// ------------------------------------------------------------------------
//   Project atila
//   Active Thing (activething.com) git.activething.com/go
//
//   File name  gogo.go
//   Created by DEV
//   Modified   23/01/2024
//
//   Copyright 2024 activething.com 
// ------------------------------------------------------------------------
// 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 js

import (
	"activething.com/go/gogo/packs"
	"encoding"
	"encoding/json"
	"math"
	"reflect"
	"strconv"
	"sync"
	"unicode/utf8"
)


const startDetectingCyclesAfter = 100

var (
	G = struct {
		hex       string
		jsonChars [utf8.RuneSelf]jsonCharAtt

		nullValue   []byte
		zeroValue   []byte
		trueValue   []byte
		falseValue  []byte

		floatNaN    []byte
		floatInfPos []byte
		floatInfNeg []byte


		packersCache sync.Map
		keyersCache  sync.Map

		jsonMarshalerType reflect.Type
		textMarshalerType reflect.Type
		packMarshalerType reflect.Type

	}{

		hex:       "0123456789abcdef",
		jsonChars: initJSONChars(),

		nullValue:   []byte{'n', 'u', 'l', 'l'},
		zeroValue:   []byte{'0'},
		trueValue:   []byte{'"','t', 'r', 'u', 'e','"'},
		falseValue:  []byte{'"','f', 'a', 'l', 's', 'e','"'},

		floatNaN:    []byte{'"', 'N', 'a', 'N', '"'},
		floatInfPos: []byte{'"', 'I', 'n', 'f', '"'},
		floatInfNeg: []byte{'"', '-', 'I', 'n', 'f', '"'},


		jsonMarshalerType: reflect.TypeOf((*json.Marshaler)(nil)).Elem(),
		textMarshalerType: reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem(),
		packMarshalerType: reflect.TypeOf((*packs.Packer)(nil)).Elem(),


	}
)

func initJSONChars() [utf8.RuneSelf]jsonCharAtt {
	var tb = [utf8.RuneSelf]jsonCharAtt{
		'"':  jsonCharAttAllUnsafe,
		'&':  jsonCharAttHtmlUnsafe,
		'<':  jsonCharAttHtmlUnsafe,
		'>':  jsonCharAttHtmlUnsafe,
		'\\': jsonCharAttAllUnsafe,
	}
	for i := 0; i <= 31; i++ {
		tb[i] = jsonCharAttAllUnsafe
	}
	return tb
}



func stringifyKey(buffer []byte, value any) []byte {
	if value == nil {
		return G.nullValue
	}

	if st,is := value.(string); is {
		return append(buffer[:0],st...)
	}

	if tm,is := value.(encoding.TextMarshaler); is {
		if bf,er := tm.MarshalText(); er == nil {
			return append(buffer[:0],bf...)
		}
		return nil
	}

	switch tp := value.(type) {
	case bool:
		if tp {
			return G.trueValue
		}
		return G.falseValue

	case int    : return strconv.AppendInt (buffer[:0],int64(tp), 10)
	case int8   : return strconv.AppendInt (buffer[:0],int64(tp), 10)
	case int16  : return strconv.AppendInt (buffer[:0],int64(tp), 10)
	case int32  : return strconv.AppendInt (buffer[:0],int64(tp), 10)
	case int64  : return strconv.AppendInt (buffer[:0],tp, 10)

	case uint   : return strconv.AppendUint(buffer[:0],uint64(tp), 10)
	case uint8  : return strconv.AppendUint(buffer[:0],uint64(tp), 10)
	case uint16 : return strconv.AppendUint(buffer[:0],uint64(tp), 10)
	case uint32 : return strconv.AppendUint(buffer[:0],uint64(tp), 10)
	case uint64 : return strconv.AppendUint(buffer[:0],tp, 10)

	case float32: return stringifyFloat(buffer[:0],float64(tp),32)
	case float64: return stringifyFloat(buffer[:0],tp,64)
	}
	return nil
}


func stringifyFloat (buffer []byte, f float64, bits int) []byte {
	if math.IsInf(f, 0) || math.IsNaN(f) {
		return nil
	}

	abs := math.Abs(f)
	fmt := byte('f')

	if abs != 0 {
		if bits == 64 && (abs < 1e-6 || abs >= 1e21) || bits == 32 && (float32(abs) < 1e-6 || float32(abs) >= 1e21) {
			fmt = 'e'
		}
	}
	buffer = strconv.AppendFloat(buffer[:0], f, fmt, -1, int(bits))
	if fmt == 'e' {
		// clean up e-09 to e-9
		n := len(buffer)
		if n >= 4 && buffer[n-4] == 'e' && buffer[n-3] == '-' && buffer[n-2] == '0' {
			buffer[n-2] = buffer[n-1]
			buffer = buffer[:n-1]
		}
	}
	return buffer
}