"""PM Approval workflow endpoints."""
from datetime import datetime
from typing import List

from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from database import get_db
from models import (
    ApprovalCreate, ApprovalFlow, ApprovalOut, ApprovalResult,
    SRRequest, SRStatus, AuditLog, compute_log_hash
)

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


async def _write_audit(db: AsyncSession, sr_id: str, actor: str, action: str, detail: str) -> None:
    result = await db.execute(
        select(AuditLog).where(AuditLog.sr_id == sr_id)
                         .order_by(AuditLog.id.desc()).limit(1)
    )
    last = result.scalars().first()
    prev_hash = last.log_hash if last else None
    ts = datetime.now().isoformat()
    log_hash = compute_log_hash(prev_hash, actor, action, detail, ts)
    db.add(AuditLog(
        sr_id=sr_id, actor=actor, action=action, detail=detail,
        prev_hash=prev_hash, log_hash=log_hash
    ))


@router.get("/{sr_id}", response_model=List[ApprovalOut])
async def list_approvals(sr_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(
        select(ApprovalFlow).where(ApprovalFlow.sr_id == sr_id)
                             .order_by(ApprovalFlow.created_at)
    )
    return result.scalars().all()


@router.post("/{sr_id}", response_model=ApprovalOut, status_code=201)
async def decide_approval(sr_id: str, payload: ApprovalCreate,
                            db: AsyncSession = Depends(get_db)):
    r = await db.execute(select(SRRequest).where(SRRequest.sr_id == sr_id))
    sr = r.scalars().first()
    if not sr:
        raise HTTPException(404, detail="SR을 찾을 수 없습니다.")
    if sr.status != SRStatus.PENDING_APPROVAL:
        raise HTTPException(400, detail="승인 대기 상태의 SR만 처리할 수 있습니다.")

    apv = ApprovalFlow(
        sr_id=sr_id,
        approver=payload.approver,
        result=payload.result,
        comment=payload.comment,
        decided_at=datetime.now(),
    )
    db.add(apv)

    if payload.result == ApprovalResult.APPROVED:
        sr.status = SRStatus.APPROVED
        action, detail = "SR_APPROVED", f"{payload.approver} 승인"
    else:
        sr.status = SRStatus.REJECTED
        action, detail = "SR_REJECTED", f"{payload.approver} 반려: {payload.comment or ''}"

    sr.updated_at = datetime.now()
    await _write_audit(db, sr_id, payload.approver, action, detail)
    await db.commit()
    await db.refresh(apv)
    return apv