cargo-rail 0.22.2

//! Command-independent dependency universe for conservative planning.

use std::collections::{BTreeMap, HashSet};
use std::path::Path;

use cargo_metadata::{Dependency, DependencyKind, Metadata, Package, PackageId, TargetKind};
use rustc_hash::FxHashMap;
use serde::Serialize;

use super::{ImpactDomain, ImpactFallback, ImpactPropagation, ImpactStep};
use crate::error::{RailError, RailResult};
use crate::source::ContentDigest;

pub(crate) const DEPENDENCY_UNIVERSE_MODE: &str = "declared_dependencies";
const DEPENDENCY_UNIVERSE_VERSION: u32 = 1;

#[derive(Debug, Clone, PartialEq, Eq)]
struct DeclaredEdge {
    dependent: PackageId,
    alias: String,
    kind: DependencyKind,
    target: Option<String>,
    optional: bool,
    uses_default_features: bool,
    features: Vec<String>,
}

#[derive(Debug, Clone, Copy)]
struct PackageFacts {
    workspace_member: bool,
    proc_macro: bool,
}

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Serialize)]
struct PortableEdge {
    dependency: String,
    dependent: String,
    alias: String,
    kind: u8,
    target: Option<String>,
    optional: bool,
    uses_default_features: bool,
    features: Vec<String>,
}

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Serialize)]
struct PortableDeclaration {
    dependent: String,
    dependency_name: String,
    dependency_source: String,
    requirement: String,
    alias: String,
    kind: u8,
    target: Option<String>,
    optional: bool,
    uses_default_features: bool,
    features: Vec<String>,
}

#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Serialize)]
struct PortablePackageFacts {
    package: String,
    workspace_member: bool,
    proc_macro: bool,
}

/// Every declared dependency edge that can resolve between captured packages.
///
/// This is deliberately narrower than [`super::WorkspaceGraph`]. It owns one
/// reverse adjacency index for conservative planner propagation and cannot be
/// queried as an exact Cargo resolution.
pub(crate) struct DependencyUniverse {
    packages: FxHashMap<PackageId, PackageFacts>,
    reverse_edges: FxHashMap<PackageId, Vec<DeclaredEdge>>,
    identity: String,
}

impl DependencyUniverse {
    /// Build the declared universe from the metadata already owned by the workspace capture.
    pub(crate) fn from_metadata(metadata: &Metadata, source_root: &Path) -> RailResult<Self> {
        let source_root = crate::utils::canonicalize_existing(source_root).map_err(|error| {
            RailError::message(format!(
                "failed to resolve dependency universe source root '{}': {error}",
                source_root.display()
            ))
        })?;
        let workspace_ids = metadata.workspace_members.iter().cloned().collect::<HashSet<_>>();
        let packages: FxHashMap<PackageId, PackageFacts> = metadata
            .packages
            .iter()
            .map(|package| {
                (
                    package.id.clone(),
                    PackageFacts {
                        workspace_member: workspace_ids.contains(&package.id),
                        proc_macro: package
                            .targets
                            .iter()
                            .any(|target| target.is_kind(TargetKind::ProcMacro)),
                    },
                )
            })
            .collect();
        let packages_by_name = package_indices_by_name(metadata);
        let portable_package_ids = metadata
            .packages
            .iter()
            .map(|package| (package.id.clone(), portable_package_id(package, &source_root)))
            .collect::<FxHashMap<_, _>>();
        let mut portable_packages = metadata
            .packages
            .iter()
            .map(|package| {
                let facts = packages[&package.id];
                PortablePackageFacts {
                    package: portable_package_ids[&package.id].clone(),
                    workspace_member: facts.workspace_member,
                    proc_macro: facts.proc_macro,
                }
            })
            .collect::<Vec<_>>();
        let mut reverse_edges = FxHashMap::<PackageId, Vec<DeclaredEdge>>::default();
        let mut portable_declarations = Vec::new();
        let mut portable_edges = Vec::new();

        for dependent in &metadata.packages {
            for declaration in &dependent.dependencies {
                let mut declaration_features = declaration.features.clone();
                declaration_features.sort();
                declaration_features.dedup();
                portable_declarations.push(PortableDeclaration {
                    dependent: portable_package_ids[&dependent.id].clone(),
                    dependency_name: declaration.name.clone(),
                    dependency_source: portable_dependency_source(declaration, &source_root),
                    requirement: declaration.req.to_string(),
                    alias: cargo_alias(declaration.rename.as_deref().unwrap_or(&declaration.name)),
                    kind: dependency_kind_rank(declaration.kind),
                    target: declaration.target.as_ref().map(ToString::to_string),
                    optional: declaration.optional,
                    uses_default_features: declaration.uses_default_features,
                    features: declaration_features.clone(),
                });
                let Some(candidates) = packages_by_name.get(declaration.name.as_str()) else {
                    continue;
                };
                for &candidate_index in candidates {
                    let dependency = &metadata.packages[candidate_index];
                    if !declaration_matches_package(declaration, dependency) {
                        continue;
                    }

                    let edge = DeclaredEdge {
                        dependent: dependent.id.clone(),
                        alias: cargo_alias(declaration.rename.as_deref().unwrap_or(&declaration.name)),
                        kind: declaration.kind,
                        target: declaration.target.as_ref().map(ToString::to_string),
                        optional: declaration.optional,
                        uses_default_features: declaration.uses_default_features,
                        features: declaration_features.clone(),
                    };
                    portable_edges.push(PortableEdge {
                        dependency: portable_package_ids[&dependency.id].clone(),
                        dependent: portable_package_ids[&edge.dependent].clone(),
                        alias: edge.alias.clone(),
                        kind: dependency_kind_rank(edge.kind),
                        target: edge.target.clone(),
                        optional: edge.optional,
                        uses_default_features: edge.uses_default_features,
                        features: edge.features.clone(),
                    });
                    reverse_edges.entry(dependency.id.clone()).or_default().push(edge);
                }
            }
        }

        for edges in reverse_edges.values_mut() {
            edges.sort_by(declared_edge_order);
            edges.dedup();
        }
        portable_packages.sort();
        portable_packages.dedup();
        portable_declarations.sort();
        portable_declarations.dedup();
        portable_edges.sort();
        portable_edges.dedup();
        let encoded = serde_json::to_vec(&(
            DEPENDENCY_UNIVERSE_VERSION,
            &portable_packages,
            &portable_declarations,
            &portable_edges,
        ))
        .map_err(|error| RailError::message(format!("failed to encode dependency universe identity: {error}")))?;
        let identity = format!(
            "resolution-universe-v{DEPENDENCY_UNIVERSE_VERSION}:sha256:{}",
            ContentDigest::sha256(&encoded)
        );

        Ok(Self {
            packages,
            reverse_edges,
            identity,
        })
    }

    /// Return the root-independent identity of all package facts, declarations, and matched destinations.
    pub(crate) fn identity(&self) -> &str {
        &self.identity
    }

    /// Propagate package changes through every potentially active declared edge.
    pub(crate) fn propagate(&self, seeds: &HashSet<PackageId>) -> RailResult<ImpactPropagation> {
        if seeds.is_empty() {
            return Ok(ImpactPropagation::default());
        }
        if let Some(missing) = seeds.iter().find(|seed| !self.packages.contains_key(*seed)) {
            return Err(RailError::message(format!(
                "Package ID '{}' is missing from the declared dependency universe",
                missing
            )));
        }

        let mut stack = seeds.iter().cloned().collect::<Vec<_>>();
        stack.sort();
        let mut visited = seeds.clone();
        let mut impact = ImpactPropagation::default();
        let mut node_visits = 0;
        let mut edge_visits = 0;

        while let Some(dependency) = stack.pop() {
            node_visits += 1;
            let Some(edges) = self.reverse_edges.get(&dependency) else {
                continue;
            };
            for edge in edges {
                edge_visits += 1;
                let domain = match edge.kind {
                    DependencyKind::Development => ImpactDomain::Development,
                    DependencyKind::Normal | DependencyKind::Build | DependencyKind::Unknown => ImpactDomain::Build,
                };

                if self.packages[&edge.dependent].workspace_member && !seeds.contains(&edge.dependent) {
                    match domain {
                        ImpactDomain::Build => {
                            impact.build.insert(edge.dependent.clone());
                        }
                        ImpactDomain::Development => {
                            impact.development.insert(edge.dependent.clone());
                        }
                    }
                    impact.steps.push(ImpactStep {
                        dependency: dependency.clone(),
                        dependent: edge.dependent.clone(),
                        alias: edge.alias.clone(),
                        kind: edge.kind,
                        target: edge.target.clone(),
                        optional: edge.optional,
                        uses_default_features: edge.uses_default_features,
                        features: edge.features.clone(),
                        proc_macro: self.packages[&dependency].proc_macro,
                        host: edge.kind == DependencyKind::Build || self.packages[&dependency].proc_macro,
                        domain,
                        fallbacks: (edge.kind == DependencyKind::Unknown)
                            .then_some(ImpactFallback::UnknownDependencyKind)
                            .into_iter()
                            .collect(),
                    });
                }

                if domain == ImpactDomain::Build && visited.insert(edge.dependent.clone()) {
                    stack.push(edge.dependent.clone());
                }
            }
        }

        crate::instrumentation::record_graph_traversal(node_visits, edge_visits);
        impact.normalize();
        Ok(impact)
    }
}

fn package_indices_by_name(metadata: &Metadata) -> BTreeMap<&str, Vec<usize>> {
    let mut packages = BTreeMap::<&str, Vec<usize>>::new();
    for (index, package) in metadata.packages.iter().enumerate() {
        packages.entry(package.name.as_str()).or_default().push(index);
    }
    for candidates in packages.values_mut() {
        candidates.sort_by(|left, right| metadata.packages[*left].id.cmp(&metadata.packages[*right].id));
    }
    packages
}

fn declaration_matches_package(declaration: &Dependency, package: &Package) -> bool {
    if declaration.name.as_str() != package.name.as_str() || !declaration.req.matches(&package.version) {
        return false;
    }
    if let Some(path) = &declaration.path {
        return package.manifest_path.parent() == Some(path.as_path());
    }
    // A Cargo patch may replace the declared source. Keeping every captured
    // name/version candidate is conservative; comparing sources can omit one.
    true
}

fn cargo_alias(alias: &str) -> String {
    alias.replace('-', "_")
}

fn portable_package_id(package: &Package, source_root: &Path) -> String {
    if let Some(source) = &package.source {
        return format!("{}@{}#{}", package.name, package.version, source.repr);
    }
    let package_root = package.manifest_path.parent().map(|path| path.as_std_path());
    let relative = package_root
        .and_then(|path| portable_relative_path(path, source_root))
        .unwrap_or_else(|| "<outside-source-root>".to_string());
    format!("{}@{}#path:{relative}", package.name, package.version)
}

fn portable_dependency_source(dependency: &Dependency, source_root: &Path) -> String {
    if let Some(path) = &dependency.path {
        let relative = portable_relative_path(path.as_std_path(), source_root)
            .unwrap_or_else(|| "<outside-source-root>".to_string());
        return format!("path:{relative}");
    }
    dependency
        .source
        .as_ref()
        .map_or_else(|| "registry:default".to_string(), |source| source.repr.clone())
}

fn portable_relative_path(path: &Path, source_root: &Path) -> Option<String> {
    crate::utils::canonicalize_existing(path)
        .ok()?
        .strip_prefix(source_root)
        .ok()
        .map(normalized_path)
}

fn normalized_path(path: &Path) -> String {
    path.components()
        .map(|component| component.as_os_str().to_string_lossy())
        .collect::<Vec<_>>()
        .join("/")
}

fn declared_edge_order(left: &DeclaredEdge, right: &DeclaredEdge) -> std::cmp::Ordering {
    (
        &left.dependent,
        dependency_kind_rank(left.kind),
        &left.target,
        &left.alias,
        left.optional,
        left.uses_default_features,
        &left.features,
    )
        .cmp(&(
            &right.dependent,
            dependency_kind_rank(right.kind),
            &right.target,
            &right.alias,
            right.optional,
            right.uses_default_features,
            &right.features,
        ))
}

const fn dependency_kind_rank(kind: DependencyKind) -> u8 {
    match kind {
        DependencyKind::Normal => 0,
        DependencyKind::Development => 1,
        DependencyKind::Build => 2,
        DependencyKind::Unknown => 3,
    }
}

#[cfg(test)]
mod tests {
    use std::fs;

    use super::*;

    #[test]
    fn portable_paths_resolve_equivalent_platform_spellings() {
        let root = tempfile::tempdir().expect("source root");
        let package = root.path().join("crates/example");
        fs::create_dir_all(&package).expect("package directory");
        let source_root = crate::utils::canonicalize_existing(root.path()).expect("canonical source root");
        let platform_spelling = fs::canonicalize(&package).expect("platform package spelling");

        assert_eq!(
            portable_relative_path(&platform_spelling, &source_root).as_deref(),
            Some("crates/example")
        );
    }
}