polytrack_codes/v3/
mod.rs

1#![allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
2#[cfg(test)]
3mod tests;
4
5use crate::tools::{self, hash_vec, prelude::*};
6
7pub const CP_IDS: [u8; 4] = [52, 65, 75, 77];
8
9#[derive(Debug, PartialEq, Eq, Clone)]
10pub struct TrackInfo {
11    pub parts: Vec<Part>,
12}
13
14#[derive(Debug, PartialEq, Eq, Clone)]
15pub struct Part {
16    pub id: u8,
17    pub amount: u32,
18    pub blocks: Vec<Block>,
19}
20
21#[derive(Debug, PartialEq, Eq, Clone)]
22pub struct Block {
23    pub x: i32,
24    pub y: i32,
25    pub z: i32,
26
27    pub rotation: u8,
28    pub cp_order: Option<u16>,
29}
30
31#[must_use]
32pub fn decode_track_code(track_code: &str) -> Option<Track> {
33    let track_code = track_code.get(2..)?;
34    let metadata = tools::decode(track_code.get(..2)?)?;
35    let name_len_step1 = *metadata.first()? as usize;
36    let name_len = (name_len_step1 * 4).div_ceil(3);
37    let track_name_raw = tools::decode(track_code.get(2..2 + name_len)?)?;
38    let name = String::from_utf8(track_name_raw).ok()?;
39    let track_data = tools::decompress(&tools::decode(track_code.get(2 + name_len..)?)?)?;
40    Some(Track {
41        name,
42        author: None,
43        last_modified: None,
44        track_data,
45    })
46}
47
48#[must_use]
49/// Encodes the given track struct into a track code.
50/// Returns [`None`] if something failed in the process.
51///
52/// Output might differ slightly from Polytrack's output
53/// because of Zlib shenanigans, but is still compatible.
54pub fn encode_track_code(track: &Track) -> Option<String> {
55    let track_data = tools::encode(&tools::compress_final(&track.track_data)?)?;
56
57    let name_raw = track.name.as_bytes().to_vec();
58    let name = tools::encode(&name_raw)?;
59    let metadata = tools::encode(&[(name.len() * 3 / 4) as u8])?;
60
61    // prepend the "v2"
62    let track_code = String::from("v2") + &metadata + &name + &track_data;
63    Some(track_code)
64}
65
66#[must_use]
67pub fn decode_track_data(data: &[u8]) -> Option<TrackInfo> {
68    let mut offset = 0;
69    let mut parts = Vec::new();
70    while offset < data.len() {
71        let id = read_u16(data, &mut offset)? as u8;
72        let amount = read_u32(data, &mut offset)?;
73
74        let mut blocks = Vec::new();
75        for _ in 0..amount {
76            let x = read_i24(data, &mut offset)? - i32::pow(2, 23);
77            let y = read_i24(data, &mut offset)?;
78            let z = read_i24(data, &mut offset)? - i32::pow(2, 23);
79
80            let rotation = read_u8(data, &mut offset)? & 3;
81
82            let cp_order = if CP_IDS.contains(&id) {
83                Some(read_u16(data, &mut offset)?)
84            } else {
85                None
86            };
87            blocks.push(Block {
88                x,
89                y,
90                z,
91                rotation,
92                cp_order,
93            });
94        }
95        parts.push(Part { id, amount, blocks });
96    }
97
98    Some(TrackInfo { parts })
99}
100
101#[must_use]
102/// Encodes the `TrackInfo` struct into raw binary data.
103pub fn encode_track_data(track_info: &TrackInfo) -> Option<Vec<u8>> {
104    let mut data = Vec::new();
105    for part in &track_info.parts {
106        write_u16(&mut data, part.id.into());
107        write_u32(&mut data, part.amount);
108        for block in &part.blocks {
109            write_u24(&mut data, (block.x + i32::pow(2, 23)).cast_unsigned());
110            write_u24(&mut data, block.y.cast_unsigned());
111            write_u24(&mut data, (block.z + i32::pow(2, 23)).cast_unsigned());
112            data.push(block.rotation);
113            if let Some(cp_order) = block.cp_order {
114                write_u16(&mut data, cp_order.into());
115            }
116        }
117    }
118
119    Some(data)
120}
121
122#[must_use]
123pub fn export_to_id(track_code: &str) -> Option<String> {
124    let track_data = decode_track_code(track_code)?;
125    let data = track_data.track_data;
126    let id = hash_vec(data);
127    Some(id)
128}
polytrack_codes/v3/mod.rs

polytrack_codes/v3/
mod.rs
