"""Deterministic domain types for scheduling / board building.

These are pure data classes — no model inference, no network calls.
See design/det-vs-inf.md for the deterministic boundary.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from datetime import datetime, time
from enum import Enum
from typing import Optional


class AppointmentStatus(str, Enum):
    """Standardized appointment status."""
    CONFIRMED = "confirmed"
    PENDING = "pending"
    CANCELLED = "cancelled"
    COMPLETED = "completed"
    NO_SHOW = "no_show"


@dataclass(frozen=True)
class Appointment:
    """A single salon appointment — the core domain object.

    Fields match what the daily-board (A1) needs to display:
    time, client, service, staff, status, confirmation flag.
    """
    appointment_id: str
    start_time: datetime
    end_time: datetime
    client_name: str
    service_name: str
    staff_name: str
    status: AppointmentStatus
    notes: str = ""
    # Whether the client still needs a confirmation call/message.
    # Derived at build time from status + last_contact, but stored here
    # for fixture convenience.
    needs_confirmation: bool = False

    def __post_init__(self) -> None:
        """Validate that end_time is after start_time."""
        if self.end_time < self.start_time:
            raise ValueError(
                f"end_time ({self.end_time}) must be >= start_time ({self.start_time}) "
                f"for appointment {self.appointment_id}"
            )

    def __repr__(self) -> str:
        return (
            f"Appointment(id={self.appointment_id!r}, "
            f"{self.start_time:%H:%M}-{self.end_time:%H:%M}, "
            f"{self.client_name!r}, {self.status.value})"
        )

    def duration_minutes(self) -> int:
        """Appointment duration in whole minutes."""
        delta = self.end_time - self.start_time
        return int(delta.total_seconds() // 60)

    def start_time_only(self) -> time:
        return self.start_time.time()

    def end_time_only(self) -> time:
        return self.end_time.time()


@dataclass(frozen=True)
class Gap:
    """An unbooked time slot between two appointments (or day boundary)."""
    start_time: time
    end_time: time
    duration_minutes: int
    staff_name: str
    # The appointment immediately before this gap (if any).
    preceding_appointment_id: Optional[str] = None
    # The appointment immediately after this gap (if any).
    following_appointment_id: Optional[str] = None

    def __repr__(self) -> str:
        return (
            f"Gap({self.start_time:%H:%M}-{self.end_time:%H:%M}, "
            f"{self.duration_minutes}min, {self.staff_name!r})"
        )


@dataclass(frozen=True)
class DayBoard:
    """The complete daily board for one staff member or the whole salon.

    This is the structured output that the daily-board skill presents.
    All data is deterministic — no model inference.
    """
    date: str  # YYYY-MM-DD
    salon_name: str
    source: str  # "fixtures" | "offline" | "vagaro" | "square" (future)
    is_offline: bool  # True when source is fixtures or offline
    appointments: list[Appointment] = field(default_factory=list)
    gaps: list[Gap] = field(default_factory=list)
    needs_confirmation: list[Appointment] = field(default_factory=list)
    total_booked_minutes: int = 0
    total_gap_minutes: int = 0

    def __repr__(self) -> str:
        return (
            f"DayBoard({self.date}, {self.salon_name!r}, "
            f"{len(self.appointments)} appts, {len(self.gaps)} gaps)"
        )

    @property
    def utilization_rate(self) -> float:
        """Fraction of the day that is booked (0.0–1.0).

        Returns 0.0 when there is no total time to compute against.
        """
        total = self.total_booked_minutes + self.total_gap_minutes
        if total == 0:
            return 0.0
        return self.total_booked_minutes / total

    def to_dict(self) -> dict:
        """Serialize to a plain dict for JSON output."""
        return {
            "date": self.date,
            "salon_name": self.salon_name,
            "source": self.source,
            "is_offline": self.is_offline,
            "appointments": [
                {
                    "id": a.appointment_id,
                    "start": a.start_time.isoformat(),
                    "end": a.end_time.isoformat(),
                    "client": a.client_name,
                    "service": a.service_name,
                    "staff": a.staff_name,
                    "status": a.status.value,
                    "needs_confirmation": a.needs_confirmation,
                    "notes": a.notes,
                }
                for a in self.appointments
            ],
            "gaps": [
                {
                    "start": g.start_time.isoformat(),
                    "end": g.end_time.isoformat(),
                    "duration_minutes": g.duration_minutes,
                    "staff": g.staff_name,
                    "preceding_appointment_id": g.preceding_appointment_id,
                    "following_appointment_id": g.following_appointment_id,
                }
                for g in self.gaps
            ],
            "needs_confirmation": [
                a.appointment_id for a in self.needs_confirmation
            ],
            "total_booked_minutes": self.total_booked_minutes,
            "total_gap_minutes": self.total_gap_minutes,
            "utilization_rate": round(self.utilization_rate, 4),
        }