refactor(diff): Improve api with lua types and more flexibility

lua/jj/cmd.lua

@@ -975,18 +975,28 @@ function M.register_command()
 		desc = "Execute jj commands with subcommand support",
 	})
 
-	vim.api.nvim_create_user_command("Jdiff", diff.open_vdiff, {
-		nargs = "?",
-		desc = "Diff against jj revision",
-	})
-	vim.api.nvim_create_user_command("Jhdiff", diff.open_hdiff, {
-		nargs = "?",
-		desc = "Horizontal diff against jj revision",
-	})
-	vim.api.nvim_create_user_command("Jvdiff", diff.open_vdiff, {
-		nargs = "?",
-		desc = "Vertical diff against jj revision",
-	})
+	-- Unified creation of jj diff commands with optional revision argument
+	local function create_diff_command(name, fn, desc)
+		vim.api.nvim_create_user_command(name, function(opts)
+			local rev = opts.fargs[1]
+			if rev then
+				fn({ rev = rev })
+			else
+				fn()
+			end
+		end, {
+			nargs = "?",
+			desc = desc .. " (optionally pass jj revision)",
+		})
+	end
+
+	-- Commands:
+	-- Jdiff  : vertical diff by default
+	-- Jhdiff : horizontal diff
+	-- Jvdiff : vertical diff (explicit)
+	create_diff_command("Jdiff", diff.open_vdiff, "Vertical diff against jj revision")
+	create_diff_command("Jhdiff", diff.open_hdiff, "Horizontal diff against jj revision")
+	create_diff_command("Jvdiff", diff.open_vdiff, "Vertical diff against jj revision")
 end
 
 return M

lua/jj/diff.lua

@@ -45,15 +45,20 @@ function M.open_revision(rev, path)
 	vim.api.nvim_win_set_buf(0, buf)
 end
 
+---@class jj.diff.diff_opts
+---@field rev string the revision to diff against
+
 --- Open a diff split for a specific revision of the current file
 --- @param split_fun function Split function for the diff
---- @param args table Any passed arguments
-function M.open_diff(split_fun, args)
+--- @param opts? jj.diff.diff_opts Any passed arguments
+function M.open_diff(split_fun, opts)
 	if not utils.ensure_jj() then
 		return
 	end
 
-	local rev = args[1] or "@-"
+	-- Ensure opts is a table to avoid indexing nil
+	opts = opts or {}
+	local rev = opts.rev or "@-"
 	local path = vim.api.nvim_buf_get_name(0)
 
 	vim.cmd.diffthis()
@@ -62,13 +67,16 @@ function M.open_diff(split_fun, args)
 	vim.cmd.diffthis()
 end
 
+-- Open a vertical diff split for a specific revision of the current file
+--- @param opts? jj.diff.diff_opts Any passed arguments
 function M.open_vdiff(opts)
-	M.open_diff(vim.cmd.vsplit, opts.fargs)
+	M.open_diff(vim.cmd.vsplit, opts)
 end
 
+-- Open a horizontal diff split for a specific revision of the current file
+--- @param opts? jj.diff.diff_opts Any passed arguments
 function M.open_hdiff(opts)
-	M.open_diff(vim.cmd.split, opts.fargs)
+	M.open_diff(vim.cmd.split, opts)
 end
 
 return M
-