use crate::{
    feat_graph::{FeatGraph, HasIndex},
    metadata::{DepKindInfo, Link},
};

use petgraph::{
    graph::NodeIndex,
    visit::{Dfs, EdgeFiltered, EdgeRef, IntoEdgesDirected, Reversed},
};
use semver::Version;
use std::collections::BTreeSet;
use tracing::{debug, info};

fn collect_packages(
    fg: &mut FeatGraph,

    krate: &str,
    feature: Option<&String>,
    version: Option<&Version>,
) -> Vec<NodeIndex> {
    fg.features
        .node_indices()
        .filter(|&ix| {
            if let Some(fid) = fg.features[ix].fid() {
                let package = fid.pid.package();
                // name must match.
                // feature must match if given, otherwise look for base
                // version must match if given
                package.name == krate
                    && feature.map_or(fid.pid.base() == fid, |f| fid.pid.named(f) == fid)
                    && version.map_or(true, |v| package.version == *v)
            } else {
                false
            }
        })
        .collect::<Vec<_>>()
}

pub fn tree<'a>(
    fg: &'a mut FeatGraph<'a>,
    krate: Option<&String>,
    feature: Option<&String>,
    version: Option<&Version>,
    package_nodes: bool,
    workspace: bool,
    no_dev: bool,
    stdout: bool,
) -> anyhow::Result<()> {
    fg.shrink_to_target()?;

    let mut packages = match krate {
        Some(krate) => collect_packages(fg, krate, feature, version),
        None => {
            let members = fg.workspace_members.clone();
            members
                .iter()
                .map(|f| fg.fid_index(f.base()))
                .collect::<Vec<_>>()
        }
    };

    info!("Found {} matching package(s)", packages.len());

    let g = EdgeFiltered::from_fn(&fg.features, |e| {
        (fg.features[e.target()].is_workspace() || !workspace)
            && (!no_dev || !e.weight().is_dev_only())
    });

    let mut dfs = Dfs::new(&g, fg.root);

    let mut nodes = BTreeSet::new();
    let mut edges = BTreeSet::new();
    let mut new_edges = BTreeSet::new();

    debug!("Collecting dependencies");
    while let Some(next) = packages.pop() {
        dfs.move_to(next);
        while let Some(node) = dfs.next(&g) {
            let this_node = if package_nodes {
                fg.base_node(node).expect("base node must exist")
            } else {
                node
            };
            nodes.insert(this_node);
            for edge in g.edges_directed(node, petgraph::EdgeDirection::Outgoing) {
                if package_nodes {
                    new_edges.insert((
                        fg.base_node(edge.target()).expect("base node must exist"),
                        this_node,
                    ));
                } else {
                    edges.insert(edge.id());
                }
            }
        }
    }

    if package_nodes {
        for (a, b) in new_edges {
            let a = a.get_index(fg)?;
            if a != b {
                let link = Link {
                    optional: false,
                    kinds: vec![DepKindInfo::NORMAL],
                };
                edges.insert(fg.features.add_edge(b, a, link));
            }
        }
    }

    info!("Done traversing");
    debug!("Found {} nodes and {} edges", nodes.len(), edges.len());

    fg.focus_nodes = Some(nodes);
    fg.focus_edges = Some(edges);
    dump_fg(fg, stdout)
}

pub fn explain<'a>(
    fg: &'a mut FeatGraph<'a>,
    krate: &str,
    feature: Option<&String>,
    version: Option<&Version>,
    package_nodes: bool,
    stdout: bool,
) -> anyhow::Result<()> {
    fg.shrink_to_target()?;
    let mut packages = collect_packages(fg, krate, feature, version);

    info!("Found {} matching package(s)", packages.len());

    if packages.is_empty() {
        anyhow::bail!("Can't find crate {krate} with feature {feature:?} and version {version:?}");
    }

    if package_nodes {
        fg.focus_targets = Some(
            packages
                .iter()
                .filter_map(|&ix| fg.base_node(ix))
                .collect::<BTreeSet<_>>(),
        );
    } else {
        fg.focus_targets = Some(packages.iter().copied().collect::<BTreeSet<_>>());
    }
    let g = EdgeFiltered::from_fn(Reversed(&fg.features), |e| {
        !fg.features[e.source()].is_workspace()
    });

    let mut dfs = Dfs::new(&g, fg.root);

    let mut nodes = BTreeSet::new();
    let mut edges = BTreeSet::new();
    let mut new_edges = BTreeSet::new();

    debug!("Collecting dependencies");
    while let Some(next) = packages.pop() {
        dfs.move_to(next);
        while let Some(node) = dfs.next(&g) {
            let this_node = if package_nodes {
                fg.base_node(node).expect("base package node must exist")
            } else {
                node
            };
            nodes.insert(this_node);
            for edge in g.edges_directed(node, petgraph::EdgeDirection::Outgoing) {
                if package_nodes {
                    new_edges.insert((
                        fg.base_node(edge.target()).expect("base node must exist"),
                        this_node,
                    ));
                } else {
                    edges.insert(edge.id());
                }
            }
        }
    }

    if package_nodes {
        for (a, b) in new_edges {
            let a = a.get_index(fg)?;
            if a != b {
                let link = Link {
                    optional: false,
                    kinds: vec![DepKindInfo::NORMAL],
                };
                edges.insert(fg.features.add_edge(a, b, link));
            }
        }
    }

    info!("Done traversing");
    debug!("Found {} nodes and {} edges", nodes.len(), edges.len());

    fg.focus_nodes = Some(nodes);
    fg.focus_edges = Some(edges);
    dump_fg(fg, stdout)
}

fn dump_fg(fg: &FeatGraph, stdout: bool) -> anyhow::Result<()> {
    if !stdout {
        let mut file = tempfile::NamedTempFile::new()?;
        dot::render(fg, &mut file)?;
        if std::process::Command::new("xdot")
            .args([file.path()])
            .output()
            .is_ok()
        {
            return Ok(());
        }
    }

    dot::render(fg, &mut std::io::stdout())?;

    Ok(())
}