// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
// All rights reserved.

// operand-fraction.go
package expr

import (
	"fmt"
	"strings"
)

type fraction struct {
	num, den int64
}

func (f *fraction) ToString(opt FmtOpt) string {
	var sb strings.Builder
	sb.WriteString(fmt.Sprintf("%d|%d", f.num, f.den))
	return sb.String()
}

// -------- fraction term
func newFractionTerm(tk *Token) *term {
	return &term{
		tk:       *tk,
		parent:   nil,
		children: make([]*term, 0, 2),
		position: posInfix,
		priority: priFraction,
		evalFunc: evalFraction,
	}
}

// -------- eval func
func evalFraction(ctx ExprContext, self *term) (v any, err error) {
	var numValue, denValue any
	var num, den int64
	var ok bool

	if numValue, denValue, err = self.evalInfix(ctx); err != nil {
		return
	}
	if num, ok = numValue.(int64); !ok {
		err = fmt.Errorf("numerator must be integer, got %T (%v)", numValue, numValue)
	}
	if den, ok = denValue.(int64); !ok {
		err = fmt.Errorf("denominator must be integer, got %T (%v)", denValue, denValue)
	}

	v = &fraction{num, den}
	return
}

// init
func init() {
	registerTermConstructor(SymVertBar, newFractionTerm)
}