"""Round 38: one merge window, and play counts that can't conflict.

Two bugs stacked fifteen "Synced changes merged" windows on the desktop: the
dialog was never reused, and playing a song rewrote all 15 MB of library.json —
so Syncthing produced a conflict file roughly once per track. The dialog is now
a session-long log, and play counts live in per-machine journal files that only
their owner ever writes.
"""
from datetime import datetime

import pytest

from lintunes.storage.conflict_resolver import ConflictSummary


def _summary(file="library.json", lines=("2 track(s) reconciled.",), backup="/b/1"):
    return ConflictSummary(file, "library", list(lines), backup)


@pytest.fixture
def dialog_cls(qapp):
    from lintunes.gui.conflict_dialog import ConflictSummaryDialog
    return ConflictSummaryDialog


class TestOneMergeWindow:
    def test_second_merge_appends_instead_of_replacing(self, dialog_cls):
        dlg = dialog_cls([_summary(lines=["first merge"])], manager=None)
        dlg.add_event([_summary(lines=["second merge"])])

        text = dlg._body.toPlainText()
        assert "first merge" in text and "second merge" in text
        # Newest first.
        assert text.index("second merge") < text.index("first merge")

    def test_events_are_timestamped_once_there_is_more_than_one(self, dialog_cls):
        dlg = dialog_cls([_summary()], manager=None)
        assert "──" not in dlg._body.toPlainText()  # a lone merge needs no header

        dlg.add_event([_summary()], when=datetime(2026, 8, 20, 18, 42))
        text = dlg._body.toPlainText()
        assert "6:42 PM" in text
        assert "2 merges this session." in dlg._intro.text()

    def test_restore_targets_the_newest_backup_and_names_it(self, dialog_cls):
        dlg = dialog_cls([_summary(backup="/b/old")], manager=None)
        assert dlg._backup_dir == "/b/old"

        dlg.add_event([_summary(backup="/b/new")], when=datetime(2026, 8, 20, 18, 42))
        assert dlg._backup_dir == "/b/new"
        assert dlg._restore_btn.text() == "Restore backup from 6:42 PM"

    def test_empty_event_leaves_the_previous_backup_reachable(self, dialog_cls):
        dlg = dialog_cls([_summary(backup="/b/old")], manager=None)
        dlg.add_event([])
        assert dlg._backup_dir == "/b/old"
        assert dlg._restore_btn.isEnabled()

    def test_no_backup_disables_the_backup_buttons(self, dialog_cls):
        dlg = dialog_cls([_summary(backup="")], manager=None)
        assert not dlg._open_btn.isEnabled()
        assert not dlg._restore_btn.isEnabled()


class TestWindowReuse:
    """MainWindow isn't constructible headless, so exercise the two real methods
    on a minimal QWidget host — that's where the stacking bug lived."""

    @pytest.fixture
    def host(self, qapp):
        from PyQt6.QtWidgets import QWidget
        from lintunes.gui.main_window import MainWindow

        class Host(QWidget):
            _manager = None
            _conflict_dialog = None
            show_conflict_summary = MainWindow.show_conflict_summary
            _on_conflict_dialog_closed = MainWindow._on_conflict_dialog_closed

        return Host()

    def test_repeated_merges_make_exactly_one_dialog(self, host):
        from lintunes.gui.conflict_dialog import ConflictSummaryDialog

        for i in range(15):
            host.show_conflict_summary([_summary(lines=[f"merge {i}"])])

        dialogs = host.findChildren(ConflictSummaryDialog)
        assert len(dialogs) == 1
        text = dialogs[0]._body.toPlainText()
        assert "merge 0" in text and "merge 14" in text

    def test_closing_lets_the_next_merge_open_a_fresh_window(self, host):
        host.show_conflict_summary([_summary()])
        first = host._conflict_dialog
        first.accept()  # "Keep merged"
        assert host._conflict_dialog is None

        host.show_conflict_summary([_summary()])
        assert host._conflict_dialog is not None
        assert host._conflict_dialog is not first