log: allow diffing specific revisions

3 files changed, 72 insertions, 33 deletions

diff --git a/src/get_routes.rs b/src/get_routes.rs
index 73c9301..17b7941 100644
--- a/src/get_routes.rs
+++ b/src/get_routes.rs
@@ -1,7 +1,9 @@
 use chrono::NaiveDateTime;
+use git2::Commit;
 use git2::FileMode;
 use git2::ObjectType;
 use git2::Oid;
+use git2::Repository;
 use git2::Tree;
 use git2::TreeEntry;
 use hyper::header;
@@ -166,7 +168,10 @@ fn log_blob<C: Controller>(
         // the very first commit of the branch
         commits.push(prev_commit);
     }
-    page.body.push_str("<div>");
+    page.body.push_str(
+        "<form><input type=hidden name=action value=diff>\
+        <button>Compare selected revisions</button>",
+    );
     let mut prev_date = None;
     for c in commits {
         let date = NaiveDateTime::from_timestamp(c.time().seconds(), 0).date();
@@ -175,50 +180,71 @@ fn log_blob<C: Controller>(
                 page.body.push_str("</ul>");
             }
             page.body.push_str(&format!(
-                "<h2 class=regular-text>{}</h2><ul>",
+                "<h2 class=regular-text>{}</h2><ul class=rev-list>",
                 date.format("%b %d, %Y")
             ));
         }
 
         page.body.push_str(&format!(
-            "<li><a href='?action=diff&id={}'>{}: {}</a></li>",
+            "<li>\
+            <input type=radio name=oldid required value={0}>\
+            <input type=radio name=id required value={0}> ",
+            c.id().to_string()
+        ));
+        page.body.push_str(&format!(
+            "<a href='?action=diff&id={}'>{}: {}</a></li>",
             html_escape(c.id().to_string()),
             html_escape(c.author().name().unwrap_or_default()),
             html_escape(c.summary().unwrap_or_default()),
         ));
         prev_date = Some(date);
     }
-    page.body.push_str("</ul></div>");
+    page.body.push_str("</ul></form>");
     Ok(page.into())
 }
 
 #[derive(Deserialize)]
-struct DiffParam {
+struct DiffParams {
     id: String,
+    oldid: Option<String>,
+}
+
+fn find_commit<'a>(repo: &'a Repository, id: &str, branch_head: &Oid) -> Option<Commit<'a>> {
+    let oid = Oid::from_str(id).ok()?;
+    repo.find_commit(oid)
+        .ok()
+        // disallow viewing commits from other branches you shouldn't have access to
+        .filter(|c| oid == *branch_head || repo.graph_descendant_of(*branch_head, c.id()).unwrap())
 }
 
 fn diff_blob<C: Controller>(
     _entr: TreeEntry,
-    params: ActionParam,
+    action_param: ActionParam,
     controller: &C,
     ctx: Context,
 ) -> Result<Response, Error> {
-    let param: DiffParam = ctx.parts.query()?;
+    let params: DiffParams = ctx.parts.query()?;
     let branch_commit = ctx.branch_head()?;
 
-    let commit = ctx
-        .repo
-        .find_commit(Oid::from_str(&param.id)?)
-        .map_err(|_| Error::NotFound("commit not found".into()))?;
+    let mut commit = find_commit(&ctx.repo, &params.id, &branch_commit.id())
+        .ok_or_else(|| Error::NotFound("commit not found".into()))?;
 
-    if branch_commit.id() != commit.id()
-        && !ctx
-            .repo
-            .graph_descendant_of(branch_commit.id(), commit.id())?
-    {
-        // disallow viewing commits from other branches you shouldn't have access to
-        return Err(Error::NotFound("commit not found".into()));
-    }
+    let old_commit = if let Some(oldid) = &params.oldid {
+        let other_commit = find_commit(&ctx.repo, &oldid, &branch_commit.id())
+            .ok_or_else(|| Error::NotFound("commit not found".into()))?;
+
+        if other_commit.time() > commit.time() {
+            // TODO: redirect instead
+            let c = commit;
+            commit = other_commit;
+            Some(c)
+        } else {
+            Some(other_commit)
+        }
+    } else {
+        // TODO: what if there are multiple parents?
+        commit.parents().next()
+    };
 
     let blob_id = if let Ok(entry) = commit.tree()?.get_path(&ctx.path) {
         entry.id()
@@ -226,36 +252,44 @@ fn diff_blob<C: Controller>(
         return Ok(Page {
             title: format!("Commit for {}", ctx.file_name().unwrap()),
             body: "file removed".into(),
-            header: Some(action_links(&params.action, controller, &ctx)),
+            header: Some(action_links(&action_param.action, controller, &ctx)),
             controller,
             parts: &ctx.parts,
         }
         .into());
     };
 
-    // TODO: what if there are multiple parents?
-    let old_blob_id = commit
-        .parents()
-        .next()
+    let old_blob_id = old_commit
         .and_then(|p| p.tree().unwrap().get_path(&ctx.path).ok())
         .map(|e| e.id());
 
     if Some(blob_id) == old_blob_id {
-        return Err(Error::NotFound("commit not found".into()));
+        return Err(Error::NotFound("no difference".into()));
     }
 
     let mut page = Page {
-        title: format!("Commit for {}", ctx.file_name().unwrap()),
-        header: Some(action_links(&params.action, controller, &ctx)),
-        body: format!(
-            "<h1>{}</h1>{} committed on {}",
-            html_escape(commit.summary().unwrap_or_default()),
-            html_escape(commit.author().name().unwrap_or_default()),
-            NaiveDateTime::from_timestamp(commit.time().seconds(), 0).format("%b %d, %Y, %H:%M")
+        title: format!(
+            "{} for {}",
+            if params.oldid.is_some() {
+                "Diff"
+            } else {
+                "Commit"
+            },
+            ctx.file_name().unwrap()
         ),
+        header: Some(action_links(&action_param.action, controller, &ctx)),
+        body: String::new(),
         controller,
         parts: &ctx.parts,
     };
+    if params.oldid.is_none() {
+        page.body.push_str(&format!(
+            "<h1>{}</h1>{} committed on {}",
+            html_escape(commit.summary().unwrap_or_default()),
+            html_escape(commit.author().name().unwrap_or_default()),
+            NaiveDateTime::from_timestamp(commit.time().seconds(), 0).format("%b %d, %Y, %H:%M")
+        ));
+    }
 
     // TODO: if UTF-8 decoding fails, link ?action=raw&rev=
     if let Some(old_blob_id) = old_blob_id {
diff --git a/src/static/style.css b/src/static/style.css
index a91b9df..0733d56 100644
--- a/src/static/style.css
+++ b/src/static/style.css
@@ -81,6 +81,11 @@ label {
 	font-weight: inherit;
 }
 
+.rev-list {
+	list-style: none;
+	padding-left: 0;
+}
+
 .addition { background: #e6ffed; }
 .deletion { background: #ffeef0; }
 .addition ins {background: #acf2bd; text-decoration: none; }
diff --git a/src/static/style.css.sha256 b/src/static/style.css.sha256
index 434cce7..17a3812 100644
--- a/src/static/style.css.sha256
+++ b/src/static/style.css.sha256
@@ -1 +1 @@
-nNLYarzU1i7D9yDyQw5R+15yNbfgxY838qGt/MH3I0E=
\ No newline at end of file
+pVajQAgXar+xHqEuGZsATyQGTVFvnr82Sf28zZ3g4e0=
\ No newline at end of file