//! Transforms the output of [`cargo metadata`] into a graph, [`Krates`], where
//! crates are nodes and dependency links are edges.
//!
//! ```no_run
//! use krates::{Builder, Cmd, Krates, cm, petgraph};
//!
//! fn main() -> Result<(), krates::Error> {
//!     let mut cmd = Cmd::new();
//!     cmd.manifest_path("path/to/a/Cargo.toml");
//!     // Enable all features, works for either an entire workspace or a single crate
//!     cmd.all_features();
//!
//!     let mut builder = Builder::new();
//!     // Let's filter out any crates that aren't used by x86_64 windows
//!     builder.include_targets(std::iter::once(("x86_64-pc-windows-msvc", vec![])));
//!
//!     let krates: Krates = builder.build(cmd, |pkg: cm::Package| {
//!         println!("Crate {} was filtered out", pkg.id);
//!     })?;
//!
//!     // Print a dot graph of the entire crate graph
//!     println!("{:?}", petgraph::dot::Dot::new(krates.graph()));
//!
//!     Ok(())
//! }
//! ```

pub use cargo_metadata as cm;
pub use cfg_expr;

#[cfg(feature = "targets")]
pub use cfg_expr::target_lexicon;

use cm::DependencyKind as DK;
pub use petgraph;
pub use semver;

pub use cm::camino::{self, Utf8Path, Utf8PathBuf};
use petgraph::{graph::EdgeIndex, graph::NodeIndex, visit::EdgeRef, Direction};

mod builder;
mod errors;
mod pkgspec;

pub use builder::{
    features::{Feature, ParsedFeature},
    index, Builder, Cmd, LockOptions, NoneFilter, OnFilter, Scope, Target,
};
pub use errors::Error;
pub use pkgspec::PkgSpec;

/// A crate's unique identifier
pub type Kid = cargo_metadata::PackageId;

/// The set of features that have been enabled on a crate
pub type EnabledFeatures = std::collections::BTreeSet<String>;

/// The dependency kind. A crate can depend on the same crate multiple times
/// with different dependency kinds
#[derive(Debug, Copy, Clone, PartialEq, Eq)]
pub enum DepKind {
    Normal,
    Build,
    Dev,
}

impl From<DK> for DepKind {
    fn from(dk: DK) -> Self {
        match dk {
            DK::Normal => Self::Normal,
            DK::Build => Self::Build,
            DK::Development => Self::Dev,
            DK::Unknown => unreachable!(),
        }
    }
}

impl PartialEq<DK> for DepKind {
    fn eq(&self, other: &DK) -> bool {
        matches!(
            (self, *other),
            (Self::Normal, DK::Normal) | (Self::Build, DK::Build) | (Self::Dev, DK::Development)
        )
    }
}

use std::fmt;

impl fmt::Display for DepKind {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Normal => Ok(()),
            Self::Build => f.write_str("build"),
            Self::Dev => f.write_str("dev"),
        }
    }
}

/// A node identifier.
pub type NodeId = NodeIndex<u32>;
pub type EdgeId = EdgeIndex<u32>;

/// A node in the crate graph.
pub enum Node<N> {
    Krate {
        /// The unique identifier for this node.
        id: Kid,
        /// Associated user data with the node. Must be From<cargo_metadata::Package>
        krate: N,
        /// List of features enabled on the crate
        features: EnabledFeatures,
    },
    Feature {
        /// The node index for the crate this feature is for
        krate_index: NodeId,
        name: String,
    },
}

impl<N> fmt::Display for Node<N>
where
    N: fmt::Display,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Krate { krate, .. } => {
                write!(f, "crate {krate}")
            }
            Self::Feature { name, .. } => {
                write!(f, "feature {name}")
            }
        }
    }
}

impl<N> fmt::Debug for Node<N>
where
    N: fmt::Debug,
{
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Krate { id, krate, .. } => {
                write!(f, "crate {} {krate:?}", id.repr)
            }
            Self::Feature { name, .. } => {
                write!(f, "feature {name}")
            }
        }
    }
}

/// The default type used for edges in the crate graph.
#[derive(Debug, Clone)]
pub enum Edge {
    Dep {
        /// The dependency kind for the edge link
        kind: DepKind,
        /// A possible cfg() or <target-triple> applied to this dependency
        cfg: Option<String>,
    },
    /// An edge from one feature to another
    Feature,
    DepFeature {
        /// The dependency kind for the edge link
        kind: DepKind,
        /// A possible cfg() or <target-triple> applied to this dependency
        cfg: Option<String>,
    },
}

impl fmt::Display for Edge {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if let Self::DepFeature { kind, cfg } | Self::Dep { kind, cfg } = self {
            match kind {
                DepKind::Normal => {}
                DepKind::Build => f.write_str("(build)")?,
                DepKind::Dev => f.write_str("(dev)")?,
            };

            if let Some(cfg) = cfg {
                write!(f, " '{cfg}'")?;
            }
        }

        Ok(())
    }
}

/// A crate graph. Each unique crate is a node, and each unique dependency
/// between 2 crates is an edge.
pub struct Krates<N = cm::Package, E = Edge> {
    graph: petgraph::Graph<Node<N>, E, petgraph::Directed, u32>,
    workspace_members: Vec<Kid>,
    workspace_root: Utf8PathBuf,
    /// We split the graph between crate and feature nodes, but keep the crates
    /// grouped together in the front since most queries are against them
    krates_end: usize,
}

#[allow(clippy::len_without_is_empty)]
impl<N, E> Krates<N, E> {
    /// The number of unique crates in the graph
    #[inline]
    pub fn len(&self) -> usize {
        self.krates_end
    }

    /// Path to the root of the workspace where the graph metadata was acquired from
    #[inline]
    pub fn workspace_root(&self) -> &Utf8Path {
        &self.workspace_root
    }

    /// Get access to the raw petgraph
    #[inline]
    pub fn graph(&self) -> &petgraph::Graph<Node<N>, E> {
        &self.graph
    }

    /// Get an iterator over the crate nodes in the graph. The crates are always
    /// ordered lexicographically by their identfier.
    ///
    /// ```no_run
    /// use krates::Krates;
    ///
    /// fn print_krates(krates: &Krates) {
    ///     for (name, version) in krates.krates().map(|krate| (&krate.name, &krate.version)) {
    ///         println!("Crate {} @ {}", name, version);
    ///     }
    /// }
    /// ```
    #[inline]
    pub fn krates(&self) -> impl Iterator<Item = &N> {
        self.graph.raw_nodes()[..self.krates_end]
            .iter()
            .filter_map(move |node| {
                if let Node::Krate { krate, .. } = &node.weight {
                    Some(krate)
                } else {
                    None
                }
            })
    }

    /// Get an iterator over each dependency of the specified crate. The same
    /// dependency can be returned multiple times if the crate depends on it
    /// with more than 1 dependency kind.
    ///
    /// ```no_run
    /// use krates::{Krates, Kid, DepKind};
    ///
    /// fn count_build_deps(krates: &Krates, pkg: &Kid) -> usize {
    ///     krates.get_deps(krates.nid_for_kid(pkg).unwrap())
    ///         .filter(|(_, edge)| matches!(
    ///             edge,
    ///             krates::Edge::Dep { kind: DepKind::Build, .. } |
    ///             krates::Edge::DepFeature { kind: DepKind::Build, .. }
    ///         ))
    ///         .count()
    /// }
    /// ```
    #[inline]
    pub fn get_deps(&self, id: NodeId) -> impl Iterator<Item = (&Node<N>, &E)> {
        self.graph
            .edges_directed(id, Direction::Outgoing)
            .map(move |edge| {
                let krate = &self.graph[edge.target()];
                (krate, edge.weight())
            })
    }

    /// Gets crates directly depended upon by the specified node
    #[inline]
    pub fn direct_dependencies(&self, nid: NodeId) -> Vec<DirectDependency<'_, N>> {
        let graph = self.graph();
        let mut direct_dependencies = Vec::new();
        let mut stack = vec![nid];
        let mut visited = std::collections::BTreeSet::new();

        while let Some(nid) = stack.pop() {
            for edge in graph.edges_directed(nid, Direction::Outgoing) {
                match &self.graph[edge.target()] {
                    Node::Krate { krate, .. } => {
                        if visited.insert(edge.target()) {
                            direct_dependencies.push(DirectDependency {
                                krate,
                                node_id: edge.target(),
                                edge_id: edge.id(),
                            });
                        }
                    }
                    Node::Feature { .. } => {
                        if visited.insert(edge.target()) {
                            stack.push(edge.target());
                        }
                    }
                }
            }
        }

        direct_dependencies
    }

    /// Gets the crates that have a direct dependency on the specified node
    #[inline]
    pub fn direct_dependents(&self, nid: NodeId) -> Vec<DirectDependent<'_, N>> {
        let graph = self.graph();
        let mut direct_dependents = Vec::new();
        let mut stack = vec![nid];
        let mut visited = std::collections::BTreeSet::new();

        while let Some(nid) = stack.pop() {
            for edge in graph.edges_directed(nid, Direction::Incoming) {
                match &self.graph[edge.source()] {
                    Node::Krate { krate, .. } => {
                        if visited.insert(edge.source()) {
                            direct_dependents.push(DirectDependent {
                                krate,
                                node_id: edge.source(),
                                edge_id: edge.id(),
                            });
                        }
                    }
                    Node::Feature { krate_index, .. } => {
                        if *krate_index == nid && visited.insert(edge.source()) {
                            stack.push(edge.source());
                        }
                    }
                }
            }
        }

        direct_dependents
    }

    /// Get the node identifier for the specified crate identifier
    #[inline]
    pub fn nid_for_kid(&self, kid: &Kid) -> Option<NodeId> {
        self.graph.raw_nodes()[..self.krates_end]
            .binary_search_by(|rn| {
                if let Node::Krate { id, .. } = &rn.weight {
                    id.cmp(kid)
                } else {
                    unreachable!();
                }
            })
            .ok()
            .map(NodeId::new)
    }

    /// Get the node for the specified crate identifier
    #[inline]
    pub fn node_for_kid(&self, kid: &Kid) -> Option<&Node<N>> {
        self.nid_for_kid(kid).map(|nid| &self.graph[nid])
    }

    #[inline]
    pub fn get_node(&self, kid: &Kid, feature: Option<&str>) -> Option<(NodeId, &Node<N>)> {
        self.nid_for_kid(kid).and_then(|nid| {
            if let Some(feat) = feature {
                self.graph
                    .edges_directed(nid, Direction::Incoming)
                    .find_map(|edge| {
                        if let Node::Feature { krate_index, name } = &self.graph[edge.source()] {
                            if *krate_index == nid && name == feat {
                                return Some((edge.source(), &self.graph[edge.source()]));
                            }
                        }

                        None
                    })
            } else {
                Some((nid, &self.graph[nid]))
            }
        })
    }

    /// Gets the features enabled for the specified crate
    #[inline]
    pub fn get_enabled_features(&self, kid: &Kid) -> Option<&EnabledFeatures> {
        self.node_for_kid(kid).map(|node| {
            if let Node::Krate { features, .. } = node {
                features
            } else {
                unreachable!()
            }
        })
    }

    /// Get an iterator over the nodes for the members of the workspace
    #[inline]
    pub fn workspace_members(&self) -> impl Iterator<Item = &Node<N>> {
        self.workspace_members
            .iter()
            .filter_map(move |pid| self.nid_for_kid(pid).map(|ind| &self.graph[ind]))
    }
}

/// A direct dependency of a crate
pub struct DirectDependency<'krates, N> {
    /// The crate in the node
    pub krate: &'krates N,
    /// The crate's node id
    pub node_id: NodeId,
    /// The edge that links the crate with the crate that depends on it
    pub edge_id: EdgeId,
}

/// A crate that has a direct dependency on another crate
pub struct DirectDependent<'krates, N> {
    /// The crate in the node
    pub krate: &'krates N,
    /// The crate's node id
    pub node_id: NodeId,
    /// The edge that links the crate with the dependency
    pub edge_id: EdgeId,
}

/// A trait that can be applied to the type stored in the graph nodes to give
/// additional features on `Krates`.
pub trait KrateDetails {
    /// The name of the crate
    fn name(&self) -> &str;
    /// The version of the crate
    fn version(&self) -> &semver::Version;
}

impl KrateDetails for cm::Package {
    fn name(&self) -> &str {
        &self.name
    }

    fn version(&self) -> &semver::Version {
        &self.version
    }
}

/// If the node type N supports [`KrateDetails`], we can also iterator over krates
/// of a given name and or version
impl<N, E> Krates<N, E>
where
    N: KrateDetails,
{
    /// Get an iterator over the crates that match the specified name, as well
    /// as satisfy the specified semver requirement.
    ///
    /// ```no_run
    /// use krates::{Krates, semver::VersionReq};
    ///
    /// fn print(krates: &Krates, name: &str) {
    ///     let req = VersionReq::parse("=0.2").unwrap();
    ///     for vs in krates.search_matches(name, req.clone()).map(|(_, krate)| &krate.version) {
    ///         println!("found version {} matching {}!", vs, req);
    ///     }
    /// }
    /// ```
    pub fn search_matches(
        &self,
        name: impl Into<String>,
        req: semver::VersionReq,
    ) -> impl Iterator<Item = (NodeId, &N)> {
        let raw_nodes = &self.graph.raw_nodes()[0..self.krates_end];

        let name = name.into();

        raw_nodes.iter().enumerate().filter_map(move |(id, node)| {
            if let Node::Krate { krate, .. } = &node.weight {
                if krate.name() == name && req.matches(krate.version()) {
                    return Some((NodeId::new(id), krate));
                }
            }

            None
        })
    }

    /// Get an iterator over all of the crates in the graph with the given name,
    /// in the case there are multiple versions, or sources, of the crate.
    ///
    /// ```
    /// use krates::Krates;
    ///
    /// fn print_all_versions(krates: &Krates, name: &str) {
    ///     for vs in krates.krates_by_name(name).map(|(_, krate)| &krate.version) {
    ///         println!("found version {}", vs);
    ///     }
    /// }
    /// ```
    pub fn krates_by_name(&self, name: impl Into<String>) -> impl Iterator<Item = (NodeId, &N)> {
        let raw_nodes = &self.graph.raw_nodes()[0..self.krates_end];

        let name = name.into();

        raw_nodes.iter().enumerate().filter_map(move |(id, node)| {
            if let Node::Krate { krate, .. } = &node.weight {
                if krate.name() == name {
                    return Some((NodeId::new(id), krate));
                }
            }

            None
        })
    }
}

impl<N, E> std::ops::Index<NodeId> for Krates<N, E> {
    type Output = N;

    #[inline]
    fn index(&self, id: NodeId) -> &Self::Output {
        match &self.graph[id] {
            Node::Krate { krate, .. } => krate,
            Node::Feature { .. } => panic!("indexed outside of crate graph"),
        }
    }
}

impl<N, E> std::ops::Index<usize> for Krates<N, E> {
    type Output = N;

    #[inline]
    fn index(&self, idx: usize) -> &Self::Output {
        match &self.graph.raw_nodes()[idx].weight {
            Node::Krate { krate, .. } => krate,
            Node::Feature { .. } => panic!("indexed outside of crate graph"),
        }
    }
}