refactor(git): rewrite diff module around :diffsplit

plugin/git.lua

@@ -142,22 +142,18 @@ end
 
 local DIFF_DIRECTIONS = { "vertical", "horizontal" }
 
-local function default_vertical()
-    return vim.tbl_contains(vim.opt.diffopt:get(), "vertical")
-end
-
 vim.api.nvim_create_user_command("Gdiffsplit", function(opts)
     local fargs = opts.fargs
-    local vertical = default_vertical()
+    local mods = nil
     local rev_idx = 1
     if fargs[1] == "vertical" then
-        vertical = true
+        mods = { vertical = true }
         rev_idx = 2
     elseif fargs[1] == "horizontal" then
-        vertical = false
+        mods = { vertical = false }
         rev_idx = 2
     end
-    require("git.diff").split({ rev = fargs[rev_idx], vertical = vertical })
+    require("git.diff").split({ target = fargs[rev_idx], mods = mods })
 end, {
     nargs = "*",
     complete = function(arg_lead, cmd_line, _)
@@ -219,16 +215,22 @@ vim.keymap.set("n", "<Plug>(git-edit)", function()
 end, { silent = true, desc = "Edit a git object" })
 
 vim.keymap.set("n", "<Plug>(git-diff-vertical)", function()
-    require("git.diff").split({ vertical = true })
+    require("git.diff").split({ mods = { vertical = true } })
 end, { silent = true, desc = "Diff against index (vertical)" })
 vim.keymap.set("n", "<Plug>(git-diff-horizontal)", function()
-    require("git.diff").split({ vertical = false })
+    require("git.diff").split({ mods = { vertical = false } })
 end, { silent = true, desc = "Diff against index (horizontal)" })
 vim.keymap.set("n", "<Plug>(git-diff-vertical-head)", function()
-    require("git.diff").split({ rev = "HEAD", vertical = true })
+    require("git.diff").split({
+        target = "HEAD",
+        mods = { vertical = true },
+    })
 end, { silent = true, desc = "Diff against HEAD (vertical)" })
 vim.keymap.set("n", "<Plug>(git-diff-horizontal-head)", function()
-    require("git.diff").split({ rev = "HEAD", vertical = false })
+    require("git.diff").split({
+        target = "HEAD",
+        mods = { vertical = false },
+    })
 end, { silent = true, desc = "Diff against HEAD (horizontal)" })
 
 vim.keymap.set("n", "<Plug>(git-status-toggle)", function()