workshop_rs/
gameplay_data.rs

1//! Embedded, provenance-pinned hero gameplay data.
2//!
3//! The data file is a checked-in projection of the user-provided
4//! `workshop-data` export. This module owns parsing, schema validation, and
5//! dataset-digest verification; query and calculation APIs remain separate.
6
7use sha2::{Digest, Sha256};
8use std::sync::OnceLock;
9
10use crate::gameplay::{GameplayCatalog, GameplayDataError, GameplayDatasetIdentity, Hero};
11
12/// The canonical gameplay dataset embedded in the crate.
13pub const GAMEPLAY_DATA: &str = include_str!("data/gameplay.json");
14
15const SCHEMA_VERSION: u32 = 1;
16
17#[derive(serde::Deserialize)]
18#[serde(rename_all = "camelCase")]
19struct GameplayFile {
20    schema_version: u32,
21    identity: GameplayDatasetIdentity,
22    heroes: Vec<Hero>,
23}
24
25/// Load and validate a gameplay dataset from its JSON representation.
26pub fn load(json: &str) -> Result<GameplayCatalog, GameplayDataError> {
27    let file: GameplayFile = serde_json::from_str(json)
28        .map_err(|error| GameplayDataError::Malformed(error.to_string()))?;
29    if file.schema_version != SCHEMA_VERSION {
30        return Err(GameplayDataError::UnsupportedSchema(file.schema_version));
31    }
32
33    let computed = content_digest(json)?;
34    if file.identity.digest != computed {
35        return Err(GameplayDataError::DigestMismatch {
36            declared: file.identity.digest,
37            computed,
38        });
39    }
40
41    GameplayCatalog::new(file.identity, file.heroes)
42}
43
44/// Load the checked-in gameplay dataset.
45pub fn builtin() -> Result<GameplayCatalog, GameplayDataError> {
46    builtin_ref().cloned().map_err(Clone::clone)
47}
48
49/// Borrow the cached checked-in gameplay dataset without cloning it.
50pub(crate) fn builtin_ref() -> Result<&'static GameplayCatalog, &'static GameplayDataError> {
51    static DATA: OnceLock<Result<GameplayCatalog, GameplayDataError>> = OnceLock::new();
52    match DATA.get_or_init(|| load(GAMEPLAY_DATA)) {
53        Ok(catalog) => Ok(catalog),
54        Err(error) => Err(error),
55    }
56}
57
58/// Compute the deterministic SHA-256 identity of a gameplay dataset.
59///
60/// The self-referential `identity.digest` field is excluded before the JSON
61/// value is serialized with sorted object keys. Whitespace and source key
62/// ordering therefore do not change the dataset identity.
63pub fn content_digest(json: &str) -> Result<String, GameplayDataError> {
64    let mut value: serde_json::Value = serde_json::from_str(json)
65        .map_err(|error| GameplayDataError::Malformed(error.to_string()))?;
66    let identity = value
67        .as_object_mut()
68        .and_then(|root| root.get_mut("identity"))
69        .and_then(serde_json::Value::as_object_mut)
70        .ok_or_else(|| GameplayDataError::Malformed("missing identity object".to_string()))?;
71    identity
72        .remove("digest")
73        .ok_or_else(|| GameplayDataError::Malformed("missing identity.digest".to_string()))?;
74
75    let mut canonical = String::new();
76    write_canonical_json(&value, &mut canonical).map_err(GameplayDataError::Malformed)?;
77    Ok(format!("sha256:{:x}", Sha256::digest(canonical.as_bytes())))
78}
79
80fn write_canonical_json(value: &serde_json::Value, output: &mut String) -> Result<(), String> {
81    match value {
82        serde_json::Value::Null => output.push_str("null"),
83        serde_json::Value::Bool(value) => output.push_str(if *value { "true" } else { "false" }),
84        serde_json::Value::Number(value) => output.push_str(&value.to_string()),
85        serde_json::Value::String(value) => {
86            output.push_str(&serde_json::to_string(value).map_err(|error| error.to_string())?)
87        }
88        serde_json::Value::Array(values) => {
89            output.push('[');
90            for (index, value) in values.iter().enumerate() {
91                if index > 0 {
92                    output.push(',');
93                }
94                write_canonical_json(value, output)?;
95            }
96            output.push(']');
97        }
98        serde_json::Value::Object(values) => {
99            output.push('{');
100            let mut keys: Vec<_> = values.keys().collect();
101            keys.sort_unstable();
102            for (index, key) in keys.into_iter().enumerate() {
103                if index > 0 {
104                    output.push(',');
105                }
106                output.push_str(&serde_json::to_string(key).map_err(|error| error.to_string())?);
107                output.push(':');
108                write_canonical_json(&values[key], output)?;
109            }
110            output.push('}');
111        }
112    }
113    Ok(())
114}
workshop_rs/gameplay_data.rs

workshop_rs/
gameplay_data.rs
