package ffjson

/**
 *  Copyright 2015 Paul Querna, Klaus Post
 *
 *  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.
 *
 */

import (
	"encoding/json"
	"errors"
	fflib "github.com/pquerna/ffjson/fflib/v1"
	"reflect"
)

type marshalerFaster interface {
	MarshalJSONBuf(buf fflib.EncodingBuffer) error
}

type unmarshalFaster interface {
	UnmarshalJSONFFLexer(l *fflib.FFLexer, state fflib.FFParseState) error
}

// Marshal will act the same way as json.Marshal, except
// it will choose the ffjson marshal function before falling
// back to using json.Marshal.
// Using this function will bypass the internal copying and parsing
// the json library normally does, which greatly speeds up encoding time.
// It is ok to call this function even if no ffjson code has been
// generated for the data type you pass in the interface.
func Marshal(v interface{}) ([]byte, error) {
	f, ok := v.(marshalerFaster)
	if ok {
		buf := fflib.Buffer{}
		err := f.MarshalJSONBuf(&buf)
		b := buf.Bytes()
		if err != nil {
			if len(b) > 0 {
				Pool(b)
			}
			return nil, err
		}
		return b, nil
	}

	j, ok := v.(json.Marshaler)
	if ok {
		return j.MarshalJSON()
	}
	return json.Marshal(v)
}

// MarshalFast will marshal the data if fast marshal is available.
// This function can be used if you want to be sure the fast
// marshal is used or in testing.
// If you would like to have fallback to encoding/json you can use the
// Marshal() method.
func MarshalFast(v interface{}) ([]byte, error) {
	_, ok := v.(marshalerFaster)
	if !ok {
		return nil, errors.New("ffjson marshal not available for type " + reflect.TypeOf(v).String())
	}
	return Marshal(v)
}

// Unmarshal will act the same way as json.Unmarshal, except
// it will choose the ffjson unmarshal function before falling
// back to using json.Unmarshal.
// The overhead of unmarshal is lower than on Marshal,
// however this should still provide a speedup for your encoding.
// It is ok to call this function even if no ffjson code has been
// generated for the data type you pass in the interface.
func Unmarshal(data []byte, v interface{}) error {
	f, ok := v.(unmarshalFaster)
	if ok {
		fs := fflib.NewFFLexer(data)
		return f.UnmarshalJSONFFLexer(fs, fflib.FFParse_map_start)
	}

	j, ok := v.(json.Unmarshaler)
	if ok {
		return j.UnmarshalJSON(data)
	}
	return json.Unmarshal(data, v)
}

// UnmarshalFast will unmarshal the data if fast marshall is available.
// This function can be used if you want to be sure the fast
// unmarshal is used or in testing.
// If you would like to have fallback to encoding/json you can use the
// Unmarshal() method.
func UnmarshalFast(data []byte, v interface{}) error {
	_, ok := v.(unmarshalFaster)
	if !ok {
		return errors.New("ffjson unmarshal not available for type " + reflect.TypeOf(v).String())
	}
	return Unmarshal(data, v)
}