from typing import Literal, Optional

from fastapi import APIRouter, Depends, HTTPException, Query
from pydantic import BaseModel
from sqlalchemy import desc, func, or_, select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.database import get_db
from app.models import Bill, BillAction, BillBrief, BillDocument, NewsArticle, TrendScore
from app.schemas.schemas import (
    BillDetailSchema,
    BillSchema,
    BillActionSchema,
    NewsArticleSchema,
    PaginatedResponse,
    TrendScoreSchema,
)

_BILL_TYPE_LABELS: dict[str, str] = {
    "hr": "H.R.",
    "s": "S.",
    "hjres": "H.J.Res.",
    "sjres": "S.J.Res.",
    "hconres": "H.Con.Res.",
    "sconres": "S.Con.Res.",
    "hres": "H.Res.",
    "sres": "S.Res.",
}


class DraftLetterRequest(BaseModel):
    stance: Literal["yes", "no"]
    recipient: Literal["house", "senate"]
    tone: Literal["short", "polite", "firm"]
    selected_points: list[str]
    include_citations: bool = True
    zip_code: str | None = None  # not stored, not logged


class DraftLetterResponse(BaseModel):
    draft: str

router = APIRouter()


@router.get("", response_model=PaginatedResponse[BillSchema])
async def list_bills(
    chamber: Optional[str] = Query(None),
    topic: Optional[str] = Query(None),
    sponsor_id: Optional[str] = Query(None),
    q: Optional[str] = Query(None),
    page: int = Query(1, ge=1),
    per_page: int = Query(20, ge=1, le=100),
    sort: str = Query("latest_action_date"),
    db: AsyncSession = Depends(get_db),
):
    query = (
        select(Bill)
        .options(
            selectinload(Bill.sponsor),
            selectinload(Bill.briefs),
            selectinload(Bill.trend_scores),
        )
    )

    if chamber:
        query = query.where(Bill.chamber == chamber)
    if sponsor_id:
        query = query.where(Bill.sponsor_id == sponsor_id)
    if topic:
        query = query.join(BillBrief, Bill.bill_id == BillBrief.bill_id).where(
            BillBrief.topic_tags.contains([topic])
        )
    if q:
        query = query.where(
            or_(
                Bill.bill_id.ilike(f"%{q}%"),
                Bill.title.ilike(f"%{q}%"),
                Bill.short_title.ilike(f"%{q}%"),
            )
        )

    # Count total
    count_query = select(func.count()).select_from(query.subquery())
    total = await db.scalar(count_query) or 0

    # Sort
    sort_col = getattr(Bill, sort, Bill.latest_action_date)
    query = query.order_by(desc(sort_col)).offset((page - 1) * per_page).limit(per_page)

    result = await db.execute(query)
    bills = result.scalars().unique().all()

    # Single batch query: which of these bills have at least one document?
    bill_ids = [b.bill_id for b in bills]
    doc_result = await db.execute(
        select(BillDocument.bill_id).where(BillDocument.bill_id.in_(bill_ids)).distinct()
    )
    bills_with_docs = {row[0] for row in doc_result}

    # Attach latest brief, trend, and has_document to each bill
    items = []
    for bill in bills:
        bill_dict = BillSchema.model_validate(bill)
        if bill.briefs:
            bill_dict.latest_brief = bill.briefs[0]
        if bill.trend_scores:
            bill_dict.latest_trend = bill.trend_scores[0]
        bill_dict.has_document = bill.bill_id in bills_with_docs
        items.append(bill_dict)

    return PaginatedResponse(
        items=items,
        total=total,
        page=page,
        per_page=per_page,
        pages=max(1, (total + per_page - 1) // per_page),
    )


@router.get("/{bill_id}", response_model=BillDetailSchema)
async def get_bill(bill_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(
        select(Bill)
        .options(
            selectinload(Bill.sponsor),
            selectinload(Bill.actions),
            selectinload(Bill.briefs),
            selectinload(Bill.news_articles),
            selectinload(Bill.trend_scores),
        )
        .where(Bill.bill_id == bill_id)
    )
    bill = result.scalar_one_or_none()
    if not bill:
        from fastapi import HTTPException
        raise HTTPException(status_code=404, detail="Bill not found")

    detail = BillDetailSchema.model_validate(bill)
    if bill.briefs:
        detail.latest_brief = bill.briefs[0]
    if bill.trend_scores:
        detail.latest_trend = bill.trend_scores[0]
    doc_exists = await db.scalar(
        select(func.count()).select_from(BillDocument).where(BillDocument.bill_id == bill_id)
    )
    detail.has_document = bool(doc_exists)

    # Trigger a background news refresh if no articles are stored but trend
    # data shows there are gnews results out there waiting to be fetched.
    latest_trend = bill.trend_scores[0] if bill.trend_scores else None
    has_gnews = latest_trend and (latest_trend.gnews_count or 0) > 0
    if not bill.news_articles and has_gnews:
        try:
            from app.workers.news_fetcher import fetch_news_for_bill
            fetch_news_for_bill.delay(bill_id)
        except Exception:
            pass

    return detail


@router.get("/{bill_id}/actions", response_model=list[BillActionSchema])
async def get_bill_actions(bill_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(
        select(BillAction)
        .where(BillAction.bill_id == bill_id)
        .order_by(desc(BillAction.action_date))
    )
    return result.scalars().all()


@router.get("/{bill_id}/news", response_model=list[NewsArticleSchema])
async def get_bill_news(bill_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(
        select(NewsArticle)
        .where(NewsArticle.bill_id == bill_id)
        .order_by(desc(NewsArticle.published_at))
        .limit(20)
    )
    return result.scalars().all()


@router.get("/{bill_id}/trend", response_model=list[TrendScoreSchema])
async def get_bill_trend(bill_id: str, days: int = Query(30, ge=7, le=365), db: AsyncSession = Depends(get_db)):
    from datetime import date, timedelta
    cutoff = date.today() - timedelta(days=days)
    result = await db.execute(
        select(TrendScore)
        .where(TrendScore.bill_id == bill_id, TrendScore.score_date >= cutoff)
        .order_by(TrendScore.score_date)
    )
    return result.scalars().all()


@router.post("/{bill_id}/draft-letter", response_model=DraftLetterResponse)
async def generate_letter(bill_id: str, body: DraftLetterRequest, db: AsyncSession = Depends(get_db)):
    from app.models.setting import AppSetting
    from app.services.llm_service import generate_draft_letter

    bill = await db.get(Bill, bill_id)
    if not bill:
        raise HTTPException(status_code=404, detail="Bill not found")

    if not body.selected_points:
        raise HTTPException(status_code=422, detail="At least one point must be selected")

    prov_row = await db.get(AppSetting, "llm_provider")
    model_row = await db.get(AppSetting, "llm_model")
    llm_provider_override = prov_row.value if prov_row else None
    llm_model_override = model_row.value if model_row else None

    type_label = _BILL_TYPE_LABELS.get((bill.bill_type or "").lower(), (bill.bill_type or "").upper())
    bill_label = f"{type_label} {bill.bill_number}"

    try:
        draft = generate_draft_letter(
            bill_label=bill_label,
            bill_title=bill.short_title or bill.title or bill_label,
            stance=body.stance,
            recipient=body.recipient,
            tone=body.tone,
            selected_points=body.selected_points,
            include_citations=body.include_citations,
            zip_code=body.zip_code,
            llm_provider=llm_provider_override,
            llm_model=llm_model_override,
        )
    except Exception as exc:
        msg = str(exc)
        if "insufficient_quota" in msg or "quota" in msg.lower():
            detail = "LLM quota exceeded. Check your API key billing."
        elif "rate_limit" in msg.lower() or "429" in msg:
            detail = "LLM rate limit hit. Wait a moment and try again."
        elif "auth" in msg.lower() or "401" in msg or "403" in msg:
            detail = "LLM authentication failed. Check your API key."
        else:
            detail = f"LLM error: {msg[:200]}"
        raise HTTPException(status_code=502, detail=detail)
    return {"draft": draft}