//! The command registry. Each area has its own module; [`ALL`] lists every command.

mod geometry;
mod mesh;
mod model;

use serde_json::Value;

use crate::{CommandSpec, EngineError, Result};

pub static ALL: &[CommandSpec] = &[
    model::INFO,
    geometry::OPEN,
    geometry::BODIES,
    geometry::TESSELLATE,
    geometry::IMPORT_MESH,
    mesh::NODE_ADD,
    mesh::NODE_REMOVE,
    mesh::ELEMENT_ADD,
    mesh::ELEMENT_REMOVE,
];

/// A required label parameter (1..=u32::MAX; the model checks its own range).
pub(crate) fn label(p: &Value, key: &str) -> Result<u32> {
    p.get(key)
        .and_then(Value::as_u64)
        .and_then(|v| u32::try_from(v).ok())
        .ok_or_else(|| EngineError::Params(format!("`{key}` must be a positive whole number")))
}

/// A required `[x, y, z]` parameter.
pub(crate) fn xyz(p: &Value, key: &str) -> Result<[f64; 3]> {
    let bad = || EngineError::Params(format!("`{key}` must be [x, y, z]"));
    let a = p.get(key).and_then(Value::as_array).filter(|a| a.len() == 3).ok_or_else(bad)?;
    let mut out = [0.0; 3];
    for (o, v) in out.iter_mut().zip(a) {
        *o = v.as_f64().ok_or_else(bad)?;
    }
    Ok(out)
}

/// A file's bytes, refusing anything over `cap`.
pub(crate) fn read_capped(path: &str, cap: usize) -> Result<Vec<u8>> {
    use std::io::Read;
    let err = |e: std::io::Error| EngineError::File(format!("{path}: {e}"));
    let f = std::fs::File::open(path).map_err(err)?;
    let len = f.metadata().map(|m| m.len()).unwrap_or(0);
    let mut bytes = Vec::with_capacity(usize::try_from(len).unwrap_or(0).min(cap));
    f.take(cap as u64 + 1).read_to_end(&mut bytes).map_err(err)?;
    if bytes.len() > cap {
        return Err(EngineError::File(format!("{path}: larger than {} MB", cap >> 20)));
    }
    Ok(bytes)
}