"""Tests for the main-window UI contract.

Covers:

* Single-tab panes show no close button; a second tab restores it on every
  tab; removing the second tab hides it again.
* Default splitter sizes give the right (ISO) pane a non-zero width on
  first launch and keep the transfer column narrow.
* Toolbar and pane column-sizing contracts.

Requires PySide6 + pycdlib; skipped otherwise.
"""

from __future__ import annotations

import os
import sys
from pathlib import Path

import pytest

# Skip the entire module if PySide6 or pycdlib isn't installed -- the
# rest of the test suite (test_deps.py) must still run.
PySide6 = pytest.importorskip("PySide6")
pycdlib = pytest.importorskip("pycdlib")

from PySide6.QtWidgets import QApplication, QHeaderView, QTabBar, QToolBar, QWidget

# Make the project root importable.
ROOT = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(ROOT))

# Construct a single QApplication for all tests in this module.
@pytest.fixture(scope="module")
def qapp():
    os.environ.setdefault("QT_QPA_PLATFORM", "offscreen")
    app = QApplication.instance() or QApplication([])
    yield app


@pytest.fixture
def main_window(qapp):
    from iso_scalpel.main_window import MainWindow
    win = MainWindow()
    yield win
    win.close()


# ==========================================================================
# Single-tab close button is hidden
# ==========================================================================
class TestPaneTabBarCloseButton:
    """The close-button hiding is deferred to the next event-loop
    iteration (via ``QTimer.singleShot(0, ...)``) so it doesn't
    interfere with Qt's internal tab-insert/remove layout.  Tests must
    call ``qapp.processEvents()`` to let the deferred call run before
    asserting on the button state.
    """

    def test_single_tab_has_no_close_button(self, main_window, qapp):
        """The screenshot showed a confusing red 'X' next to the 'FS' tab
        on a single-tab pane.  The close button must be None when there
        is only one tab.
        """
        qapp.processEvents()  # let deferred _refresh_close_button run
        tb = main_window._left_tabs.tabBar()
        assert tb.count() == 1
        assert tb.tabButton(0, QTabBar.RightSide) is None

    def test_two_tabs_have_close_buttons(self, main_window, qapp):
        """When a second tab is added, every tab must show its close
        button (so the user can close either one).
        """
        qapp.processEvents()
        tb = main_window._left_tabs.tabBar()
        extra = QWidget()
        main_window._left_tabs.addTab(extra, "FS2")
        qapp.processEvents()  # let deferred _refresh_close_button run
        try:
            assert tb.count() == 2
            assert tb.tabButton(0, QTabBar.RightSide) is not None
            assert tb.tabButton(1, QTabBar.RightSide) is not None
        finally:
            # Clean up so other tests see a clean state.
            main_window._left_tabs.removeTab(1)
            qapp.processEvents()

    def test_close_button_hidden_again_after_removing_second_tab(self, main_window, qapp):
        """Removing the second tab must re-hide the close button on the
        lone remaining tab.
        """
        qapp.processEvents()
        tb = main_window._left_tabs.tabBar()
        extra = QWidget()
        main_window._left_tabs.addTab(extra, "FS2")
        qapp.processEvents()
        assert tb.tabButton(0, QTabBar.RightSide) is not None
        main_window._left_tabs.removeTab(1)
        qapp.processEvents()  # let deferred _refresh_close_button run
        assert tb.count() == 1
        assert tb.tabButton(0, QTabBar.RightSide) is None


# ==========================================================================
# Default splitter sizes
# ==========================================================================
class TestSplitterSizes:
    def test_splitter_has_three_sections(self, main_window):
        """Splitter must have 3 sections: left pane, transfer column, right pane."""
        assert main_window._splitter.count() == 3

    def test_transfer_column_section_is_narrow(self, main_window):
        """The middle transfer column must stay narrow (<= 50px) so the
        two panes get the bulk of the width.
        """
        sizes = main_window._splitter.sizes()
        assert sizes[1] <= 50, f"transfer column too wide: {sizes[1]}"

    def test_right_pane_gets_nonzero_width(self, main_window):
        """Critical: the right (ISO) pane must get a non-zero initial
        width -- this was the regression that made the right pane appear
        blank/missing in the screenshot.
        """
        sizes = main_window._splitter.sizes()
        assert sizes[2] > 100, f"right pane too narrow: {sizes[2]}"

    def test_panes_split_width_roughly_equally(self, main_window):
        """Both panes should get roughly equal widths so neither side is
        starved when the window is resized.
        """
        sizes = main_window._splitter.sizes()
        left, _mid, right = sizes
        # Allow up to 40% asymmetry (in case one pane has a slightly
        # different min-size hint), but they should be in the same order
        # of magnitude.
        assert left > 80 and right > 80
        ratio = min(left, right) / max(left, right)
        assert ratio > 0.6, f"panes not balanced: left={left}, right={right}, ratio={ratio:.2f}"


# ==========================================================================
# Boot Image action has an icon
# ==========================================================================
class TestToolbarIcons:
    def test_boot_action_has_icon(self, main_window):
        """The 'Boot Image…' toolbar button was text-only in the
        screenshot, inconsistent with the other toolbar buttons.  It
        must now carry a standard icon.
        """
        assert not main_window.act_boot.icon().isNull(), (
            "Boot Image action should have a non-null icon"
        )


# ==========================================================================
# FsPane column sizing
# ==========================================================================
class TestFsPaneColumns:
    def test_name_column_uses_stretch_mode(self, main_window):
        """The Name column must use Stretch so it fills available width
        and the other columns (Size, Type, Date Modified) aren't cramped.
        """
        hdr = main_window._fs_pane.view.header()
        assert hdr.sectionResizeMode(0) == QHeaderView.Stretch

    def test_size_column_uses_resize_to_contents(self, main_window):
        """The Size column should auto-fit its contents (regression: in
        the screenshot the Date Modified column was cramped because all
        columns used the default Interactive mode).
        """
        hdr = main_window._fs_pane.view.header()
        if hdr.count() >= 2:
            assert hdr.sectionResizeMode(1) == QHeaderView.ResizeToContents


# ==========================================================================
# Directional transfer buttons
# ==========================================================================
class TestTransferColumn:
    """The transfer column carries two directional buttons:
    ``→`` (Add, FS→ISO) and ``←`` (Extract, ISO→FS).

    The column is narrow (36px) and both buttons disable when no image is
    open.  These tests verify the structure and wiring.
    """

    def test_transfer_column_exists(self, main_window):
        from iso_scalpel.main_window import _TransferColumn
        assert isinstance(main_window._transfer_col, _TransferColumn)

    def test_add_button_uses_right_arrow(self, main_window):
        """The Add button must use a right-pointing arrow → to make the
        data-flow direction (FS → ISO) unambiguous.
        """
        assert main_window._transfer_col.add_btn.text() == "→"

    def test_extract_button_uses_left_arrow(self, main_window):
        """The Extract button must use a left-pointing arrow ← to make
        the data-flow direction (ISO → FS) unambiguous.
        """
        assert main_window._transfer_col.extract_btn.text() == "←"

    def test_transfer_column_is_narrow(self, main_window):
        """The transfer column must be narrow (36px) so the two panes
        flanking it get the bulk of the splitter width -- this is what
        eliminates the 'orphaned icon in a sea of empty space' problem.
        """
        assert main_window._transfer_col.maximumWidth() == 36

    def test_transfer_buttons_disabled_when_no_image_open(self, main_window):
        """Both transfer buttons must be disabled when no ISO image is
        open, since Add/Extract require an open image to operate on.
        """
        # MainWindow starts with no image open.
        assert not main_window._handler.is_open
        assert not main_window._transfer_col.add_btn.isEnabled()
        assert not main_window._transfer_col.extract_btn.isEnabled()

    def test_swap_button_absent(self, main_window):
        """No ``_swap_btn`` attribute exists on the main window; the
        directional transfer column is the sole on-screen swap surface.
        """
        assert not hasattr(main_window, "_swap_btn"), (
            "_swap_btn must not exist; the transfer column is the on-screen swap surface"
        )

    def test_swap_action_still_exists_for_keyboard(self, main_window):
        """The swap_panes() method and act_swap action remain bound so
        Ctrl+Shift+X and the Navigate menu keep working.
        """
        assert hasattr(main_window, "swap_panes")
        assert hasattr(main_window, "act_swap")
        # Verify the keyboard shortcut is bound.
        from PySide6.QtGui import QKeySequence
        assert main_window.act_swap.shortcut() == QKeySequence("Ctrl+Shift+X")


# ==========================================================================
# Toolbar omits the swap action
# ==========================================================================
class TestToolbarNoSwap:
    def test_swap_action_not_in_toolbar(self, main_window):
        """The swap action is absent from every toolbar -- the directional
        transfer buttons in the splitter gutter cover on-screen swap, and a
        duplicate toolbar entry would be ambiguous.
        """
        toolbars = main_window.findChildren(QToolBar)
        assert toolbars, "expected at least one toolbar"
        for tb in toolbars:
            actions = tb.actions()
            assert main_window.act_swap not in actions, (
                "swap action must not appear in any toolbar"
            )


# ==========================================================================
# Filter boxes have a max width so they don't stretch on large windows
# ==========================================================================
class TestFilterBoxMaxWidth:
    def test_fs_pane_filter_has_max_width(self, main_window):
        """The FS pane filter box must have a maximum width so it
        doesn't stretch absurdly wide on large windows -- the breadcrumb
        bar should get the bulk of the horizontal space.
        """
        max_w = main_window._fs_pane.filter_edit.maximumWidth()
        assert 100 <= max_w <= 300, f"unreasonable max width: {max_w}"

    def test_iso_pane_filter_has_max_width(self, main_window):
        """Same for the ISO pane filter box."""
        max_w = main_window._iso_pane.filter_edit.maximumWidth()
        assert 100 <= max_w <= 300, f"unreasonable max width: {max_w}"