// Copyright 2021 The Tint 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.

#include "src/tint/ast/break_statement.h"
#include "src/tint/ast/continue_statement.h"
#include "src/tint/ast/fallthrough_statement.h"
#include "src/tint/ast/switch_statement.h"
#include "src/tint/resolver/resolver_test_helper.h"

namespace tint::resolver {
namespace {

class ResolverControlBlockValidationTest : public TestHelper,
                                           public testing::Test {};

TEST_F(ResolverControlBlockValidationTest,
       SwitchSelectorExpressionNoneIntegerType_Fail) {
  // var a : f32 = 3.14;
  // switch (a) {
  //   default: {}
  // }
  auto* var = Var("a", ty.f32(), Expr(3.14f));

  auto* block = Block(Decl(var), Switch(Expr(Source{{12, 34}}, "a"),  //
                                        DefaultCase()));

  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "12:34 error: switch statement selector expression must be of a "
            "scalar integer type");
}

TEST_F(ResolverControlBlockValidationTest, SwitchWithoutDefault_Fail) {
  // var a : i32 = 2;
  // switch (a) {
  //   case 1: {}
  // }
  auto* var = Var("a", ty.i32(), Expr(2));

  auto* block = Block(Decl(var),                     //
                      Switch(Source{{12, 34}}, "a",  //
                             Case(Expr(1))));

  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "12:34 error: switch statement must have a default clause");
}

TEST_F(ResolverControlBlockValidationTest, SwitchWithTwoDefault_Fail) {
  // var a : i32 = 2;
  // switch (a) {
  //   default: {}
  //   case 1: {}
  //   default: {}
  // }
  auto* var = Var("a", ty.i32(), Expr(2));

  auto* block = Block(Decl(var),             //
                      Switch("a",            //
                             DefaultCase(),  //
                             Case(Expr(1)),  //
                             DefaultCase(Source{{12, 34}})));

  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(
      r()->error(),
      "12:34 error: switch statement must have exactly one default clause");
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_Loop_continue) {
  // loop {
  //   if (false) { break; }
  //   var z: i32;
  //   continue;
  //   z = 1;
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* cont = Continue();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(
      Loop(Block(If(false, Block(Break())), decl_z, cont, assign_z)));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(cont)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest,
       UnreachableCode_Loop_continue_InBlocks) {
  // loop {
  //   if (false) { break; }
  //   var z: i32;
  //   {{{continue;}}}
  //   z = 1;
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* cont = Continue();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(Loop(Block(If(false, Block(Break())), decl_z,
                            Block(Block(Block(cont))), assign_z)));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(cont)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_ForLoop_continue) {
  // for (;false;) {
  //   var z: i32;
  //   continue;
  //   z = 1;
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* cont = Continue();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(For(nullptr, false, nullptr,  //
                     Block(decl_z, cont, assign_z)));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(cont)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest,
       UnreachableCode_ForLoop_continue_InBlocks) {
  // for (;false;) {
  //   var z: i32;
  //   {{{continue;}}}
  //   z = 1;
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* cont = Continue();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(For(nullptr, false, nullptr,
                     Block(decl_z, Block(Block(Block(cont))), assign_z)));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(cont)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_break) {
  // switch (1) {
  //   case 1: {
  //     var z: i32;
  //     break;
  //     z = 1;
  //   default: {}
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* brk = Break();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(                                                //
      Block(Switch(1,                                            //
                   Case(Expr(1), Block(decl_z, brk, assign_z)),  //
                   DefaultCase())));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(brk)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_break_InBlocks) {
  // loop {
  //   switch (1) {
  //     case 1: { {{{break;}}} var a : u32 = 2;}
  //     default: {}
  //   }
  //   break;
  // }
  auto* decl_z = Decl(Var("z", ty.i32()));
  auto* brk = Break();
  auto* assign_z = Assign(Source{{12, 34}}, "z", 1);
  WrapInFunction(Loop(Block(
      Switch(1,  //
             Case(Expr(1), Block(decl_z, Block(Block(Block(brk))), assign_z)),
             DefaultCase()),  //
      Break())));

  ASSERT_TRUE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 warning: code is unreachable");
  EXPECT_TRUE(Sem().Get(decl_z)->IsReachable());
  EXPECT_TRUE(Sem().Get(brk)->IsReachable());
  EXPECT_FALSE(Sem().Get(assign_z)->IsReachable());
}

TEST_F(ResolverControlBlockValidationTest,
       SwitchConditionTypeMustMatchSelectorType2_Fail) {
  // var a : u32 = 2;
  // switch (a) {
  //   case 1: {}
  //   default: {}
  // }
  auto* var = Var("a", ty.i32(), Expr(2));

  auto* block = Block(Decl(var), Switch("a",                                 //
                                        Case(Source{{12, 34}}, {Expr(1u)}),  //
                                        DefaultCase()));
  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "12:34 error: the case selector values must have the same type as "
            "the selector expression.");
}

TEST_F(ResolverControlBlockValidationTest,
       SwitchConditionTypeMustMatchSelectorType_Fail) {
  // var a : u32 = 2;
  // switch (a) {
  //   case -1: {}
  //   default: {}
  // }
  auto* var = Var("a", ty.u32(), Expr(2u));

  auto* block = Block(Decl(var),                                  //
                      Switch("a",                                 //
                             Case(Source{{12, 34}}, {Expr(-1)}),  //
                             DefaultCase()));
  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "12:34 error: the case selector values must have the same type as "
            "the selector expression.");
}

TEST_F(ResolverControlBlockValidationTest,
       NonUniqueCaseSelectorValueUint_Fail) {
  // var a : u32 = 3;
  // switch (a) {
  //   case 0u: {}
  //   case 2u, 3u, 2u: {}
  //   default: {}
  // }
  auto* var = Var("a", ty.u32(), Expr(3u));

  auto* block = Block(Decl(var),   //
                      Switch("a",  //
                             Case(Expr(0u)),
                             Case({
                                 Expr(Source{{12, 34}}, 2u),
                                 Expr(3u),
                                 Expr(Source{{56, 78}}, 2u),
                             }),
                             DefaultCase()));
  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "56:78 error: duplicate switch case '2'\n"
            "12:34 note: previous case declared here");
}

TEST_F(ResolverControlBlockValidationTest,
       NonUniqueCaseSelectorValueSint_Fail) {
  // var a : i32 = 2;
  // switch (a) {
  //   case -10: {}
  //   case 0,1,2,-10: {}
  //   default: {}
  // }
  auto* var = Var("a", ty.i32(), Expr(2));

  auto* block = Block(Decl(var),   //
                      Switch("a",  //
                             Case(Expr(Source{{12, 34}}, -10)),
                             Case({
                                 Expr(0),
                                 Expr(1),
                                 Expr(2),
                                 Expr(Source{{56, 78}}, -10),
                             }),
                             DefaultCase()));
  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "56:78 error: duplicate switch case '-10'\n"
            "12:34 note: previous case declared here");
}

TEST_F(ResolverControlBlockValidationTest,
       LastClauseLastStatementIsFallthrough_Fail) {
  // var a : i32 = 2;
  // switch (a) {
  //   default: { fallthrough; }
  // }
  auto* var = Var("a", ty.i32(), Expr(2));
  auto* fallthrough = create<ast::FallthroughStatement>(Source{{12, 34}});
  auto* block = Block(Decl(var),   //
                      Switch("a",  //
                             DefaultCase(Block(fallthrough))));
  WrapInFunction(block);

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(),
            "12:34 error: a fallthrough statement must not be used in the last "
            "switch case");
}

TEST_F(ResolverControlBlockValidationTest, SwitchCase_Pass) {
  // var a : i32 = 2;
  // switch (a) {
  //   default: {}
  //   case 5: {}
  // }
  auto* var = Var("a", ty.i32(), Expr(2));

  auto* block = Block(Decl(var),                             //
                      Switch("a",                            //
                             DefaultCase(Source{{12, 34}}),  //
                             Case(Expr(5))));
  WrapInFunction(block);

  EXPECT_TRUE(r()->Resolve()) << r()->error();
}

TEST_F(ResolverControlBlockValidationTest, SwitchCaseAlias_Pass) {
  // type MyInt = u32;
  // var v: MyInt;
  // switch(v){
  //   default: {}
  // }

  auto* my_int = Alias("MyInt", ty.u32());
  auto* var = Var("a", ty.Of(my_int), Expr(2u));
  auto* block = Block(Decl(var),  //
                      Switch("a", DefaultCase(Source{{12, 34}})));

  WrapInFunction(block);

  EXPECT_TRUE(r()->Resolve()) << r()->error();
}

}  // namespace
}  // namespace tint::resolver