# Copyright (c) Streamlit Inc. (2018-2022) Snowflake Inc. (2022-2024)
#
# 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 dataclasses import dataclass
from textwrap import dedent
from typing import TYPE_CHECKING, Union, cast

from typing_extensions import TypeAlias

from streamlit.elements.lib.form_utils import current_form_id
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,
    to_key,
)
from streamlit.elements.widgets.file_uploader import _get_upload_files
from streamlit.proto.CameraInput_pb2 import CameraInput as CameraInputProto
from streamlit.proto.Common_pb2 import FileUploaderState as FileUploaderStateProto
from streamlit.proto.Common_pb2 import UploadedFileInfo as UploadedFileInfoProto
from streamlit.runtime.metrics_util import gather_metrics
from streamlit.runtime.scriptrunner import ScriptRunContext, get_script_run_ctx
from streamlit.runtime.state import (
    WidgetArgs,
    WidgetCallback,
    WidgetKwargs,
    register_widget,
)
from streamlit.runtime.uploaded_file_manager import DeletedFile, UploadedFile

if TYPE_CHECKING:
    from streamlit.delta_generator import DeltaGenerator

SomeUploadedSnapshotFile: TypeAlias = Union[UploadedFile, DeletedFile, None]


@dataclass
class CameraInputSerde:
    def serialize(
        self,
        snapshot: SomeUploadedSnapshotFile,
    ) -> FileUploaderStateProto:
        state_proto = FileUploaderStateProto()

        if snapshot is None or isinstance(snapshot, DeletedFile):
            return state_proto

        file_info: UploadedFileInfoProto = state_proto.uploaded_file_info.add()
        file_info.file_id = snapshot.file_id
        file_info.name = snapshot.name
        file_info.size = snapshot.size
        file_info.file_urls.CopyFrom(snapshot._file_urls)

        return state_proto

    def deserialize(
        self, ui_value: FileUploaderStateProto | None, widget_id: str
    ) -> SomeUploadedSnapshotFile:
        upload_files = _get_upload_files(ui_value)
        if len(upload_files) == 0:
            return_value = None
        else:
            return_value = upload_files[0]
        return return_value


class CameraInputMixin:
    @gather_metrics("camera_input")
    def camera_input(
        self,
        label: str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only arguments:
        disabled: bool = False,
        label_visibility: LabelVisibility = "visible",
    ) -> UploadedFile | None:
        r"""Display a widget that returns pictures from the user's webcam.

        Parameters
        ----------
        label : str
            A short label explaining to the user what this widget is used 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. Display unsupported elements as literal
            characters by backslash-escaping them. E.g.,
            ``"1\. Not an ordered list"``.

            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

        key : str or int
            An optional string or integer to use as the unique key for the widget.
            If this is omitted, a key will be generated for the widget
            based on its content. No two widgets may have the same key.

        help : str
            A tooltip that gets displayed next to the camera input.

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

        args : tuple
            An optional 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 camera input if set to
            ``True``. Default is ``False``.

        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 alligned with other widgets.
            If this is ``"collapsed"``, Streamlit displays no label or spacer.

        Returns
        -------
        None or UploadedFile
            The UploadedFile class is a subclass of BytesIO, and therefore is
            "file-like". This means you can pass an instance of it anywhere a
            file is expected.

        Examples
        --------
        >>> import streamlit as st
        >>>
        >>> enable = st.checkbox("Enable camera")
        >>> picture = st.camera_input("Take a picture", disabled=not enable)
        >>>
        >>> if picture:
        ...     st.image(picture)

        .. output::
           https://doc-camera-input.streamlit.app/
           height: 600px

        """
        ctx = get_script_run_ctx()
        return self._camera_input(
            label=label,
            key=key,
            help=help,
            on_change=on_change,
            args=args,
            kwargs=kwargs,
            disabled=disabled,
            label_visibility=label_visibility,
            ctx=ctx,
        )

    def _camera_input(
        self,
        label: str,
        key: Key | None = None,
        help: str | None = None,
        on_change: WidgetCallback | None = None,
        args: WidgetArgs | None = None,
        kwargs: WidgetKwargs | None = None,
        *,  # keyword-only arguments:
        disabled: bool = False,
        label_visibility: LabelVisibility = "visible",
        ctx: ScriptRunContext | None = None,
    ) -> UploadedFile | None:
        key = to_key(key)

        check_widget_policies(
            self.dg,
            key,
            on_change,
            default_value=None,
            writes_allowed=False,
        )
        maybe_raise_label_warnings(label, label_visibility)

        element_id = compute_and_register_element_id(
            "camera_input",
            user_key=key,
            form_id=current_form_id(self.dg),
            label=label,
            help=help,
        )

        camera_input_proto = CameraInputProto()
        camera_input_proto.id = element_id
        camera_input_proto.label = label
        camera_input_proto.form_id = current_form_id(self.dg)
        camera_input_proto.disabled = disabled
        camera_input_proto.label_visibility.value = get_label_visibility_proto_value(
            label_visibility
        )

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

        serde = CameraInputSerde()

        camera_input_state = register_widget(
            camera_input_proto.id,
            on_change_handler=on_change,
            args=args,
            kwargs=kwargs,
            deserializer=serde.deserialize,
            serializer=serde.serialize,
            ctx=ctx,
            value_type="file_uploader_state_value",
        )

        self.dg._enqueue("camera_input", camera_input_proto)

        if isinstance(camera_input_state.value, DeletedFile):
            return None
        return camera_input_state.value

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