import curses
from pathlib import Path

import pytest

from app.navigator import Navigator, VisibleEntry
from app.ui import (
    HistoryLine,
    RenderLine,
    TerminalUI,
    build_history_lines,
    build_render_lines,
    clamp_scroll_offset,
    format_entry,
    move_selection,
    open_terminal_streams,
)


def test_move_selection_stays_within_bounds() -> None:
    assert move_selection(current_index=0, step=-1, entry_count=3) == 0
    assert move_selection(current_index=1, step=1, entry_count=3) == 2
    assert move_selection(current_index=2, step=1, entry_count=3) == 2


def test_format_entry_supports_parent_and_tree_indicators(tmp_path: Path) -> None:
    parent_entry = VisibleEntry(
        name="..",
        path=tmp_path,
        depth=0,
        has_children=True,
        is_expanded=False,
        is_parent=True,
    )
    collapsed_entry = VisibleEntry(
        name="scripts",
        path=tmp_path / "scripts",
        depth=0,
        has_children=True,
        is_expanded=False,
    )
    expanded_child = VisibleEntry(
        name="build",
        path=tmp_path / "scripts" / "build",
        depth=1,
        has_children=False,
        is_expanded=False,
    )

    assert format_entry(parent_entry) == ".."
    assert format_entry(collapsed_entry) == "▶ scripts"
    assert format_entry(expanded_child) == "      build"


def test_build_render_lines_marks_selected_entry(tmp_path: Path) -> None:
    workspace = tmp_path / "workspace"
    workspace.mkdir()
    alpha = workspace / "alpha"
    beta = workspace / "beta"
    alpha.mkdir()
    beta.mkdir()

    navigator = Navigator(workspace)
    navigator.set_selected_index(2)

    assert build_render_lines(navigator) == [
        RenderLine(text="..", is_selected=False),
        RenderLine(text="  alpha", is_selected=False),
        RenderLine(text="  beta", is_selected=True),
    ]


def test_build_history_lines_marks_selected_history_entry(tmp_path: Path) -> None:
    first = tmp_path / "first"
    second = tmp_path / "second"

    assert build_history_lines((first, second), selected_index=1) == [
        HistoryLine(text=str(first), is_selected=False),
        HistoryLine(text=str(second), is_selected=True),
    ]


def test_clamp_scroll_offset_keeps_selection_visible_when_moving_down() -> None:
    assert clamp_scroll_offset(5, scroll_offset=0, visible_count=3, total_count=10) == 3


def test_clamp_scroll_offset_keeps_selection_visible_when_moving_up() -> None:
    assert clamp_scroll_offset(1, scroll_offset=4, visible_count=3, total_count=10) == 1


def test_clamp_scroll_offset_returns_zero_when_all_items_fit() -> None:
    assert clamp_scroll_offset(2, scroll_offset=1, visible_count=5, total_count=3) == 0


def test_toggle_history_mode_selects_current_history_entry(tmp_path: Path) -> None:
    root = tmp_path / "root"
    child = root / "child"
    root.mkdir()
    child.mkdir()

    navigator = Navigator(root)
    navigator.set_selected_index(1)
    navigator.enter_selected_directory()
    ui = TerminalUI()

    ui._toggle_history_mode(navigator)

    assert ui._history_mode is True
    assert ui._history_selected_index == 1


def test_history_mode_enter_selects_entry_and_exits(tmp_path: Path) -> None:
    root = tmp_path / "root"
    first = root / "first"
    second = root / "second"
    root.mkdir()
    first.mkdir()
    second.mkdir()

    navigator = Navigator(root)
    navigator.set_selected_index(1)
    navigator.enter_selected_directory()
    navigator.go_to_parent_directory()
    navigator.set_selected_index(2)
    navigator.enter_selected_directory()

    ui = TerminalUI()
    ui._toggle_history_mode(navigator)
    ui._handle_history_key(curses.KEY_UP, navigator)
    ui._handle_history_key(10, navigator)

    assert ui._history_mode is False
    assert navigator.current_path == root.resolve()
    assert navigator.selected_index == 0


def test_history_mode_toggle_off_keeps_current_directory(tmp_path: Path) -> None:
    root = tmp_path / "root"
    root.mkdir()
    navigator = Navigator(root)
    ui = TerminalUI()

    ui._toggle_history_mode(navigator)
    ui._toggle_history_mode(navigator)

    assert ui._history_mode is False
    assert navigator.current_path == root.resolve()


def test_right_arrow_expands_collapsed_directory(tmp_path: Path) -> None:
    workspace = tmp_path / "workspace"
    scripts = workspace / "scripts"
    build = scripts / "build"
    workspace.mkdir()
    scripts.mkdir()
    build.mkdir()

    navigator = Navigator(workspace)
    navigator.set_selected_index(1)
    ui = TerminalUI()

    assert ui._handle_tree_key(curses.KEY_RIGHT, navigator) is None
    assert navigator.current_path == workspace.resolve()
    assert [entry.name for entry in navigator.visible_entries] == [
        "..",
        "scripts",
        "build",
    ]


def test_right_arrow_enters_already_expanded_directory(tmp_path: Path) -> None:
    workspace = tmp_path / "workspace"
    scripts = workspace / "scripts"
    build = scripts / "build"
    workspace.mkdir()
    scripts.mkdir()
    build.mkdir()

    navigator = Navigator(workspace)
    navigator.set_selected_index(1)
    navigator.expand_selected_directory()
    ui = TerminalUI()

    assert ui._handle_tree_key(curses.KEY_RIGHT, navigator) is None
    assert navigator.current_path == scripts.resolve()
    assert navigator.selected_index == 0


def test_left_arrow_goes_to_parent_when_selected_entry_is_collapsed(
    tmp_path: Path,
) -> None:
    parent = tmp_path / "parent"
    current = parent / "current"
    child = current / "child"
    parent.mkdir()
    current.mkdir()
    child.mkdir()

    navigator = Navigator(current)
    navigator.set_selected_index(1)
    ui = TerminalUI()

    assert ui._handle_tree_key(curses.KEY_LEFT, navigator) is None
    assert navigator.current_path == parent.resolve()
    assert navigator.selected_index == 0


def test_enter_returns_selected_path_without_navigating(tmp_path: Path) -> None:
    workspace = tmp_path / "workspace"
    child = workspace / "child"
    workspace.mkdir()
    child.mkdir()

    navigator = Navigator(workspace)
    navigator.set_selected_index(1)
    ui = TerminalUI()

    result = ui._handle_tree_key(10, navigator)

    assert result == child.resolve()
    assert navigator.current_path == workspace.resolve()


def test_open_terminal_streams_raises_without_terminal(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    def raise_os_error(*args: object, **kwargs: object) -> object:
        raise OSError

    monkeypatch.setattr("builtins.open", raise_os_error)
    monkeypatch.setattr("sys.stdin.isatty", lambda: False)
    monkeypatch.setattr("sys.stderr.isatty", lambda: False)

    with pytest.raises(RuntimeError, match="Interactive terminal is required"):
        with open_terminal_streams():
            pass