/*
 * Copyright 2021 ByteDance Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package sonic

import (
	"encoding/json"
	"reflect"
	"strings"
	"testing"

	"github.com/bytedance/sonic/decoder"
)

type atofTest struct {
	in  string
	out string
	err error
}

// Tests from Go strconv package, https://github.com/golang/go/blob/master/src/strconv/atof_test.go
// All tests are passed in Go encoding/json.
var atoftests = []atofTest{
	{"1.234e", "1.234", nil},
	{"1i", "1", nil},
	{"1", "1", nil},
	{"1e23", "1e+23", nil},
	{"1E23", "1e+23", nil},
	{"100000000000000000000000", "1e+23", nil},
	{"1e-100", "1e-100", nil},
	{"123456700", "1.234567e+08", nil},
	{"99999999999999974834176", "9.999999999999997e+22", nil},
	{"100000000000000000000001", "1.0000000000000001e+23", nil},
	{"100000000000000008388608", "1.0000000000000001e+23", nil},
	{"100000000000000016777215", "1.0000000000000001e+23", nil},
	{"100000000000000016777216", "1.0000000000000003e+23", nil},
	{"-1", "-1", nil},
	{"-0.1", "-0.1", nil},
	{"-0", "-0", nil},
	{"1e-20", "1e-20", nil},
	{"625e-3", "0.625", nil},

	// zeros
	{"0", "0", nil},
	{"0e0", "0", nil},
	{"-0e0", "-0", nil},
	{"0e-0", "0", nil},
	{"-0e-0", "-0", nil},
	{"0e+0", "0", nil},
	{"-0e+0", "-0", nil},
	{"0e+01234567890123456789", "0", nil},
	{"0.00e-01234567890123456789", "0", nil},
	{"-0e+01234567890123456789", "-0", nil},
	{"-0.00e-01234567890123456789", "-0", nil},

	{"0e291", "0", nil}, // issue 15364
	{"0e292", "0", nil}, // issue 15364
	{"0e347", "0", nil}, // issue 15364
	{"0e348", "0", nil}, // issue 15364
	{"-0e291", "-0", nil},
	{"-0e292", "-0", nil},
	{"-0e347", "-0", nil},
	{"-0e348", "-0", nil},

	// largest float64
	{"1.7976931348623157e308", "1.7976931348623157e+308", nil},
	{"-1.7976931348623157e308", "-1.7976931348623157e+308", nil},

	// the border is ...158079
	// borderline - okay
	{"1.7976931348623158e308", "1.7976931348623157e+308", nil},
	{"-1.7976931348623158e308", "-1.7976931348623157e+308", nil},

	// a little too large
	{"1e308", "1e+308", nil},

	// denormalized
	{"1e-305", "1e-305", nil},
	{"1e-306", "1e-306", nil},
	{"1e-307", "1e-307", nil},
	{"1e-308", "1e-308", nil},
	{"1e-309", "1e-309", nil},
	{"1e-310", "1e-310", nil},
	{"1e-322", "1e-322", nil},
	// smallest denormal
	{"5e-324", "5e-324", nil},
	{"4e-324", "5e-324", nil},
	{"3e-324", "5e-324", nil},
	// too small
	{"2e-324", "0", nil},
	// way too small
	{"1e-350", "0", nil},
	{"1e-400000", "0", nil},

	// try to overflow exponent
	{"1e-4294967296", "0", nil},
	{"1e-18446744073709551616", "0", nil},

	// https://www.exploringbinary.com/java-hangs-when-converting-2-2250738585072012e-308/
	{"2.2250738585072012e-308", "2.2250738585072014e-308", nil},
	// https://www.exploringbinary.com/php-hangs-on-numeric-value-2-2250738585072011e-308/
	{"2.2250738585072011e-308", "2.225073858507201e-308", nil},

	// A very large number (initially wrongly parsed by the fast algorithm).
	{"4.630813248087435e+307", "4.630813248087435e+307", nil},

	// A different kind of very large number.
	{"22.222222222222222", "22.22222222222222", nil},
	{"2." + strings.Repeat("2", 800) + "e+1", "22.22222222222222", nil},

	// Exactly halfway between 1 and math.Nextafter(1, 2).
	// Round to even (down).
	{"1.00000000000000011102230246251565404236316680908203125", "1", nil},
	// Slightly lower; still round down.
	{"1.00000000000000011102230246251565404236316680908203124", "1", nil},
	// Slightly higher; round up.
	{"1.00000000000000011102230246251565404236316680908203126", "1.0000000000000002", nil},
	// Slightly higher, but you have to read all the way to the end.
	{"1.00000000000000011102230246251565404236316680908203125" + strings.Repeat("0", 10000) + "1", "1.0000000000000002", nil},

	// Halfway between x := math.Nextafter(1, 2) and math.Nextafter(x, 2)
	// Round to even (up).
	{"1.00000000000000033306690738754696212708950042724609375", "1.0000000000000004", nil},

	// Halfway between 1090544144181609278303144771584 and 1090544144181609419040633126912
	// (15497564393479157p+46, should round to even 15497564393479156p+46, issue 36657)
	{"1090544144181609348671888949248", "1.0905441441816093e+30", nil},
	// slightly above, rounds up
	{"1090544144181609348835077142190", "1.0905441441816094e+30", nil},
}

func TestDecodeFloat(t *testing.T) {
	var sonicout, stdout interface{}
	for _, tt := range atoftests {
		// default float64
		sonicerr := decoder.NewDecoder(tt.in).Decode(&sonicout)
		stderr := json.NewDecoder(strings.NewReader(tt.in)).Decode(&stdout)
		if !reflect.DeepEqual(sonicout, stdout) {
			t.Fatalf("Test %#v\ngot:\n   %#v\nexp:\n   %#v\n", tt.in, sonicout, stdout)
		}
		if !reflect.DeepEqual(sonicerr == nil, stderr == nil) {
			t.Fatalf("Test %#v\ngot:\n   %#v\nexp:\n   %#v\n", tt.in, sonicerr, stderr)
		}
	}
}