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

namespace tint {
namespace {

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

TEST_F(ResolverControlBlockValidationTest,
       SwitchSelectorExpressionNoneIntegerType_Fail) {
  // var a : f32 = 3.14;
  // switch (a) {
  //   default: {}
  // }
  auto* var = Var("a", ty.f32(), ast::StorageClass::kNone, 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(), ast::StorageClass::kNone, Expr(2));

  auto* block = Block(Decl(var),                     //
                      Switch(Source{{12, 34}}, "a",  //
                             Case(Literal(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(), ast::StorageClass::kNone, Expr(2));

  auto* block = Block(Decl(var),                //
                      Switch("a",               //
                             DefaultCase(),     //
                             Case(Literal(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 {
  //   var z: i32;
  //   continue;
  //   z = 1;
  // }
  WrapInFunction(Loop(Block(Decl(Var("z", ty.i32(), ast::StorageClass::kNone)),
                            create<ast::ContinueStatement>(),
                            Assign(Source{{12, 34}}, "z", 1))));

  EXPECT_FALSE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

TEST_F(ResolverControlBlockValidationTest,
       UnreachableCode_Loop_continue_InBlocks) {
  // loop {
  //   var z: i32;
  //   {{{continue;}}}
  //   z = 1;
  // }
  WrapInFunction(
      Loop(Block(Decl(Var("z", ty.i32(), ast::StorageClass::kNone)),
                 Block(Block(Block(create<ast::ContinueStatement>()))),
                 Assign(Source{{12, 34}}, "z", 1))));

  EXPECT_FALSE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_ForLoop_continue) {
  // for (;;) {
  //   var z: i32;
  //   continue;
  //   z = 1;
  // }
  WrapInFunction(
      For(nullptr, nullptr, nullptr,
          Block(create<ast::ContinueStatement>(),
                Decl(Source{{12, 34}},
                     Var("z", ty.i32(), ast::StorageClass::kNone)))));

  EXPECT_FALSE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

TEST_F(ResolverControlBlockValidationTest,
       UnreachableCode_ForLoop_continue_InBlocks) {
  // for (;;) {
  //   var z: i32;
  //   {{{continue;}}}
  //   z = 1;
  // }
  WrapInFunction(
      For(nullptr, nullptr, nullptr,
          Block(Decl(Var("z", ty.i32(), ast::StorageClass::kNone)),
                Block(Block(Block(create<ast::ContinueStatement>()))),
                Assign(Source{{12, 34}}, "z", 1))));

  EXPECT_FALSE(r()->Resolve()) << r()->error();
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_break) {
  // switch (1) {
  //   case 1: { break; var a : u32 = 2;}
  //   default: {}
  // }
  auto* decl = Decl(Source{{12, 34}},
                    Var("a", ty.i32(), ast::StorageClass::kNone, Expr(2)));

  WrapInFunction(                                                //
      Loop(Block(Switch(1,                                       //
                        Case(Literal(1), Block(Break(), decl)),  //
                        DefaultCase()))));

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

TEST_F(ResolverControlBlockValidationTest, UnreachableCode_break_InBlocks) {
  // loop {
  //   switch (1) {
  //     case 1: { {{{break;}}} var a : u32 = 2;}
  //     default: {}
  //   }
  // }
  auto* decl = Decl(Source{{12, 34}},
                    Var("a", ty.i32(), ast::StorageClass::kNone, Expr(2)));

  WrapInFunction(Loop(
      Block(Switch(1,  //
                   Case(Literal(1), Block(Block(Block(Block(Break()))), decl)),
                   DefaultCase()))));

  EXPECT_FALSE(r()->Resolve());
  EXPECT_EQ(r()->error(), "12:34 error: code is unreachable");
}

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

  auto* block =
      Block(Decl(var), Switch("a",                                    //
                              Case(Source{{12, 34}}, {Literal(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(), ast::StorageClass::kNone, Expr(2u));

  auto* block = Block(Decl(var),                                     //
                      Switch("a",                                    //
                             Case(Source{{12, 34}}, {Literal(-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(), ast::StorageClass::kNone, Expr(3u));

  auto* block = Block(Decl(var),   //
                      Switch("a",  //
                             Case(Literal(0u)),
                             Case({
                                 Literal(Source{{12, 34}}, 2u),
                                 Literal(3u),
                                 Literal(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(), ast::StorageClass::kNone, Expr(2));

  auto* block = Block(Decl(var),   //
                      Switch("a",  //
                             Case(Literal(Source{{12, 34}}, -10)),
                             Case({
                                 Literal(0),
                                 Literal(1),
                                 Literal(2),
                                 Literal(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(), ast::StorageClass::kNone, 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 appear as the last "
            "statement in last clause of a switch");
}

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

  auto* block = Block(Decl(var),                             //
                      Switch("a",                            //
                             DefaultCase(Source{{12, 34}}),  //
                             Case(Literal(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), ast::StorageClass::kNone, Expr(2u));
  auto* block = Block(Decl(var),  //
                      Switch("a", DefaultCase(Source{{12, 34}})));

  WrapInFunction(block);

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

}  // namespace
}  // namespace tint