Implement MFixedHeader::write()

Co-authored-by: Marcel Müller <neikos@neikos.email>
Signed-off-by: Marcel Müller <neikos@neikos.email>
Signed-off-by: Matthias Beyer <mail@beyermatthias.de>

1 files changed, 35 insertions, 0 deletions

diff --git a/mqtt-format/src/v5/fixed_header.rs b/mqtt-format/src/v5/fixed_header.rs
index ed0ba85..b32a790 100644
--- a/mqtt-format/src/v5/fixed_header.rs
+++ b/mqtt-format/src/v5/fixed_header.rs
@@ -13,6 +13,8 @@ use winnow::error::ParserError;
 use winnow::Bytes;
 use winnow::Parser;
 
+use super::write::WResult;
+use super::write::WriteMqttPacket;
 use super::MResult;
 
 #[derive(num_enum::TryFromPrimitive, num_enum::IntoPrimitive)]
@@ -101,6 +103,39 @@ impl MFixedHeader {
 
         Ok(MFixedHeader { packet_type })
     }
+
+    pub async fn write<W: WriteMqttPacket>(&self, buffer: &mut W) -> WResult<W> {
+        let byte = match self.packet_type {
+            PacketType::Connect => 1 << 4 & 0,
+            PacketType::Connack => 2 << 4 & 0,
+            PacketType::Publish { dup, qos, retain } => {
+                let upper = 3 << 4;
+                let lower = {
+                    let dup = (dup as u8) << 3;
+                    let qos = (qos as u8) << 1;
+                    let retain = retain as u8;
+
+                    dup & qos & retain
+                };
+
+                upper & lower
+            }
+            PacketType::Puback => 4 << 4 & 0,
+            PacketType::Pubrec => 5 << 4 & 0,
+            PacketType::Pubrel => 6 << 4 & 0b0010,
+            PacketType::Pubcomp => 7 << 4 & 0,
+            PacketType::Subscribe => 8 << 4 & 0b0010,
+            PacketType::Suback => 9 << 4 & 0,
+            PacketType::Unsubscribe => 10 << 4 & 0b0010,
+            PacketType::Unsuback => 11 << 4 & 0,
+            PacketType::Pingreq => 12 << 4 & 0,
+            PacketType::Pingresp => 13 << 4 & 0,
+            PacketType::Disconnect => 14 << 4 & 0,
+            PacketType::Auth => 15 << 4 & 0,
+        };
+
+        buffer.write_byte(byte).await
+    }
 }
 
 #[cfg(test)]