"""Helpers for data entry flows for helper config entries."""
from __future__ import annotations

from abc import abstractmethod
from collections.abc import Callable, Mapping
import copy
from dataclasses import dataclass
from typing import Any

import voluptuous as vol

from homeassistant import config_entries
from homeassistant.core import HomeAssistant, callback, split_entity_id
from homeassistant.data_entry_flow import FlowResult, UnknownHandler

from . import entity_registry as er


class HelperFlowError(Exception):
    """Validation failed."""


@dataclass
class HelperFlowStep:
    """Define a helper config or options flow step."""

    # Optional schema for requesting and validating user input. If schema validation
    # fails, the step will be retried. If the schema is None, no user input is requested.
    schema: vol.Schema | None

    # Optional function to validate user input.
    # The validate_user_input function is called if the schema validates successfully.
    # The validate_user_input function is passed the user input from the current step.
    # The validate_user_input should raise HelperFlowError is user input is invalid.
    validate_user_input: Callable[[dict[str, Any]], dict[str, Any]] = lambda x: x

    # Optional function to identify next step.
    # The next_step function is called if the schema validates successfully or if no
    # schema is defined. The next_step function is passed the union of config entry
    # options and user input from previous steps.
    # If next_step returns None, the flow is ended with RESULT_TYPE_CREATE_ENTRY.
    next_step: Callable[[dict[str, Any]], str | None] = lambda _: None


class HelperCommonFlowHandler:
    """Handle a config or options flow for helper."""

    def __init__(
        self,
        handler: HelperConfigFlowHandler | HelperOptionsFlowHandler,
        flow: dict[str, HelperFlowStep],
        config_entry: config_entries.ConfigEntry | None,
    ) -> None:
        """Initialize a common handler."""
        self._flow = flow
        self._handler = handler
        self._options = dict(config_entry.options) if config_entry is not None else {}

    async def async_step(
        self, step_id: str, user_input: dict[str, Any] | None = None
    ) -> FlowResult:
        """Handle a step."""
        next_step_id: str = step_id

        if user_input is not None and self._flow[next_step_id].schema is not None:
            # Do extra validation of user input
            try:
                user_input = self._flow[next_step_id].validate_user_input(user_input)
            except HelperFlowError as exc:
                return self._show_next_step(next_step_id, exc, user_input)

        if user_input is not None:
            # User input was validated successfully, update options
            self._options.update(user_input)

        if self._flow[next_step_id].next_step and (
            user_input is not None or self._flow[next_step_id].schema is None
        ):
            # Get next step
            next_step_id_or_end_flow = self._flow[next_step_id].next_step(self._options)
            if next_step_id_or_end_flow is None:
                # Flow done, create entry or update config entry options
                return self._handler.async_create_entry(data=self._options)

            next_step_id = next_step_id_or_end_flow

        return self._show_next_step(next_step_id)

    def _show_next_step(
        self,
        next_step_id: str,
        error: HelperFlowError | None = None,
        user_input: dict[str, Any] | None = None,
    ) -> FlowResult:
        """Show step for next step."""
        options = dict(self._options)
        if user_input:
            options.update(user_input)
        if (data_schema := self._flow[next_step_id].schema) and data_schema.schema:
            # Make a copy of the schema with suggested values set to saved options
            schema = {}
            for key, val in data_schema.schema.items():
                new_key = key
                if key in options and isinstance(key, vol.Marker):
                    # Copy the marker to not modify the flow schema
                    new_key = copy.copy(key)
                    new_key.description = {"suggested_value": options[key]}
                schema[new_key] = val
            data_schema = vol.Schema(schema)

        errors = {"base": str(error)} if error else None

        # Show form for next step
        return self._handler.async_show_form(
            step_id=next_step_id, data_schema=data_schema, errors=errors
        )


class HelperConfigFlowHandler(config_entries.ConfigFlow):
    """Handle a config flow for helper integrations."""

    config_flow: dict[str, HelperFlowStep]
    options_flow: dict[str, HelperFlowStep] | None = None

    VERSION = 1

    # pylint: disable-next=arguments-differ
    def __init_subclass__(cls, **kwargs: Any) -> None:
        """Initialize a subclass."""
        super().__init_subclass__(**kwargs)

        @callback
        def _async_get_options_flow(
            config_entry: config_entries.ConfigEntry,
        ) -> config_entries.OptionsFlow:
            """Get the options flow for this handler."""
            if cls.options_flow is None:
                raise UnknownHandler

            return HelperOptionsFlowHandler(config_entry, cls.options_flow)

        # Create an async_get_options_flow method
        cls.async_get_options_flow = _async_get_options_flow  # type: ignore[assignment]

        # Create flow step methods for each step defined in the flow schema
        for step in cls.config_flow:
            setattr(cls, f"async_step_{step}", cls._async_step)

    def __init__(self) -> None:
        """Initialize config flow."""
        self._common_handler = HelperCommonFlowHandler(self, self.config_flow, None)

    @classmethod
    @callback
    def async_supports_options_flow(
        cls, config_entry: config_entries.ConfigEntry
    ) -> bool:
        """Return options flow support for this handler."""
        return cls.options_flow is not None

    async def _async_step(self, user_input: dict[str, Any] | None = None) -> FlowResult:
        """Handle a config flow step."""
        step_id = self.cur_step["step_id"] if self.cur_step else "user"
        result = await self._common_handler.async_step(step_id, user_input)

        return result

    # pylint: disable-next=no-self-use
    @abstractmethod
    def async_config_entry_title(self, options: Mapping[str, Any]) -> str:
        """Return config entry title.

        The options parameter contains config entry options, which is the union of user
        input from the config flow steps.
        """

    @callback
    def async_create_entry(  # pylint: disable=arguments-differ
        self,
        data: Mapping[str, Any],
        **kwargs: Any,
    ) -> FlowResult:
        """Finish config flow and create a config entry."""
        return super().async_create_entry(
            data={}, options=data, title=self.async_config_entry_title(data), **kwargs
        )


class HelperOptionsFlowHandler(config_entries.OptionsFlow):
    """Handle an options flow for helper integrations."""

    def __init__(
        self,
        config_entry: config_entries.ConfigEntry,
        options_flow: dict[str, vol.Schema],
    ) -> None:
        """Initialize options flow."""
        self._common_handler = HelperCommonFlowHandler(self, options_flow, config_entry)
        self._config_entry = config_entry

        for step in options_flow:
            setattr(self, f"async_step_{step}", self._async_step)

    async def _async_step(self, user_input: dict[str, Any] | None = None) -> FlowResult:
        """Handle an options flow step."""
        # pylint: disable-next=unsubscriptable-object # self.cur_step is a dict
        step_id = self.cur_step["step_id"] if self.cur_step else "init"
        return await self._common_handler.async_step(step_id, user_input)

    @callback
    def async_create_entry(  # pylint: disable=arguments-differ
        self,
        **kwargs: Any,
    ) -> FlowResult:
        """Finish config flow and create a config entry."""
        return super().async_create_entry(title="", **kwargs)


@callback
def wrapped_entity_config_entry_title(
    hass: HomeAssistant, entity_id_or_uuid: str
) -> str:
    """Generate title for a config entry wrapping a single entity.

    If the entity is registered, use the registry entry's name.
    If the entity is in the state machine, use the name from the state.
    Otherwise, fall back to the object ID.
    """
    registry = er.async_get(hass)
    entity_id = er.async_validate_entity_id(registry, entity_id_or_uuid)
    object_id = split_entity_id(entity_id)[1]
    entry = registry.async_get(entity_id)
    if entry:
        return entry.name or entry.original_name or object_id
    state = hass.states.get(entity_id)
    if state:
        return state.name or object_id
    return object_id