/*
NAME
  amf.go

DESCRIPTION
  Action Message Format (AMF) encoding/decoding functions.
  See https://en.wikipedia.org/wiki/Action_Message_Format.

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

LICENSE
  amf.go is Copyright (C) 2017-2019 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

import (
	"encoding/binary"
	"math"
)

const (
	amfNumber = iota
	amfBoolean
	amfString
	amfObject
	amfMovieClip // reserved, not implemented
	amfNull
	amfUndefined
	amfReference
	amfEcmaArray
	amfObjectEnd
	amfStrictArray
	amfDate
	amfLongSring
	amfUnsupported
	amfRecordset // reserved, not implemented
	amfXmlDoc
	amfTypedObject
	amfAvmplus // reserved, not implemented
	amfInvalid = 0xff
)

type AMF struct {
	props []AMFProperty
}

type AMFProperty struct {
	name      string
	atype     AMFDataType
	vu        vu
	UTCoffset int16
}

type vu struct {
	number float64
	aval   string
	obj    AMF
}

type AMFDataType int32

var (
	amfObjInvalid  AMF
	amfPropInvalid = AMFProperty{atype: amfInvalid}
)

func amfDecodeInt16(data []byte) uint16 {
	return uint16(binary.BigEndian.Uint16(data))
}

func amfDecodeInt24(data []byte) uint32 {
	return uint32(data[0])<<16 | uint32(data[1])<<8 | uint32(data[2])
	//       return uint16(data[0])<<8 | uint16(data[1])
}

func amfDecodeInt32(data []byte) uint32 {
	return uint32(binary.BigEndian.Uint32(data))
}

func amfDecodeString(data []byte) string {
	n := amfDecodeInt16(data)
	return string(data[2 : 2+n])
}

func amfDecodeLongString(data []byte) string {
	n := amfDecodeInt32(data)
	return string(data[2 : 2+n])
}

func amfDecodeNumber(data []byte) float64 {
	return math.Float64frombits(binary.BigEndian.Uint64(data))
}

func amfDecodeBoolean(data []byte) bool {
	return data[0] != 0
}

func amfEncodeInt24(dst []byte, val int32) []byte {
	if len(dst) < 3 {
		return nil
	}
	dst[0] = byte(val >> 16)
	dst[1] = byte(val >> 8)
	dst[2] = byte(val)
	if len(dst) == 3 {
		return nil
	}
	return dst[3:]
}

func amfEncodeInt32(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:]
}

func amfEncodeString(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] = amfString
		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] = amfLongSring
	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):]
}

func amfEncodeNumber(dst []byte, val float64) []byte {
	if len(dst) < 9 {
		return nil
	}
	dst[0] = amfNumber
	dst = dst[1:]
	binary.BigEndian.PutUint64(dst, math.Float64bits(val))
	return dst[8:]
}

func amfEncodeBoolean(dst []byte, val bool) []byte {
	if len(dst) < 2 {
		return nil
	}
	dst[0] = amfBoolean
	if val {
		dst[1] = 1
	}
	if len(dst) == 2 {
		return nil
	}
	return dst[2:]

}

func amfEncodeNamedString(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 amfEncodeString(dst[len(key):], val)
}

func amfEncodeNamedNumber(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 amfEncodeNumber(dst[len(key):], val)
}

func amfEncodeNamedBoolean(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 amfEncodeBoolean(dst[len(key):], val)
}

func amfPropSetName(prop *AMFProperty, name string) {
	prop.name = name
}

func amfPropGetNumber(prop *AMFProperty) float64 {
	return prop.vu.number
}

func amfPropGetString(prop *AMFProperty) string {
	if prop.atype == amfString {
		return prop.vu.aval
	}
	return ""
}

func amfPropGetObject(prop *AMFProperty, a *AMF) {
	if prop.atype == amfObject {
		*a = prop.vu.obj
	} else {
		*a = amfObjInvalid
	}
}

func amfPropEncode(p *AMFProperty, dst []byte) []byte {
	if p.atype == amfInvalid {
		return nil
	}

	if p.atype != amfNull && len(p.name)+2+1 >= len(dst) {
		return nil
	}

	if p.atype != amfNull && len(p.name) != 0 {
		binary.BigEndian.PutUint16(dst[:2], uint16(len(p.name)))
		dst = dst[2:]
		copy(dst, p.name)
		dst = dst[len(p.name):]
	}

	switch p.atype {
	case amfNumber:
		dst = amfEncodeNumber(dst, p.vu.number)
	case amfBoolean:
		dst = amfEncodeBoolean(dst, p.vu.number != 0)
	case amfString:
		dst = amfEncodeString(dst, p.vu.aval)
	case amfNull:
		if len(dst) < 2 {
			return nil
		}
		dst[0] = amfNull
		dst = dst[1:]
	case amfObject:
		dst = amfEncode(&p.vu.obj, dst)
	case amfEcmaArray:
		dst = amfEncodeEcmaArray(&p.vu.obj, dst)
	case amfStrictArray:
		dst = amfEncodeArray(&p.vu.obj, dst)
	default:
		// ??? log.Println("amfPropEncode: invalid type!")
		dst = nil
	}
	return dst
}

func amfProDecode(prop *AMFProperty, data []byte, bDecodeName int32) int32 {
	prop.name = ""

	nOriginalSize := len(data)
	if len(data) == 0 {
		// TODO use new logger here
		// RTMLog(RTMLOGDEBUG, "%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
		// RTMLog(RTMLOGDEBUG, "%s: Not enough data for decoding with name, less than 4 bytes!",__FUNCTION__);
		return -1
	}

	if bDecodeName != 0 {
		nNameSize := amfDecodeInt16(data[:2])
		if int(nNameSize) > len(data)-2 {
			// TODO use new logger here
			//RTMLog(RTMLOGDEBUG, "%s: Name size out of range: namesize (%d) > len (%d) - 2",__FUNCTION__, nNameSize, nSize);
			return -1
		}

		prop.name = amfDecodeString(data)
		data = data[2+nNameSize:]
	}

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

	prop.atype = AMFDataType(data[0])
	data = data[1:]

	var nRes int32
	switch prop.atype {
	case amfNumber:
		if len(data) < 8 {
			return -1
		}
		prop.vu.number = amfDecodeNumber(data[:8])
		data = data[8:]

	case amfBoolean:
		panic("amfBoolean not supported")

	case amfString:
		nStringSize := amfDecodeInt16(data[:2])
		if len(data) < int(nStringSize+2) {
			return -1
		}
		prop.vu.aval = amfDecodeString(data)
		data = data[2+nStringSize:]

	case amfObject:
		nRes := amfDecode(&prop.vu.obj, data, 1)
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]

	case amfMovieClip:
		// TODO use new logger here
		// ??? log.Println("AMFProDecode: MAF_MOVIECLIP reserved!")
		//RTMLog(RTMLOGERROR, "amfMovieClip reserved!");
		return -1

	case amfNull, amfUndefined, amfUnsupported:
		prop.atype = amfNull

	case amfReference:
		// TODO use new logger here
		// ??? log.Println("AMFProDecode: amfReference not supported!")
		//RTMLog(RTMLOGERROR, "amfReference not supported!");
		return -1

	case amfEcmaArray:
		// next comes the rest, mixed array has a final 0x000009 mark and names, so its an object
		data = data[4:]
		nRes = amfDecode(&prop.vu.obj, data, 1)
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]

	case amfObjectEnd:
		return -1

	case amfStrictArray:
		panic("amfStrictArray not supported")

	case amfDate:
		panic("amfDate not supported")

	case amfLongSring, amfXmlDoc:
		panic("amfLongSring, amfXmlDoc not supported")

	case amfRecordset:
		// TODO use new logger here
		// ??? log.Println("AMFProDecode: amfRecordset reserved!")
		//RTMLog(RTMLOGERROR, "amfRecordset reserved!");
		return -1

	case amfTypedObject:
		// TODO use new logger here
		// RTMLog(RTMLOGERROR, "amfTyped_object not supported!")
		return -1

	case amfAvmplus:
		panic("amfAvmplus not supported")

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

	return int32(nOriginalSize - len(data))
}

func amfPropReset(prop *AMFProperty) {
	if prop.atype == amfObject || prop.atype == amfEcmaArray ||
		prop.atype == amfStrictArray {
		amfReset(&prop.vu.obj)
	} else {
		prop.vu.aval = ""
	}
	prop.atype = amfInvalid
}

func amfEncode(a *AMF, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = amfObject
	dst = dst[1:]

	for i := 0; i < len(a.props); i++ {
		dst = amfPropEncode(&a.props[i], dst)
		if dst == nil {
			// ??? log.Println("amfEncode: failed to encode property in index")
			break
		}
	}

	if len(dst) < 4 {
		return nil
	}
	return amfEncodeInt24(dst, amfObjectEnd)
}

func amfEncodeEcmaArray(a *AMF, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = amfEcmaArray
	dst = dst[1:]
	binary.BigEndian.PutUint32(dst[:4], uint32(len(a.props)))
	dst = dst[4:]

	for i := 0; i < len(a.props); i++ {
		dst = amfPropEncode(&a.props[i], dst)
		if dst == nil {
			// ??? log.Println("amfEncodeEcmaArray: failed to encode property!")
			break
		}
	}

	if len(dst) < 4 {
		return nil
	}
	return amfEncodeInt24(dst, amfObjectEnd)
}

// not used?
func amfEncodeArray(a *AMF, dst []byte) []byte {
	if len(dst) < 5 {
		return nil
	}

	dst[0] = amfStrictArray
	dst = dst[1:]
	binary.BigEndian.PutUint32(dst[:4], uint32(len(a.props)))
	dst = dst[4:]

	for i := 0; i < len(a.props); i++ {
		dst = amfPropEncode(&a.props[i], dst)
		if dst == nil {
			// ??? log.Println("amfEncodeArray: failed to encode property!")
			break
		}
	}

	return dst
}

func amfDecode(a *AMF, data []byte, bDecodeName int32) int32 {
	nOriginalSize := len(data)

	a.props = a.props[:0]
	for len(data) != 0 {
		if len(data) >= 3 && amfDecodeInt24(data[:3]) == amfObjectEnd {
			data = data[3:]
			break
		}

		var prop AMFProperty
		nRes := amfProDecode(&prop, data, bDecodeName)
		// nRes = int32(C.AMFProDecode(&prop, (*byte)(unsafe.Pointer(pBuffer)),
		// int32(nSize), int32(bDecodeName)))
		if nRes == -1 {
			return -1
		}
		data = data[nRes:]
		a.props = append(a.props, prop)
	}

	return int32(nOriginalSize - len(data))
}

func amfGetProp(a *AMF, name string, idx int32) *AMFProperty {
	if idx >= 0 {
		if idx < int32(len(a.props)) {
			return &a.props[idx]
		}
	} else {
		for i, p := range a.props {
			if p.name == name {
				return &a.props[i]
			}
		}
	}
	return &amfPropInvalid
}

func amfReset(a *AMF) {
	for i := range a.props {
		amfPropReset(&a.props[i])
	}
	*a = AMF{}
}