from __future__ import annotations

import base64
import binascii
import json
import time
from datetime import datetime, timezone
from typing import Any
from uuid import UUID

from app.core.logger import get_logger
from app.generation.models import GenerationJob
from app.projects.errors import (
    ProjectInvalidCursorError,
    ProjectInvalidNameError,
    ProjectInvalidStatusError,
    ProjectThumbnailInvalidError,
)
from app.projects.models import Project, ProjectGenerationJob
from app.projects.repositories.project_repository import ProjectRepository
from app.projects.schemas import (
    ProjectAssetListResponse,
    ProjectAssetResponse,
    ProjectCreate,
    ProjectGenerationJobListResponse,
    ProjectGenerationJobResponse,
    ProjectListResponse,
    ProjectResponse,
    ProjectStatus,
    ProjectUpdate,
    normalize_project_name,
)
from app.brand.repositories.brand_repository import BrandKitRepository
from app.security.assets import CanonicalAssetNotFoundError, CanonicalAssetService
from app.security.audit import AuditService
from app.security.models import CanonicalMediaAsset

logger = get_logger(__name__)


class ProjectService:
    """Coordinates validation, tenant ownership, persistence, and audit."""

    def __init__(
        self,
        repository: ProjectRepository,
        assets: CanonicalAssetService,
        audit: AuditService,
        brand_kits: BrandKitRepository,
    ) -> None:
        self.repository = repository
        self.assets = assets
        self.audit = audit
        self.brand_kits = brand_kits

    async def get_active_brand_kit(self, *, workspace_id: str, project_id: str, user_id: str) -> Any | None:
        project = await self.repository.get(workspace_id, project_id, user_id=user_id)
        if not project.brand_kit_id:
            return None
        return await self.brand_kits.get_latest_version(workspace_id, project.brand_kit_id, user_id=user_id)

    async def create(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        payload: ProjectCreate,
    ) -> ProjectResponse:
        started = time.monotonic()
        try:
            name = normalize_project_name(payload.name)
        except ValueError as exc:
            raise ProjectInvalidNameError(str(exc)) from exc
        await self._validate_thumbnail(workspace_id, user_id, payload.thumbnail_asset_id)
        project = await self.repository.create(
            Project(
                workspace_id=workspace_id,
                created_by=user_id,
                name=name,
                description=payload.description,
                status=ProjectStatus.ACTIVE.value,
                thumbnail_asset_id=payload.thumbnail_asset_id,
                metadata_json=dict(payload.metadata),
            ),
            user_id=user_id,
        )
        await self._audit(
            project,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            event_type="project.created",
            metadata={"has_thumbnail": project.thumbnail_asset_id is not None},
        )
        self._log("create", project, started, "success")
        return self._response(project)

    async def list(
        self,
        *,
        workspace_id: str,
        user_id: str,
        status: ProjectStatus | None,
        search: str | None,
        limit: int,
        cursor: str | None,
    ) -> ProjectListResponse:
        cursor_updated_at, cursor_id = self._decode_cursor(cursor)
        projects, has_more = await self.repository.list(
            workspace_id,
            user_id=user_id,
            status=status,
            search=search.strip() if search else None,
            limit=limit,
            cursor_updated_at=cursor_updated_at,
            cursor_id=cursor_id,
        )
        next_cursor = self._encode_cursor(projects[-1]) if has_more and projects else None
        
        # NOTE: For listing, we might want to optimize this to avoid N+1 queries.
        # Keeping it simple for now as requested.
        responses = []
        for project in projects:
            active_version = None
            if project.brand_kit_id:
                active_version = await self.brand_kits.get_latest_version(workspace_id, project.brand_kit_id, user_id=user_id)
            responses.append(self._response(project, active_version.id if active_version else None))
            
        return ProjectListResponse(
            items=responses,
            next_cursor=next_cursor,
            limit=limit,
        )

    async def get(self, *, workspace_id: str, user_id: str, project_id: str) -> ProjectResponse:
        project = await self.repository.get(workspace_id, project_id, user_id=user_id)
        active_version = None
        if project.brand_kit_id:
            active_version = await self.brand_kits.get_latest_version(workspace_id, project.brand_kit_id, user_id=user_id)
        return self._response(project, active_version.id if active_version else None)

    async def update(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        payload: ProjectUpdate,
    ) -> ProjectResponse:
        started = time.monotonic()
        fields = payload.model_dump(exclude_unset=True)
        if "name" in fields:
            try:
                fields["name"] = normalize_project_name(str(fields["name"]))
            except ValueError as exc:
                raise ProjectInvalidNameError(str(exc)) from exc
        if "thumbnail_asset_id" in fields:
            await self._validate_thumbnail(workspace_id, user_id, fields["thumbnail_asset_id"])
        if "metadata" in fields:
            fields["metadata_json"] = fields.pop("metadata")
        if "status" in fields:
            status = fields["status"]
            try:
                fields["status"] = ProjectStatus(status).value
            except ValueError as exc:
                raise ProjectInvalidStatusError("Project status is invalid.") from exc
        project = await self.repository.update(
            workspace_id,
            project_id,
            user_id=user_id,
            fields=fields,
        )
        archived = fields.get("status") == ProjectStatus.ARCHIVED.value
        await self._audit(
            project,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            event_type="project.archived" if archived else "project.updated",
            metadata={"fields": sorted(payload.model_fields_set)},
        )
        self._log("update", project, started, "success")
        return self._response(project)

    async def delete(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
    ) -> None:
        started = time.monotonic()
        project = await self.repository.archive(workspace_id, project_id, user_id=user_id)
        await self._audit(
            project,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            event_type="project.deleted",
            metadata={"disposition": "archived"},
        )
        self._log("delete", project, started, "success")

    async def list_assets(
        self, *, workspace_id: str, user_id: str, project_id: str
    ) -> ProjectAssetListResponse:
        assets = await self.repository.list_assets(workspace_id, project_id, user_id=user_id)
        return ProjectAssetListResponse(items=[self._asset_response(asset) for asset in assets])

    async def attach_asset(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        asset_id: str,
    ) -> ProjectAssetResponse:
        asset, attached = await self.repository.attach_asset(
            workspace_id, project_id, asset_id, user_id=user_id
        )
        if attached:
            await self._audit_resource(
                workspace_id=workspace_id,
                user_id=user_id,
                api_key_id=api_key_id,
                request_id=request_id,
                project_id=project_id,
                event_type="project.asset_attached",
                resource_id=asset.id,
            )
        return self._asset_response(asset)

    async def detach_asset(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        asset_id: str,
    ) -> None:
        asset = await self.repository.detach_asset(
            workspace_id, project_id, asset_id, user_id=user_id
        )
        await self._audit_resource(
            workspace_id=workspace_id,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            project_id=project_id,
            event_type="project.asset_detached",
            resource_id=asset.id,
        )

    async def list_generation_jobs(
        self, *, workspace_id: str, user_id: str, project_id: str
    ) -> ProjectGenerationJobListResponse:
        jobs = await self.repository.list_generation_jobs(workspace_id, project_id, user_id=user_id)
        return ProjectGenerationJobListResponse(
            items=[self._job_response(association, job) for association, job in jobs]
        )

    async def attach_generation_job(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        generation_job_id: str,
    ) -> ProjectGenerationJobResponse:
        association, job, attached = await self.repository.attach_generation_job(
            workspace_id, project_id, generation_job_id, user_id=user_id
        )
        if attached:
            await self._audit_resource(
                workspace_id=workspace_id,
                user_id=user_id,
                api_key_id=api_key_id,
                request_id=request_id,
                project_id=project_id,
                event_type="project.job_attached",
                resource_id=job.id,
            )
        return self._job_response(association, job)

    async def detach_generation_job(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        generation_job_id: str,
    ) -> None:
        _, job = await self.repository.detach_generation_job(
            workspace_id, project_id, generation_job_id, user_id=user_id
        )
        await self._audit_resource(
            workspace_id=workspace_id,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            project_id=project_id,
            event_type="project.job_detached",
            resource_id=job.id,
        )

    async def _validate_thumbnail(self, workspace_id: str, user_id: str, asset_id: Any) -> None:
        if asset_id is None:
            return
        if not isinstance(asset_id, str):
            raise ProjectThumbnailInvalidError("Project thumbnail reference is invalid.")
        try:
            await self.assets.get_owned_by_id(
                workspace_id=workspace_id, user_id=user_id, asset_id=asset_id
            )
        except CanonicalAssetNotFoundError as exc:
            raise ProjectThumbnailInvalidError(
                "Project thumbnail is not an owned canonical asset."
            ) from exc

    async def _audit(
        self,
        project: Project,
        *,
        user_id: str,
        api_key_id: str,
        request_id: str,
        event_type: str,
        metadata: dict[str, object],
    ) -> None:
        await self.audit.record_event(
            workspace_id=project.workspace_id,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            event_type=event_type,
            entity_type="project",
            entity_id=project.id,
            metadata=metadata,
        )

    async def _audit_resource(
        self,
        *,
        workspace_id: str,
        user_id: str,
        api_key_id: str,
        request_id: str,
        project_id: str,
        event_type: str,
        resource_id: str,
    ) -> None:
        await self.audit.record_event(
            workspace_id=workspace_id,
            user_id=user_id,
            api_key_id=api_key_id,
            request_id=request_id,
            event_type=event_type,
            entity_type="project",
            entity_id=project_id,
            metadata={"resource_id": resource_id},
        )

    @staticmethod
    def _response(project: Project, active_version_id: str | None = None) -> ProjectResponse:
        return ProjectResponse(
            id=project.id,
            workspace_id=project.workspace_id,
            name=project.name,
            description=project.description,
            status=ProjectStatus(project.status),
            thumbnail_asset_id=project.thumbnail_asset_id,
            brand_kit_id=project.brand_kit_id,
            brand_kit_version_id=active_version_id,
            metadata=dict(project.metadata_json or {}),
            created_by=project.created_by,
            created_at=project.created_at,
            updated_at=project.updated_at,
            archived_at=project.archived_at,
        )

    @staticmethod
    def _asset_response(asset: CanonicalMediaAsset) -> ProjectAssetResponse:
        return ProjectAssetResponse(
            id=asset.id,
            project_id=str(asset.project_id),
            request_id=asset.request_id,
            filename=asset.filename,
            mime_type=asset.mime_type,
            file_size=asset.file_size,
            metadata=dict(asset.metadata_json or {}),
            created_by_user_id=asset.created_by_user_id,
            created_at=asset.created_at,
            updated_at=asset.updated_at,
        )

    @staticmethod
    def _job_response(
        association: ProjectGenerationJob, job: GenerationJob
    ) -> ProjectGenerationJobResponse:
        return ProjectGenerationJobResponse(
            id=job.id,
            project_id=association.project_id,
            generation_request_id=job.generation_request_id,
            provider=job.provider,
            status=job.status,
            output_asset_id=job.output_asset_id,
            error_code=job.error_code,
            created_at=job.created_at,
            started_at=job.started_at,
            completed_at=job.completed_at,
            updated_at=job.updated_at,
            attached_at=association.created_at,
        )

    @staticmethod
    def _encode_cursor(project: Project) -> str:
        payload = json.dumps(
            {"updated_at": project.updated_at.isoformat(), "id": project.id},
            separators=(",", ":"),
        ).encode("utf-8")
        return base64.urlsafe_b64encode(payload).decode("ascii").rstrip("=")

    @staticmethod
    def _decode_cursor(cursor: str | None) -> tuple[datetime | None, str | None]:
        if cursor is None:
            return None, None
        try:
            padding = "=" * (-len(cursor) % 4)
            payload = json.loads(base64.urlsafe_b64decode(cursor + padding))
            updated_at = datetime.fromisoformat(payload["updated_at"])
            if updated_at.tzinfo is None:
                updated_at = updated_at.replace(tzinfo=timezone.utc)
            project_id = payload["id"]
            if not isinstance(project_id, str):
                raise ValueError
            UUID(project_id)
            return updated_at, project_id
        except (KeyError, TypeError, ValueError, binascii.Error, json.JSONDecodeError) as exc:
            raise ProjectInvalidCursorError("Project pagination cursor is invalid.") from exc

    @staticmethod
    def _log(
        operation: str,
        project: Project,
        started: float,
        result: str,
    ) -> None:
        logger.info(
            "project operation completed",
            extra={
                "operation": operation,
                "project_id": project.id,
                "workspace_id": project.workspace_id,
                "duration_ms": max(0, round((time.monotonic() - started) * 1000)),
                "result": result,
            },
        )