# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2026)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

from textwrap import dedent
from typing import TYPE_CHECKING, Any, Generic, TypeVar, cast, overload

from typing_extensions import Never

from streamlit.dataframe_util import OptionSequence, convert_anything_to_list
from streamlit.elements.lib.form_utils import current_form_id
from streamlit.elements.lib.layout_utils import (
    Width,
    create_layout_config,
)
from streamlit.elements.lib.options_selector_utils import (
    create_mappings,
    maybe_coerce_enum,
    validate_and_sync_value_with_options,
)
from streamlit.elements.lib.policies import (
    check_widget_policies,
    maybe_raise_label_warnings,
)
from streamlit.elements.lib.utils import (
    Key,
    LabelVisibility,
    compute_and_register_element_id,
    get_label_visibility_proto_value,
    save_for_app_testing,
    to_key,
)
from streamlit.errors import StreamlitAPIException
from streamlit.proto.Radio_pb2 import Radio as RadioProto
from streamlit.runtime.metrics_util import gather_metrics
from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx
from streamlit.runtime.state import (
    BindOption,
    PersistStateOption,
    WidgetArgs,
    WidgetCallback,
    WidgetKwargs,
    get_session_state,
    register_widget,
)
from streamlit.type_util import (
    check_python_comparable,
)

if TYPE_CHECKING:
    from collections.abc import Callable, Sequence

    from streamlit.delta_generator import DeltaGenerator

T = TypeVar("T")


class RadioSerde(Generic[T]):
    """Serializer/deserializer for Radio widget values.

    Uses string-based values (formatted option strings) for robust handling
    of dynamic option changes, similar to SelectboxSerde.
    """

    options: Sequence[T]
    formatted_options: list[str]
    formatted_option_to_option_index: dict[str, int]
    default_option_index: int | None
    format_func: Callable[[Any], str]

    def __init__(
        self,
        options: Sequence[T],
        *,
        formatted_options: list[str],
        formatted_option_to_option_index: dict[str, int],
        default_option_index: int | None = None,
        format_func: Callable[[Any], str] = str,
    ) -> None:
        self.options = options
        self.formatted_options = formatted_options
        self.formatted_option_to_option_index = formatted_option_to_option_index
        self.default_option_index = default_option_index
        self.format_func = format_func

    def serialize(self, v: T | str | None) -> str | None:
        if v is None:
            return None
        if len(self.options) == 0:
            return None

        # Use format_func to find the formatted option instead of using
        # index_(self.options, v) which relies on == comparison. This is necessary
        # because widget values are deepcopied, and for custom classes without
        # __eq__, the deepcopied instances would fail identity comparison.
        try:
            formatted_value = self.format_func(v)
        except Exception:
            # format_func failed (e.g., v is a string but format_func expects
            # an object with specific attributes). Use str(v) to ensure we return
            # a proper string, not the original object. This handles both cases:
            # - v is already a string -> str(v) returns it unchanged
            # - v is a custom object -> str(v) gives its string representation
            return str(v)

        if formatted_value in self.formatted_option_to_option_index:
            return formatted_value
        # Value not found in options - return the formatted string (not the original
        # object) to maintain type consistency since serialize() must return str|None
        return formatted_value

    def deserialize(self, ui_value: str | None) -> T | str | None:
        # If no options, there's no valid value - return None
        if len(self.options) == 0:
            return None

        if ui_value is None:
            return (
                self.options[self.default_option_index]
                if self.default_option_index is not None
                else None
            )

        option_index = self.formatted_option_to_option_index.get(ui_value)
        return self.options[option_index] if option_index is not None else ui_value


class RadioMixin:
    @overload
    def radio(
        self,
        label: str,
        options: Sequence[Never],
        index: int = 0,
        format_func: Callable[[Any], Any] = str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only args:
        disabled: bool = False,
        horizontal: bool = False,
        captions: Sequence[str] | None = None,
        label_visibility: LabelVisibility = "visible",
        width: Width = "content",
        bind: BindOption = None,
        persist_state: PersistStateOption = None,
    ) -> None: ...

    @overload
    def radio(
        self,
        label: str,
        options: OptionSequence[T],
        index: int = 0,
        format_func: Callable[[Any], Any] = str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only args:
        disabled: bool = False,
        horizontal: bool = False,
        captions: Sequence[str] | None = None,
        label_visibility: LabelVisibility = "visible",
        width: Width = "content",
        bind: BindOption = None,
        persist_state: PersistStateOption = None,
    ) -> T: ...

    @overload
    def radio(
        self,
        label: str,
        options: OptionSequence[T],
        index: None,
        format_func: Callable[[Any], Any] = str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only args:
        disabled: bool = False,
        horizontal: bool = False,
        captions: Sequence[str] | None = None,
        label_visibility: LabelVisibility = "visible",
        width: Width = "content",
        bind: BindOption = None,
        persist_state: PersistStateOption = None,
    ) -> T | None: ...

    @gather_metrics("radio")
    def radio(
        self,
        label: str,
        options: OptionSequence[T],
        index: int | None = 0,
        format_func: Callable[[Any], Any] = str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only args:
        disabled: bool = False,
        horizontal: bool = False,
        captions: Sequence[str] | None = None,
        label_visibility: LabelVisibility = "visible",
        width: Width = "content",
        bind: BindOption = None,
        persist_state: PersistStateOption = None,
    ) -> T | None:
        r"""Display a radio button widget.

        Parameters
        ----------
        label : str
            A short label explaining to the user what this radio group is for.
            The label can optionally contain GitHub-flavored Markdown of the
            following types: Bold, Italics, Strikethroughs, Inline Code, Links,
            and Images. Images display like icons, with a max height equal to
            the font height.

            Unsupported Markdown elements are unwrapped so only their children
            (text contents) render. Common block-level Markdown (headings,
            lists, blockquotes) is automatically escaped and displays as
            literal text in labels.

            See the ``body`` parameter of |st.markdown|_ for additional,
            supported Markdown directives.

            For accessibility reasons, you should never set an empty label, but
            you can hide it with ``label_visibility`` if needed. In the future,
            we may disallow empty labels by raising an exception.

            .. |st.markdown| replace:: ``st.markdown``
            .. _st.markdown: https://docs.streamlit.io/develop/api-reference/text/st.markdown

        options : Iterable
            Labels for the select options in an ``Iterable``. This can be a
            ``list``, ``set``, or anything supported by ``st.dataframe``. If
            ``options`` is dataframe-like, the first column will be used. Each
            label will be cast to ``str`` internally by default.

            Labels can include markdown as described in the ``label`` parameter.

        index : int or None
            The index of the preselected option on first render. If ``None``,
            will initialize empty and return ``None`` until the user selects an option.
            Defaults to 0 (the first option).

        format_func : function
            Function to modify the display of radio options. It receives
            the raw option as an argument and should output the label to be
            shown for that option. This has no impact on the return value of
            the radio.

        key : str, int, or None
            An optional string or integer to use as the unique key for
            the widget. If this is ``None`` (default), a key will be
            generated for the widget based on the values of the other
            parameters. No two widgets may have the same key. Assigning
            a key stabilizes the widget's identity and preserves its
            state across reruns even when other parameters change.

            A key lets you read or update the widget's value via
            ``st.session_state[key]``. For more details, see `Widget
            behavior <https://docs.streamlit.io/develop/concepts/architecture/widget-behavior>`_.

            Additionally, if ``key`` is provided, it will be used as a
            CSS class name prefixed with ``st-key-``.

        help : str or None
            A tooltip that gets displayed next to the widget label. Streamlit
            only displays the tooltip when ``label_visibility="visible"``. If
            this is ``None`` (default), no tooltip is displayed.

            The tooltip can optionally contain GitHub-flavored Markdown,
            including the Markdown directives described in the ``body``
            parameter of ``st.markdown``.

        on_change : callable
            An optional callback invoked when this radio's value changes.

        args : list or tuple
            An optional list or tuple of args to pass to the callback.

        kwargs : dict
            An optional dict of kwargs to pass to the callback.

        disabled : bool
            An optional boolean that disables the radio button if set to
            ``True``. The default is ``False``.

        horizontal : bool
            An optional boolean, which orients the radio group horizontally.
            The default is false (vertical buttons).

        captions : iterable of str or None
            A list of captions to show below each radio button. If None (default),
            no captions are shown.

        label_visibility : "visible", "hidden", or "collapsed"
            The visibility of the label. The default is ``"visible"``. If this
            is ``"hidden"``, Streamlit displays an empty spacer instead of the
            label, which can help keep the widget aligned with other widgets.
            If this is ``"collapsed"``, Streamlit displays no label or spacer.

        width : "content", "stretch", or int
            The width of the radio button widget. This can be one of the
            following:

            - ``"content"`` (default): The width of the widget matches the
              width of its content, but doesn't exceed the width of the parent
              container.
            - ``"stretch"``: The width of the widget matches the width of the
              parent container.
            - An integer specifying the width in pixels: The widget has a
              fixed width. If the specified width is greater than the width of
              the parent container, the width of the widget matches the width
              of the parent container.

        bind : "query-params" or None
            Binding mode for syncing the widget's value with a URL query
            parameter. If this is ``None`` (default), the widget's value
            is not synced to the URL. When this is set to
            ``"query-params"``, changes to the widget update the URL, and
            the widget can be initialized or updated through a query
            parameter in the URL. This requires ``key`` to be set. The
            key is used as the query parameter name.

            When the widget's value equals its default, the query
            parameter is removed from the URL to keep it clean. A bound
            query parameter can't be set or deleted through
            ``st.query_params``; it can only be programmatically changed
            through ``st.session_state``.

            Invalid query parameter values are ignored and removed
            from the URL. If ``index`` is ``None``, an empty query
            parameter (e.g., ``?my_key=``) clears the widget.

        persist_state : "page", "session", or None
            How long to preserve the widget's value when it isn't rendered.
            If this is ``None`` (default), the value is lost when the widget
            stops being rendered or the user switches pages. If this is
            ``"page"``, the value is preserved only while the user stays on the
            page where the widget is defined (for example, while the widget is
            conditionally hidden); it is discarded on a page switch and is not
            restored if the user returns to the page. If this is ``"session"``,
            the value is preserved for the entire session, including across
            page switches, so it returns when the user navigates back. This
            requires ``key`` to be set. If ``bind="query-params"`` is also set,
            the binding takes precedence: the value is stored in the URL, so it
            persists across page switches regardless of the ``persist_state``
            scope.

        Returns
        -------
        any
            The selected option or ``None`` if no option is selected.

            This is a copy of the selected option, not the original.

        Examples
        --------
        >>> import streamlit as st
        >>>
        >>> genre = st.radio(
        ...     "What's your favorite movie genre",
        ...     [":rainbow[Comedy]", "***Drama***", "Documentary :movie_camera:"],
        ...     captions=[
        ...         "Laugh out loud.",
        ...         "Get the popcorn.",
        ...         "Never stop learning.",
        ...     ],
        ... )
        >>>
        >>> if genre == ":rainbow[Comedy]":
        ...     st.write("You selected comedy.")
        ... else:
        ...     st.write("You didn't select comedy.")

        .. output::
           https://doc-radio.streamlit.app/
           height: 300px

        To initialize an empty radio widget, use ``None`` as the index value:

        >>> import streamlit as st
        >>>
        >>> genre = st.radio(
        ...     "What's your favorite movie genre",
        ...     [":rainbow[Comedy]", "***Drama***", "Documentary :movie_camera:"],
        ...     index=None,
        ... )
        >>>
        >>> st.write("You selected:", genre)

        .. output::
           https://doc-radio-empty.streamlit.app/
           height: 300px

        """
        ctx = get_script_run_ctx()
        return self._radio(
            label=label,
            options=options,
            index=index,
            format_func=format_func,
            key=key,
            help=help,
            on_change=on_change,
            args=args,
            kwargs=kwargs,
            disabled=disabled,
            horizontal=horizontal,
            captions=captions,
            label_visibility=label_visibility,
            bind=bind,
            persist_state=persist_state,
            ctx=ctx,
            width=width,
        )

    def _radio(
        self,
        label: str,
        options: OptionSequence[T],
        index: int | None = 0,
        format_func: Callable[[Any], Any] = str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only args:
        disabled: bool = False,
        horizontal: bool = False,
        label_visibility: LabelVisibility = "visible",
        captions: Sequence[str] | None = None,
        bind: BindOption = None,
        persist_state: PersistStateOption = None,
        ctx: ScriptRunContext | None = None,
        width: Width = "content",
    ) -> T | None:
        key = to_key(key)

        check_widget_policies(
            self.dg,
            key,
            on_change,
            default_value=None if index == 0 else index,
        )
        maybe_raise_label_warnings(label, label_visibility)

        layout_config = create_layout_config(width=width, allow_content_width=True)

        opt = convert_anything_to_list(options)
        check_python_comparable(opt)

        formatted_options, formatted_option_to_option_index = create_mappings(
            opt, format_func
        )

        element_id = compute_and_register_element_id(
            "radio",
            user_key=key,
            key_as_main_identity=True,
            dg=self.dg,
            label=label,
            options=formatted_options,
            index=index,
            help=help,
            horizontal=horizontal,
            captions=captions,
            width=width,
        )

        if not isinstance(index, int) and index is not None:
            raise StreamlitAPIException(
                f"Radio Value has invalid type: {type(index).__name__}"
            )

        if index is not None and len(opt) > 0 and not 0 <= index < len(opt):
            raise StreamlitAPIException(
                "Radio index must be between 0 and length of options"
            )

        def handle_captions(caption: str | None) -> str:
            if caption is None:
                return ""
            if isinstance(caption, str):
                return caption
            raise StreamlitAPIException(
                f"Radio captions must be strings. Passed type: {type(caption).__name__}"
            )

        session_state = get_session_state().filtered_state
        if key is not None and key in session_state and session_state[key] is None:
            index = None

        radio_proto = RadioProto()
        radio_proto.id = element_id
        radio_proto.label = label
        if index is not None:
            radio_proto.default = index
        radio_proto.options[:] = formatted_options
        radio_proto.form_id = current_form_id(self.dg)
        radio_proto.horizontal = horizontal
        radio_proto.disabled = disabled
        radio_proto.label_visibility.value = get_label_visibility_proto_value(
            label_visibility
        )

        if captions is not None:
            radio_proto.captions[:] = map(handle_captions, captions)

        if help is not None:
            radio_proto.help = dedent(help)

        # Set query param key if bound
        if bind == "query-params" and key is not None:
            radio_proto.query_param_key = str(key)

        serde = RadioSerde(
            opt,
            formatted_options=formatted_options,
            formatted_option_to_option_index=formatted_option_to_option_index,
            default_option_index=index,
            format_func=format_func,
        )

        widget_state = register_widget(
            radio_proto.id,
            on_change_handler=on_change,
            args=args,
            kwargs=kwargs,
            deserializer=serde.deserialize,
            serializer=serde.serialize,
            ctx=ctx,
            value_type="string_value",
            disabled=disabled,
            bind=bind,
            persist_state=persist_state,
            # Clearable when index=None: the widget can be in an empty state,
            # so ?key= (empty URL param) should clear the widget to None.
            clearable=(index is None),
            # Pass formatted_options so _seed_widget_from_url can reject
            # invalid option strings from URLs (e.g., ?size=Random).
            formatted_options=formatted_options,
        )
        widget_state = maybe_coerce_enum(widget_state, options, opt)

        # Validate the current value against the new options.
        # If the value is no longer valid (not in options), reset to default.
        # This handles the case where options change dynamically and the
        # previously selected value is no longer available.
        # Cast to T | None since radio doesn't support accept_new_options,
        # so string values that aren't in options will be reset to default.
        current_value, value_needs_reset = validate_and_sync_value_with_options(
            cast("T | None", widget_state.value), opt, index, key, format_func
        )

        if value_needs_reset or widget_state.value_changed:
            serialized_value = serde.serialize(current_value)
            if serialized_value is not None:
                radio_proto.raw_value = serialized_value
            radio_proto.set_value = True

        if ctx:
            save_for_app_testing(ctx, element_id, format_func)
        self.dg._enqueue(
            "radio",
            radio_proto,
            layout_config=layout_config,
            has_one_shot_effect=value_needs_reset or widget_state.value_changed,
        )
        return current_value

    @property
    def dg(self) -> DeltaGenerator:
        """The associated DeltaGenerator."""
        return cast("DeltaGenerator", self)
