package rtmp

import (
	"net"
	"time"
	"encoding/binary"
)

// see adobe specs for RTMP
func DoHandshake(conn net.Conn) (hs_success bool) {
	C0C1C2 := make([]byte, 1536*2 + 1)
	S0S1S2 := make([]byte, 1536*2 + 1)
	
	S0S1S2[0] = 3
	binary.BigEndian.PutUint32(S0S1S2[1:1+4], uint32(time.Now().UnixMilli()))
	
	// force handshake to finish in under 15 seconds (aribtrary) or throw an error
	conn.SetDeadline(time.Now().Add(15 * time.Second))

	if _, err := conn.Read(C0C1C2); err != nil || C0C1C2[0] != 3 {
		return
	}
	copy(C0C1C2[1:1536], S0S1S2[1+1536:])
	binary.BigEndian.PutUint32(S0S1S2[1+1536+4:1+1536+8], uint32(time.Now().UnixMilli()))

	if _, err := conn.Write(S0S1S2); err != nil { // specs say only send S0S1 and wait for C2 before sending S2, obs doesn't care apparently
		return
	}
	if _, err := conn.Read(C0C1C2[1+1536:]); err != nil {
		return
	}
	hs_success = true
	conn.SetDeadline(time.Time{}) // remove deadline for next function
	return
}