from unittest.mock import patch

import pytest
import torch

# --- Fast tests (no model loading required) ---


def test_app_imports_without_model_load():
    """Importing app should not trigger model download."""
    import app

    assert hasattr(app, "translate")
    assert hasattr(app, "_load_tokenizer")
    assert hasattr(app, "_load_model")


def test_app_has_main_function():
    """main() should be callable (UI construction)."""
    import app

    assert callable(app.main)


def test_translate_accepts_generation_params():
    """translate() signature must accept generation parameters."""
    import inspect

    import app

    sig = inspect.signature(app.translate)
    params = list(sig.parameters.keys())
    assert "max_new_tokens" in params
    assert "num_beams" in params
    assert "temperature" in params


def test_translate_signature_defaults():
    """translate() should have correct default values for generation parameters."""
    import inspect

    import app

    sig = inspect.signature(app.translate)
    assert sig.parameters["max_new_tokens"].default == 512
    assert sig.parameters["num_beams"].default == 1
    assert sig.parameters["temperature"].default == 1.0


def test_get_device_returns_cpu_when_no_cuda():
    """_get_device() should return CPU when CUDA is not available."""
    import app

    with patch("app.torch.cuda.is_available", return_value=False):
        with pytest.warns(UserWarning):
            device = app._get_device()
    assert device.type == "cpu"


def test_get_device_warns_on_cpu():
    """_get_device() should emit a UserWarning when falling back to CPU."""
    import app

    with patch("app.torch.cuda.is_available", return_value=False):
        with pytest.warns(UserWarning, match="No GPU available"):
            app._get_device()


# --- UI component tests ---


@pytest.fixture
def demo():
    import app

    return app._build_demo()


def test_demo_has_no_tabs(demo):
    """Redesigned UI should have no Tab components."""
    tabs = [b for b in demo.blocks.values() if type(b).__name__ == "Tab"]
    assert len(tabs) == 0, f"Expected no tabs, found {len(tabs)}"


def test_demo_has_no_sliders(demo):
    """Redesigned UI should have no Slider components."""
    sliders = [b for b in demo.blocks.values() if type(b).__name__ == "Slider"]
    assert len(sliders) == 0, f"Expected no sliders, found {len(sliders)}"


def test_demo_has_english_dropdown(demo):
    """UI should have a non-interactive English dropdown."""
    dropdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Dropdown"]
    english = [d for d in dropdowns if d.interactive is False and d.value == "English"]
    assert len(english) == 1, "Expected exactly one non-interactive English dropdown"


def test_demo_has_dropdown(demo):
    """UI should have two dropdowns (English + target language)."""
    dropdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Dropdown"]
    assert len(dropdowns) == 2, f"Expected 2 dropdowns, found {len(dropdowns)}"


def test_dropdown_default_is_french(demo):
    """Default dropdown value should be French (fr)."""
    dropdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Dropdown"]
    interactive = [d for d in dropdowns if d.interactive is not False]
    assert interactive[0].value == "French (fr)"


def test_dropdown_is_filterable(demo):
    """Dropdown should be filterable/searchable."""
    dropdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Dropdown"]
    interactive = [d for d in dropdowns if d.interactive is not False]
    assert interactive[0].filterable is True


def test_dropdown_choices_include_locale_codes(demo):
    """Dropdown choices should include locale codes like 'French (fr)'."""
    dropdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Dropdown"]
    interactive = [d for d in dropdowns if d.interactive is not False]
    # Gradio stores choices as (label, value) tuples
    labels = [c[0] if isinstance(c, tuple) else c for c in interactive[0].choices]
    assert all("(" in label and ")" in label for label in labels), f"Expected locale codes in choices: {labels}"


def test_demo_has_two_textboxes(demo):
    """UI should have input and output textboxes."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    assert len(textboxes) == 2, f"Expected 2 textboxes, found {len(textboxes)}"


def test_input_textbox_height(demo):
    """Input textbox should use lines=6."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    interactive = [t for t in textboxes if t.interactive is not False]
    assert interactive[0].lines == 6, f"Expected lines=6, got {interactive[0].lines}"


def test_input_textbox_max_length(demo):
    """Input textbox should enforce 2000 character limit."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    interactive = [t for t in textboxes if t.interactive is not False]
    assert interactive[0].max_length == 2000, f"Expected max_length=2000, got {interactive[0].max_length}"


def test_input_textbox_has_no_placeholder(demo):
    """Input textbox should have no placeholder text."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    interactive = [t for t in textboxes if t.interactive is not False]
    assert interactive[0].placeholder is None, f"Expected no placeholder, got {interactive[0].placeholder!r}"


def test_output_textbox_is_non_interactive(demo):
    """Output textbox should be non-interactive."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    output = [t for t in textboxes if t.interactive is False]
    assert len(output) == 1, "Expected exactly one non-interactive textbox"


def test_output_textbox_height(demo):
    """Output textbox should use lines=6."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    non_interactive = [t for t in textboxes if t.interactive is False]
    assert non_interactive[0].lines == 6, f"Expected lines=6, got {non_interactive[0].lines}"


def test_output_placeholder(demo):
    """Output textbox should have 'Translation' as placeholder."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    output = [t for t in textboxes if t.interactive is False]
    assert output[0].placeholder == "Translation"


def test_demo_has_translate_button(demo):
    """UI should have a Translate button."""
    buttons = [b for b in demo.blocks.values() if type(b).__name__ == "Button"]
    assert any(b.value == "Translate" for b in buttons), "Expected a 'Translate' button"


def _find_ancestor(block, ancestor_type: str):
    """Walk up the parent chain to find the nearest ancestor of a given type."""
    node = getattr(block, "parent", None)
    while node is not None:
        if type(node).__name__ == ancestor_type:
            return node
        node = getattr(node, "parent", None)
    return None


def test_translate_button_in_input_column(demo):
    """Translate button should be in the same column as the input textbox."""
    textboxes = [b for b in demo.blocks.values() if type(b).__name__ == "Textbox"]
    input_tb = [t for t in textboxes if t.interactive is not False][0]
    buttons = [b for b in demo.blocks.values() if type(b).__name__ == "Button" and b.value == "Translate"]
    assert len(buttons) == 1
    input_column = _find_ancestor(input_tb, "Column")
    button_column = _find_ancestor(buttons[0], "Column")
    assert input_column is not None, "Input textbox should be inside a Column"
    assert input_column is button_column, "Translate button should be in the input column"


def test_translate_handlers_wire_text_and_language(demo):
    """Translate click and submit handlers should wire input text and target language."""
    translate_fns = [fn for fn in demo.fns.values() if [type(i).__name__ for i in fn.inputs] == ["Textbox", "Dropdown"]]
    assert len(translate_fns) == 2, f"Expected 2 translate handlers (click + submit), found {len(translate_fns)}"


def test_char_count_handler_exists(demo):
    """Character count handler should wire input text to the HTML info element."""
    char_fns = [
        fn
        for fn in demo.fns.values()
        if [type(i).__name__ for i in fn.inputs] == ["Textbox"] and [type(o).__name__ for o in fn.outputs] == ["HTML"]
    ]
    assert len(char_fns) == 1, f"Expected 1 char count handler, found {len(char_fns)}"


def test_char_count_shows_limit(demo):
    """HTML info element should show '0 / 2,000' format."""
    html_blocks = [b for b in demo.blocks.values() if type(b).__name__ == "HTML"]
    assert any("2,000" in (h.value or "") for h in html_blocks), "Expected '2,000' in an HTML block"


def test_shortcut_hint_exists(demo):
    """HTML info element should include shortcut hint."""
    html_blocks = [b for b in demo.blocks.values() if type(b).__name__ == "HTML"]
    assert any("Press Ctrl+Enter to apply" in (h.value or "") for h in html_blocks), "Expected hint in an HTML block"


def test_no_title(demo):
    """UI should not have an H1 title."""
    markdowns = [b for b in demo.blocks.values() if type(b).__name__ == "Markdown"]
    for md in markdowns:
        assert not md.value.startswith("# "), f"Found unexpected title: {md.value}"


# --- Slow tests (require CUDA + model download) ---

gpu_available = torch.cuda.is_available()


@pytest.fixture(scope="module")
def loaded_app():
    import app

    # Force model/tokenizer loading
    app._load_tokenizer()
    app._load_model()
    return app


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_name_to_code_matches_language_names(loaded_app):
    name_to_code, language_names = loaded_app._build_language_mappings()
    assert set(name_to_code.keys()) == set(language_names)


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_language_names_sorted(loaded_app):
    _, language_names = loaded_app._build_language_mappings()
    assert language_names == sorted(language_names)


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_all_codes_are_bcp47_tokens(loaded_app):
    name_to_code, _ = loaded_app._build_language_mappings()
    for name, code in name_to_code.items():
        assert code.startswith("<2") and code.endswith(">"), f"Invalid code {code} for {name}"


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_unsupported_language(loaded_app):
    with pytest.raises(ValueError, match="Unsupported language"):
        loaded_app.translate("hello", "FakeLanguage")


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_returns_string(loaded_app):
    result = loaded_app.translate("Hello", "French (fr)")
    assert isinstance(result, str)
    assert len(result) > 0


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_with_beam_search(loaded_app):
    """Translation with beam search (num_beams=4) should return a string."""
    result = loaded_app.translate("Hello", "French (fr)", num_beams=4)
    assert isinstance(result, str)
    assert len(result) > 0


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_with_custom_temperature(loaded_app):
    """Translation with custom temperature should return a string."""
    result = loaded_app.translate("Hello", "French (fr)", temperature=0.5)
    assert isinstance(result, str)
    assert len(result) > 0


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_with_custom_max_tokens(loaded_app):
    """Translation with low max_new_tokens should return a short string."""
    result = loaded_app.translate("Hello", "French (fr)", max_new_tokens=10)
    assert isinstance(result, str)


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_empty_string(loaded_app):
    """Translating an empty string should not crash."""
    result = loaded_app.translate("", "French (fr)")
    assert isinstance(result, str)


@pytest.mark.slow
@pytest.mark.skipif(not gpu_available, reason="Requires CUDA")
def test_translate_beam_search_ignores_temperature(loaded_app):
    """When beam search is active with non-default temperature, gr.Info should be called."""
    with patch("app.gr.Info") as mock_info:
        result = loaded_app.translate("Hello", "French (fr)", num_beams=4, temperature=0.5)
        mock_info.assert_called_once()
    assert isinstance(result, str)