package commands

import (
	"fmt"
	"strings"

	"c65gm/internal/compiler"
	"c65gm/internal/preproc"
	"c65gm/internal/utils"
)

// ElseCommand handles ELSE statements in IF...ELSE...ENDIF blocks
// Syntax: ELSE
type ElseCommand struct {
	skipLabel string
	endLabel  string
}

func (c *ElseCommand) WillHandle(line preproc.Line) bool {
	params, err := utils.ParseParams(line.Text)
	if err != nil || len(params) == 0 {
		return false
	}

	return strings.ToUpper(params[0]) == "ELSE"
}

func (c *ElseCommand) Interpret(line preproc.Line, ctx *compiler.CompilerContext) error {
	params, err := utils.ParseParams(line.Text)
	if err != nil {
		return err
	}

	if len(params) != 1 {
		return fmt.Errorf("ELSE: wrong number of parameters (%d), expected 1", len(params))
	}

	// Pop the IF skip label
	label, err := ctx.IfStack.Pop()
	if err != nil {
		return fmt.Errorf("ELSE: %w", err)
	}
	c.skipLabel = label

	// Push new end label
	c.endLabel = ctx.IfStack.Push()

	return nil
}

func (c *ElseCommand) Generate(_ *compiler.CompilerContext) ([]string, error) {
	var asm []string

	// Jump to end (skip else block if condition was true)
	asm = append(asm, fmt.Sprintf("\tjmp %s", c.endLabel))

	// Place skip label (jumped here if condition was false)
	asm = append(asm, c.skipLabel)

	return asm, nil
}