cimoxide-model 0.6.1

//! Where a family's class table comes from.
//!
//! By default it is the table `cimgen` generated. With the `dynamic-schema`
//! feature, an ENTSO-E RDFS directory can supply it instead, so a new profile
//! version is a data load rather than a recompile.
//!
//! Resolution order, highest first:
//!
//! 1. [`load_from`] — an explicit call, for libraries and tests
//! 2. `CIMOXIDE_RDFS_DIR` — for the CLI and the Python bindings. It may list
//!    several directories, separated as in `PATH`; each serves the family
//!    whose vocabularies it holds (see [`family_of_dir`]), so NC's directory
//!    alone leaves CGMES on its generated table
//! 3. the generated table
//!
//! A directory that is missing or fails to parse falls back to the generated
//! table **with a warning**. Silently serving a stale schema because a path had
//! a typo is the worst outcome available here.

use crate::base::Schema;

/// Resolve the schema for a family.
///
/// `generated` is the table `cimgen` emitted, used unless something overrides it.
pub fn resolve(family: &'static str, generated: &'static Schema) -> &'static Schema {
    #[cfg(feature = "dynamic-schema")]
    {
        dynamic::resolve(family, generated)
    }
    #[cfg(not(feature = "dynamic-schema"))]
    {
        let _ = family;
        generated
    }
}

#[cfg(feature = "dynamic-schema")]
pub use dynamic::{family_of_dir, load_from, load_table, SchemaError, RDFS_DIR_ENV};

#[cfg(feature = "dynamic-schema")]
mod dynamic {
    use std::collections::HashMap;
    use std::path::{Path, PathBuf};
    use std::sync::atomic::{AtomicBool, Ordering};
    use std::sync::{Mutex, OnceLock};

    use cimschema::family::{self, Family};
    use cimschema::model::{CimAttribute, CimSpecification};

    use crate::base::{AttrDef, AttrKind, ClassDef, EnumDef, EnumValueDef, Schema};

    /// Environment variable naming RDFS directories — one, or several separated
    /// as in `PATH`, each serving the family whose vocabularies it holds.
    pub const RDFS_DIR_ENV: &str = "CIMOXIDE_RDFS_DIR";

    #[derive(Debug)]
    pub enum SchemaError {
        /// The registry was already built, so this load would have been ignored.
        TooLate,
        /// A table was already loaded for this family.
        AlreadyLoaded,
        /// No family with this id.
        UnknownFamily(String),
        Parse(String),
    }

    impl std::fmt::Display for SchemaError {
        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
            match self {
                Self::TooLate => write!(
                    f,
                    "the type registry is already built; load the schema before decoding"
                ),
                Self::AlreadyLoaded => write!(f, "a schema is already loaded for this family"),
                Self::UnknownFamily(id) => write!(f, "unknown family: {id}"),
                Self::Parse(e) => write!(f, "{e}"),
            }
        }
    }

    impl std::error::Error for SchemaError {}

    fn explicit() -> &'static Mutex<HashMap<&'static str, &'static Schema>> {
        static E: OnceLock<Mutex<HashMap<&'static str, &'static Schema>>> = OnceLock::new();
        E.get_or_init(|| Mutex::new(HashMap::new()))
    }

    /// Set once `resolve` has run, so a late [`load_from`] can report that it
    /// would have had no effect instead of silently doing nothing.
    static RESOLVED: AtomicBool = AtomicBool::new(false);

    /// Load a family's class table from a directory of RDFS vocabularies.
    ///
    /// Takes precedence over `CIMOXIDE_RDFS_DIR`. Must be called before the
    /// first decode: the registry is memoized, so afterwards this returns
    /// [`SchemaError::TooLate`] rather than being quietly ignored.
    pub fn load_from(family_id: &str, dir: &Path) -> Result<(), SchemaError> {
        let family = family::by_id(family_id)
            
            .ok_or_else(|| SchemaError::UnknownFamily(family_id.to_string()))?;
        if RESOLVED.load(Ordering::SeqCst) {
            return Err(SchemaError::TooLate);
        }
        let classes = load_table(family.id, dir)?;
        let mut map = explicit().lock().unwrap();
        if map.contains_key(family.id) {
            return Err(SchemaError::AlreadyLoaded);
        }
        map.insert(family.id, classes);
        Ok(())
    }

    pub(super) fn resolve(
        family_id: &'static str,
        generated: &'static Schema,
    ) -> &'static Schema {
        RESOLVED.store(true, Ordering::SeqCst);

        if let Some(classes) = explicit().lock().unwrap().get(family_id) {
            return classes;
        }

        let Some(dirs) = env_dirs() else {
            return generated;
        };
        let Some(family) = family::by_id(family_id) else {
            return generated;
        };
        let Some(dir) = dirs.iter().find(|d| family_of_dir(d).is_some_and(|f| f.id == family.id)) else {
            return generated;
        };
        match load_family(family, dir) {
            Ok(classes) => classes,
            Err(e) => {
                eprintln!(
                    "warning: {RDFS_DIR_ENV} set but the {family_id} schema could not be \
                     loaded ({e}); falling back to the generated class table"
                );
                generated
            }
        }
    }

    /// The directories `CIMOXIDE_RDFS_DIR` lists, or `None` when it is unset. A
    /// directory holding neither family's vocabularies is reported once.
    fn env_dirs() -> Option<&'static [PathBuf]> {
        static DIRS: OnceLock<Option<Vec<PathBuf>>> = OnceLock::new();
        DIRS.get_or_init(|| {
            let value = std::env::var_os(RDFS_DIR_ENV)?;
            let dirs: Vec<PathBuf> = std::env::split_paths(&value).collect();
            for d in &dirs {
                if family_of_dir(d).is_none() {
                    eprintln!(
                        "warning: {RDFS_DIR_ENV} lists {}, which holds no CGMES or NC RDFS \
                         vocabularies; ignoring it",
                        d.display()
                    );
                }
            }
            Some(dirs)
        })
        .as_deref()
    }

    /// Which family's vocabularies an RDFS directory holds, by the families'
    /// file-name patterns. NC's pattern (`*-AP-Voc-RDFS2020.rdf`) also matches
    /// CGMES's files, so CGMES's narrower one is tried first.
    pub fn family_of_dir(dir: &Path) -> Option<&'static Family> {
        let names: Vec<String> = std::fs::read_dir(dir)
            .ok()?
            .filter_map(|e| e.ok())
            .map(|e| e.file_name().to_string_lossy().into_owned())
            .collect();
        let matches = |f: &Family| {
            let pattern = Path::new(f.default_schema)
                .file_name()
                .map(|n| n.to_string_lossy().into_owned())
                .unwrap_or_default();
            let (prefix, suffix) = pattern.split_once('*').unwrap_or((&pattern, ""));
            names.iter().any(|n| n.starts_with(prefix) && n.ends_with(suffix))
        };
        [&family::CGMES, &family::NC].into_iter().find(|f| matches(f))
    }

    /// Build a family's class table from RDFS without installing it.
    ///
    /// Useful for inspecting what a schema directory would produce, and for
    /// checking it against the generated table.
    pub fn load_table(family_id: &str, dir: &Path) -> Result<&'static Schema, SchemaError> {
        let family = family::by_id(family_id)
            
            .ok_or_else(|| SchemaError::UnknownFamily(family_id.to_string()))?;
        load_family(family, dir)
    }

    fn load_family(
        family: &'static Family,
        dir: &Path,
    ) -> Result<&'static Schema, SchemaError> {
        // Reuse the family's own filename pattern so a directory of mixed
        // artefacts selects the same files cimgen would.
        let file_pattern = Path::new(family.default_schema)
            .file_name()
            .map(|n| n.to_string_lossy().into_owned())
            .unwrap_or_else(|| "*.rdf".to_string());
        let pattern = dir.join(file_pattern);

        let spec = cimschema::import::import_schema_files(&pattern.to_string_lossy(), family, false)
            .map_err(|e| SchemaError::Parse(e.to_string()))?;
        Ok(build(&spec))
    }

    /// Interns schema strings so they satisfy the `&'static` signatures the
    /// element trait and registry require. Bounded by schema size and leaked
    /// once per process.
    #[derive(Default)]
    struct Interner {
        seen: HashMap<String, &'static str>,
    }

    impl Interner {
        fn intern(&mut self, s: &str) -> &'static str {
            if let Some(v) = self.seen.get(s) {
                return v;
            }
            let leaked: &'static str = Box::leak(s.to_string().into_boxed_str());
            self.seen.insert(s.to_string(), leaked);
            leaked
        }

        fn intern_all(&mut self, items: &[String]) -> &'static [&'static str] {
            let v: Vec<&'static str> = items.iter().map(|s| self.intern(s)).collect();
            Vec::leak(v)
        }
    }

    // Classification, ranges, datatypes and namespaces come from
    // `cimschema::table`, which `cimgen::generator::classes_gen` calls too; the
    // `runtime_table_matches_generated` tests check the rendering on top.
    fn attr_kind(a: &CimAttribute) -> AttrKind {
        match cimschema::table::attr_kind(a) {
            cimschema::table::Kind::Literal => AttrKind::Literal,
            cimschema::table::Kind::Association => AttrKind::Association,
            cimschema::table::Kind::Enum => AttrKind::Enum,
        }
    }

    fn build(spec: &CimSpecification) -> &'static Schema {
        // Sorted key order, because the index in this vector is the class id
        // that `super_class` refers to.
        let mut ids: Vec<&String> = spec.types.keys().collect();
        ids.sort();
        let index_of: HashMap<&str, usize> = ids
            .iter()
            .enumerate()
            .map(|(i, id)| (id.as_str(), i))
            .collect();

        let mut interner = Interner::default();
        let mut out: Vec<ClassDef> = Vec::with_capacity(ids.len());

        for id in &ids {
            let t = &spec.types[*id];
            let attrs: Vec<AttrDef> = t
                .attributes
                .iter()
                .map(|a| AttrDef {
                    id: interner.intern(&a.id),
                    ns: interner.intern(&a.namespace),
                    kind: attr_kind(a),
                    range: interner.intern(cimschema::table::attr_range(a)),
                    is_list: a.is_list,
                    used: a.is_association_used,
                    xsd: cimschema::table::xsd_type(a),
                    value_ns: interner.intern(cimschema::table::value_namespace(spec, a)),
                    origins: interner.intern_all(&a.origins),
                    comment: interner.intern(&a.comment),
                })
                .collect();

            let qualified = format!("{}{}", spec.family.type_prefix, t.id);
            out.push(ClassDef {
                ns: interner.intern(&t.namespace),
                local: interner.intern(&t.id),
                qualified: interner.intern(&qualified),
                super_class: index_of.get(t.super_type.as_str()).copied(),
                concrete: !t.concrete_in.is_empty(),
                attrs: Vec::leak(attrs),
                origins: interner.intern_all(&t.origins),
                comment: interner.intern(&t.comment),
            });
        }

        let pairs = |interner: &mut Interner, v: Vec<(&str, &str)>| -> &'static [(&'static str, &'static str)] {
            Vec::leak(v.into_iter().map(|(a, b)| (interner.intern(a), interner.intern(b))).collect())
        };
        let profiles = pairs(&mut interner, cimschema::table::profile_uris(spec));
        let namespaces = pairs(&mut interner, cimschema::table::namespaces(spec));
        let enums: Vec<EnumDef> = cimschema::table::enums(spec)
            .into_iter()
            .map(|e| EnumDef {
                ns: interner.intern(&e.namespace),
                local: interner.intern(&e.id),
                comment: interner.intern(&e.comment),
                values: Vec::leak(
                    e.values
                        .iter()
                        .map(|v| EnumValueDef { id: interner.intern(&v.id), comment: interner.intern(&v.comment) })
                        .collect(),
                ),
            })
            .collect();
        Box::leak(Box::new(Schema { classes: Vec::leak(out), profiles, namespaces, enums: Vec::leak(enums) }))
    }
}