neiam /gitgud

defmodule GitGud.GitTest do
  use ExUnit.Case, async: true

  alias GitGud.Git

  @moduletag :git_required

  setup do
    if System.find_executable("git") == nil do
      {:skip, "git not on PATH"}
    else
      dir =
        Path.join(System.tmp_dir!(), "gitgud-git-test-#{System.unique_integer([:positive])}")

      on_exit(fn -> _ = File.rm_rf(dir) end)
      File.mkdir_p!(dir)
      {:ok, dir: dir}
    end
  end

  test "init_bare creates a bare repo", %{dir: dir} do
    assert :ok = Git.init_bare(dir)
    assert File.exists?(Path.join(dir, "HEAD"))
    assert File.exists?(Path.join(dir, "objects"))
  end

  test "round-trip blob + tree + commit via plumbing", %{dir: dir} do
    :ok = Git.init_bare(dir)

    # Write a blob via tempfile.
    tmp = Path.join(System.tmp_dir!(), "git-test-blob-#{System.unique_integer([:positive])}")
    File.write!(tmp, "hello\n")
    on_exit(fn -> _ = File.rm(tmp) end)

    {hex_blob, 0} =
      System.cmd("git", ["-C", dir, "hash-object", "-w", tmp], stderr_to_stdout: false)

    {:ok, blob_sha} = Git.from_hex(String.trim(hex_blob))

    assert {:ok, meta} = Git.blob_meta(dir, blob_sha)
    assert meta.size == 6
    assert meta.is_binary == false

    # Build a tree with that blob and commit it.
    index = Path.join(System.tmp_dir!(), "git-test-index-#{System.unique_integer([:positive])}")
    on_exit(fn -> _ = File.rm(index) end)

    {_, 0} =
      System.cmd(
        "git",
        [
          "-C",
          dir,
          "update-index",
          "--add",
          "--cacheinfo",
          "100644," <> Git.to_hex(blob_sha) <> ",hello.txt"
        ],
        env: [{"GIT_INDEX_FILE", index}]
      )

    {tree_hex, 0} =
      System.cmd("git", ["-C", dir, "write-tree"], env: [{"GIT_INDEX_FILE", index}])

    {:ok, tree_sha} = Git.from_hex(String.trim(tree_hex))

    assert {:ok, commit_sha} =
             Git.commit_tree(dir, tree_sha, [], "initial",
               author: {"Test", "test@example.com", DateTime.utc_now(:second)}
             )

    assert :ok = Git.update_ref(dir, "refs/heads/main", commit_sha, nil)

    # List refs picks it up.
    assert {:ok, refs} = Git.list_refs(dir)
    assert Enum.any?(refs, &(&1.name == "refs/heads/main" and &1.target_sha == commit_sha))

    # tree() returns the entry we put in.
    assert {:ok, entries} = Git.tree(dir, tree_sha)
    assert [%{name: "hello.txt", type: "blob", sha: ^blob_sha}] = entries
  end
end