polytrack_codes/v2/
mod.rs

1#![allow(clippy::cast_possible_truncation)]
2#[cfg(test)]
3mod tests;
4
5use crate::tools::prelude::*;
6use base64::prelude::*;
7
8#[derive(Debug, PartialEq, Eq, Clone)]
9pub struct RawTrackInfo {
10    pub parts: Vec<RawPart>,
11}
12#[derive(Debug, PartialEq, Eq, Clone)]
13pub struct RawPart {
14    pub id: u8,
15    pub amount: u32,
16    pub blocks: Vec<RawBlock>,
17}
18#[derive(Debug, PartialEq, Eq, Clone)]
19pub struct RawBlock {
20    pub x: i32,
21    pub y: i32,
22    pub z: i32,
23    pub rotation: u8,
24}
25
26fn decode(input: &str) -> Option<Vec<u8>> {
27    let input = input.replace('-', "+").replace('_', "/");
28    let base64_decoded = BASE64_STANDARD_NO_PAD.decode(input).ok()?;
29    Some(base64_decoded)
30}
31
32fn encode(input: &[u8]) -> String {
33    let base64_encoded = BASE64_STANDARD_NO_PAD.encode(input);
34    base64_encoded.replace('+', "-").replace('/', "_")
35}
36
37#[must_use]
38pub fn decode_track_code(track_code: &str) -> Option<Track> {
39    let track_code = track_code.get(3..)?;
40    let metadata = decode(track_code.get(..2)?)?;
41    let name_len = *metadata.first()? as usize;
42    let name = track_code.get(2..2 + name_len)?.to_string();
43    let track_data = decode(track_code.get(2 + name_len..)?)?;
44    Some(Track {
45        name,
46        author: None,
47        last_modified: None,
48        track_data,
49    })
50}
51
52#[must_use]
53/// Encodes the given track struct into a track code.
54/// Returns [`None`] if something failed in the process.
55///
56/// Output might differ slightly from Polytrack's output
57/// because of Zlib shenanigans, but is still compatible.
58pub fn encode_track_code(track: &Track) -> Option<String> {
59    let track_data = encode(&track.track_data);
60
61    let metadata = encode(&[(track.name.len()) as u8]);
62
63    // prepend the "v1n"
64    let track_code = String::from("v1n") + &metadata + &track.name + &track_data;
65    Some(track_code)
66}
67
68#[must_use]
69pub fn decode_track_data(data: &[u8]) -> Option<RawTrackInfo> {
70    let mut offset = 0;
71    let mut parts = Vec::new();
72    while offset < data.len() {
73        let id = read_u16(data, &mut offset)? as u8;
74        let amount = read_u32(data, &mut offset)?;
75
76        let mut blocks = Vec::new();
77        for _ in 0..amount {
78            let x = read_i24(data, &mut offset)? - i32::pow(2, 23);
79            let y = read_i24(data, &mut offset)?;
80            let z = read_i24(data, &mut offset)? - i32::pow(2, 23);
81
82            let rotation = read_u8(data, &mut offset)? & 3;
83
84            blocks.push(RawBlock { x, y, z, rotation });
85        }
86        parts.push(RawPart { id, amount, blocks });
87    }
88
89    Some(RawTrackInfo { parts })
90}
91
92#[must_use]
93/// Encodes the `TrackInfo` struct into raw binary data.
94pub fn encode_track_data(track_info: &RawTrackInfo) -> Option<Vec<u8>> {
95    let mut data = Vec::new();
96    for part in &track_info.parts {
97        write_u16(&mut data, part.id.into());
98        write_u32(&mut data, part.amount);
99        for block in &part.blocks {
100            write_u24(&mut data, (block.x + i32::pow(2, 23)).cast_unsigned());
101            write_u24(&mut data, block.y.cast_unsigned());
102            write_u24(&mut data, (block.z + i32::pow(2, 23)).cast_unsigned());
103            data.push(block.rotation);
104        }
105    }
106
107    Some(data)
108}
polytrack_codes/v2/mod.rs

polytrack_codes/v2/
mod.rs
