Implement new graph data structure and dijkstra

brood/src/commands/path2.rs

@@ -0,0 +1,77 @@
+use std::{
+    fs::File,
+    io::{self, BufReader},
+    path::Path,
+};
+
+use crate::{
+    algo::Dijkstra,
+    data::{info::PageInfo, store},
+    graph::{Graph, NodeIdx},
+    util,
+};
+
+pub fn find_index_of_title(pages: &[PageInfo], title: &str) -> NodeIdx {
+    let title = util::normalize_link(title);
+    pages
+        .iter()
+        .enumerate()
+        .find(|(_, p)| util::normalize_link(&p.title) == title)
+        .map(|(i, _)| NodeIdx::new(i))
+        .expect("invalid title")
+}
+
+pub fn resolve_redirects(pages: &[PageInfo], graph: &Graph, mut page: NodeIdx) -> NodeIdx {
+    loop {
+        if pages[page.usize()].redirect {
+            if let Some(next) = graph.edges_for(page).first() {
+                page = *next;
+                continue;
+            }
+        }
+
+        return page;
+    }
+}
+
+pub fn path(datafile: &Path, start: &str, goal: &str) -> io::Result<()> {
+    println!(">> Import");
+    let mut databuf = BufReader::new(File::open(datafile)?);
+    let (pages, _links, graph) = store::read_graph(&mut databuf)?;
+
+    println!(">> Locate from and to");
+    let start = resolve_redirects(&pages, &graph, find_index_of_title(&pages, start));
+    let goal = resolve_redirects(&pages, &graph, find_index_of_title(&pages, goal));
+    println!("Start: {:?}", pages[start.usize()].title);
+    println!("Goal:  {:?}", pages[goal.usize()].title);
+
+    println!(">> Find path");
+    println!("> Preparing dijkstra");
+    let mut dijkstra = Dijkstra::new(&graph);
+    println!("> Running dijkstra");
+    dijkstra.run(
+        start,
+        |node| node == goal,
+        |source, _edge, _target| !pages[source.usize()].redirect as u32,
+    );
+
+    if dijkstra.cost(goal) == u32::MAX {
+        println!("No path found");
+        return Ok(());
+    }
+
+    println!("> Collecting path");
+    let path = dijkstra.path(goal);
+    let cost = dijkstra.cost(goal);
+    println!("Path found (cost {cost}, length {}):", path.len());
+    for page in path {
+        let info = &pages[page.usize()];
+        if info.redirect {
+            println!(" v {:?}", info.title);
+        } else {
+            println!(" - {:?}", info.title);
+        }
+    }
+
+    Ok(())
+}