import uuid
from datetime import datetime, timezone

from pydantic import BaseModel, Field, field_validator


def _calc_heartbeat_status(last_heartbeat_at: datetime | None) -> str:
    """Berechnet den Liveness-Status aus dem letzten Heartbeat-Zeitstempel."""
    if last_heartbeat_at is None:
        return "offline"
    now = datetime.now(timezone.utc)
    # last_heartbeat_at könnte timezone-naive sein (ältere DB-Einträge)
    if last_heartbeat_at.tzinfo is None:
        last_heartbeat_at = last_heartbeat_at.replace(tzinfo=timezone.utc)
    delta = (now - last_heartbeat_at).total_seconds()
    if delta <= 90:
        return "online"
    if delta <= 300:  # 5 Minuten
        return "stale"
    return "offline"


# ── Admin-Schemas ─────────────────────────────────────────────────────────────

class KioskDeviceCreate(BaseModel):
    name: str = Field(..., min_length=1, max_length=255)
    location: str | None = Field(None, max_length=255)
    public_key: str  # Ed25519 PEM oder OpenSSH
    ip_whitelist: str | None = None  # CIDR-Liste kommasepariert, z.B. "10.0.0.0/24,192.168.1.0/24"

    @field_validator("name")
    @classmethod
    def name_not_blank(cls, v: str) -> str:
        if not v.strip():
            raise ValueError("Name darf nicht nur aus Leerzeichen bestehen.")
        return v.strip()

    @field_validator("public_key")
    @classmethod
    def public_key_not_blank(cls, v: str) -> str:
        if not v.strip():
            raise ValueError("Public Key darf nicht leer sein.")
        return v.strip()


class KioskDeviceUpdate(BaseModel):
    name: str | None = Field(None, min_length=1, max_length=255)
    location: str | None = Field(None, max_length=255)
    ip_whitelist: str | None = None

    @field_validator("name")
    @classmethod
    def name_not_blank(cls, v: str | None) -> str | None:
        if v is not None:
            if not v.strip():
                raise ValueError("Name darf nicht nur aus Leerzeichen bestehen.")
            return v.strip()
        return v


class KioskDeviceOut(BaseModel):
    model_config = {"from_attributes": True}

    id: uuid.UUID
    company_id: uuid.UUID
    name: str
    location: str | None
    status: str  # pending / approved / revoked
    public_key: str | None
    key_algorithm: str
    last_heartbeat_at: datetime | None
    client_version: str | None
    offline_queue_size: int
    ip_whitelist: str | None
    created_at: datetime
    heartbeat_status: str = "offline"  # wird in model_validator gesetzt

    @classmethod
    def model_validate(cls, obj, *args, **kwargs):  # type: ignore[override]
        instance = super().model_validate(obj, *args, **kwargs)
        instance.heartbeat_status = _calc_heartbeat_status(instance.last_heartbeat_at)
        return instance


class KioskApproveResponse(BaseModel):
    id: uuid.UUID
    status: str
    message: str


# ── Heartbeat-Schemas ─────────────────────────────────────────────────────────

class HeartbeatRequest(BaseModel):
    uptime_seconds: int | None = None
    current_user_id: uuid.UUID | None = None
    browser_version: str | None = None
    queued_offline_entries: int = 0
    client_version: str | None = None


class HeartbeatResponse(BaseModel):
    server_time: str         # ISO-8601-Zeitstempel des Servers
    heartbeat_interval_sec: int
    device_status: str       # pending / approved / revoked