hara-native 0.1.10

use super::{declared_namespace, files_in, Project};
use sha2::{Digest, Sha256};
use std::collections::BTreeMap;
use std::fs;
use std::path::{Path, PathBuf};
use std::time::UNIX_EPOCH;

#[path = "resources/installed.rs"]
mod installed;

/// A source-only namespace catalog used by native runtimes.
///
/// The catalog deliberately stores paths rather than source text. Project
/// startup scans each file for its top-level namespace declaration (some
/// legacy library paths do not mirror their namespace); source is retained and
/// fully parsed/evaluated only when a namespace is actually required.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct SourceCatalog {
    entries: BTreeMap<String, PathBuf>,
}

#[derive(Clone, Copy, Debug, PartialEq, Eq)]
struct FileStamp {
    length: u64,
    modified_seconds: u64,
    modified_nanos: u32,
}

#[derive(Clone, Debug)]
struct IndexedSource {
    stamp: FileStamp,
    namespace: String,
}

const SOURCE_INDEX_HEADER: &str = "hara-source-index-v1";

fn source_index_path(project_root: &Path) -> PathBuf {
    project_root.join("target/hara/source-catalog-v1.index")
}

fn file_stamp(path: &Path) -> Option<FileStamp> {
    let metadata = fs::metadata(path).ok()?;
    let modified = metadata.modified().ok()?.duration_since(UNIX_EPOCH).ok()?;
    Some(FileStamp {
        length: metadata.len(),
        modified_seconds: modified.as_secs(),
        modified_nanos: modified.subsec_nanos(),
    })
}

fn load_source_index(project_root: &Path) -> BTreeMap<String, IndexedSource> {
    let Ok(source) = fs::read_to_string(source_index_path(project_root)) else {
        return BTreeMap::new();
    };
    let mut lines = source.lines();
    if lines.next() != Some(SOURCE_INDEX_HEADER) {
        return BTreeMap::new();
    }
    let mut entries = BTreeMap::new();
    for line in lines {
        let mut fields = line.splitn(5, '\t');
        let Some(path) = fields
            .next()
            .and_then(|value| serde_json::from_str::<String>(value).ok())
        else {
            return BTreeMap::new();
        };
        let Some(length) = fields.next().and_then(|value| value.parse().ok()) else {
            return BTreeMap::new();
        };
        let Some(modified_seconds) = fields.next().and_then(|value| value.parse().ok()) else {
            return BTreeMap::new();
        };
        let Some(modified_nanos) = fields.next().and_then(|value| value.parse().ok()) else {
            return BTreeMap::new();
        };
        let Some(namespace) = fields
            .next()
            .and_then(|value| serde_json::from_str(value).ok())
        else {
            return BTreeMap::new();
        };
        entries.insert(
            path,
            IndexedSource {
                stamp: FileStamp {
                    length,
                    modified_seconds,
                    modified_nanos,
                },
                namespace,
            },
        );
    }
    entries
}

fn write_source_index(project_root: &Path, entries: &BTreeMap<String, IndexedSource>) {
    let mut output = String::from(SOURCE_INDEX_HEADER);
    output.push('\n');
    for (path, entry) in entries {
        let Ok(path) = serde_json::to_string(path) else {
            return;
        };
        let Ok(namespace) = serde_json::to_string(&entry.namespace) else {
            return;
        };
        output.push_str(&format!(
            "{path}\t{}\t{}\t{}\t{namespace}\n",
            entry.stamp.length, entry.stamp.modified_seconds, entry.stamp.modified_nanos,
        ));
    }
    let path = source_index_path(project_root);
    if fs::create_dir_all(path.parent().expect("source index has a parent")).is_ok() {
        let _ = fs::write(path, output);
    }
}

impl SourceCatalog {
    pub(crate) fn entries(&self) -> &BTreeMap<String, PathBuf> {
        &self.entries
    }

    pub fn path(&self, namespace: &str) -> Option<&Path> {
        self.entries.get(namespace).map(PathBuf::as_path)
    }

    pub fn namespaces(&self) -> impl Iterator<Item = &str> {
        self.entries.keys().map(String::as_str)
    }

    /// Returns a stable fingerprint of the indexed source set. The source
    /// cache keys individual programs by source bytes as well; this broader
    /// index fingerprint invalidates programs whose compilation depends on a
    /// changed sibling namespace configuration without rereading every source
    /// body during startup.
    pub fn fingerprint(&self) -> Result<[u8; 32], String> {
        let mut digest = Sha256::new();
        digest.update(b"hara-source-index-v1\0");
        for (namespace, path) in &self.entries {
            let stamp = file_stamp(path)
                .ok_or_else(|| format!("cannot stat source file {}", path.display()))?;
            digest.update(namespace.as_bytes());
            digest.update([0]);
            digest.update(path.to_string_lossy().as_bytes());
            digest.update([0]);
            digest.update(stamp.length.to_le_bytes());
            digest.update(stamp.modified_seconds.to_le_bytes());
            digest.update(stamp.modified_nanos.to_le_bytes());
        }
        Ok(digest.finalize().into())
    }

    fn add_project(&mut self, project: &Project, owner: &str) -> Result<(), String> {
        let project_root = project
            .root
            .canonicalize()
            .map_err(|error| format!("cannot resolve {}: {error}", project.root.display()))?;
        let mut files = Vec::new();
        for source_root in &project.source_paths {
            let source_root = project.root.join(source_root);
            if !source_root.exists() {
                continue;
            }
            let source_root = source_root.canonicalize().map_err(|error| {
                format!(
                    "cannot resolve source root {}: {error}",
                    source_root.display()
                )
            })?;
            if !source_root.starts_with(&project_root) {
                return Err(format!(
                    "source root escapes project root: {}",
                    source_root.display()
                ));
            }
            files.extend(files_in(
                &project.root,
                &[source_root_for_project(&project_root, &source_root)?],
            )?);
        }
        files.sort();
        let cached = load_source_index(&project_root);
        let mut refreshed = BTreeMap::new();
        let mut owned = BTreeMap::<String, PathBuf>::new();
        for path in files {
            let path = path
                .canonicalize()
                .map_err(|error| format!("cannot resolve {}: {error}", path.display()))?;
            if !path.starts_with(&project_root) {
                return Err(format!(
                    "source file escapes project root: {}",
                    path.display()
                ));
            }
            let stamp = file_stamp(&path)
                .ok_or_else(|| format!("cannot stat source file {}", path.display()))?;
            let key = path.to_string_lossy().into_owned();
            let namespace =
                if let Some(entry) = cached.get(&key).filter(|entry| entry.stamp == stamp) {
                    entry.namespace.clone()
                } else {
                    let source = fs::read_to_string(&path)
                        .map_err(|error| format!("cannot read {}: {error}", path.display()))?;
                    declared_namespace_header(&source)
                        .map_err(|error| format!("{}: {error}", path.display()))?
                        .ok_or_else(|| {
                            format!("{} does not declare an ns or ns+ namespace", path.display())
                        })?
                };
            if let Some(previous) = owned.insert(namespace.clone(), path.clone()) {
                if previous != path {
                    return Err(format!(
                        "duplicate namespace {namespace} in {owner}: {} and {}",
                        previous.display(),
                        path.display()
                    ));
                }
            }
            refreshed.insert(key, IndexedSource { stamp, namespace });
        }
        write_source_index(&project_root, &refreshed);
        // Later project layers intentionally overlay earlier layers.  This
        // preserves the existing lite-project-then-application ordering while
        // keeping duplicate files within one project an error.
        self.entries.extend(owned);
        Ok(())
    }
}

fn source_root_for_project(project_root: &Path, source_root: &Path) -> Result<PathBuf, String> {
    source_root
        .strip_prefix(project_root)
        .map(Path::to_path_buf)
        .map_err(|_| {
            format!(
                "source root {} is outside project root {}",
                source_root.display(),
                project_root.display()
            )
        })
}

fn declared_namespace_header(source: &str) -> Result<Option<String>, String> {
    let mut depth = 0;
    let mut form_start = None;
    let mut in_comment = false;
    let mut in_string = false;
    let mut escaped = false;
    let mut skip_character = false;
    for (index, character) in source.char_indices() {
        if skip_character {
            skip_character = false;
            continue;
        }
        if in_comment {
            if character == '\n' {
                in_comment = false;
            }
            continue;
        }
        if in_string {
            if escaped {
                escaped = false;
            } else if character == '\\' {
                escaped = true;
            } else if character == '"' {
                in_string = false;
            }
            continue;
        }
        match character {
            ';' => in_comment = true,
            '"' => in_string = true,
            '\\' => skip_character = true,
            '(' | '[' | '{' => {
                if depth == 0 && character == '(' {
                    form_start = Some(index);
                }
                depth += 1;
            }
            ')' | ']' | '}' if depth > 0 => {
                depth -= 1;
                if depth == 0 {
                    if let Some(start) = form_start.take() {
                        let end = index + character.len_utf8();
                        if let Some(namespace) = declared_namespace(&source[start..end])? {
                            return Ok(Some(namespace));
                        }
                    }
                }
            }
            _ => {}
        }
    }
    Ok(None)
}

/// Builds a path-backed source catalog for one project and its installed Hara
/// dependencies.
pub fn source_catalog(project: &Project) -> Result<SourceCatalog, String> {
    source_catalogs(&[project])
}

/// Builds a path-backed source catalog for several ordered project layers.
/// Each project contributes its verified installed dependencies first,
/// followed by its own source paths; later project layers take precedence.
pub fn source_catalogs(projects: &[&Project]) -> Result<SourceCatalog, String> {
    let distribution_root = dist_root();
    let mut catalog = SourceCatalog::default();
    for project in projects {
        for dependency in installed::resolve(project, &distribution_root)? {
            catalog.add_project(
                &dependency.project,
                &format!("{}@{}", dependency.coordinate, dependency.version),
            )?;
        }
        catalog.add_project(project, &format!("{}@{}", project.id, project.version))?;
    }
    Ok(catalog)
}

/// Returns namespace resources from installed dependencies followed by the
/// automatically selected native Rust profile of the consuming project.
pub fn source_resources(project: &Project) -> Result<Vec<(String, String)>, String> {
    source_resources_at(project, &dist_root())
}

pub(crate) fn source_resources_at(
    project: &Project,
    distribution_root: &Path,
) -> Result<Vec<(String, String)>, String> {
    let mut resources = Vec::new();
    let mut declarations = BTreeMap::<String, (String, PathBuf)>::new();
    for dependency in installed::resolve(project, distribution_root)? {
        collect_project(
            &dependency.project,
            &format!("{}@{}", dependency.coordinate, dependency.version),
            &mut declarations,
            &mut resources,
        )?;
    }
    collect_project(
        project,
        &format!("{}@{}", project.id, project.version),
        &mut declarations,
        &mut resources,
    )?;
    Ok(resources)
}

fn collect_project(
    project: &Project,
    owner: &str,
    declarations: &mut BTreeMap<String, (String, PathBuf)>,
    resources: &mut Vec<(String, String)>,
) -> Result<(), String> {
    for path in files_in(&project.root, &project.source_paths)? {
        let source = fs::read_to_string(&path)
            .map_err(|error| format!("cannot read {}: {error}", path.display()))?;
        let namespace = declared_namespace(&source)
            .map_err(|error| format!("{}: {error}", path.display()))?
            .ok_or_else(|| format!("{} does not declare an ns or ns+ namespace", path.display()))?;
        if let Some((previous_owner, previous_path)) =
            declarations.insert(namespace.clone(), (owner.to_owned(), path.clone()))
        {
            return Err(format!(
                "duplicate namespace {namespace}: {previous_owner} ({}) and {owner} ({})",
                previous_path.display(),
                path.display()
            ));
        }
        resources.push((namespace, source));
    }
    Ok(())
}

fn dist_root() -> PathBuf {
    if let Some(root) = std::env::var_os("HARA_DIST_HOME") {
        return PathBuf::from(root);
    }
    std::env::var_os("HOME")
        .map(PathBuf::from)
        .unwrap_or_else(|| PathBuf::from("."))
        .join(".hara/dist")
}