From 8bb94b18470cd2e0c75001c32276d5fe11d87141 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Sat, 22 Oct 2022 19:54:08 +0200
Subject: [PATCH] Allow redirects to have 0 links

---
 brood/src/commands/path.rs | 12 +++++++-----
 brood/src/data.rs          | 19 ++++++++++++++++---
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/brood/src/commands/path.rs b/brood/src/commands/path.rs
index 53bbbad..7207f76 100644
--- a/brood/src/commands/path.rs
+++ b/brood/src/commands/path.rs
@@ -18,12 +18,14 @@ fn find_index_of_title(pages: &[Page<PageInfo>], title: &str) -> u32 {
 
 fn resolve_redirects(data: &AdjacencyList<PageInfo, LinkInfo>, mut page_idx: u32) -> u32 {
     loop {
-        let page = &data.page(page_idx);
-        if page.data.redirect {
-            page_idx = data.link(page.link_idx).to;
-        } else {
-            break page_idx;
+        if data.page(page_idx).data.redirect {
+            if let Some(link_idx) = data.link_redirect(page_idx) {
+                page_idx = data.link(link_idx).to;
+                continue;
+            }
         }
+
+        return page_idx;
     }
 }
 
diff --git a/brood/src/data.rs b/brood/src/data.rs
index 0ab5c78..afca0e1 100644
--- a/brood/src/data.rs
+++ b/brood/src/data.rs
@@ -215,15 +215,18 @@ impl AdjacencyList<PageInfo, LinkInfo> {
             }
         }
 
-        // Check that all redirect pages have exactly one link
+        // Check that all redirect pages have at most one link
         for page_idx in 0..self.pages.len() as u32 - 1 {
             let page = self.page(page_idx);
             if page.data.redirect {
                 let start_idx = page.link_idx;
                 let end_idx = self.page(page_idx + 1).link_idx;
                 let n_links = end_idx - start_idx;
-                if n_links != 1 {
-                    panic!("Redirect {:?} has {n_links} links", page.data.title);
+                if n_links > 1 {
+                    panic!(
+                        "Redirect {:?} has too many ({n_links}) links",
+                        page.data.title
+                    );
                 }
             }
         }
@@ -245,6 +248,16 @@ impl<P, L> AdjacencyList<P, L> {
         start_idx..end_idx
     }
 
+    pub fn link_redirect(&self, page_idx: u32) -> Option<u32> {
+        let start_idx = self.page(page_idx).link_idx;
+        let end_idx = self.page(page_idx + 1).link_idx;
+        if start_idx == end_idx {
+            None
+        } else {
+            Some(start_idx)
+        }
+    }
+
     pub fn link(&self, idx: u32) -> &Link<L> {
         &self.links[idx as usize]
     }