package org.shedlang.compiler.shid.instructions;

import org.pcollections.PVector;
import org.shedlang.compiler.ast.typed.FreeVariables;
import org.shedlang.compiler.sources.Source;
import org.shedlang.compiler.sources.Sources;
import org.shedlang.compiler.util.P;

import java.util.List;

/**
 * Push a function value onto the temporary value stack with the given
 * definition.
 */
public record ShidDefineFunction(
    String name,
    List<ShidParam> positionalParams,
    List<ShidParam> namedParams,
    FreeVariables freeVariables,
    ShidBlock body,
    Variant variant,
    Source source
) implements ShidInstruction {

    public enum Variant {
        EFFECT_HANDLER_METHOD,
        FUNCTION,
    }

    @Override
    public boolean isBlockTerminator() {
        return false;
    }

    public static Builder builder() {
        return new Builder(
            "f",
            P.vector(),
            P.vector(),
            FreeVariables.builder(),
            P.vector(),
            Variant.FUNCTION
        );
    }

    public record Builder(
        String name,
        PVector<ShidParam> positionalParams,
        PVector<ShidParam> namedParams,
        FreeVariables.Builder freeVariables,
        PVector<ShidInstruction> body,
        ShidDefineFunction.Variant variant
    ) {
        public ShidDefineFunction build() {
            return new ShidDefineFunction(
                name,
                positionalParams,
                namedParams,
                freeVariables.build(),
                new ShidBlock(List.of(), body, Sources.NULL),
                variant,
                Sources.NULL
            );
        }

        public Builder withName(String name) {
            return new Builder(
                name,
                this.positionalParams,
                this.namedParams,
                this.freeVariables,
                this.body,
                this.variant
            );
        }

        public Builder addPositionalParam(String name) {
            return new Builder(
                this.name,
                this.positionalParams.plus(new ShidParam(name, Sources.NULL)),
                this.namedParams,
                this.freeVariables,
                this.body,
                this.variant
            );
        }

        public Builder addNamedParam(String name) {
            return new Builder(
                this.name,
                this.positionalParams,
                this.namedParams.plus(new ShidParam(name, Sources.NULL)),
                this.freeVariables,
                this.body,
                this.variant
            );
        }

        public Builder addFreeVariable(String name) {
            return new Builder(
                this.name,
                this.positionalParams,
                this.namedParams,
                this.freeVariables.plus(name, Sources.NULL),
                this.body,
                this.variant
            );
        }

        public Builder addBodyInstruction(ShidInstruction instruction) {
            return new Builder(
                this.name,
                this.positionalParams,
                this.namedParams,
                this.freeVariables,
                this.body.plus(instruction),
                this.variant
            );
        }
    }
}