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 ShidCodeGenAssignTests {
    @Test
    public void targetIgnoreIsCompiledToDiscard() {
        var node = Typed.assign(
            Typed.targetIgnore(),
            Typed.reference("x")
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("x");

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

        assertThat(result.instructions(), isSequence(
            isShidLocalLoad("x__0"),
            isShidDiscard()
        ));
    }

    @Test
    public void whenTargetIsReassignThenExpressionIsEvaluatedAndStoredAsVar() {
        var node = Typed.assign(
            Typed.targetReassign("x"),
            Typed.stringLiteral("hello")
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("x");

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

        assertThat(result.instructions(), isSequence(
            isShidPushString("hello"),
            isShidVarStore("x__0")
        ));
    }

    @Test
    public void whenTargetIsTupleThenExpressionIsDeconstructed() {
        var node = Typed.assign(
            Typed.targetTuple(List.of(
                Typed.targetVal("a"),
                Typed.targetVal("b"),
                Typed.targetVal("c")
            )),
            Typed.reference("x")
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("x")
            .addShedVal("a")
            .addShedVal("b")
            .addShedVal("c");

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

        assertThat(result.instructions(), isSequence(
            isShidLocalLoad("x__0"),
            isShidDuplicate(),
            isShidTupleGet(0),
            isShidLocalStore("a__0"),
            isShidDuplicate(),
            isShidTupleGet(1),
            isShidLocalStore("b__0"),
            isShidTupleGet(2),
            isShidLocalStore("c__0")
        ));
    }

    @Test
    public void deconstructingEmptyTupleDiscardsExpression() {
        var node = Typed.assign(
            Typed.targetTuple(List.of()),
            Typed.reference("x")
        );
        var context = ShidCodeGen.Context.EMPTY
            .addShedVal("x");

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

        assertThat(result.instructions(), isSequence(
            isShidLocalLoad("x__0"),
            isShidDiscard()
        ));
    }
}