Try out petgraph

brood/src/commands/path_petgraph.rs

@@ -0,0 +1,77 @@
+use std::{
+    fs::File,
+    io::{self, BufReader},
+    path::Path,
+};
+
+use petgraph::{
+    algo,
+    graph::NodeIndex,
+    visit::{EdgeRef, IntoNodeReferences},
+    Graph,
+};
+
+use crate::{
+    data::{
+        info::{LinkInfo, PageInfo},
+        store,
+    },
+    util::{self, normalize_link},
+};
+
+pub fn find_index_of_title(graph: &Graph<PageInfo, LinkInfo>, title: &str) -> NodeIndex {
+    let title = util::normalize_link(title);
+    graph
+        .node_references()
+        .find(|(_, nw)| normalize_link(&nw.title) == title)
+        .map(|(ni, _)| ni)
+        .expect("invalid title")
+}
+
+pub fn resolve_redirects(graph: &Graph<PageInfo, LinkInfo>, mut page: NodeIndex) -> NodeIndex {
+    loop {
+        if graph.node_weight(page).unwrap().redirect {
+            if let Some(link) = graph.edges(page).next() {
+                page = link.target();
+                continue;
+            }
+        }
+        return page;
+    }
+}
+
+pub fn path(datafile: &Path, from: &str, to: &str) -> io::Result<()> {
+    println!(">> Import");
+    let mut databuf = BufReader::new(File::open(datafile)?);
+    let graph = store::read_petgraph(&mut databuf)?;
+
+    println!(">> Locate from and to");
+    let start = resolve_redirects(&graph, find_index_of_title(&graph, from));
+    let goal = resolve_redirects(&graph, find_index_of_title(&graph, to));
+    println!("From: {:?}", graph.node_weight(start).unwrap().title);
+    println!("To:   {:?}", graph.node_weight(goal).unwrap().title);
+
+    println!(">> Find path");
+    let Some((cost, path)) = algo::astar(
+        &graph,
+        start,
+        |n| n == goal,
+        |e| !graph.node_weight(e.source()).unwrap().redirect as u32,
+        |_| 0,
+    ) else {
+        println!("No path found");
+        return Ok(());
+    };
+
+    println!("Path found (cost {cost}, length {}):", path.len());
+    for page in path {
+        let page = graph.node_weight(page).unwrap();
+        if page.redirect {
+            println!(" v {:?}", page.title);
+        } else {
+            println!(" - {:?}", page.title);
+        }
+    }
+
+    Ok(())
+}