"""Round 25: folder highlight while dragging a playlist.

Hovering a folder mid-drag lights it up so the user can see the drop would
land inside it (previously there was no indication at all). A folder in the
dragged row's own branch is never highlighted — the manager rejects that drop
as a cycle, so lighting it up would lie. The autoscroll tick's highlight
refresh is now kind-aware so a folder highlight survives edge auto-scrolling.

Synthetic QDropEvents report source() == None, so the internal-move branch of
dragMoveEvent can't be driven directly; _highlight_drop_target carries the
logic and is what gets tested.
"""

from PyQt6.QtCore import QPoint

from lintunes.models import Library, Track
from lintunes.library_manager import LibraryManager
from lintunes.gui.sidebar import PlaylistTree


def _tree(qapp, tmp_path, height=400):
    library = Library(tracks={1: Track(track_id=1, name="One")})
    manager = LibraryManager(library, tmp_path)
    tree = PlaylistTree(manager)
    tree.resize(200, height)
    tree.show()
    return manager, tree


def _pos_over(tree, item) -> QPoint:
    return tree.visualItemRect(item).center()


class TestFolderHighlight:
    def test_folder_highlighted_while_dragging_playlist(self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path)
        folder = manager.create_folder("a folder")
        playlist = manager.create_playlist("a playlist")
        folder_item = tree._find_item(folder.persistent_id)
        tree.setCurrentItem(tree._find_item(playlist.persistent_id))

        tree._highlight_drop_target(_pos_over(tree, folder_item), "folder")
        assert tree._drop_target is folder_item

    def test_leaving_the_folder_clears_the_highlight(self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path)
        folder = manager.create_folder("a folder")
        playlist = manager.create_playlist("a playlist")
        folder_item = tree._find_item(folder.persistent_id)
        tree.setCurrentItem(tree._find_item(playlist.persistent_id))

        tree._highlight_drop_target(_pos_over(tree, folder_item), "folder")
        assert tree._drop_target is not None
        # Hover empty space below the rows (drop there = top level).
        tree._highlight_drop_target(
            QPoint(10, tree.viewport().height() - 2), "folder")
        assert tree._drop_target is None

    def test_playlist_row_is_not_a_folder_target(self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path)
        playlist = manager.create_playlist("a playlist")
        other = manager.create_playlist("another playlist")
        tree.setCurrentItem(tree._find_item(other.persistent_id))

        tree._highlight_drop_target(
            _pos_over(tree, tree._find_item(playlist.persistent_id)), "folder")
        assert tree._drop_target is None

    def test_dragged_folder_cannot_drop_into_its_own_branch(
            self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path)
        outer = manager.create_folder("a outer")
        inner = manager.create_folder("b inner", outer.persistent_id)
        other = manager.create_folder("c other")
        outer_item = tree._find_item(outer.persistent_id)
        inner_item = tree._find_item(inner.persistent_id)
        other_item = tree._find_item(other.persistent_id)
        outer_item.setExpanded(True)
        tree.setCurrentItem(outer_item)  # dragging "outer"

        # Onto itself: no highlight (manager would no-op the drop).
        tree._highlight_drop_target(_pos_over(tree, outer_item), "folder")
        assert tree._drop_target is None
        # Into its own subfolder: no highlight (manager rejects the cycle).
        tree._highlight_drop_target(_pos_over(tree, inner_item), "folder")
        assert tree._drop_target is None
        # Into an unrelated folder: highlighted.
        tree._highlight_drop_target(_pos_over(tree, other_item), "folder")
        assert tree._drop_target is other_item

    def test_track_drag_still_highlights_playlists(self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path)
        folder = manager.create_folder("a folder")
        playlist = manager.create_playlist("a playlist")
        folder_item = tree._find_item(folder.persistent_id)
        playlist_item = tree._find_item(playlist.persistent_id)

        tree._highlight_drop_target(_pos_over(tree, playlist_item), "playlist")
        assert tree._drop_target is playlist_item
        # Folders are not track-drop targets.
        tree._highlight_drop_target(_pos_over(tree, folder_item), "playlist")
        assert tree._drop_target is None


class TestKindAwareTick:
    def test_tick_clears_folder_highlight_scrolled_out_from_under_cursor(
            self, qapp, tmp_path):
        manager, tree = _tree(qapp, tmp_path, height=100)
        folder = manager.create_folder("aaa folder")  # sorts to the top row
        dragged = None
        for i in range(60):
            dragged = manager.create_playlist(f"playlist {i}")
        tree.setCurrentItem(tree._find_item(dragged.persistent_id))
        tree.scrollToTop()  # setCurrentItem scrolled the dragged row into view

        pos = _pos_over(tree, tree._find_item(folder.persistent_id))
        tree._highlight_drop_target(pos, "folder")
        assert tree._drop_target is not None

        # Cursor held still over that spot while the edge auto-scroll rolls:
        # the folder scrolls away and a non-target row takes its place.
        tree._drag_target_kind = "folder"
        tree._autoscroll_pos = pos
        tree._autoscroll_dir = 1
        assert tree.verticalScrollBar().value() == 0
        tree._autoscroll_tick()

        assert tree.verticalScrollBar().value() == 1
        assert tree._drop_target is None

    def test_stop_autoscroll_resets_drag_target_kind(self, qapp, tmp_path):
        _manager, tree = _tree(qapp, tmp_path)
        tree._drag_target_kind = "folder"
        tree._stop_autoscroll()
        assert tree._drag_target_kind is None