(** Unit tests for Day10_lib.Atomic_swap module.

    These tests verify the atomic swap mechanism for graceful degradation:
    - Successful swaps replace old docs with new
    - Failed builds preserve existing docs
    - Interrupted swaps are recovered on startup *)

let test_dir = ref ""

let setup () =
  let dir = Filename.temp_dir "test-atomic-swap-" "" in
  test_dir := dir;
  (* Create html/p structure *)
  let html_dir = Filename.concat dir "html" in
  let p_dir = Filename.concat html_dir "p" in
  Unix.mkdir html_dir 0o755;
  Unix.mkdir p_dir 0o755;
  html_dir

let teardown () =
  if !test_dir <> "" then begin
    ignore (Sys.command (Printf.sprintf "rm -rf %s" !test_dir));
    test_dir := ""
  end

let write_file path content =
  let oc = open_out path in
  output_string oc content;
  close_out oc

let read_file path =
  let ic = open_in path in
  let content = really_input_string ic (in_channel_length ic) in
  close_in ic;
  content

let file_exists path = Sys.file_exists path

(** Test: cleanup_stale_dirs removes .new directories *)
let test_cleanup_stale_new () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;
  let stale_new = Filename.concat pkg_dir "1.0.0.new" in
  Unix.mkdir stale_new 0o755;
  write_file (Filename.concat stale_new "index.html") "stale content";

  assert (file_exists stale_new);
  Day10_lib.Atomic_swap.cleanup_stale_dirs ~html_dir;
  assert (not (file_exists stale_new));

  teardown ();
  Printf.printf "PASS: test_cleanup_stale_new\n%!"

(** Test: cleanup_stale_dirs removes .old directories *)
let test_cleanup_stale_old () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;
  let stale_old = Filename.concat pkg_dir "1.0.0.old" in
  Unix.mkdir stale_old 0o755;
  write_file (Filename.concat stale_old "index.html") "stale old content";

  assert (file_exists stale_old);
  Day10_lib.Atomic_swap.cleanup_stale_dirs ~html_dir;
  assert (not (file_exists stale_old));

  teardown ();
  Printf.printf "PASS: test_cleanup_stale_old\n%!"

(** Test: cleanup_stale_dirs preserves normal directories *)
let test_cleanup_preserves_normal () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;
  let normal_dir = Filename.concat pkg_dir "1.0.0" in
  Unix.mkdir normal_dir 0o755;
  write_file (Filename.concat normal_dir "index.html") "good content";

  Day10_lib.Atomic_swap.cleanup_stale_dirs ~html_dir;
  assert (file_exists normal_dir);
  assert (read_file (Filename.concat normal_dir "index.html") = "good content");

  teardown ();
  Printf.printf "PASS: test_cleanup_preserves_normal\n%!"

(** Test: get_swap_paths returns correct paths for blessed packages *)
let test_swap_paths_blessed () =
  let html_dir = "/test/html" in
  let staging, final, old = Day10_lib.Atomic_swap.get_swap_paths
    ~html_dir ~pkg:"my-pkg" ~version:"2.0.0" ~blessed:true ~universe:"ignored" in
  assert (staging = "/test/html/p/my-pkg/2.0.0.new");
  assert (final = "/test/html/p/my-pkg/2.0.0");
  assert (old = "/test/html/p/my-pkg/2.0.0.old");
  Printf.printf "PASS: test_swap_paths_blessed\n%!"

(** Test: get_swap_paths returns correct paths for universe packages *)
let test_swap_paths_universe () =
  let html_dir = "/test/html" in
  let staging, final, old = Day10_lib.Atomic_swap.get_swap_paths
    ~html_dir ~pkg:"my-pkg" ~version:"2.0.0" ~blessed:false ~universe:"abc123" in
  assert (staging = "/test/html/u/abc123/my-pkg/2.0.0.new");
  assert (final = "/test/html/u/abc123/my-pkg/2.0.0");
  assert (old = "/test/html/u/abc123/my-pkg/2.0.0.old");
  Printf.printf "PASS: test_swap_paths_universe\n%!"

(** Test: commit swaps staging to final *)
let test_commit_success () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;

  (* Create staging directory with new content *)
  let staging_dir = Filename.concat pkg_dir "1.0.0.new" in
  Unix.mkdir staging_dir 0o755;
  write_file (Filename.concat staging_dir "index.html") "new content";

  let result = Day10_lib.Atomic_swap.commit ~html_dir ~pkg:"test-pkg" ~version:"1.0.0" ~blessed:true ~universe:"" in
  assert result;

  (* Verify staging was moved to final *)
  let final_dir = Filename.concat pkg_dir "1.0.0" in
  assert (file_exists final_dir);
  assert (read_file (Filename.concat final_dir "index.html") = "new content");
  assert (not (file_exists staging_dir));

  teardown ();
  Printf.printf "PASS: test_commit_success\n%!"

(** Test: commit replaces existing with atomic swap *)
let test_commit_replaces_existing () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;

  (* Create existing final directory with old content *)
  let final_dir = Filename.concat pkg_dir "1.0.0" in
  Unix.mkdir final_dir 0o755;
  write_file (Filename.concat final_dir "index.html") "old content";

  (* Create staging directory with new content *)
  let staging_dir = Filename.concat pkg_dir "1.0.0.new" in
  Unix.mkdir staging_dir 0o755;
  write_file (Filename.concat staging_dir "index.html") "new content";

  let result = Day10_lib.Atomic_swap.commit ~html_dir ~pkg:"test-pkg" ~version:"1.0.0" ~blessed:true ~universe:"" in
  assert result;

  (* Verify old was replaced with new *)
  assert (read_file (Filename.concat final_dir "index.html") = "new content");
  assert (not (file_exists staging_dir));
  (* .old should be cleaned up *)
  assert (not (file_exists (Filename.concat pkg_dir "1.0.0.old")));

  teardown ();
  Printf.printf "PASS: test_commit_replaces_existing\n%!"

(** Test: rollback removes staging, preserves existing *)
let test_rollback_preserves_existing () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;

  (* Create existing final directory *)
  let final_dir = Filename.concat pkg_dir "1.0.0" in
  Unix.mkdir final_dir 0o755;
  write_file (Filename.concat final_dir "index.html") "original content";

  (* Create staging directory (simulating failed build) *)
  let staging_dir = Filename.concat pkg_dir "1.0.0.new" in
  Unix.mkdir staging_dir 0o755;
  write_file (Filename.concat staging_dir "index.html") "incomplete content";

  Day10_lib.Atomic_swap.rollback ~html_dir ~pkg:"test-pkg" ~version:"1.0.0" ~blessed:true ~universe:"";

  (* Verify staging was removed but original preserved *)
  assert (not (file_exists staging_dir));
  assert (file_exists final_dir);
  assert (read_file (Filename.concat final_dir "index.html") = "original content");

  teardown ();
  Printf.printf "PASS: test_rollback_preserves_existing\n%!"

(** Test: commit returns false when staging doesn't exist *)
let test_commit_no_staging () =
  let html_dir = setup () in
  let pkg_dir = Filename.concat (Filename.concat html_dir "p") "test-pkg" in
  Unix.mkdir pkg_dir 0o755;

  let result = Day10_lib.Atomic_swap.commit ~html_dir ~pkg:"test-pkg" ~version:"1.0.0" ~blessed:true ~universe:"" in
  assert (not result);

  teardown ();
  Printf.printf "PASS: test_commit_no_staging\n%!"

let () =
  Printf.printf "Running atomic swap tests...\n%!";
  test_cleanup_stale_new ();
  test_cleanup_stale_old ();
  test_cleanup_preserves_normal ();
  test_swap_paths_blessed ();
  test_swap_paths_universe ();
  test_commit_success ();
  test_commit_replaces_existing ();
  test_rollback_preserves_existing ();
  test_commit_no_staging ();
  Printf.printf "\nAll atomic swap tests passed!\n%!"