// 附錄比較表的 benchmark。跟 appendix_demo.go.txt 放同一個目錄執行：
//
//	go test -bench=. -benchmem -count=5
package main

import (
	"math/big"
	"strconv"
	"testing"

	"github.com/shopspring/decimal"
)

var (
	fa, fb = 123456.789, 987.654321
	ia     = big.NewInt(123456789)
	ib     = big.NewInt(987654321)
	bfa, _ = new(big.Float).SetPrec(200).SetString("123456.789")
	bfb, _ = new(big.Float).SetPrec(200).SetString("987.654321")
	bra, _ = new(big.Rat).SetString("123456.789")
	brb, _ = new(big.Rat).SetString("987.654321")
	da     = decimal.RequireFromString("123456.789")
	db     = decimal.RequireFromString("987.654321")

	sink    any
	sinkF   float64
	sinkStr string
)

func BenchmarkAddFloat64(b *testing.B) {
	for b.Loop() {
		sinkF = fa + fb
	}
}
func BenchmarkMulFloat64(b *testing.B) {
	for b.Loop() {
		sinkF = fa * fb
	}
}

func BenchmarkAddBigInt(b *testing.B) {
	z := new(big.Int)
	for b.Loop() {
		z.Add(ia, ib)
	}
	sink = z
}
func BenchmarkMulBigInt(b *testing.B) {
	z := new(big.Int)
	for b.Loop() {
		z.Mul(ia, ib)
	}
	sink = z
}

func BenchmarkAddBigFloat(b *testing.B) {
	z := new(big.Float).SetPrec(200)
	for b.Loop() {
		z.Add(bfa, bfb)
	}
	sink = z
}
func BenchmarkMulBigFloat(b *testing.B) {
	z := new(big.Float).SetPrec(200)
	for b.Loop() {
		z.Mul(bfa, bfb)
	}
	sink = z
}

func BenchmarkAddBigRat(b *testing.B) {
	z := new(big.Rat)
	for b.Loop() {
		z.Add(bra, brb)
	}
	sink = z
}
func BenchmarkMulBigRat(b *testing.B) {
	z := new(big.Rat)
	for b.Loop() {
		z.Mul(bra, brb)
	}
	sink = z
}

func BenchmarkAddDecimal(b *testing.B) {
	var z decimal.Decimal
	for b.Loop() {
		z = da.Add(db)
	}
	sink = z
}
func BenchmarkMulDecimal(b *testing.B) {
	var z decimal.Decimal
	for b.Loop() {
		z = da.Mul(db)
	}
	sink = z
}
func BenchmarkDivDecimal(b *testing.B) {
	var z decimal.Decimal
	for b.Loop() {
		z = da.Div(db)
	}
	sink = z
}

// 三條不同的列印路徑。
func BenchmarkFormatFloat64(b *testing.B) {
	for b.Loop() {
		sinkStr = strconv.FormatFloat(fa, 'f', -1, 64)
	}
}
func BenchmarkFormatBigFloat(b *testing.B) {
	for b.Loop() {
		sinkStr = bfa.Text('f', -1)
	}
}
func BenchmarkFormatDecimal(b *testing.B) {
	for b.Loop() {
		sinkStr = da.String()
	}
}

// float64 → Decimal 走的是 decimal-go.go 裡那份 2009 年的最短列印複製。
func BenchmarkDecimalNewFromFloat(b *testing.B) {
	for b.Loop() {
		sink = decimal.NewFromFloat(fa)
	}
}