal.
    testSame("var x = ({a:0}); this.a = 1; alert(x.a)");
  }

  @Test
  public void testExtern() {
    // A property defined in the externs is can not be removed.
    testSame("this.ext = 2");
  }

  @Test
  public void testExport() {
    // An exported property can not be removed.
    testSame("this.ext = 2; window['export'] = this.ext;");
    testSame("function f() { this.ext = 2; } window['export'] = this.ext;");
  }

  @Test
  public void testAssignOp1() {
    // Properties defined using a compound assignment can be removed if the
    // result of the assignment expression is not immediately used.
    test("this.x += 2", "");
    testSame("const x = (this.x += 2)");
    testSame("this.x += 2; const x = this.x;");
    // But, of course, a later use prevents its removal.
    testSame("this.x += 2; let x = {}; x.x;");
  }

  @Test
  public void testAssignOp2() {
    // Properties defined using a compound assignment can be removed if the
    // result of the assignment expression is not immediately used.
    test("this.a += 2, alert(1)", "alert(1)");
    test("const x = (this.a += 2, alert(1))", "const x = alert(1)");
    testSame("const x = (alert(1), this.a += 2)");
  }

  @Test
  public void testInc1() {
    // Increments and Decrements are handled similarly to compound assignments
    // but need a placeholder value when replaced.
    test("this.x++", "");
    testSame("let x = (this.x++)");
    testSame("this.x++; let x = this.x;");

    test("--this.x", "");
    testSame("let x = (--this.x)");
    testSame("--this.x; let x = this.x;");
  }

  @Test
  public void testInc2() {
    // Increments and Decrements are handled similarly to compound assignments
    // but need a placeholder value when replaced.
    test("this.a++, alert()", "alert()");
    test("let x = (this.a++, alert())", "let x = alert()");
    testSame("let x = (alert(), this.a++)");

    test("--this.a, alert()", "alert()");
    test("let x = (--this.a, alert())", "let x = alert()");
    testSame("let x = (alert(), --this.a)");
  }

  @Test
  public void testExprResult() {
    test("this.x", "");
    test("externFunction().prototype.x", "externFunction()");
  }

  @Test
  public void testJSCompiler_renameProperty() {
    // JSCompiler_renameProperty introduces a use of the property
    testSame("var x; this.a = 2; x[JSCompiler_renameProperty('a')]");
    testSame("this.a = 2; JSCompiler_renameProperty('a')");
  }

  @Test
  public void testForIn() {
    // This is the basic assumption that this pass makes:
    // it can remove properties even when the object is used in a FOR-IN loop
    test(
        "let x = {}; this.y = 1;for (var a in x) { alert(x[a]) }",
        "let x = {};            for (var a in x) { alert(x[a]) }");
  }

  @Test
  public void testObjectKeys() {
    // This is the basic assumption that this pass makes:
    // it can remove properties even when the object are referenced
    test(
        "this.y = 1;alert(Object.keys(this))", // preserve format
        "           alert(Object.keys(this))");
  }

  @Test
  public void testObjectReflection1() {
    // Verify reflection prevents removal.
    testSame(
        lines(
            "/** @constructor */", // preserve newlines
            "function A() { this.foo = 1; }",
            "use(goog.reflect.object(A, {foo: 'foo'}));"));
  }

  @Test
  public void testObjectReflection2() {
    // Any object literal definition prevents removal.
    // Type based removal would allow this to be removed.
    testSame(
        lines(
            "/** @constructor */", // preserve newlines
            "function A() {this.foo = 1;}",
            "use({foo: 'foo'});"));
  }

  @Test
  public void testIssue730() {
    // Partial removal of properties can causes problems if the object is
    // sealed.
    testSame(
        lines(
            "function A() {this.foo = 0;}",
            "function B() {this.a = new A();}",
            "B.prototype.dostuff = function() { this.a.foo++; alert('hi'); }",
            "new B().dostuff();"));
  }

  @Test
  public void testPrototypeProps1() {
    test(
        lines(
            "function A() {this.foo = 1;}",
            "A.prototype.foo = 0;",
            "A.prototype.method = function() {this.foo++};",
            "new A().method()"),
        lines(
            "function A() {             }",
            "                    ",
            "A.prototype.method = function() {          };",
            "new A().method()"));
  }

  @Test
  public void testPrototypeProps2() {
    // don't remove properties that are exported by convention
    testSame(
        "function A() {this._foo = 1;}\n" +
        "A.prototype._foo = 0;\n" +
        "A.prototype.method = function() {this._foo++};\n" +
        "new A().method()\n");
  }

  @Test
  public void testConstructorProperty1() {
    enableTypeCheck();

    test(
        "/** @constructor */ function C() {} C.prop = 1;",
        "/** @constructor */ function C() {}            ");
  }

  @Test
  public void testConstructorProperty2() {
    enableTypeCheck();

    testSame(
        lines(
            "/** @constructor */ function C() {} ",
            "C.prop = 1; ",
            "function foo(a) { alert(a.prop) }; ",
            "foo(C)"));
  }

  @Test
  public void testES6StaticProperty() {
    // TODO(bradfordcsmith): Neither type checker understands ES6 classes yet.
    disableTypeCheck();

    test(
        "class C { static prop() {} }", // preserve newline
        "class C {                  }");
  }

  @Test
  public void testES6StaticProperty2() {
    disableTypeCheck();

    // TODO(bradfordcsmith): When NTI understands ES6 classes it will allow removal of `C.prop = 1`.
    testSame("class C {} C.prop = 1;");
  }

  @Test
  public void testObjectDefineProperties1() {
    enableTypeCheck();

    testSame(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {prop:{value:1}});",
            "function foo(a) { alert(a.prop) };",
            "foo(C)"));
  }

  @Test
  public void testObjectDefineProperties2() {
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {prop:{value:1}});"),
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {});"));
  }

  @Test
  public void testObjectDefineProperties3() {
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, ",
            "  {prop:{",
            "    get:function(){},",
            "    set:function(a){},",
            "}});"),
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {});"));
  }

  // side-effect in definition retains property definition, but doesn't count as a reference
  @Test
  public void testObjectDefineProperties4() {
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() { this.prop = 3; }",
            "Object.defineProperties(C, {prop:alert('')});"),
        lines(
            "/** @constructor */ function C() {                }",
            "Object.defineProperties(C, {prop:alert('')});"));
  }

  // quoted properties retains property
  @Test
  public void testObjectDefineProperties5() {
    enableTypeCheck();

    testSame(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {'prop': {value: 1}});"));
  }

  @Test
  public void testObjectDefineProperties6() {
    enableTypeCheck();

    // an unknown destination object doesn't prevent removal.
    test(
        "Object.defineProperties(externVar(), {prop:{value:1}});",
        "Object.defineProperties(externVar(), {              });");
  }

  @Test
  public void testObjectDefineProperties7() {
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {prop:{get:function () {return new C}}});"),
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {});"));
  }

  @Test
  public void testObjectDefineProperties8() {
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {prop:{set:function (a) {return alert(a)}}});"),
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {});"));
  }

  @Test
  public void testObjectDefinePropertiesQuotesPreventRemoval() {
    enableTypeCheck();

    testSame(
        lines(
            "/** @constructor */ function C() { this.prop = 1; }",
            "Object.defineProperties(C, {'prop':{set:function (a) {return alert(a.prop)}}});"));
  }

  @Test
  public void testObjectDefineProperties_used_setter_removed() {
    // TODO(bradfordcsmith): Either remove, fix this, or document it as a limitation of advanced
    // mode optimizations.
    enableTypeCheck();

    test(
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {prop:{set:function (a) {alert(2)}}});",
            "C.prop = 2;"),
        lines(
            "/** @constructor */ function C() {}",
            "Object.defineProperties(C, {                                  });"));
  }

  @Test
  public void testEs6GettersWithoutTranspilation() {
    test(
        "class C { get value() { return 0; } }", // preserve newline
        "class C {                           }");
    testSame("class C { get value() { return 0; } } const x = (new C()).value");
  }

  @Test
  public void testES6ClassComputedProperty() {
    testSame("class C { ['test' + 3]() { return 0; } }");
  }

  @Test
  public void testEs6SettersWithoutTranspilation() {
    test(
        "class C { set value(val) { this.internalVal = val; } }", // preserve newline
        "class C {                                            }");

    test(
        "class C { set value(val) { this.internalVal = val; } } (new C()).value = 3;",
        "class C { set value(val) {                         } } (new C()).value = 3;");
    testSame(
        lines(
            "class C {",
            "  set value(val) {",
            "    this.internalVal = val;",
            "  }",
            "  get value() {",
            "    return this.internalVal;",
            "  }",
            "}",
            "const y = new C();",
            "y.value = 3;",
            "const x = y.value;"));
  }

  // All object literal fields are not removed, but the following
  // tests assert that the pass does not fail.
  @Test
  public void testEs6EnhancedObjLiteralsComputedValuesNotRemoved() {
    testSame(
        lines(
            "function getCar(make, model, value) {",
            "  return {",
            "    ['make' + make] : true",
            "  };",
            "}"));
  }

  @Test
  public void testEs6EnhancedObjLiteralsMethodShortHandNotRemoved() {
    testSame(
        lines(
            "function getCar(make, model, value) {",
            "  return {",
            "    getModel() {",
            "      return model;",
            "    }",
            "  };",
            "}"));
  }

  @Test
  public void testEs6EnhancedObjLiteralsPropertyShorthand() {
    testSame("function getCar(make, model, value) { return {model}; }");
  }

  @Test
  public void testTranspiledEs6GettersRemoval() {
    enableTypeCheck();
    test(
        // This is the output of ES6->ES5 class getter converter.
        // See Es6TranspilationIntegrationTest.testEs5GettersAndSettersClasses test method.
        lines(
            "/** @constructor @struct */",
            "var C = function() {};",
            "/** @type {?} */",
            "C.prototype.value;",
            "$jscomp.global.Object.defineProperties(C.prototype, {",
            "  value: {",
            "    configurable: true,",
            "    enumerable: true,",
            "    /** @this {C} */",
            "    get: function() {",
            "      return 0;",
            "    }",
            "  }",
            "});"),
        lines(
            "/** @constructor @struct */var C=function(){};",
            "$jscomp.global.Object.defineProperties(C.prototype, {});"));
  }

  @Test
  public void testTranspiledEs6SettersRemoval() {
    enableTypeCheck();
    test(
        // This is the output of ES6->ES5 class setter converter.
        // See Es6TranspilationIntegrationTest.testEs5GettersAndSettersClasses test method.
        lines(
            "/** @constructor @struct */",
            "var C = function() {};",
            "/** @type {?} */",
            "C.prototype.value;",
            "/** @type {?} */",
            "C.prototype.internalVal;",
            "$jscomp.global.Object.defineProperties(C.prototype, {",
            "  value: {",
            "    configurable: true,",
            "    enumerable: true,",
            "    /** @this {C} */",
            "    set: function(val) {",
            "      this.internalVal = val;",
            "    }",
            "  }",
            "});"),
        lines(
            "/** @constructor @struct */var C=function(){};",
            "$jscomp.global.Object.defineProperties(C.prototype, {});"));
  }

  @Test
  public void testEs6ArrowFunction() {
    test(
        "const arrow = () => this.a = 1;", // preserve newline
        "const arrow = () =>          1;");
    testSame("const arrow = () => ({a: 2})");
    testSame("var y = {}; const arrow = () => {y.a = 2; this.a = 2;}");
    test(
        lines(
            "function A() {",
            "  this.foo = 1;",
            "}",
            "A.prototype.foo = 0;",
            "A.prototype.getIncr = function() {",
            "  return () => { this.foo++; };",
            "};",
            "new A().getIncr()"),
        lines(
            "function A() {",
            "               ",
            "}",
            "                  ",
            "A.prototype.getIncr = function() {",
            "  return () => {             };",
            "};",
            "new A().getIncr()"));
  }

  @Test
  public void testEs6Generator() {
    test(
        "function* gen() { yield this.a = 1; }", // preserve newline
        "function* gen() { yield          1; }");
    testSame("function* gen() { yield this.a = 1; yield this.a; }");
  }

  @Test
  public void testEs6Destructuring() {
    // Test normal destructuring removal
    test(
        "[this.x, this.y] = [1, 2]", // preserve newline
        "[              ] = [1, 2]");

    // Test normal destructuring, assignment prevent removal
    test(
        lines(
            "[this.x, this.y] = [1, 2]", // preserve newline
            "var p = this.x;"),
        lines(
            "[this.x        ] = [1, 2]", // preserve newline
            "var p = this.x;"));

    // Test rest destructuring removal
    test(
        "[this.x, ...this.z] = [1, 2, 3]", // preserve newline
        "[                 ] = [1, 2, 3]");

    // Test rest destructuring with normal variable
    test(
        "let z; [this.x, ...z] = [1, 2]", // preserve newline
        "let z; [      , ...z] = [1, 2]");

    // Test rest destructuring, assignment prevent removal
    test(
        lines(
            "[this.x, ...this.y] = [1, 2];", // preserve newline
            "var p = this.y;"),
        lines(
            "[      , ...this.y] = [1, 2];", // preserve newline
            "var p = this.y;"));

    // Test destructuring rhs prevent removal
    testSame(
        lines(
            "let a;",
            "this.x = 1;", // preserve newline
            "this.y = 2;",
            "[...a] = [this.x, this.y];"));

    // Test nested destructuring
    test(
        "let z; [this.x, [this.y, ...z]] = [1, [2]]", // preserve newline
        "let z; [      , [      , ...z]] = [1, [2]]");

    // Test normal object destructuring full removal
    test("({a: this.x, b: this.y} = {a: 1, b: 2})", "({} = {a: 1, b: 2})");

    // Test normal object destructuring partial removal
    test("let y; ({a: this.x, b: y} = {a: 1, b: 2})", "let y; ({           b: y} = {a: 1, b: 2})");

    // Test obj destructuring prevent removal
    test(
        lines(
            "({a: this.x, b: this.y} = {a: 1, b: 2});",
            "var p = this.x;"),
        lines(
            "({a: this.x} = {a: 1, b: 2});",
            "var p = this.x;"));

    // Test obj destructuring with old style class
    testSame(
        lines(
            "/** @constructor */ function C () {",
            "  this.a = 1;",
            "}",
            "let x;",
            "({a: x} = new C());"));

    // Test obj destructuring with new style class
    testSame(
        lines(
            "class C {",
            "  constructor() {",
            "     this.a = 1;",
            "  }",
            "}",
            "let x;",
            "({a: x} = new C());"));

    // Test let destructuring
    testSame(
        lines(
            "class C {",
            "  constructor() {",
            "     this.a = 1;",
            "  }",
            "}",
            "let {a: x} = new C();"));

    // Test obj created at a different location and later used in destructuring
    testSame(
        lines(
            "class C {",
            "  constructor() {",
            "     this.a = 1;",
            "  }",
            "}",
            "var obj = new C()",
            "let x;",
            "({a: x} = obj);"));

    // Test obj destructuring with default value
    testSame(
        lines(
            "class C {",
            "  constructor() {",
            "     this.a = 1;",
            "  }",
            "}",
            "let a;",
            "({a = 2} = new C());"));

    // Test obj nested destructuring
    testSame(
        lines(
            "class C {",
            "  constructor() {",
            "     this.a = 1;",
            "  }",
            "}",
            "var obj = new C()",
            "let a;",
            "({x: {a}} = {x: obj});"));

    // Computed Property string expression doesn't prevent removal.
    test(
        "({['a']:0}); this.a = 1;", // preserve newline
        "({['a']:0});            ");
  }

  @Test
  public void testEs6DefaultParameter() {
    test(
        "function foo(x, y = this.a = 1) {}", // preserve newline
        "function foo(x, y =          1) {}");
    testSame("this.a = 1; function foo(x, y = this.a) {}");
  }

  @Test
  public void testEs8AsyncFunction() {
    test(
        lines(
            "async function foo(promise) {", // preserve newlines
            "   this.x = 1;",
            "   return await promise;",
            "}"),
        lines(
            "async function foo(promise) {", // preserve newlines
            "              ",
            "   return await promise;",
            "}"));

    testSame(
        lines(
            "async function foo() {",
            "   this.x = 1;",
            "   return await this.x;",
            "}"));

    testSame(
        lines(
            "this.x = 1;",
            "async function foo() {",
            "   return await this.x;",
            "}"));
  }
}