feat(git/cmd): make :G diff output navigable

lua/git/object.lua

@@ -221,7 +221,7 @@ function M.read_uri(buf)
     local state = r:state(buf) --[[@as -nil]]
 
     vim.bo[buf].swapfile = false
-    vim.bo[buf].bufhidden = "hide"
+    vim.bo[buf].bufhidden = "delete"
 
     local rev_sha = r:rev_parse(rev:format(), true)
     if not rev_sha then
@@ -284,42 +284,53 @@ local function refresh(buf, r)
 end
 
 ---@param r ow.Git.Repo
----@param blob string?
+---@param ref string?  -- nil = worktree, ":" = index, else commit/sha
 ---@param path string
----@param sha string
+---@param blob string?  -- diff section blob hash; if zero, side has no content
 ---@return integer?
-local function blob_buf(r, blob, path, sha)
-    if is_zero(blob) then
+local function side_buf(r, ref, path, blob)
+    if blob and is_zero(blob) then
         return nil
     end
-    return M.buf_for(r, Revision.new({ base = sha, path = path }))
+    if ref == nil then
+        local p = vim.fs.joinpath(r.worktree, path)
+        if not vim.uv.fs_stat(p) then
+            return nil
+        end
+        local buf = vim.fn.bufadd(p)
+        vim.fn.bufload(buf)
+        return buf
+    end
+    local rev = ref == ":" and Revision.new({ stage = 0, path = path })
+        or Revision.new({ base = ref, path = path })
+    return M.buf_for(r, rev)
 end
 
 ---@param r ow.Git.Repo
----@param blob string?
+---@param ref string?
 ---@param path string
----@param sha string
-local function load_blob(r, blob, path, sha)
-    local buf = blob_buf(r, blob, path, sha)
+---@param blob string?
+local function load_side(r, ref, path, blob)
+    local buf = side_buf(r, ref, path, blob)
     if not buf then
-        util.error("no content for %s at %s", path, sha)
+        util.error("no content for %s", path)
         return
     end
     vim.cmd.normal({ "m'", bang = true })
     vim.api.nvim_set_current_buf(buf)
 end
 
----@param s ow.Git.Repo.BufState
+---@param r ow.Git.Repo
+---@param left_ref string?
+---@param right_ref string?
 ---@param section ow.Git.DiffSection
-local function open_section(s, section)
+local function open_section(r, left_ref, right_ref, section)
     if not section.blob_a or not section.blob_b then
         util.error("no index line, cannot determine blob SHAs")
         return
     end
-    local parent = s.parent_sha or "0"
-    local left = blob_buf(s.repo, section.blob_a, section.path_a, parent)
-    local right =
-        blob_buf(s.repo, section.blob_b, section.path_b, s.sha --[[@as string]])
+    local left = side_buf(r, left_ref, section.path_a, section.blob_a)
+    local right = side_buf(r, right_ref, section.path_b, section.blob_b)
     if left and right then
         require("git.diff").open(left, right, true)
         return
@@ -359,56 +370,68 @@ end
 ---@return boolean dispatched
 function M.open_under_cursor()
     local s = repo.state()
-    if not s or not s.sha then
+    if not s then
         return false
     end
 
     local line = vim.api.nvim_get_current_line()
     local r = s.repo
 
-    local sha = line:match("^commit (%x+)$")
-        or line:match("^parent (%x+)$")
-        or line:match("^tree (%x+)$")
-        or line:match("^object (%x+)$")
-    if sha then
-        M.open(r, sha, { split = false })
-        return true
+    if s.sha and not s.left_ref then
+        local sha = line:match("^commit (%x+)$")
+            or line:match("^parent (%x+)$")
+            or line:match("^tree (%x+)$")
+            or line:match("^object (%x+)$")
+        if sha then
+            M.open(r, sha, { split = false })
+            return true
+        end
+
+        local entry_type, entry_sha, entry_name =
+            line:match("^%d+ (%w+) (%x+)\t(.+)$")
+        if entry_sha then
+            local nav_rev = entry_type == "blob"
+                    and Revision.new({ base = s.sha, path = entry_name }):format()
+                or entry_sha
+            M.open(r, nav_rev, { split = false })
+            return true
+        end
     end
 
-    local entry_type, entry_sha, entry_name =
-        line:match("^%d+ (%w+) (%x+)\t(.+)$")
-    if entry_sha then
-        local nav_rev = entry_type == "blob"
-                and Revision.new({ base = s.sha, path = entry_name }):format()
-            or entry_sha
-        M.open(r, nav_rev, { split = false })
-        return true
+    local left_ref, right_ref
+    if s.left_ref then
+        left_ref = s.left_ref
+        right_ref = s.right_ref
+    elseif s.sha then
+        left_ref = s.parent_sha or "0"
+        right_ref = s.sha
+    else
+        return false
     end
 
     local section = diff_section()
     if not section then
         return false
     end
-    local parent = s.parent_sha or "0"
 
     if line:match("^diff %-%-git ") then
-        open_section(s, section)
+        open_section(r, left_ref, right_ref, section)
         return true
     end
     if line:match("^%-%-%- ") then
-        load_blob(r, section.blob_a, section.path_a, parent)
+        load_side(r, left_ref, section.path_a, section.blob_a)
         return true
     end
     if line:match("^%+%+%+ ") then
-        load_blob(r, section.blob_b, section.path_b, s.sha --[[@as string]])
+        load_side(r, right_ref, section.path_b, section.blob_b)
         return true
     end
     local prefix = line:sub(1, 1)
     if prefix == "+" then
-        load_blob(r, section.blob_b, section.path_b, s.sha --[[@as string]])
+        load_side(r, right_ref, section.path_b, section.blob_b)
         return true
     elseif prefix == "-" then
-        load_blob(r, section.blob_a, section.path_a, parent)
+        load_side(r, left_ref, section.path_a, section.blob_a)
         return true
     end
     return false