import hashlib
import json
from typing import Optional

from sqlalchemy import func, update
from sqlalchemy.future import select
from sqlalchemy.orm import load_only, selectinload

from api.db.base_client import BaseDBClient
from api.db.models import WorkflowDefinitionModel, WorkflowModel, WorkflowRunModel


class WorkflowClient(BaseDBClient):
    def _generate_workflow_hash(self, workflow_definition: dict) -> str:
        """Generate a consistent hash for workflow definition."""
        # Convert to JSON with sorted keys for consistent hashing
        json_str = json.dumps(
            workflow_definition, sort_keys=True, separators=(",", ":")
        )
        return hashlib.sha256(json_str.encode()).hexdigest()

    async def _get_or_create_workflow_definition(
        self, workflow_definition: dict, session, workflow_id: int = None
    ) -> WorkflowDefinitionModel:
        """Get existing workflow definition by hash or create a new one."""
        workflow_hash = self._generate_workflow_hash(workflow_definition)

        # Try to find existing definition
        result = await session.execute(
            select(WorkflowDefinitionModel).where(
                WorkflowDefinitionModel.workflow_hash == workflow_hash,
                WorkflowDefinitionModel.workflow_id == workflow_id,
            )
        )
        existing_definition = result.scalars().first()

        if existing_definition:
            return existing_definition

        # Create new definition if it doesn't exist
        new_definition = WorkflowDefinitionModel(
            workflow_hash=workflow_hash,
            workflow_json=workflow_definition,
            workflow_id=workflow_id,
        )
        session.add(new_definition)
        await session.flush()  # Flush to get the ID without committing
        return new_definition

    async def create_workflow(
        self,
        name: str,
        workflow_definition: dict,
        user_id: int,
        organization_id: int = None,
    ) -> WorkflowModel:
        async with self.async_session() as session:
            try:
                new_workflow = WorkflowModel(
                    name=name,
                    workflow_definition=workflow_definition,  # Keep for backwards compatibility
                    user_id=user_id,
                    organization_id=organization_id,
                )
                session.add(new_workflow)
                await session.flush()  # Flush to get the workflow ID

                # Now get or create workflow definition with the workflow_id
                definition = await self._get_or_create_workflow_definition(
                    workflow_definition, session, new_workflow.id
                )

                # Mark this definition as the current one and unset others
                definition.is_current = True
                await session.execute(
                    update(WorkflowDefinitionModel)
                    .where(
                        WorkflowDefinitionModel.workflow_id == new_workflow.id,
                        WorkflowDefinitionModel.id != definition.id,
                    )
                    .values(is_current=False)
                )

                await session.commit()
            except Exception as e:
                await session.rollback()
                raise e
            await session.refresh(new_workflow)
        return new_workflow

    async def get_all_workflows(
        self, user_id: int = None, organization_id: int = None, status: str = None
    ) -> list[WorkflowModel]:
        async with self.async_session() as session:
            query = select(WorkflowModel).options(
                selectinload(WorkflowModel.current_definition)
            )

            if organization_id:
                # Filter by organization_id when provided
                query = query.where(WorkflowModel.organization_id == organization_id)
            elif user_id:
                # Fallback to user_id for backwards compatibility
                query = query.where(WorkflowModel.user_id == user_id)

            # Filter by status if provided
            if status:
                query = query.where(WorkflowModel.status == status)

            result = await session.execute(query)
            return result.scalars().all()

    async def get_all_workflows_for_listing(
        self, organization_id: int = None, status: str = None
    ) -> list[WorkflowModel]:
        """Get workflows with only the columns needed for listing.

        This is an optimized version that excludes large JSON columns like
        workflow_definition, template_context_variables, etc.

        Args:
            organization_id: Filter by organization ID
            status: Filter by status (active/archived)

        Returns:
            List of WorkflowModel with only id, name, status, created_at loaded
        """
        async with self.async_session() as session:
            query = select(WorkflowModel).options(
                load_only(
                    WorkflowModel.id,
                    WorkflowModel.name,
                    WorkflowModel.status,
                    WorkflowModel.created_at,
                )
            )

            if organization_id:
                query = query.where(WorkflowModel.organization_id == organization_id)

            if status:
                query = query.where(WorkflowModel.status == status)

            result = await session.execute(query)
            return result.scalars().all()

    async def get_workflow_counts(self, organization_id: int = None) -> dict[str, int]:
        """Get workflow counts by status.

        Args:
            organization_id: Filter by organization ID

        Returns:
            Dict with 'total', 'active', 'archived' counts
        """
        async with self.async_session() as session:
            query = select(
                WorkflowModel.status,
                func.count(WorkflowModel.id).label("count"),
            )

            if organization_id:
                query = query.where(WorkflowModel.organization_id == organization_id)

            query = query.group_by(WorkflowModel.status)

            result = await session.execute(query)
            rows = result.all()

            counts = {"total": 0, "active": 0, "archived": 0}
            for status, count in rows:
                counts[status] = count
                counts["total"] += count

            return counts

    async def get_workflow(
        self, workflow_id: int, user_id: int = None, organization_id: int = None
    ) -> WorkflowModel | None:
        async with self.async_session() as session:
            query = (
                select(WorkflowModel)
                .options(selectinload(WorkflowModel.current_definition))
                .where(WorkflowModel.id == workflow_id)
            )

            if organization_id:
                # Filter by organization_id when provided
                query = query.where(WorkflowModel.organization_id == organization_id)
            elif user_id:
                # Fallback to user_id for backwards compatibility
                query = query.where(WorkflowModel.user_id == user_id)

            result = await session.execute(query)
            return result.scalars().first()

    async def get_workflow_by_id(self, workflow_id: int) -> WorkflowModel | None:
        async with self.async_session() as session:
            result = await session.execute(
                select(WorkflowModel)
                .options(selectinload(WorkflowModel.current_definition))
                .where(WorkflowModel.id == workflow_id)
            )
            return result.scalars().first()

    async def update_workflow(
        self,
        workflow_id: int,
        name: str | None,
        workflow_definition: dict | None,
        template_context_variables: dict | None,
        workflow_configurations: dict | None,
        user_id: int = None,
        organization_id: int = None,
    ) -> WorkflowModel:
        """
        Update an existing workflow in the database.

        Args:
            workflow_id: The ID of the workflow to update
            name: The new name for the workflow
            workflow_definition: The new workflow definition
            template_context_variables: The template context variables
            user_id: The user ID (for backwards compatibility)
            organization_id: The organization ID

        Returns:
            The updated WorkflowModel

        Raises:
            ValueError: If the workflow with the given ID is not found
        """
        async with self.async_session() as session:
            query = (
                select(WorkflowModel)
                .options(selectinload(WorkflowModel.current_definition))
                .where(WorkflowModel.id == workflow_id)
            )

            if organization_id:
                # Filter by organization_id when provided
                query = query.where(WorkflowModel.organization_id == organization_id)
            elif user_id:
                # Fallback to user_id for backwards compatibility
                query = query.where(WorkflowModel.user_id == user_id)

            result = await session.execute(query)
            workflow = result.scalars().first()
            if not workflow:
                raise ValueError(f"Workflow with ID {workflow_id} not found")

            if name is not None:
                workflow.name = name

            if template_context_variables is not None:
                workflow.template_context_variables = template_context_variables

            if workflow_configurations is not None:
                workflow.workflow_configurations = workflow_configurations

            # In case of only name update, the workflow_definition can be None
            if workflow_definition:
                # Get or create new workflow definition
                definition = await self._get_or_create_workflow_definition(
                    workflow_definition, session, workflow_id
                )

                # Update legacy field for backwards compatibility
                workflow.workflow_definition = workflow_definition

                # Mark new definition as current and reset others
                definition.is_current = True
                await session.execute(
                    update(WorkflowDefinitionModel)
                    .where(
                        WorkflowDefinitionModel.workflow_id == workflow_id,
                        WorkflowDefinitionModel.id != definition.id,
                    )
                    .values(is_current=False)
                )

            try:
                await session.commit()
            except Exception as e:
                await session.rollback()
                raise e
            await session.refresh(workflow)
        return workflow

    async def get_workflows_by_ids(
        self, workflow_ids: list[int], organization_id: int
    ) -> list[WorkflowModel]:
        """Get workflows by IDs for a specific organization"""
        async with self.async_session() as session:
            result = await session.execute(
                select(WorkflowModel)
                .join(WorkflowModel.user)
                .where(
                    WorkflowModel.id.in_(workflow_ids),
                    WorkflowModel.user.has(selected_organization_id=organization_id),
                )
            )
            return result.scalars().all()

    async def get_workflow_name(
        self, workflow_id: int, user_id: int = None, organization_id: int = None
    ) -> Optional[str]:
        """Get just the workflow name by ID"""
        async with self.async_session() as session:
            query = select(WorkflowModel.name).where(WorkflowModel.id == workflow_id)

            if organization_id:
                # Filter by organization_id when provided
                query = query.where(WorkflowModel.organization_id == organization_id)
            elif user_id:
                # Fallback to user_id for backwards compatibility
                query = query.where(WorkflowModel.user_id == user_id)

            result = await session.execute(query)
            return result.scalar_one_or_none()

    async def update_workflow_status(
        self,
        workflow_id: int,
        status: str,
        organization_id: int = None,
    ) -> WorkflowModel:
        """
        Update the status of a workflow.

        Args:
            workflow_id: The ID of the workflow to update
            status: The new status (active/archived)
            organization_id: The organization ID

        Returns:
            The updated WorkflowModel

        Raises:
            ValueError: If the workflow is not found
        """
        async with self.async_session() as session:
            query = (
                select(WorkflowModel)
                .options(selectinload(WorkflowModel.current_definition))
                .where(WorkflowModel.id == workflow_id)
            )

            if organization_id:
                query = query.where(WorkflowModel.organization_id == organization_id)

            result = await session.execute(query)
            workflow = result.scalars().first()

            if not workflow:
                raise ValueError(f"Workflow with ID {workflow_id} not found")

            workflow.status = status

            try:
                await session.commit()
            except Exception as e:
                await session.rollback()
                raise e
            await session.refresh(workflow)
        return workflow

    async def get_workflow_run_count(self, workflow_id: int) -> int:
        """Get the count of runs for a workflow."""
        async with self.async_session() as session:
            result = await session.execute(
                select(func.count(WorkflowRunModel.id)).where(
                    WorkflowRunModel.workflow_id == workflow_id
                )
            )
            return result.scalar() or 0

    async def update_definition_node_summaries(
        self, definition_id: int, node_summaries: dict
    ) -> None:
        """Update the node_summaries field within a workflow definition's workflow_json.

        Args:
            definition_id: The ID of the WorkflowDefinitionModel to update
            node_summaries: Dict mapping node_id to summary data
                (e.g. {"summary": "...", "trace_url": "..."})
        """
        async with self.async_session() as session:
            result = await session.execute(
                select(WorkflowDefinitionModel).where(
                    WorkflowDefinitionModel.id == definition_id
                )
            )
            definition = result.scalars().first()
            if not definition:
                return

            workflow_json = dict(definition.workflow_json)
            workflow_json["node_summaries"] = node_summaries
            definition.workflow_json = workflow_json

            try:
                await session.commit()
            except Exception as e:
                await session.rollback()
                raise e

    async def get_workflow_run_counts(self, workflow_ids: list[int]) -> dict[int, int]:
        """Get run counts for multiple workflows in a single query.

        Args:
            workflow_ids: List of workflow IDs to get counts for

        Returns:
            Dict mapping workflow_id to run count
        """
        if not workflow_ids:
            return {}

        async with self.async_session() as session:
            result = await session.execute(
                select(
                    WorkflowRunModel.workflow_id,
                    func.count(WorkflowRunModel.id).label("run_count"),
                )
                .where(WorkflowRunModel.workflow_id.in_(workflow_ids))
                .group_by(WorkflowRunModel.workflow_id)
            )
            rows = result.all()

            # Build dict with counts, defaulting to 0 for workflows with no runs
            counts = {workflow_id: 0 for workflow_id in workflow_ids}
            for workflow_id, run_count in rows:
                counts[workflow_id] = run_count

            return counts