Bugfix: Updates Diff Hashes (#106)

Rather than using branch names we are using the hashes provided directly in the Gitlab API response, to compare the point at which the branch diverged from the target to the head commit. We are additionally flashing a warning if the MR contains a merge conflict.

lua/gitlab/reviewer/diffview.lua

@@ -10,8 +10,19 @@ local M = {
 }
 
 M.open = function()
-  vim.api.nvim_command(string.format("DiffviewOpen %s", state.INFO.target_branch))
+  local diff_refs = state.INFO.diff_refs
+  if diff_refs == nil then
+    u.notify("Gitlab did not provide diff refs required to review this MR", vim.log.levels.ERROR)
+    return
+  end
+
+  vim.api.nvim_command(string.format("DiffviewOpen %s..%s", diff_refs.base_sha, diff_refs.head_sha))
   M.tabnr = vim.api.nvim_get_current_tabpage()
+
+  if state.INFO.has_conflicts then
+    u.notify("This merge request has conflicts!", vim.log.levels.WARN)
+  end
+
   local group = vim.api.nvim_create_augroup("gitlab.diffview.autocommand.close", {})
   vim.api.nvim_create_autocmd("User", {
     pattern = { "DiffviewViewClosed" },