// Copyright 2025 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT

//go:build goexperiment.jsonv2

package json

import (
	"bytes"
	jsonv1 "encoding/json"    //nolint:depguard // this package wraps it
	jsonv2 "encoding/json/v2" //nolint:depguard // this package wraps it
	"io"
)

// JSONv2 implements Interface via encoding/json/v2
// Requires GOEXPERIMENT=jsonv2 to be set at build time
type JSONv2 struct {
	marshalOptions                  jsonv2.Options
	marshalKeepOptionalEmptyOptions jsonv2.Options
	unmarshalOptions                jsonv2.Options
	unmarshalCaseInsensitiveOptions jsonv2.Options
}

var jsonV2 JSONv2

func init() {
	commonMarshalOptions := []jsonv2.Options{
		jsonv2.FormatNilSliceAsNull(true),
		jsonv2.FormatNilMapAsNull(true),
	}
	jsonV2.marshalOptions = jsonv2.JoinOptions(commonMarshalOptions...)
	jsonV2.unmarshalOptions = jsonv2.DefaultOptionsV2()

	// By default, "json/v2" omitempty removes all `""` empty strings, no matter where it comes from.
	// v1 has a different behavior: if the `""` is from a null pointer, or a Marshal function, it is kept.
	// Golang issue: https://github.com/golang/go/issues/75623 encoding/json/v2: unable to make omitempty work with pointer or Optional type with goexperiment.jsonv2
	jsonV2.marshalKeepOptionalEmptyOptions = jsonv2.JoinOptions(append(commonMarshalOptions, jsonv1.OmitEmptyWithLegacySemantics(true))...)

	// Some legacy code uses case-insensitive matching (for example: parsing oci.ImageConfig)
	jsonV2.unmarshalCaseInsensitiveOptions = jsonv2.JoinOptions(jsonv2.MatchCaseInsensitiveNames(true))
}

func getDefaultJSONHandler() Interface {
	return &jsonV2
}

func MarshalKeepOptionalEmpty(v any) ([]byte, error) {
	return jsonv2.Marshal(v, jsonV2.marshalKeepOptionalEmptyOptions)
}

func (j *JSONv2) Marshal(v any) ([]byte, error) {
	return jsonv2.Marshal(v, j.marshalOptions)
}

func (j *JSONv2) Unmarshal(data []byte, v any) error {
	return jsonv2.Unmarshal(data, v, j.unmarshalOptions)
}

func (j *JSONv2) NewEncoder(writer io.Writer) Encoder {
	return &jsonV2Encoder{writer: writer, opts: j.marshalOptions}
}

func (j *JSONv2) NewDecoder(reader io.Reader) Decoder {
	return &jsonV2Decoder{reader: reader, opts: j.unmarshalOptions}
}

// Indent implements Interface using standard library (JSON v2 doesn't have Indent yet)
func (*JSONv2) Indent(dst *bytes.Buffer, src []byte, prefix, indent string) error {
	return jsonv1.Indent(dst, src, prefix, indent)
}

type jsonV2Encoder struct {
	writer io.Writer
	opts   jsonv2.Options
}

func (e *jsonV2Encoder) Encode(v any) error {
	return jsonv2.MarshalWrite(e.writer, v, e.opts)
}

type jsonV2Decoder struct {
	reader io.Reader
	opts   jsonv2.Options
}

func (d *jsonV2Decoder) Decode(v any) error {
	return jsonv2.UnmarshalRead(d.reader, v, d.opts)
}

func NewDecoderCaseInsensitive(reader io.Reader) Decoder {
	return &jsonV2Decoder{reader: reader, opts: jsonV2.unmarshalCaseInsensitiveOptions}
}