1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

//! Contains biomes and the biome registry. Minecraft's default biomes are added
//! to the registry by default.
//!
//! ### **NOTE:**
//! - Modifying the biome registry after the server has started can break
//!   invariants within instances and clients! Make sure there are no instances
//!   or clients spawned before mutating.
//! - A biome named "minecraft:plains" must exist. Otherwise, vanilla clients
//!   will be disconnected.

use std::ops::{Deref, DerefMut};

use bevy_app::prelude::*;
use bevy_ecs::prelude::*;
use serde::{Deserialize, Serialize};
use tracing::error;
use valence_ident::{ident, Ident};
use valence_nbt::serde::CompoundSerializer;

use crate::codec::{RegistryCodec, RegistryValue};
use crate::{Registry, RegistryIdx, RegistrySet};

pub struct BiomePlugin;

impl Plugin for BiomePlugin {
    fn build(&self, app: &mut App) {
        app.init_resource::<BiomeRegistry>()
            .add_systems(PreStartup, load_default_biomes)
            .add_systems(PostUpdate, update_biome_registry.before(RegistrySet));
    }
}

fn load_default_biomes(mut reg: ResMut<BiomeRegistry>, codec: Res<RegistryCodec>) {
    let mut helper = move || -> anyhow::Result<()> {
        for value in codec.registry(BiomeRegistry::KEY) {
            let biome = Biome::deserialize(value.element.clone())?;

            reg.insert(value.name.clone(), biome);
        }

        // Move "plains" to the front so that `BiomeId::default()` is the ID of plains.
        reg.swap_to_front(ident!("plains"));

        Ok(())
    };

    if let Err(e) = helper() {
        error!("failed to load default biomes from registry codec: {e:#}");
    }
}

fn update_biome_registry(reg: Res<BiomeRegistry>, mut codec: ResMut<RegistryCodec>) {
    if reg.is_changed() {
        let biomes = codec.registry_mut(BiomeRegistry::KEY);

        biomes.clear();

        biomes.extend(reg.iter().map(|(_, name, biome)| {
            RegistryValue {
                name: name.into(),
                element: biome
                    .serialize(CompoundSerializer)
                    .expect("failed to serialize biome"),
            }
        }));
    }
}

#[derive(Resource, Default, Debug)]
pub struct BiomeRegistry {
    reg: Registry<BiomeId, Biome>,
}

impl BiomeRegistry {
    pub const KEY: Ident<&'static str> = ident!("worldgen/biome");
}

impl Deref for BiomeRegistry {
    type Target = Registry<BiomeId, Biome>;

    fn deref(&self) -> &Self::Target {
        &self.reg
    }
}

impl DerefMut for BiomeRegistry {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.reg
    }
}

#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Default, Debug)]
pub struct BiomeId(u32);

impl BiomeId {
    pub const DEFAULT: Self = BiomeId(0);
}

impl RegistryIdx for BiomeId {
    const MAX: usize = u32::MAX as usize;

    #[inline]
    fn to_index(self) -> usize {
        self.0 as usize
    }

    #[inline]
    fn from_index(idx: usize) -> Self {
        Self(idx as u32)
    }
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct Biome {
    pub downfall: f32,
    pub effects: BiomeEffects,
    pub has_precipitation: bool,
    pub temperature: f32,
    // TODO: more stuff.
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct BiomeEffects {
    pub fog_color: u32,
    pub sky_color: u32,
    pub water_color: u32,
    pub water_fog_color: u32,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub grass_color: Option<u32>,
    // TODO: more stuff.
}

impl Default for Biome {
    fn default() -> Self {
        Self {
            downfall: 0.4,
            effects: BiomeEffects::default(),
            has_precipitation: true,
            temperature: 0.8,
        }
    }
}

impl Default for BiomeEffects {
    fn default() -> Self {
        Self {
            fog_color: 12638463,
            sky_color: 7907327,
            water_color: 4159204,
            water_fog_color: 329011,
            grass_color: None,
        }
    }
}