package core

import (
	"git.urbach.dev/cli/q/src/asm"
	"git.urbach.dev/cli/q/src/ast"
)

// CompileIf compiles a branch instruction.
func (f *Function) CompileIf(branch *ast.If) error {
	for _, register := range f.CPU.Input {
		f.SaveRegister(register)
	}

	f.count.branch++

	var (
		end     asm.Label
		success = f.CreateLabel("if true", f.count.branch, asm.ControlLabel)
		fail    = f.CreateLabel("if false", f.count.branch, asm.ControlLabel)
		err     = f.CompileCondition(branch.Condition, success, fail)
	)

	if err != nil {
		return err
	}

	f.AddLabel(success)
	f.PushScope(branch.Body, f.File.Bytes)
	err = f.CompileAST(branch.Body)

	if err != nil {
		return err
	}

	if branch.Else != nil {
		end = f.CreateLabel("if end", f.count.branch, asm.ControlLabel)
		f.Jump(asm.JUMP, end)
	}

	f.PopScope()
	f.AddLabel(fail)

	if branch.Else != nil {
		f.PushScope(branch.Else, f.File.Bytes)
		err = f.CompileAST(branch.Else)

		if err != nil {
			return err
		}

		f.PopScope()
		f.AddLabel(end)
		return nil
	}

	return nil
}