feat(git): trim hunk preview header, focus float on re-invoke

lua/git/hunks.lua

@@ -446,12 +446,9 @@ function M.nav(direction)
 end
 
 ---@param h ow.Git.Hunks.Hunk
----@param state ow.Git.Hunks.BufState
----@return string
-local function build_patch(h, state)
+---@return string[]
+local function hunk_body(h)
     local lines = {
-        "--- a/" .. state.rel,
-        "+++ b/" .. state.rel,
         string.format(
             "@@ -%d,%d +%d,%d @@",
             h.old_start,
@@ -466,6 +463,15 @@ local function build_patch(h, state)
     for _, l in ipairs(h.new_lines) do
         table.insert(lines, "+" .. l)
     end
+    return lines
+end
+
+---@param h ow.Git.Hunks.Hunk
+---@param state ow.Git.Hunks.BufState
+---@return string
+local function build_patch(h, state)
+    local lines = { "--- a/" .. state.rel, "+++ b/" .. state.rel }
+    vim.list_extend(lines, hunk_body(h))
     return table.concat(lines, "\n") .. "\n"
 end
 
@@ -543,16 +549,22 @@ function M.select_hunk(buf)
     vim.api.nvim_win_set_cursor(0, { last, 0 })
 end
 
+local preview_win ---@type integer?
+
 ---@param buf? integer
 function M.preview_hunk(buf)
-    local _, state, h = cursor_hunk(buf)
+    if preview_win and vim.api.nvim_win_is_valid(preview_win) then
+        vim.api.nvim_set_current_win(preview_win)
+        return
+    end
+    local target, state, h = cursor_hunk(buf)
     if not state then
         return
     end
     if not h then
         return
     end
-    local lines = util.split_lines(build_patch(h, state))
+    local lines = hunk_body(h)
     local pbuf = vim.api.nvim_create_buf(false, true)
     vim.api.nvim_buf_set_lines(pbuf, 0, -1, false, lines)
     vim.bo[pbuf].filetype = "diff"
@@ -573,19 +585,33 @@ function M.preview_hunk(buf)
         height = height,
         style = "minimal",
     })
-    vim.api.nvim_create_autocmd({ "CursorMoved", "InsertEnter", "BufLeave" }, {
-        once = true,
-        callback = function()
-            if vim.api.nvim_win_is_valid(win) then
-                vim.api.nvim_win_close(win, true)
-            end
-        end,
-    })
-    vim.keymap.set("n", "q", function()
+    preview_win = win
+
+    local function close()
         if vim.api.nvim_win_is_valid(win) then
             vim.api.nvim_win_close(win, true)
         end
-    end, { buffer = pbuf, nowait = true })
+    end
+    local group =
+        vim.api.nvim_create_augroup("ow.git.hunks.preview", { clear = true })
+    vim.api.nvim_create_autocmd(
+        { "CursorMoved", "CursorMovedI", "InsertEnter" },
+        { group = group, buffer = target, callback = close }
+    )
+    vim.api.nvim_create_autocmd("WinLeave", {
+        group = group,
+        buffer = pbuf,
+        callback = close,
+    })
+    vim.api.nvim_create_autocmd("WinClosed", {
+        group = group,
+        pattern = tostring(win),
+        callback = function()
+            preview_win = nil
+            pcall(vim.api.nvim_del_augroup_by_name, "ow.git.hunks.preview")
+        end,
+    })
+    vim.keymap.set("n", "q", close, { buffer = pbuf, nowait = true })
 end
 
 repo.on("change", function(r, change)