"""Reusable Add Event form widget for Calendar TUI.

This widget can be used standalone in modals or embedded in other screens.
"""

from dataclasses import dataclass
from datetime import datetime, date, time, timedelta
from typing import Optional

from textual.app import ComposeResult
from textual.containers import Horizontal, Vertical, ScrollableContainer
from textual.message import Message
from textual.widget import Widget
from textual.widgets import Input, Label, Select, TextArea, Checkbox, MaskedInput


@dataclass
class EventFormData:
    """Data from the add event form."""

    title: str
    start_date: date
    start_time: time
    end_date: date
    end_time: time
    location: Optional[str] = None
    description: Optional[str] = None
    calendar: Optional[str] = None
    all_day: bool = False

    @property
    def start_datetime(self) -> datetime:
        """Get start as datetime."""
        return datetime.combine(self.start_date, self.start_time)

    @property
    def end_datetime(self) -> datetime:
        """Get end as datetime."""
        return datetime.combine(self.end_date, self.end_time)


class AddEventForm(Widget):
    """A reusable form widget for creating/editing calendar events.

    This widget emits EventFormData when submitted and can be embedded
    in various contexts (modal screens, sidebars, etc.)
    """

    DEFAULT_CSS = """
    AddEventForm {
        width: 100%;
        height: auto;
        padding: 1;
    }

    AddEventForm ScrollableContainer {
        height: auto;
        max-height: 100%;
    }

    AddEventForm .form-row {
        width: 100%;
        height: auto;
        margin-bottom: 1;
    }

    AddEventForm .form-label {
        width: 12;
        height: 2;
        padding-top: 1;
        padding-right: 1;
    }

    AddEventForm .form-input {
        width: 1fr;
    }

    AddEventForm #title-input {
        width: 1fr;
    }

    AddEventForm .date-input {
        width: 18;
    }

    AddEventForm .time-input {
        width: 10;
    }

    AddEventForm #calendar-select {
        width: 1fr;
    }

    AddEventForm #location-input {
        width: 1fr;
    }

    AddEventForm #description-textarea {
        width: 1fr;
        height: 6;
    }

    AddEventForm .required {
        color: $error;
    }

    AddEventForm .datetime-row {
        width: 100%;
        height: auto;
    }

    AddEventForm .datetime-group {
        width: auto;
        height: auto;
        margin-right: 2;
    }

    AddEventForm .datetime-label {
        width: auto;
        padding-right: 1;
        height: 2;
        padding-top: 1;
        color: $text-muted;
    }
    """

    class Submitted(Message):
        """Message emitted when the form is submitted."""

        def __init__(self, data: EventFormData) -> None:
            super().__init__()
            self.data = data

    class Cancelled(Message):
        """Message emitted when the form is cancelled."""

        pass

    def __init__(
        self,
        calendars: list[str] | None = None,
        initial_date: date | None = None,
        initial_time: time | None = None,
        initial_data: EventFormData | None = None,
        **kwargs,
    ):
        """Initialize the add event form.

        Args:
            calendars: List of available calendar names for the dropdown
            initial_date: Pre-populate with this date
            initial_time: Pre-populate with this time
            initial_data: Pre-populate form with this data (overrides date/time)
        """
        super().__init__(**kwargs)
        self._calendars = calendars or []
        self._initial_date = initial_date or date.today()
        self._initial_time = initial_time or time(9, 0)
        self._initial_data = initial_data

    def compose(self) -> ComposeResult:
        """Compose the form layout."""
        if self._initial_data:
            initial = self._initial_data
            start_date = initial.start_date
            start_time = initial.start_time
            end_date = initial.end_date
            end_time = initial.end_time
            title = initial.title
            location = initial.location or ""
            description = initial.description or ""
            calendar = initial.calendar or ""
            all_day = initial.all_day
        else:
            start_date = self._initial_date
            start_time = self._initial_time
            # Default to 1 hour duration
            end_date = start_date
            end_time = time(start_time.hour + 1, start_time.minute)
            if start_time.hour >= 23:
                end_time = time(23, 59)
            title = ""
            location = ""
            description = ""
            calendar = ""
            all_day = False

        with ScrollableContainer():
            # Title (required)
            with Horizontal(classes="form-row"):
                yield Label("Title", classes="form-label")
                yield Label("*", classes="required")
                yield Input(
                    value=title,
                    placeholder="Event title...",
                    id="title-input",
                    classes="form-input",
                )

            # Start Date/Time
            with Vertical(classes="form-row"):
                yield Label("Start", classes="form-label")
                with Horizontal(classes="datetime-row"):
                    with Horizontal(classes="datetime-group"):
                        yield Label("Date:", classes="datetime-label")
                        yield MaskedInput(
                            template="9999-99-99",
                            value=start_date.strftime("%Y-%m-%d"),
                            id="start-date-input",
                            classes="date-input",
                        )
                    with Horizontal(classes="datetime-group"):
                        yield Label("Time:", classes="datetime-label")
                        yield MaskedInput(
                            template="99:99",
                            value=start_time.strftime("%H:%M"),
                            id="start-time-input",
                            classes="time-input",
                        )

            # End Date/Time
            with Vertical(classes="form-row"):
                yield Label("End", classes="form-label")
                with Horizontal(classes="datetime-row"):
                    with Horizontal(classes="datetime-group"):
                        yield Label("Date:", classes="datetime-label")
                        yield MaskedInput(
                            template="9999-99-99",
                            value=end_date.strftime("%Y-%m-%d"),
                            id="end-date-input",
                            classes="date-input",
                        )
                    with Horizontal(classes="datetime-group"):
                        yield Label("Time:", classes="datetime-label")
                        yield MaskedInput(
                            template="99:99",
                            value=end_time.strftime("%H:%M"),
                            id="end-time-input",
                            classes="time-input",
                        )

            # All day checkbox
            with Horizontal(classes="form-row"):
                yield Label("", classes="form-label")
                yield Checkbox("All day event", value=all_day, id="all-day-checkbox")

            # Calendar selection (optional dropdown)
            if self._calendars:
                with Horizontal(classes="form-row"):
                    yield Label("Calendar", classes="form-label")
                    options = [("(default)", "")] + [(c, c) for c in self._calendars]
                    yield Select(
                        options=options,
                        value=calendar,
                        id="calendar-select",
                        allow_blank=True,
                    )

            # Location (optional)
            with Horizontal(classes="form-row"):
                yield Label("Location", classes="form-label")
                yield Input(
                    value=location,
                    placeholder="Event location...",
                    id="location-input",
                    classes="form-input",
                )

            # Description (optional textarea)
            with Vertical(classes="form-row"):
                yield Label("Description", classes="form-label")
                yield TextArea(
                    description,
                    id="description-textarea",
                )

    def get_form_data(self) -> EventFormData:
        """Extract current form data.

        Returns:
            EventFormData with current form values
        """
        title = self.query_one("#title-input", Input).value.strip()

        # Parse start date/time from MaskedInput
        start_date_input = self.query_one("#start-date-input", MaskedInput)
        start_time_input = self.query_one("#start-time-input", MaskedInput)
        start_date_str = start_date_input.value.strip()
        start_time_str = start_time_input.value.strip()
        try:
            start_date = datetime.strptime(start_date_str, "%Y-%m-%d").date()
        except ValueError:
            start_date = date.today()
        try:
            start_time = datetime.strptime(start_time_str, "%H:%M").time()
        except ValueError:
            start_time = time(9, 0)

        # Parse end date/time from MaskedInput
        end_date_input = self.query_one("#end-date-input", MaskedInput)
        end_time_input = self.query_one("#end-time-input", MaskedInput)
        end_date_str = end_date_input.value.strip()
        end_time_str = end_time_input.value.strip()
        try:
            end_date = datetime.strptime(end_date_str, "%Y-%m-%d").date()
        except ValueError:
            end_date = start_date
        try:
            end_time = datetime.strptime(end_time_str, "%H:%M").time()
        except ValueError:
            end_time = time(start_time.hour + 1, start_time.minute)

        # All day
        all_day = self.query_one("#all-day-checkbox", Checkbox).value

        # Calendar
        calendar: str | None = None
        try:
            calendar_select = self.query_one("#calendar-select", Select)
            cal_value = calendar_select.value
            if isinstance(cal_value, str) and cal_value:
                calendar = cal_value
        except Exception:
            pass  # No calendar select

        # Location
        location = self.query_one("#location-input", Input).value.strip() or None

        # Description
        try:
            desc_area = self.query_one("#description-textarea", TextArea)
            description = desc_area.text.strip() or None
        except Exception:
            description = None

        return EventFormData(
            title=title,
            start_date=start_date,
            start_time=start_time,
            end_date=end_date,
            end_time=end_time,
            location=location,
            description=description,
            calendar=calendar,
            all_day=all_day,
        )

    def validate(self) -> tuple[bool, str]:
        """Validate the form data.

        Returns:
            Tuple of (is_valid, error_message)
        """
        data = self.get_form_data()

        if not data.title:
            return False, "Title is required"

        # Validate that end is after start
        if data.end_datetime <= data.start_datetime:
            return False, "End time must be after start time"

        return True, ""

    def submit(self) -> bool:
        """Validate and submit the form.

        Returns:
            True if form was valid and submitted, False otherwise
        """
        is_valid, error = self.validate()
        if not is_valid:
            return False

        self.post_message(self.Submitted(self.get_form_data()))
        return True

    def cancel(self) -> None:
        """Cancel the form."""
        self.post_message(self.Cancelled())