home: vim: git: use lua in hunk mappings

I thought the partial staging feature had broken, but it looks to be
unrelated [1].

[1]: https://github.com/lewis6991/gitsigns.nvim/issues/1088

modules/home/vim/plugin/settings/git.lua

@@ -1,6 +1,29 @@
 local gitsigns = require("gitsigns")
 local wk = require("which-key")
 
+--- Transform `f` into a function which acts on the current visual selection
+local function make_visual(f)
+    return function()
+        local first = vim.fn.line("v")
+        local last = vim.fn.line(".")
+        f({ first, last })
+    end
+end
+
+local function nav_hunk(dir)
+    return function()
+        if vim.wo.diff then
+            local map = {
+                prev = "[c",
+                next = "]c",
+            }
+            vim.cmd.normal({ map[dir], bang = true })
+        else
+            gitsigns.nav_hunk(dir)
+        end
+    end
+end
+
 gitsigns.setup({
     current_line_blame_opts = {
         -- Show the blame quickly
@@ -10,8 +33,8 @@ gitsigns.setup({
 
 local keys = {
     -- Navigation
-    ["[c"] = { "&diff ? '[c' : '<cmd>Gitsigns prev_hunk<CR>'", "Previous hunk/diff", expr = true },
-    ["]c"] = { "&diff ? ']c' : '<cmd>Gitsigns next_hunk<CR>'", "Next hunk/diff", expr = true },
+    ["[c"] = { nav_hunk("prev"), "Previous hunk/diff" },
+    ["]c"] = { nav_hunk("next"), "Next hunk/diff" },
 
     -- Commands
     ["<leader>g"] = {
@@ -46,10 +69,10 @@ local visual = {
     -- Only the actual command can make use of the visual selection...
     ["<leader>g"] = {
         name = "Git",
-        p = { ":Gitsigns preview_hunk<CR>", "Preview selection" },
-        r = { ":Gitsigns reset_hunk<CR>", "Restore selection" },
-        s = { ":Gitsigns stage_hunk<CR>", "Stage selection" },
-        u = { ":Gitsigns undo_stage_hunk<CR>", "Undo stage selection" },
+        p = { gitsigns.preview_hunk, "Preview selection" },
+        r = { make_visual(gitsigns.reset_hunk), "Restore selection" },
+        s = { make_visual(gitsigns.stage_hunk), "Stage selection" },
+        u = { gitsigns.undo_stage_hunk, "Undo stage selection" },
     },
 }