"""Workflow routes — CRUD, instance lifecycle, advance/cancel."""

from __future__ import annotations

import uuid

from fastapi import APIRouter, Depends, HTTPException, Query, Response, status
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.auth import check_permission
from app.core.db import get_db
from app.deps import get_current_user
from app.schemas.workflow import WorkflowCreate, WorkflowUpdate, InstanceCreate, AdvanceRequest
from app.services import workflow_service

router = APIRouter(prefix="/api/v1/workflows", tags=["workflows"])


# ─── Workflow CRUD ───

@router.get("")
async def list_workflows(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    is_active: bool | None = Query(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """List workflows with pagination."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    return await workflow_service.list_workflows(
        db, tenant_id,
        page=page, page_size=page_size,
        is_active=is_active,
    )


@router.post("", status_code=status.HTTP_201_CREATED)
async def create_workflow(
    body: WorkflowCreate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Create a new workflow definition. Requires write permission."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    role = current_user.get("role", "viewer")

    if not check_permission(role, "workflows", "create"):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={"detail": "Insufficient permissions", "code": "forbidden"},
        )

    data = body.model_dump()
    return await workflow_service.create_workflow(db, tenant_id, user_id, data)


@router.get("/instances")
async def list_instances(
    page: int = Query(1, ge=1),
    page_size: int = Query(20, ge=1, le=100),
    status: str | None = Query(None),
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """List workflow instances with optional status filter."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    return await workflow_service.list_instances(
        db, tenant_id,
        page=page, page_size=page_size,
        status_filter=status,
    )


@router.get("/{workflow_id}")
async def get_workflow(
    workflow_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Get a single workflow by ID."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    result = await workflow_service.get_workflow(db, tenant_id, workflow_id)
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.patch("/{workflow_id}")
async def update_workflow(
    workflow_id: str,
    body: WorkflowUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Update a workflow definition."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    role = current_user.get("role", "viewer")

    if not check_permission(role, "workflows", "update"):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={"detail": "Insufficient permissions", "code": "forbidden"},
        )

    data = body.model_dump(exclude_unset=True)
    result = await workflow_service.update_workflow(db, tenant_id, user_id, workflow_id, data)
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.delete("/{workflow_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_workflow(
    workflow_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Delete a workflow definition."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])
    role = current_user.get("role", "viewer")

    if not check_permission(role, "workflows", "delete"):
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail={"detail": "Insufficient permissions", "code": "forbidden"},
        )

    deleted = await workflow_service.delete_workflow(db, tenant_id, user_id, workflow_id)
    if not deleted:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return Response(status_code=status.HTTP_204_NO_CONTENT)


# ─── Instance endpoints ───

@router.post("/{workflow_id}/instances", status_code=status.HTTP_201_CREATED)
async def create_instance(
    workflow_id: str,
    body: InstanceCreate,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Create a new workflow instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    result = await workflow_service.create_instance(
        db, tenant_id, user_id,
        workflow_id=workflow_id,
        context=body.context,
        timeout_hours=body.timeout_hours,
    )
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Workflow not found", "code": "not_found"},
        )
    return result


@router.get("/instances/{instance_id}")
async def get_instance(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Get a workflow instance with step history."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    result = await workflow_service.get_instance(db, tenant_id, instance_id)
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    return result


@router.post("/instances/{instance_id}/advance")
async def advance_instance(
    instance_id: str,
    body: AdvanceRequest,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Advance or reject a workflow instance step.

    Body decision: "approve" or "reject".
    Returns 200 with updated instance.
    """
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    result = await workflow_service.advance_instance(
        db, tenant_id, user_id,
        instance_id=instance_id,
        decision=body.decision,
        comment=body.comment,
    )
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    if "error" in result:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"detail": result["error"], "code": "invalid_state"},
        )
    return result


@router.post("/instances/{instance_id}/cancel")
async def cancel_instance(
    instance_id: str,
    db: AsyncSession = Depends(get_db),
    current_user: dict = Depends(get_current_user),
):
    """Cancel a workflow instance. Returns 200 with cancelled instance."""
    tenant_id = uuid.UUID(current_user["tenant_id"])
    user_id = uuid.UUID(current_user["user_id"])

    result = await workflow_service.cancel_instance(
        db, tenant_id, user_id,
        instance_id=instance_id,
    )
    if result is None:
        raise HTTPException(
            status_code=status.HTTP_404_NOT_FOUND,
            detail={"detail": "Instance not found", "code": "not_found"},
        )
    if "error" in result:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail={"detail": result["error"], "code": "invalid_state"},
        )
    return result