/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 hessian

import (
	"reflect"
	"time"
	"unsafe"
)

import (
	perrors "github.com/pkg/errors"
)

// nil bool int8 int32 int64 float32 float64 time.Time
// string []byte []interface{} map[interface{}]interface{}
// array object struct

// Encoder struct
type Encoder struct {
	classInfoList []*ClassInfo
	buffer        []byte
	refMap        map[unsafe.Pointer]_refElem
}

// classIndex find the index of the given java name in encoder class info list.
func (e *Encoder) classIndex(javaName string) int {
	for i := range e.classInfoList {
		if javaName == e.classInfoList[i].javaName {
			return i
		}
	}
	return -1
}

// NewEncoder generate an encoder instance
func NewEncoder() *Encoder {
	buffer := make([]byte, 64)

	return &Encoder{
		buffer: buffer[:0],
		refMap: make(map[unsafe.Pointer]_refElem, 7),
	}
}

// Clean clean the Encoder (room) for a new object encoding.
func (e *Encoder) Clean() {
	buffer := make([]byte, 64)
	e.classInfoList = nil
	e.buffer = buffer[:0]
	e.refMap = make(map[unsafe.Pointer]_refElem, 7)
}

// ReuseBufferClean reuse the Encoder for a new object encoding.
// it reuse allocated buffer and reduce memory-allocation.
func (e *Encoder) ReuseBufferClean() {
	var buffer []byte
	if cap(e.buffer) <= 512 {
		// reuse buffer, avoid allocate
		buffer = e.buffer[:0]
	} else {
		// avoiding memory leak caused by growth of underlying array
		buffer = make([]byte, 64)
	}
	e.classInfoList = nil
	e.buffer = buffer[:0]
	e.refMap = make(map[unsafe.Pointer]_refElem, 7)
}

// Buffer returns byte buffer
func (e *Encoder) Buffer() []byte {
	return e.buffer[:]
}

// Append byte arr to encoder buffer
func (e *Encoder) Append(buf []byte) {
	e.buffer = append(e.buffer, buf[:]...)
}

// Encode If @v can not be encoded, the return value is nil. At present only struct may can not be encoded.
func (e *Encoder) Encode(v interface{}) error {
	if v == nil {
		e.buffer = EncNull(e.buffer)
		return nil
	}

	switch val := v.(type) {
	case nil:
		e.buffer = EncNull(e.buffer)
		return nil

	case bool:
		e.buffer = encBool(e.buffer, val)

	case uint8:
		e.buffer = encInt32(e.buffer, int32(val))
	case int8:
		e.buffer = encInt32(e.buffer, int32(val))
	case int16:
		e.buffer = encInt32(e.buffer, int32(val))
	case uint16:
		e.buffer = encInt32(e.buffer, int32(val))
	case int32:
		e.buffer = encInt32(e.buffer, int32(val))
	case uint32:
		e.buffer = encInt64(e.buffer, int64(val))

	case int:
		// if v.(int) >= -2147483648 && v.(int) <= 2147483647 {
		// 	b = encInt32(int32(v.(int)), b)
		// } else {
		// 	b = encInt64(int64(v.(int)), b)
		// }
		// use int64 type to handle int, to avoid  panic like :  reflect: Call using int32 as type int64 [recovered]
		// when decode
		e.buffer = encInt64(e.buffer, int64(val))
	case uint:
		e.buffer = encInt64(e.buffer, int64(val))

	case int64:
		e.buffer = encInt64(e.buffer, val)
	case uint64:
		e.buffer = encInt64(e.buffer, int64(val))

	case time.Time:
		if ZeroDate == val {
			e.buffer = EncNull(e.buffer)
		} else {
			e.buffer = encDateInMs(e.buffer, &val)
			// e.buffer = encDateInMimute(v.(time.Time), e.buffer)
		}

	case float32:
		e.buffer = encFloat32(e.buffer, val)

	case float64:
		e.buffer = encFloat(e.buffer, val)

	case string:
		e.buffer = encString(e.buffer, val)

	case []byte:
		e.buffer = encBinary(e.buffer, val)

	case map[interface{}]interface{}:
		return e.encUntypedMap(val)

	case POJOEnum:
		if p, ok := v.(POJOEnum); ok {
			return e.encObject(p)
		}

	default:
		t := UnpackPtrType(reflect.TypeOf(v))
		switch t.Kind() {
		case reflect.Struct:
			vv := reflect.ValueOf(v)
			if vv.Kind() != reflect.Ptr {
				v = PackPtrInterface(v, vv)
			} else {
				vv = UnpackPtr(vv)
			}
			if !vv.IsValid() {
				e.buffer = EncNull(e.buffer)
				return nil
			}
			if vv.Type().String() == "time.Time" {
				e.buffer = encDateInMs(e.buffer, v)
				return nil
			}
			if p, ok := v.(POJO); ok {
				var clazz string
				clazz = p.JavaClassName()
				if c, ok := GetSerializer(clazz); ok {
					return c.EncObject(e, p)
				}
				return e.encObject(p)
			}
			return e.encObject(vv.Interface())
		case reflect.Slice, reflect.Array:
			return e.encList(v)
		case reflect.Map: // the type must be map[string]int
			return e.encMap(v)
		case reflect.Bool:
			vv := v.(*bool)
			if vv != nil {
				e.buffer = encBool(e.buffer, *vv)
			} else {
				e.buffer = EncNull(e.buffer)
			}
		case reflect.Int32:
			if t == _typeOfRune {
				e.buffer = encString(e.buffer, string(*v.(*Rune)))
				return nil
			}

			var err error
			e.buffer, err = e.encTypeInt32(e.buffer, v)
			if err != nil {
				return err
			}
		case reflect.String,
			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int64,
			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
			reflect.Float32, reflect.Float64: // resolve base type
			vVal := reflect.ValueOf(v)
			if reflect.Ptr == vVal.Kind() {
				if vVal.IsNil() {
					e.buffer = EncNull(e.buffer)
					return nil
				}

				return e.Encode(vVal.Elem().Interface())
			}
		default:
			return perrors.Errorf("type not supported! %s", t.Kind().String())
		}
	}

	return nil
}