from __future__ import annotations

from collections.abc import Mapping
from dataclasses import dataclass, field
from datetime import datetime
from typing import Literal

TenantLifecyclePhase = Literal[
    "created",
    "suspended",
    "resumed",
    "deletion_requested",
    "erasure_completed",
]

TENANT_EVENT_CREATED = "tenant.created"
TENANT_EVENT_SUSPENDED = "tenant.suspended"
TENANT_EVENT_RESUMED = "tenant.resumed"
TENANT_EVENT_DELETION_REQUESTED = "tenant.deletion_requested"
TENANT_EVENT_ERASURE_COMPLETED = "tenant.erasure_completed"

TENANT_LIFECYCLE_EVENTS: tuple[str, ...] = (
    TENANT_EVENT_CREATED,
    TENANT_EVENT_SUSPENDED,
    TENANT_EVENT_RESUMED,
    TENANT_EVENT_DELETION_REQUESTED,
    TENANT_EVENT_ERASURE_COMPLETED,
)

_EVENT_BY_PHASE: Mapping[TenantLifecyclePhase, str] = {
    "created": TENANT_EVENT_CREATED,
    "suspended": TENANT_EVENT_SUSPENDED,
    "resumed": TENANT_EVENT_RESUMED,
    "deletion_requested": TENANT_EVENT_DELETION_REQUESTED,
    "erasure_completed": TENANT_EVENT_ERASURE_COMPLETED,
}


@dataclass(frozen=True, slots=True)
class TenantLifecycleEvent:
    event_type: str
    tenant_id: str
    tenant_slug: str | None = None
    tenant_name: str | None = None
    actor_account_id: str | None = None
    requested_by_account_id: str | None = None
    reason: str | None = None
    counts: Mapping[str, int] = field(default_factory=dict)
    occurred_at: datetime | None = None
    details: Mapping[str, object] = field(default_factory=dict)

    def audit_details(self) -> dict[str, object]:
        payload: dict[str, object] = dict(self.details)
        if self.tenant_slug is not None:
            payload["slug"] = self.tenant_slug
        if self.tenant_name is not None:
            payload["name"] = self.tenant_name
        if self.actor_account_id is not None:
            payload["actor_account_id"] = self.actor_account_id
        if self.requested_by_account_id is not None:
            payload["requested_by_account_id"] = self.requested_by_account_id
        if self.reason is not None:
            payload["reason"] = self.reason
        if self.counts:
            payload["counts"] = dict(self.counts)
        if self.occurred_at is not None:
            payload["occurred_at"] = self.occurred_at.isoformat()
        return payload


def tenant_lifecycle_event_type(phase: TenantLifecyclePhase) -> str:
    return _EVENT_BY_PHASE[phase]


def tenant_lifecycle_event(
    phase: TenantLifecyclePhase,
    *,
    tenant_id: str,
    tenant_slug: str | None = None,
    tenant_name: str | None = None,
    actor_account_id: str | None = None,
    requested_by_account_id: str | None = None,
    reason: str | None = None,
    counts: Mapping[str, int] | None = None,
    occurred_at: datetime | None = None,
    details: Mapping[str, object] | None = None,
) -> TenantLifecycleEvent:
    return TenantLifecycleEvent(
        event_type=tenant_lifecycle_event_type(phase),
        tenant_id=tenant_id,
        tenant_slug=tenant_slug,
        tenant_name=tenant_name,
        actor_account_id=actor_account_id,
        requested_by_account_id=requested_by_account_id,
        reason=reason,
        counts=dict(counts or {}),
        occurred_at=occurred_at,
        details=dict(details or {}),
    )