package org.shedlang.compiler.shid;

import org.junit.jupiter.api.Test;
import org.shedlang.compiler.ast.typed.Typed;

import java.util.List;

import static org.shedlang.compiler.shid.instructions.ShidMatchers.*;
import static org.zwobble.precisely.AssertThat.assertThat;
import static org.zwobble.precisely.Matchers.isSequence;

public class ShidCodeGenWhileTests {
    @Test
    public void whileIsCompiledToLoop() {
        var node = Typed.while_(
            Typed.reference("c"),
            Typed.block(List.of(
                Typed.expressionStatement(Typed.intLiteral(42))
            ))
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("c");

        var result = ShidCodeGen.compileFunctionStatement(node, context);

        assertThat(result.instructions(), isSequence(
            isShidLoop(
                isShidBlock(isSequence(
                    isShidLocalLoad("c__0"),
                    isShidIf(
                        isShidBlock(isSequence()),
                        isShidBlock(isSequence(
                            isShidLoopBreak()
                        ))
                    ),
                    isShidBlock(isSequence(
                        isShidPushInt(42),
                        isShidDiscard()
                    )),
                    isShidLoopContinue()
                ))
            )
        ));
    }

    @Test
    public void whenBodyYieldsValueThenValueIsDiscarded() {
        // In principle, the type checker should prevent the body from yielding
        // a value, but we check we handle this case anyway.
        var node = Typed.while_(
            Typed.reference("c"),
            Typed.block(List.of(
                Typed.blockReturn(Typed.intLiteral(42))
            ))
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("c");

        var result = ShidCodeGen.compileFunctionStatement(node, context);

        assertThat(result.instructions(), isSequence(
            isShidLoop(
                isShidBlock(isSequence(
                    isShidLocalLoad("c__0"),
                    isShidIf(
                        isShidBlock(isSequence()),
                        isShidBlock(isSequence(
                            isShidLoopBreak()
                        ))
                    ),
                    isShidBlock(isSequence(
                        isShidPushInt(42),
                        isShidDiscard()
                    )),
                    isShidLoopContinue()
                ))
            )
        ));
    }
}