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use std::borrow::Cow;
use base64::Engine;
use gltf::Gltf;
use serde_json::{json, value::to_raw_value, Value};
use crate::{Codec, Error};
/// Codec for embedding data in a GLTF file "extras" entry. It uses the extras entry in the first
/// scene in the file and stores the data as base64.
#[derive(Default)]
pub struct ExtrasEntryCodec;
impl Codec for ExtrasEntryCodec {
fn encode(&self, carrier: &[u8], payload: &[u8]) -> Result<Vec<u8>, crate::Error> {
let gltf = match Gltf::from_slice(carrier) {
Ok(gltf) => gltf,
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
let mut json = gltf.document.into_json();
let mut scene = json.scenes.remove(0);
let mut extras = match serde_json::from_str::<Value>(scene.extras.clone().unwrap_or(to_raw_value(&json!({})).unwrap()).get()) {
Ok(extras) => extras,
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
match &mut extras {
Value::Object(object) => {
let base64_payload = base64::engine::general_purpose::STANDARD.encode(payload);
object.insert("occule".into(), Value::String(base64_payload));
},
_ => return Err(Error::DataInvalid("Carrier has extras in non-object format, not gonna mess with that.".into()))
}
let extras = match to_raw_value(&extras) {
Ok(raw) => Some(raw),
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
scene.extras = extras;
json.scenes.insert(0, scene);
let json_string = match gltf_json::serialize::to_string(&json) {
Ok(json_string) => json_string,
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
let mut glb = match gltf::binary::Glb::from_slice(carrier) {
Ok(glb) => glb,
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
glb.header.length = (glb.header.length as usize - glb.json.len() + align_to_multiple_of_four(json_string.len())) as u32;
glb.json = Cow::Owned(json_string.into_bytes());
Ok(match glb.to_vec() {
Ok(vec) => vec,
Err(e) => return Err(Error::DependencyError(e.to_string()))
})
}
fn decode(&self, encoded: &[u8]) -> Result<(Vec<u8>, Vec<u8>), crate::Error> {
let gltf = match Gltf::from_slice(encoded) {
Ok(gltf) => gltf,
Err(e) => return Err(Error::DependencyError(e.to_string())),
};
let mut json = gltf.document.into_json();
let mut extras = match &json.scenes[0].extras {
Some(extras) => match serde_json::from_str::<Value>(extras.get()) {
Ok(Value::Object(value)) => value,
_ => return Err(Error::DataNotEncoded),
},
None => return Err(Error::DataNotEncoded),
};
let payload = match extras.remove("occule".into()) {
Some(Value::String(payload)) => match base64::engine::general_purpose::STANDARD.decode(payload) {
Ok(payload) => payload,
Err(e) => return Err(Error::DependencyError(e.to_string())),
},
_ => return Err(Error::DataNotEncoded),
};
json.scenes[0].extras = match to_raw_value(&Value::Object(extras)) {
Ok(extras) => Some(extras),
Err(e) => return Err(Error::DependencyError(e.to_string()))
};
// TODO: remove payload from carrier
Ok((encoded.to_vec(), payload))
}
}
fn align_to_multiple_of_four(n: usize) -> usize {
(n + 3) & !3
}
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