"""审批流程管理 API。"""
from typing import List, Optional
from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.core.database import get_db
from app.core.security import require_role
from app.models.user import User
from app.models.workflow import WorkflowDefinition, WorkflowStep
from app.schemas.workflow import (
    WorkflowCreate, WorkflowUpdate, WorkflowResponse,
    WorkflowStepCreate,
)

router = APIRouter(prefix="/workflows", tags=["审批流程"])


def _serialize_step(step: WorkflowStep) -> dict:
    return {
        "id": step.id,
        "workflow_id": step.workflow_id,
        "step_number": step.step_number,
        "name": step.name,
        "step_type": step.step_type,
        "approver_role": step.approver_role,
        "approver_ids": step.approver_ids,
        "is_required": step.is_required,
        "timeout_hours": step.timeout_hours,
        "auto_approve_on_timeout": step.auto_approve_on_timeout,
    }


def _serialize_workflow(wf: WorkflowDefinition) -> dict:
    return {
        "id": wf.id,
        "name": wf.name,
        "description": wf.description,
        "is_default": wf.is_default,
        "is_active": wf.is_active,
        "created_at": wf.created_at,
        "steps": [_serialize_step(s) for s in wf.steps],
    }


@router.get("", response_model=List[WorkflowResponse])
async def list_workflows(
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin", "dba")),
):
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.is_active == True)
        .options(selectinload(WorkflowDefinition.steps))
    )
    workflows = result.scalars().unique().all()
    return [_serialize_workflow(wf) for wf in workflows]


@router.post("", response_model=WorkflowResponse, status_code=201)
async def create_workflow(
    data: WorkflowCreate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    # 如果设为默认，取消其他默认
    if data.is_default:
        from sqlalchemy import update as sa_update
        await db.execute(
            sa_update(WorkflowDefinition)
            .where(WorkflowDefinition.is_default == True)
            .values(is_default=False)
        )

    workflow = WorkflowDefinition(
        name=data.name,
        description=data.description,
        is_default=data.is_default,
    )
    db.add(workflow)
    await db.flush()

    for step_data in data.steps:
        step = WorkflowStep(
            workflow_id=workflow.id,
            step_number=step_data.step_number,
            name=step_data.name,
            step_type=step_data.step_type,
            approver_role=step_data.approver_role,
            approver_ids=step_data.approver_ids,
            is_required=step_data.is_required,
            timeout_hours=step_data.timeout_hours,
            auto_approve_on_timeout=step_data.auto_approve_on_timeout,
        )
        db.add(step)

    await db.commit()
    # Reload with steps
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.id == workflow.id)
        .options(selectinload(WorkflowDefinition.steps))
    )
    workflow = result.scalar_one()
    return _serialize_workflow(workflow)


@router.get("/{workflow_id}", response_model=WorkflowResponse)
async def get_workflow(
    workflow_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin", "dba")),
):
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.id == workflow_id)
        .options(selectinload(WorkflowDefinition.steps))
    )
    workflow = result.scalar_one_or_none()
    if not workflow:
        raise HTTPException(status_code=404, detail="审批流程不存在")
    return _serialize_workflow(workflow)


@router.put("/{workflow_id}", response_model=WorkflowResponse)
async def update_workflow(
    workflow_id: int,
    data: WorkflowUpdate,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.id == workflow_id)
        .options(selectinload(WorkflowDefinition.steps))
    )
    workflow = result.scalar_one_or_none()
    if not workflow:
        raise HTTPException(status_code=404, detail="审批流程不存在")

    if data.name is not None:
        workflow.name = data.name
    if data.description is not None:
        workflow.description = data.description
    if data.is_active is not None:
        workflow.is_active = data.is_active

    await db.commit()
    await db.refresh(workflow)
    return _serialize_workflow(workflow)


@router.delete("/{workflow_id}")
async def delete_workflow(
    workflow_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    result = await db.execute(
        select(WorkflowDefinition).where(WorkflowDefinition.id == workflow_id)
    )
    workflow = result.scalar_one_or_none()
    if not workflow:
        raise HTTPException(status_code=404, detail="审批流程不存在")

    workflow.is_active = False
    await db.commit()
    return {"message": "审批流程已删除"}


@router.post("/{workflow_id}/set-default")
async def set_default_workflow(
    workflow_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    """设为默认审批流程。"""
    # 取消所有默认
    result = await db.execute(select(WorkflowDefinition))
    all_workflows = result.scalars().all()
    for wf in all_workflows:
        wf.is_default = False

    # 设置指定流程为默认
    result = await db.execute(
        select(WorkflowDefinition).where(WorkflowDefinition.id == workflow_id)
    )
    workflow = result.scalar_one_or_none()
    if not workflow:
        raise HTTPException(status_code=404, detail="审批流程不存在")

    workflow.is_default = True
    await db.commit()
    return {"message": "审批流程 '{}' 已设为默认".format(workflow.name)}


@router.post("/{workflow_id}/clone", response_model=WorkflowResponse)
async def clone_workflow(
    workflow_id: int,
    db: AsyncSession = Depends(get_db),
    current_user: User = Depends(require_role("admin")),
):
    """克隆审批流程。"""
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.id == workflow_id)
        .options(selectinload(WorkflowDefinition.steps))
    )
    source = result.scalar_one_or_none()
    if not source:
        raise HTTPException(status_code=404, detail="审批流程不存在")

    new_workflow = WorkflowDefinition(
        name="{} (副本)".format(source.name),
        description=source.description,
        is_default=False,
    )
    db.add(new_workflow)
    await db.flush()

    for step in source.steps:
        new_step = WorkflowStep(
            workflow_id=new_workflow.id,
            step_number=step.step_number,
            name=step.name,
            step_type=step.step_type,
            approver_role=step.approver_role,
            approver_ids=step.approver_ids,
            is_required=step.is_required,
            timeout_hours=step.timeout_hours,
            auto_approve_on_timeout=step.auto_approve_on_timeout,
        )
        db.add(new_step)

    await db.commit()
    # Reload with steps
    result = await db.execute(
        select(WorkflowDefinition)
        .where(WorkflowDefinition.id == new_workflow.id)
        .options(selectinload(WorkflowDefinition.steps))
    )
    new_workflow = result.scalar_one()
    return _serialize_workflow(new_workflow)