package bignum

import (
	"math/big"
	"testing"

	"github.com/stretchr/testify/require"
)

func TestComplexMultiplierQuo(t *testing.T) {
	const prec = 128

	newComplex := func(re, im float64) *Complex {
		return &Complex{
			new(big.Float).SetPrec(prec).SetFloat64(re),
			new(big.Float).SetPrec(prec).SetFloat64(im),
		}
	}
	f := func(v float64) *big.Float { return new(big.Float).SetPrec(prec).SetFloat64(v) }

	cm := NewComplexMultiplier()
	for _, tc := range []struct {
		name           string
		a, b           *Complex
		wantRe, wantIm float64
	}{
		// Real numerator, non-real denominator: the previously broken branch.
		{"1/(1+i)", newComplex(1, 0), newComplex(1, 1), 0.5, -0.5},
		{"1/i", newComplex(1, 0), newComplex(0, 1), 0, -1},
		{"0/i", newComplex(0, 0), newComplex(0, 1), 0, 0}, // must not panic
		// General complex division (regression guard for the other branch).
		{"(2+3i)/(1+i)", newComplex(2, 3), newComplex(1, 1), 2.5, 0.5},
	} {
		c := newComplex(0, 0)
		cm.Quo(tc.a, tc.b, c)
		require.Zerof(t, c[0].Cmp(f(tc.wantRe)), "%s real: got %v, want %v", tc.name, c[0], tc.wantRe)
		require.Zerof(t, c[1].Cmp(f(tc.wantIm)), "%s imag: got %v, want %v", tc.name, c[1], tc.wantIm)
	}
}