From 74d95d476908ec0d19fee5aa9cbffa4910250ef3 Mon Sep 17 00:00:00 2001
From: Muaz Ahmad <m.ahmed_2000@hotmail.com>
Date: Fri, 11 Aug 2023 15:22:25 +0500
Subject: [PATCH] Basic root and number AMF decoding

---
 rtmp/amf/decode.go | 60 ++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 7 deletions(-)

diff --git a/rtmp/amf/decode.go b/rtmp/amf/decode.go
index 68b62b4..b297a34 100644
--- a/rtmp/amf/decode.go
+++ b/rtmp/amf/decode.go
@@ -1,13 +1,59 @@
 package amf
 
+import (
+	"errors"
+	"encoding/binary"
+	"math"
+)
+
 type AMFObj map[interface{}]interface{}
 
 func DecodeAMF(data *[]byte) (AMFObj, error) {
-	obj := make(AMFObj)
-	test := make(AMFObj)
-	obj[0] = "connect"
-	obj[1] = float64(1)
-	obj[2] = test
-	test["tcUrl"] = "rtmp://test-domain.nil/Desktop/tmp"
-	return obj, nil
+	var byte_idx uint32
+	var root_obj_idx uint8
+	amf_root_obj := make(AMFObj)
+
+	for {
+		top_level_obj, err := read_next(data, &byte_idx)
+		if err != nil {
+			return amf_root_obj, err
+		}
+		amf_root_obj[root_obj_idx] = top_level_obj
+		root_obj_idx += 1
+	}
+	return amf_root_obj, nil
 }
+
+func read_bytes(data *[]byte, byte_idx *uint32, n uint32) ([]byte, error) {
+	if int(*byte_idx + n) > len(*data) {
+		return make([]byte, 0), errors.New("Read goes past end")
+	}
+	*byte_idx += n
+	return (*data)[*byte_idx:*byte_idx + n], nil
+}
+
+func read_number(data *[]byte, byte_idx *uint32) (float64, error) {
+	float_bytes, err := read_bytes(data, byte_idx, 8)
+	if err != nil {
+		return 0.0, err
+	}
+	return math.Float64frombits(binary.BigEndian.Uint64(float_bytes)), nil
+}
+
+func read_next(data *[]byte, byte_idx *uint32) (interface{}, error) {
+	data_type, err := read_bytes(data, byte_idx, 1)
+	if err != nil {
+		return nil, err
+	}
+	switch data_type[0] {
+	case 0:
+		next_obj, err := read_number(data, byte_idx)
+		if err != nil {
+			return nil, err
+		}
+		return next_obj, nil
+	}
+	return nil, errors.New("tmp")
+}
+
+