/*
NAME
  amf.go

DESCRIPTION
  See Readme.md

AUTHORS
  Saxon Nelson-Milton <saxon@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Jake Lane <jake@ausocean.org>

LICENSE
  amf.go is Copyright (C) 2017 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.

  Derived from librtmp under the GNU Lesser General Public License 2.1
  Copyright (C) 2005-2008 Team XBMC http://www.xbmc.org
  Copyright (C) 2008-2009 Andrej Stepanchuk
  Copyright (C) 2009-2010 Howard Chu
*/
package rtmp

/*
#include <stdlib.h>
*/
import "C"

import (
	"encoding/binary"
	"log"
	"math"
	"unsafe"
)

var (
	AMFObj_Invalid  C_AMFObject
	AMFProp_Invalid = C_AMFObjectProperty{p_type: AMF_INVALID}
)

const (
	AMF3_INTEGER_MAX = 268435455
	AMF3_INTEGER_MIN = -268435456
)

func pp2b(b, e *byte) []byte {
	if b == nil {
		return nil
	}
	base := unsafe.Pointer(b)
	len := uintptr(unsafe.Pointer(e)) - uintptr(base)
	return (*[_Gi]byte)(base)[:len]
}

func pl2b(b *byte, l int) []byte {
	if b == nil {
		return nil
	}
	base := unsafe.Pointer(b)
	return (*[_Gi]byte)(base)[:l]
}

func b2pp(buf []byte) (b, e *byte) {
	if buf == nil {
		return nil, nil
	}
	if len(buf) == 0 {
		b = *(**byte)(unsafe.Pointer(&buf))
		return b, b
	}
	b = &buf[0]
	e = (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(b)) + uintptr(len(buf))))
	return b, e
}

func bAddr(buf []byte) *byte {
	if len(buf) == 0 {
		return nil
	}
	return &buf[0]
}

// unsigned short AMF_DecodeInt16(const char* data);
// amf.c +41
func C_AMF_DecodeInt16(data []byte) uint16 {
	return uint16(data[0])<<8 | uint16(data[1])
}

// unsigned int AMF_DecodeInt24(const char* data);
// amf.c +50
func C_AMF_DecodeInt24(data []byte) uint32 {
	return uint32(data[0])<<16 | uint32(data[1])<<8 | uint32(data[2])
}

// unsigned int AMF_DeocdeInt32(const char* data);
// amf.c +59
func C_AMF_DecodeInt32(data []byte) uint32 {
	return uint32(data[0])<<24 | uint32(data[1])<<16 | uint32(data[2])<<8 | uint32(data[3])
}

// void AMF_DecodeString(const char* data, C_AVal* bv);
// amf.c +68
func C_AMF_DecodeString(data []byte) string {
	n := C_AMF_DecodeInt16(data)
	return string(data[2 : 2+n])
}

// void AMF_DecodeLongString(const char *data, AVal *bv);
// amf.c +75
func C_AMF_DecodeLongString(data []byte) string {
	n := C_AMF_DecodeInt32(data)
	return string(data[2 : 2+n])
}

// double AMF_DecodeNumber(const char* data);
// amf.c +82
func C_AMF_DecodeNumber(data []byte) float64 {
	return math.Float64frombits(binary.BigEndian.Uint64(data))
}

// int AMF_DecodeBoolean(const char *data);
// amf.c +132
func C_AMF_DecodeBoolean(data []byte) bool {
	return data[0] != 0
}

// char* AMF_EncodeInt24(char* output, char* outend, int nVal);
// amf.c +149
func C_AMF_EncodeInt24(dst []byte, val int32) []byte {
	if len(dst) < 3 {
		return nil
	}
	_ = dst[2]
	dst[0] = byte(val >> 16)
	dst[1] = byte(val >> 8)
	dst[2] = byte(val)
	if len(dst) == 3 {
		return nil
	}
	return dst[3:]
}

// char* AMF_EncodeInt32(char* output, char* outend, int nVal);
// amf.c +160
func C_AMF_EncodeInt32(dst []byte, val int32) []byte {
	if len(dst) < 4 {
		return nil
	}
	binary.BigEndian.PutUint32(dst, uint32(val))
	if len(dst) == 4 {
		return nil
	}
	return dst[4:]
}

// char* AMF_EncodeString(char* output, char* outend, const C_AVal* bv);
// amf.c +173
func C_AMF_EncodeString(dst []byte, val string) []byte {
	const typeSize = 1
	if len(val) < 65536 && len(val)+typeSize+binary.Size(int16(0)) > len(dst) {
		return nil
	}
	if len(val)+typeSize+binary.Size(int32(0)) > len(dst) {
		return nil
	}

	if len(val) < 65536 {
		dst[0] = AMF_STRING
		dst = dst[1:]
		binary.BigEndian.PutUint16(dst[:2], uint16(len(val)))
		dst = dst[2:]
		copy(dst, val)
		if len(dst) == len(val) {
			return nil
		}
		return dst[len(val):]
	}
	dst[0] = AMF_LONG_STRING
	dst = dst[1:]
	binary.BigEndian.PutUint32(dst[:4], uint32(len(val)))
	dst = dst[4:]
	copy(dst, val)
	if len(dst) == len(val) {
		return nil
	}
	return dst[len(val):]
}

// char* AMF_EncodeNumber(char* output, char* outend, double dVal);
// amf.c +199
func C_AMF_EncodeNumber(dst []byte, val float64) []byte {
	if len(dst) < 9 {
		return nil
	}
	dst[0] = AMF_NUMBER
	dst = dst[1:]
	binary.BigEndian.PutUint64(dst, math.Float64bits(val))
	return dst[8:]
}

// char* AMF_EncodeBoolean(char* output, char* outend, int bVal);
// amf.c +260
func C_AMF_EncodeBoolean(dst []byte, val bool) []byte {
	if len(dst) < 2 {
		return nil
	}
	dst[0] = AMF_BOOLEAN
	if val {
		dst[1] = 1
	}
	if len(dst) == 2 {
		return nil
	}
	return dst[2:]

}

// char* AMF_EncodeNamedString(char* output, char* outend, const C_AVal* strName, const C_AVal* strValue);
// amf.c +273
func C_AMF_EncodeNamedString(dst []byte, key, val string) []byte {
	if 2+len(key) > len(dst) {
		return nil
	}
	binary.BigEndian.PutUint16(dst[:2], uint16(len(key)))
	dst = dst[2:]
	copy(dst, key)
	if len(key) == len(dst) {
		return nil
	}
	return C_AMF_EncodeString(dst[len(key):], val)
}

// char* AMF_EncodeNamedNumber(char* output, char* outend, const C_AVal* strName, double dVal);
// amf.c +286
func C_AMF_EncodeNamedNumber(dst []byte, key string, val float64) []byte {
	if 2+len(key) > len(dst) {
		return nil
	}
	binary.BigEndian.PutUint16(dst[:2], uint16(len(key)))
	dst = dst[2:]
	copy(dst, key)
	if len(key) == len(dst) {
		return nil
	}
	return C_AMF_EncodeNumber(dst[len(key):], val)
}

// char* AMF_EncodeNamedBoolean(char* output, char* outend, const C_AVal* strname, int bVal);
// amf.c +299
func C_AMF_EncodeNamedBoolean(dst []byte, key string, val bool) []byte {
	if 2+len(key) > len(dst) {
		return nil
	}
	binary.BigEndian.PutUint16(dst[:2], uint16(len(key)))
	dst = dst[2:]
	copy(dst, key)
	if len(key) == len(dst) {
		return nil
	}
	return C_AMF_EncodeBoolean(dst[len(key):], val)
}

// void AMFProp_SetName(AMFObjectProperty *prop, AVal *name);
// amf.c +318
func C_AMFProp_SetName(prop *C_AMFObjectProperty, name string) {
	prop.p_name = name
}

// double AMFProp_GetNumber(AMFObjectProperty* prop);
// amf.c +330
func C_AMFProp_GetNumber(prop *C_AMFObjectProperty) float64 {
	return prop.p_vu.p_number
}

// void AMFProp_GetString(AMFObjectProperty* prop, AVal* str);
// amf.c +341
func C_AMFProp_GetString(prop *C_AMFObjectProperty) string {
	if prop.p_type == AMF_STRING {
		return prop.p_vu.p_aval
	}
	return ""
}

// void AMFProp_GetObject(AMFObjectProperty *prop, AMFObject *obj);
// amf.c +351
func C_AMFProp_GetObject(prop *C_AMFObjectProperty, obj *C_AMFObject) {
	if prop.p_type == AMF_OBJECT {
		*obj = prop.p_vu.p_object
	} else {
		*obj = AMFObj_Invalid
	}
}

// char* AMFPropEncode(AMFOBjectProperty* prop, char* pBufer, char* pBufEnd);
// amf.c +366
func C_AMF_PropEncode(p *C_AMFObjectProperty, dst []byte) []byte {
	if p.p_type == AMF_INVALID {
		return nil
	}

	if p.p_type != AMF_NULL && len(p.p_name)+2+1 >= len(dst) {
		return nil
	}

	if p.p_type != AMF_NULL && len(p.p_name) != 0 {
		binary.BigEndian.PutUint16(dst[:2], uint16(len(p.p_name)))
		dst = dst[2:]
		copy(dst, p.p_name)
		dst = dst[len(p.p_name):]
	}

	switch p.p_type {
	case AMF_NUMBER:
		dst = C_AMF_EncodeNumber(dst, p.p_vu.p_number)
	case AMF_BOOLEAN:
		dst = C_AMF_EncodeBoolean(dst, p.p_vu.p_number != 0)
	case AMF_STRING:
		dst = C_AMF_EncodeString(dst, p.p_vu.p_aval)
	case AMF_NULL:
		if len(dst) < 2 {
			return nil
		}
		dst[0] = AMF_NULL
		dst = dst[1:]
	case AMF_OBJECT:
		dst = C_AMF_Encode(&p.p_vu.p_object, dst)
	case AMF_ECMA_ARRAY:
		dst = C_AMF_EncodeEcmaArray(&p.p_vu.p_object, dst)
	case AMF_STRICT_ARRAY:
		dst = C_AMF_EncodeArray(&p.p_vu.p_object, dst)
	default:
		log.Println("C_AMF_PropEncode: invalid type!")
		dst = nil
	}
	return dst
}

// int AMFProp_Decode(C_AMFObjectProperty* prop, const char* pBuffer, int nSize, int bDecodeName);
// amf.c +619
func C_AMFProp_Decode(prop *C_AMFObjectProperty, data []byte, bDecodeName int32) int32 {
	prop.p_name = ""

	nOriginalSize := len(data)
	if len(data) == 0 {
		// TODO use new logger here
		// RTMP_Log(RTMP_LOGDEBUG, "%s: Empty buffer/no buffer pointer!", __FUNCTION__);
		return -1
	}

	if bDecodeName != 0 && len(data) < 4 {
		// at least name (length + at least 1 byte) and 1 byte of data
		// TODO use new logger here
		// RTMP_Log(RTMP_LOGDEBUG, "%s: Not enough data for decoding with name, less than 4 bytes!",__FUNCTION__);
		return -1
	}

	if bDecodeName != 0 {
		nNameSize := C_AMF_DecodeInt16(data[:2])
		if int(nNameSize) > len(data)-2 {
			// TODO use new logger here
			//RTMP_Log(RTMP_LOGDEBUG, "%s: Name size out of range: namesize (%d) > len (%d) - 2",__FUNCTION__, nNameSize, nSize);
			return -1
		}

		prop.p_name = C_AMF_DecodeString(data)
		data = data[2+nNameSize:]
	}

	if len(data) == 0 {
		return -1
	}

	prop.p_type = C_AMFDataType(data[0])
	data = data[1:]

	var nRes int32
	switch prop.p_type {
	case AMF_NUMBER:
		if len(data) < 8 {
			return -1
		}
		prop.p_vu.p_number = C_AMF_DecodeNumber(data[:8])
		data = data[8:]

	case AMF_BOOLEAN:
		panic("AMF_BOOLEAN not supported")

	case AMF_STRING:
		nStringSize := C_AMF_DecodeInt16(data[:2])
		if len(data) < int(nStringSize+2) {
			return -1
		}
		prop.p_vu.p_aval = C_AMF_DecodeString(data)
		data = data[2+nStringSize:]

	case AMF_OBJECT:
		nRes := C_AMF_Decode(&prop.p_vu.p_object, bAddr(data), int32(len(data)), 1)
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]

	case AMF_MOVIECLIP:
		// TODO use new logger here
		log.Println("AMFProp_Decode: MAF_MOVIECLIP reserved!")
		//RTMP_Log(RTMP_LOGERROR, "AMF_MOVIECLIP reserved!");
		return -1

	case AMF_NULL, AMF_UNDEFINED, AMF_UNSUPPORTED:
		prop.p_type = AMF_NULL

	case AMF_REFERENCE:
		// TODO use new logger here
		log.Println("AMFProp_Decode: AMF_REFERENCE not supported!")
		//RTMP_Log(RTMP_LOGERROR, "AMF_REFERENCE not supported!");
		return -1

	case AMF_ECMA_ARRAY:
		// next comes the rest, mixed array has a final 0x000009 mark and names, so its an object
		data = data[4:]
		nRes = C_AMF_Decode(&prop.p_vu.p_object, bAddr(data), int32(len(data)), 1)
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]

	case AMF_OBJECT_END:
		return -1

	case AMF_STRICT_ARRAY:
		panic("AMF_STRICT_ARRAY not supported")

	case AMF_DATE:
		panic("AMF_DATE not supported")

	case AMF_LONG_STRING, AMF_XML_DOC:
		panic("AMF_LONG_STRING, AMF_XML_DOC not supported")

	case AMF_RECORDSET:
		// TODO use new logger here
		log.Println("AMFProp_Decode: AMF_RECORDSET reserved!")
		//RTMP_Log(RTMP_LOGERROR, "AMF_RECORDSET reserved!");
		return -1

	case AMF_TYPED_OBJECT:
		// TODO use new logger here
		// RTMP_Log(RTMP_LOGERROR, "AMF_TYPED_OBJECT not supported!")
		return -1

	case AMF_AVMPLUS:
		panic("AMF_AVMPLUS not supported")

	default:
		// TODO use new logger here
		//RTMP_Log(RTMP_LOGDEBUG, "%s - unknown datatype 0x%02x, @%p", __FUNCTION__,
		//prop.p_type, pBuffer - 1);
		return -1
	}

	return int32(nOriginalSize - len(data))
}

// void AMFProp_Reset(AMFObjectProperty* prop);
// amf.c +875
func C_AMFProp_Reset(prop *C_AMFObjectProperty) {
	if prop.p_type == AMF_OBJECT || prop.p_type == AMF_ECMA_ARRAY ||
		prop.p_type == AMF_STRICT_ARRAY {
		C_AMF_Reset(&prop.p_vu.p_object)
	} else {
		prop.p_vu.p_aval = ""
	}
	prop.p_type = AMF_INVALID
}

// char* AMF_Encode(AMFObject* obj, char* pBuffer, char* pBufEnd);
// amf.c +891
func C_AMF_Encode(obj *C_AMFObject, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = AMF_OBJECT
	dst = dst[1:]

	for i := 0; i < len(obj.o_props); i++ {
		dst = C_AMF_PropEncode(&obj.o_props[i], dst)
		if dst == nil {
			log.Println("C_AMF_Encode: failed to encode property in index")
			break
		}
	}

	if len(dst) < 4 {
		return nil
	}
	return C_AMF_EncodeInt24(dst, AMF_OBJECT_END)
}

// char* AMF_EncodeEcmaArray(AMFObject* obj, char* pBuffer, char* pBufEnd);
// amf.c +924
func C_AMF_EncodeEcmaArray(obj *C_AMFObject, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = AMF_ECMA_ARRAY
	dst = dst[1:]
	binary.BigEndian.PutUint32(dst[:4], uint32(len(obj.o_props)))
	dst = dst[4:]

	for i := 0; i < len(obj.o_props); i++ {
		dst = C_AMF_PropEncode(&obj.o_props[i], dst)
		if dst == nil {
			log.Println("C_AMF_EncodeEcmaArray: failed to encode property!")
			break
		}
	}

	if len(dst) < 4 {
		return nil
	}
	return C_AMF_EncodeInt24(dst, AMF_OBJECT_END)
}

// char* AMF_EncodeArray(AMFObject* obj, char* pBuffer, char* pBufEnd);
// amf.c +959
func C_AMF_EncodeArray(obj *C_AMFObject, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = AMF_STRICT_ARRAY
	dst = dst[1:]
	binary.BigEndian.PutUint32(dst[:4], uint32(len(obj.o_props)))
	dst = dst[4:]

	for i := 0; i < len(obj.o_props); i++ {
		dst = C_AMF_PropEncode(&obj.o_props[i], dst)
		if dst == nil {
			log.Println("C_AMF_EncodeArray: failed to encode property!")
			break
		}
	}

	return dst
}

// int AMF_DecodeArray(AMFObject *obj, const char *pBuffer, int nSize, int nArrayLen, int bDecodeName);
// amf.c +993
func C_AMF_DecodeArray(obj *C_AMFObject, data []byte, nArrayLen, bDecodeName int32) int32 {
	nOriginalSize := len(data)

	obj.o_props = obj.o_props[:0]
	for ; nArrayLen > 0 && len(data) != 0; nArrayLen-- {

		var prop C_AMFObjectProperty
		nRes := C_AMFProp_Decode(&prop, data, bDecodeName)
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]
		obj.o_props = append(obj.o_props, prop)
	}

	return int32(nOriginalSize - len(data))
}

// int AMF_Decode(AMFObject *obj, const char* pBuffer, int nSize, int bDecodeName);
// amf.c +1180
func C_AMF_Decode(obj *C_AMFObject, pBuffer *byte, nSize, bDecodeName int32) int32 {
	nOriginalSize := nSize
	var bError int32

	obj.o_props = obj.o_props[:0]
	for nSize > 0 {
		var prop C_AMFObjectProperty
		var nRes int32

		if nSize >= 3 && C_AMF_DecodeInt24((*[_Gi]byte)(unsafe.Pointer(pBuffer))[:3]) == AMF_OBJECT_END {
			nSize -= 3
			bError = 0
			break
		}

		if bError != 0 {
			// TODO use new logger here
			log.Println("AMF_Decode: decoding error, ignoring bytes until next known pattern!")
			nSize--
			pBuffer = (*byte)(incBytePtr(unsafe.Pointer(pBuffer), 1))
			continue
		}
		// TODO port AMFProp_Decode
		nRes = C_AMFProp_Decode(&prop, pl2b(pBuffer, int(nSize)), bDecodeName)
		// nRes = int32(C.AMFProp_Decode(&prop, (*byte)(unsafe.Pointer(pBuffer)),
		// int32(nSize), int32(bDecodeName)))
		if nRes == -1 {
			bError = 1
			break
		} else {
			nSize -= nRes
			if nSize < 0 {
				bError = 1
				break
			}
			pBuffer = (*byte)(incBytePtr(unsafe.Pointer(pBuffer), int(nRes)))
			obj.o_props = append(obj.o_props, prop)
		}
	}

	if bError != 0 {
		return -1
	}

	return nOriginalSize - nSize
}

// AMFObjectProperty* AMF_GetProp(AMFObject *obj, const AVal* name, int nIndex);
// amf.c + 1249
func C_AMF_GetProp(obj *C_AMFObject, name string, idx int32) *C_AMFObjectProperty {
	if idx >= 0 {
		if idx < int32(len(obj.o_props)) {
			return &obj.o_props[idx]
		}
	} else {
		for i, p := range obj.o_props {
			if p.p_name == name {
				return &obj.o_props[i]
			}
		}
	}
	return &AMFProp_Invalid
}

// void AMF_Reset(AMFObject* obj);
// amf.c +1282
func C_AMF_Reset(obj *C_AMFObject) {
	for i := range obj.o_props {
		C_AMFProp_Reset(&obj.o_props[i])
	}
	obj.o_props = obj.o_props[:0]
}

/*
// void AMF3CD_AddProp(AMF3ClassDef *cd, AVal *prop);
// amf.c +1298
func AMF3CD_AddProp(cd *C.AMF3ClassDef, prop *C_AVal) {
	if cd.cd_num&0x0f == 0 {
		cd.cd_props = (*C_AVal)(realloc(unsafe.Pointer(cd.cd_props), int(uintptr(cd.cd_num+16)*unsafe.Sizeof(C_AVal{}))))
	}
	*(*C_AVal)(incPtr(unsafe.Pointer(cd.cd_props), int(cd.cd_num), int(unsafe.Sizeof(C_AVal{})))) = *prop
	cd.cd_num++
}
*/