import uuid
from datetime import datetime, timezone

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

from api.database import get_session
from api.models.decision import Decision, DecisionStatus, DecisionType
from api.schemas.decision import DecisionCreate, DecisionRead, DecisionUpdate

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

_FINANCIAL_LEGAL_KEYWORDS = (
    "financ", "legal", "payment", "purchas", "contract", "commit",
    "obligation", "external representation",
)


def _needs_escalation(body: DecisionCreate) -> str | None:
    if body.decision_type != DecisionType.pending:
        return None
    text = f"{body.title} {body.description or ''}".lower()
    for kw in _FINANCIAL_LEGAL_KEYWORDS:
        if kw in text:
            return (
                "Auto-escalated per constitution §4: this pending decision touches "
                "financial or legal territory and requires explicit human approval before action."
            )
    return None


@router.get("/", response_model=list[DecisionRead])
async def list_decisions(
    topic_id: uuid.UUID | None = None,
    workstream_id: uuid.UUID | None = None,
    status: DecisionStatus | None = None,
    decision_type: DecisionType | None = None,
    session: AsyncSession = Depends(get_session),
) -> list[Decision]:
    q = select(Decision)
    if topic_id:
        q = q.where(Decision.topic_id == topic_id)
    if workstream_id:
        q = q.where(Decision.workstream_id == workstream_id)
    if status:
        q = q.where(Decision.status == status)
    if decision_type:
        q = q.where(Decision.decision_type == decision_type)
    q = q.order_by(Decision.created_at)
    result = await session.execute(q)
    return list(result.scalars().all())


@router.post("/", response_model=DecisionRead, status_code=status.HTTP_201_CREATED)
async def create_decision(
    body: DecisionCreate,
    session: AsyncSession = Depends(get_session),
) -> Decision:
    data = body.model_dump()
    note = _needs_escalation(body)
    if note:
        data["escalation_note"] = note
        data["status"] = DecisionStatus.escalated
    decision = Decision(**data)
    session.add(decision)
    await session.commit()
    await session.refresh(decision)
    return decision


@router.get("/{decision_id}", response_model=DecisionRead)
async def get_decision(
    decision_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
) -> Decision:
    decision = await session.get(Decision, decision_id)
    if decision is None:
        raise HTTPException(status_code=404, detail="Decision not found")
    return decision


@router.patch("/{decision_id}", response_model=DecisionRead)
async def update_decision(
    decision_id: uuid.UUID,
    body: DecisionUpdate,
    session: AsyncSession = Depends(get_session),
) -> Decision:
    decision = await session.get(Decision, decision_id)
    if decision is None:
        raise HTTPException(status_code=404, detail="Decision not found")
    for field, value in body.model_dump(exclude_unset=True).items():
        setattr(decision, field, value)
    await session.commit()
    await session.refresh(decision)
    return decision


@router.delete("/{decision_id}", response_model=DecisionRead)
async def supersede_decision(
    decision_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
) -> Decision:
    decision = await session.get(Decision, decision_id)
    if decision is None:
        raise HTTPException(status_code=404, detail="Decision not found")
    decision.status = DecisionStatus.superseded
    await session.commit()
    await session.refresh(decision)
    return decision