// Copyright (C) 2022  Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later

package json

import (
	"bufio"
	"bytes"
	"encoding/json"
	"errors"
	"io"
	"strconv"

	"git.lukeshu.com/go/lowmemjson"
)

type (
	Number     = json.Number
	Marshaler  = json.Marshaler
	RawMessage = json.RawMessage

	// low-level decode errors
	//SyntaxError         = lowmemjson.DecodeSyntaxError // expose a field
	UnmarshalFieldError = json.UnmarshalFieldError
	UnmarshalTypeError  = json.UnmarshalTypeError // lowmemjson.DecodeTypeError

	// high-level decode errors
	InvalidUnmarshalError = json.InvalidUnmarshalError // lowmemjson.DecodeArgumentError

	// marshal errors
	InvalidUTF8Error      = json.InvalidUTF8Error
	MarshalerError        = lowmemjson.EncodeMethodError // expose a field
	UnsupportedTypeError  = json.UnsupportedTypeError
	UnsupportedValueError = json.UnsupportedValueError
)

/////////////////////////////////////////////////////////////////////

func MarshalIndent(v any, prefix, indent string) ([]byte, error) {
	var buf bytes.Buffer
	formatter := &lowmemjson.ReEncoder{
		Out:    &buf,
		Indent: indent,
		Prefix: prefix,
	}
	err := lowmemjson.Encode(formatter, v)
	return buf.Bytes(), err
}

func Marshal(v any) ([]byte, error) {
	var buf bytes.Buffer
	formatter := &lowmemjson.ReEncoder{
		Out:     &buf,
		Compact: true,
	}
	err := lowmemjson.Encode(formatter, v)
	return buf.Bytes(), err
}

func HTMLEscape(dst *bytes.Buffer, src []byte) {
	formatter := &lowmemjson.ReEncoder{
		Out: dst,
	}
	_, _ = formatter.Write(src)
}

func Compact(dst *bytes.Buffer, src []byte) error {
	formatter := &lowmemjson.ReEncoder{
		Out:             dst,
		Compact:         true,
		BackslashEscape: lowmemjson.EscapePreserve,
	}
	_, err := formatter.Write(src)
	return err
}

func Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
	formatter := &lowmemjson.ReEncoder{
		Out:             dst,
		Indent:          indent,
		Prefix:          prefix,
		BackslashEscape: lowmemjson.EscapePreserve,
	}
	_, err := formatter.Write(src)
	if se, ok := err.(*lowmemjson.ReEncodeSyntaxError); ok {
		err = &SyntaxError{
			msg:    se.Err.Error(),
			Offset: se.Offset + 1,
		}
	}
	return err
}

func Valid(data []byte) bool {
	formatter := &lowmemjson.ReEncoder{
		Out:     io.Discard,
		Compact: true,
	}
	_, err := formatter.Write(data)
	return err == nil
}

func Unmarshal(data []byte, ptr any) error {
	return NewDecoder(bytes.NewReader(data)).Decode(ptr)
}

/////////////////////////////////////////////////////////////////////

type Decoder struct {
	*lowmemjson.Decoder
	buf *bufio.Reader
}

func NewDecoder(r io.Reader) *Decoder {
	br, ok := r.(*bufio.Reader)
	if !ok {
		br = bufio.NewReader(r)
	}
	return &Decoder{
		Decoder: lowmemjson.NewDecoder(br),
		buf:     br,
	}
}

func (dec *Decoder) Decode(ptr any) error {
	err := dec.Decoder.Decode(ptr)
	if derr, ok := err.(*lowmemjson.DecodeError); ok {
		switch terr := derr.Err.(type) {
		case *lowmemjson.DecodeSyntaxError:
			err = &SyntaxError{
				msg:    terr.Err.Error(),
				Offset: terr.Offset,
			}
		case *lowmemjson.DecodeTypeError:
			if typeErr, ok := terr.Err.(*json.UnmarshalTypeError); ok {
				err = &UnmarshalTypeError{
					Value:  typeErr.Value,
					Type:   typeErr.Type,
					Offset: typeErr.Offset,
					Struct: derr.FieldParent,
					Field:  derr.FieldName,
				}
			} else if _, isArgErr := terr.Err.(*lowmemjson.DecodeArgumentError); terr.Err != nil &&
				!isArgErr &&
				!errors.Is(terr.Err, strconv.ErrSyntax) &&
				!errors.Is(terr.Err, strconv.ErrRange) {
				err = terr.Err
			} else {
				err = &UnmarshalTypeError{
					Value:  terr.JSONType,
					Type:   terr.GoType,
					Offset: terr.Offset,
					Struct: derr.FieldParent,
					Field:  derr.FieldName,
				}
			}
		}
	}
	return err
}

func (dec *Decoder) Buffered() io.Reader {
	dat, _ := dec.buf.Peek(dec.buf.Buffered())
	return bytes.NewReader(dat)
}

//func (dec *Decoder) Token() (Token, error)