flatland_protocol/
codec.rs

1use serde::{de::DeserializeOwned, Serialize};
2
3use crate::Envelope;
4
5#[derive(Debug, thiserror::Error)]
6pub enum CodecError {
7    #[error("postcard encode failed: {0}")]
8    PostcardEncode(postcard::Error),
9    #[error("postcard decode failed: {0}")]
10    PostcardDecode(postcard::Error),
11    #[error("bincode encode failed: {0}")]
12    BincodeEncode(bincode::Error),
13    #[error("bincode decode failed: {0}")]
14    BincodeDecode(bincode::Error),
15}
16
17pub trait Codec {
18    fn encode<T: Serialize>(&self, value: &T) -> Result<Vec<u8>, CodecError>;
19    fn decode<T: DeserializeOwned>(&self, bytes: &[u8]) -> Result<T, CodecError>;
20}
21
22/// Default on-wire codec for game traffic (compact, serde-native).
23#[derive(Debug, Clone, Copy, Default)]
24pub struct PostcardCodec;
25
26impl Codec for PostcardCodec {
27    fn encode<T: Serialize>(&self, value: &T) -> Result<Vec<u8>, CodecError> {
28        postcard::to_allocvec(value).map_err(CodecError::PostcardEncode)
29    }
30
31    fn decode<T: DeserializeOwned>(&self, bytes: &[u8]) -> Result<T, CodecError> {
32        postcard::from_bytes(bytes).map_err(CodecError::PostcardDecode)
33    }
34}
35
36/// Alternative codec used in benchmarks and for comparison.
37#[derive(Debug, Clone, Copy, Default)]
38pub struct BincodeCodec;
39
40impl Codec for BincodeCodec {
41    fn encode<T: Serialize>(&self, value: &T) -> Result<Vec<u8>, CodecError> {
42        bincode::serialize(value).map_err(CodecError::BincodeEncode)
43    }
44
45    fn decode<T: DeserializeOwned>(&self, bytes: &[u8]) -> Result<T, CodecError> {
46        bincode::deserialize(bytes).map_err(CodecError::BincodeDecode)
47    }
48}
49
50pub fn encode_envelope<T: Serialize>(codec: &impl Codec, payload: T) -> Result<Vec<u8>, CodecError> {
51    codec.encode(&Envelope::new(payload))
52}
53
54pub fn decode_envelope<T: DeserializeOwned>(
55    codec: &impl Codec,
56    bytes: &[u8],
57) -> Result<Envelope<T>, CodecError> {
58    codec.decode(bytes)
59}
60
61#[cfg(test)]
62mod tests {
63    use super::*;
64    use crate::types::{
65        BlueprintIngredientView, BlueprintView, EntityState, TickDelta, ToolRequirementView,
66        Transform, WorldClock, WorldCoord,
67    };
68
69    fn sample_tick_delta() -> TickDelta {
70        TickDelta {
71            tick: 42,
72            entities: (0..15)
73                .map(|i| EntityState {
74                    id: i + 1,
75                    label: String::new(),
76                    transform: Transform {
77                        position: WorldCoord::surface(i as f32, i as f32 * 0.5),
78                        yaw: 1.25,
79                        velocity: crate::types::Velocity2D { vx: 0.5, vy: -0.2 },
80                    },
81                    vitals: None,
82                    attributes: None,
83                skills: None,
84                    inside_building: None,
85                })
86                .collect(),
87            resource_nodes: Vec::new(),
88            buildings: Vec::new(),
89            doors: Vec::new(),
90            npcs: Vec::new(),
91            inventory: Vec::new(),
92            blueprints: Vec::new(),
93            world_clock: WorldClock::default(),
94            ground_drops: Vec::new(),
95            placed_containers: Vec::new(),
96            combat: None,
97        }
98    }
99
100    #[test]
101    fn postcard_blueprint_snapshot_roundtrip() {
102        let codec = PostcardCodec;
103        let delta = TickDelta {
104            tick: 1,
105            entities: vec![],
106            resource_nodes: vec![],
107            buildings: vec![],
108            doors: vec![],
109            npcs: vec![],
110            inventory: vec![],
111            blueprints: vec![BlueprintView {
112                id: "oak_to_lumber".into(),
113                label: "Saw Planks".into(),
114                output: "lumber".into(),
115                output_qty: 1,
116                craft_ticks: 60,
117                station: Some("woodworking".into()),
118                category: Some("woodworking".into()),
119                required_tools: vec![ToolRequirementView {
120                    item: "handsaw".into(),
121                    consumed: false,
122                }],
123                skill: None,
124                failure_chance: 0.0,
125                inputs: vec![BlueprintIngredientView {
126                    template_id: "oak_log".into(),
127                    quantity: 2,
128                    consumed: true,
129                }],
130            }],
131            world_clock: WorldClock::default(),
132            ground_drops: vec![],
133            placed_containers: vec![],
134            combat: None,
135        };
136        let bytes = codec.encode(&Envelope::new(delta.clone())).unwrap();
137        let decoded: Envelope<TickDelta> = codec.decode(&bytes).unwrap();
138        assert_eq!(decoded.payload, delta);
139    }
140
141    #[test]
142    fn postcard_roundtrip_tick_delta() {
143        let codec = PostcardCodec;
144        let original = Envelope::new(sample_tick_delta());
145        let bytes = codec.encode(&original).expect("encode");
146        let decoded: Envelope<TickDelta> = codec.decode(&bytes).expect("decode");
147        assert_eq!(original, decoded);
148    }
149
150    #[test]
151    fn bincode_roundtrip_tick_delta() {
152        let codec = BincodeCodec;
153        let original = Envelope::new(sample_tick_delta());
154        let bytes = codec.encode(&original).expect("encode");
155        let decoded: Envelope<TickDelta> = codec.decode(&bytes).expect("decode");
156        assert_eq!(original, decoded);
157    }
158
159    #[test]
160    fn postcard_many_entities_vitals_none() {
161        let delta = TickDelta {
162            tick: 42,
163            entities: (0..15)
164                .map(|i| EntityState {
165                    id: i + 1,
166                    label: String::new(),
167                    transform: Transform {
168                        position: WorldCoord::surface(i as f32, i as f32 * 0.5),
169                        yaw: 1.25,
170                        velocity: crate::types::Velocity2D { vx: 0.5, vy: -0.2 },
171                    },
172                    vitals: None,
173                    attributes: None,
174                skills: None,
175                    inside_building: None,
176                })
177                .collect(),
178            resource_nodes: vec![],
179            buildings: vec![],
180            doors: vec![],
181            npcs: vec![],
182            inventory: vec![],
183            blueprints: vec![],
184            world_clock: WorldClock::default(),
185            ground_drops: vec![],
186            placed_containers: vec![],
187            combat: None,
188        };
189        let codec = PostcardCodec;
190        let bytes = codec.encode(&Envelope::new(delta.clone())).unwrap();
191        let decoded: Envelope<TickDelta> = codec.decode(&bytes).unwrap();
192        assert_eq!(decoded.payload, delta);
193    }
194}
flatland_protocol/codec.rs

flatland_protocol/
codec.rs
