from datetime import UTC, datetime
from uuid import uuid4

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.model.audit import InteractionAudit
from app.model.configuration import ConfigRelease, PlatformConfigItem
from app.model.platform import DomainEventOutbox


class ConfigReleaseError(ValueError):
    pass


class ConfigReleaseService:
    def __init__(self, session: AsyncSession) -> None:
        self.session = session

    async def submit_for_review(self, release_id: int, actor_id: int) -> ConfigRelease:
        release = await self._get(release_id)
        if release.created_by != actor_id or release.status != "draft":
            raise ConfigReleaseError("only draft owner can submit")
        release.status = "pending_review"
        release.updated_at = self._now()
        self._audit("config.submit_review", actor_id, release)
        await self.session.flush()
        return release

    async def approve(self, release_id: int, reviewer_id: int) -> ConfigRelease:
        release = await self._get(release_id)
        if release.status != "pending_review":
            raise ConfigReleaseError("release is not pending review")
        if release.created_by == reviewer_id:
            raise ConfigReleaseError("creator cannot review own release")
        release.status = "approved"
        release.reviewer_id = reviewer_id
        release.reviewed_at = self._now()
        release.updated_at = release.reviewed_at
        self._audit("config.approve", reviewer_id, release)
        await self.session.flush()
        return release

    async def activate(self, release_id: int, actor_id: int) -> ConfigRelease:
        release = await self._get(release_id)
        if release.status != "approved":
            raise ConfigReleaseError("only approved release can activate")
        active = await self.session.scalars(
            select(ConfigRelease).where(ConfigRelease.status == "active")
        )
        now = self._now()
        for previous in active:
            previous.status = "superseded"
            previous.updated_at = now
        release.status = "active"
        release.activated_at = now
        release.updated_at = now
        self._audit("config.activate", actor_id, release)
        self.session.add(
            DomainEventOutbox(
                id=0,
                event_id=str(uuid4()),
                event_type="config.cache_invalidate_requested",
                aggregate_type="config_release",
                aggregate_id=str(release.id),
                trace_id=release.release_no,
                payload={"release_id": release.id, "release_no": release.release_no},
                status="pending",
                retry_count=0,
                occurred_at=now,
                created_at=now,
                updated_at=now,
            )
        )
        await self.session.flush()
        return release

    async def rollback(self, release_id: int, actor_id: int) -> ConfigRelease:
        target = await self._get(release_id)
        if target.status not in {"active", "superseded"}:
            raise ConfigReleaseError("release cannot be rolled back")
        now = self._now()
        current = await self.session.scalars(
            select(ConfigRelease).where(ConfigRelease.status == "active")
        )
        for release in current:
            release.status = "superseded"
            release.updated_at = now
        await self.session.flush()
        rollback = ConfigRelease(
            release_no=f"rollback-{uuid4().hex[:16]}",
            title=f"Rollback {target.release_no}",
            change_summary=f"Rollback to {target.release_no}",
            status="active",
            created_by=actor_id,
            reviewer_id=None,
            reviewed_at=None,
            activated_at=now,
            created_at=now,
            updated_at=now,
            rollback_of_release_id=target.id,
        )
        self.session.add(rollback)
        await self.session.flush()
        self.session.add(
            DomainEventOutbox(
                event_id=str(uuid4()),
                event_type="config.cache_invalidate_requested",
                aggregate_type="config_release",
                aggregate_id=str(target.id),
                trace_id=target.release_no,
                payload={"release_id": target.id, "release_no": target.release_no},
                status="pending",
                retry_count=0,
                occurred_at=now,
                created_at=now,
                updated_at=now,
            )
        )
        self._audit("config.rollback", actor_id, rollback)
        await self.session.flush()
        return rollback

    async def get_value(
        self, release_id: int, namespace: str, config_key: str
    ) -> dict[str, object] | None:
        item = await self.session.scalar(
            select(PlatformConfigItem).where(
                PlatformConfigItem.release_id == release_id,
                PlatformConfigItem.namespace == namespace,
                PlatformConfigItem.config_key == config_key,
            )
        )
        return item.value_json if item else None

    @staticmethod
    def assert_if_match(current_version: str, if_match: str | None) -> None:
        if if_match is None or if_match.strip('"') != current_version:
            raise ConfigReleaseError("CONFIG_VERSION_CONFLICT")

    async def _get(self, release_id: int) -> ConfigRelease:
        release = await self.session.get(ConfigRelease, release_id)
        if release is None:
            raise ConfigReleaseError("release not found")
        return release

    def _audit(self, action: str, actor_id: int, release: ConfigRelease) -> None:
        self.session.add(
            InteractionAudit(
                actor_type="user",
                actor_id=actor_id,
                target_customer_id=None,
                session_id=None,
                portal="admin",
                action_type=action,
                detail={"release_id": release.id, "release_no": release.release_no},
                created_at=self._now(),
            )
        )

    @staticmethod
    def _now() -> datetime:
        return datetime.now(UTC).replace(tzinfo=None)