"""
News v2 endpoints — multi-source headline + session aggregate API.

Mounted at `/api/v1/news/v2/*` to avoid conflict with the legacy
`GET /news/{ticker}` aggregator (which uses a wildcard path).

Endpoints:
  GET  /headlines                  raw headline rows
  GET  /session_aggregate          single (ticker, session_date, window)
  POST /session_aggregate/batch    many tickers in one shot
  GET  /coverage                   per-source ingest depth probe
"""

from __future__ import annotations

import asyncio
import logging
from datetime import date, datetime, timezone
from typing import Optional

from fastapi import APIRouter, Body, Depends, HTTPException, Query
from fastapi.responses import Response
from pydantic import BaseModel, Field, field_validator
from sqlalchemy import func, select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.database import get_db
from app.models.news_headline import NewsHeadline
from app.services.news.session_aggregator import (
    aggregate_session,
    aggregate_session_batch,
)
from app.services.news.session_window import session_window
from app.utils.cache import with_cache

logger = logging.getLogger("app.api.v1.news_v2")

router = APIRouter()

# Concurrency gates — prevent event-loop saturation under bulk scans
_HEADLINES_SEMAPHORE = asyncio.Semaphore(8)
_AGG_SEMAPHORE = asyncio.Semaphore(8)
_SEMAPHORE_WAIT_TIMEOUT = 10.0

_VALID_SOURCES = {"alpaca_benzinga", "stocktwits", "finnhub", "gdelt"}
_VALID_WINDOWS = {"premarket", "intraday", "post", "full_session"}


# ---------------------------------------------------------------------------
# Schemas
# ---------------------------------------------------------------------------

class HeadlineItem(BaseModel):
    source: str
    source_id: str
    ticker: str
    tickers_all: list[str] | None = None
    published_at: str
    headline: str
    summary: str | None = None
    url: str | None = None
    language: str | None = None
    vendor_categories: list[str] | None = None
    categories: list[str] | None = None
    raw_sentiment: float | None = None
    is_primary: bool
    ingested_at: str


class HeadlinesResponse(BaseModel):
    items: list[HeadlineItem]
    next_cursor: str | None = None


class SocialStatsItem(BaseModel):
    message_count: int = 0
    bull_count: int = 0
    bear_count: int = 0
    bull_bear_ratio: float | None = None


class SessionAggregateItem(BaseModel):
    ticker: str
    session_date: str
    window: str
    headline_count: int = 0
    primary_count: int = 0
    first_headline_at: str | None = None
    last_headline_at: str | None = None
    category_counts: dict[str, int] = Field(default_factory=dict)
    sentiment_mean: float | None = None
    sentiment_recency_weighted: float | None = None
    social: SocialStatsItem = Field(default_factory=SocialStatsItem)
    sources_present: list[str] = Field(default_factory=list)


class SessionAggregateBatchRequest(BaseModel):
    session_date: date
    window: str
    symbols: list[str]
    sources: list[str] | None = None

    @field_validator("window")
    @classmethod
    def _validate_window(cls, v: str) -> str:
        if v not in _VALID_WINDOWS:
            raise ValueError(f"window must be one of {sorted(_VALID_WINDOWS)}")
        return v

    @field_validator("symbols")
    @classmethod
    def _validate_symbols(cls, v: list[str]) -> list[str]:
        if not v:
            raise ValueError("symbols must not be empty")
        if len(v) > 200:
            raise ValueError("symbols max 200 per request")
        return v


class SessionAggregateBatchResponse(BaseModel):
    items: dict[str, SessionAggregateItem]


class CoverageResponse(BaseModel):
    source: str
    symbol: str | None = None
    earliest: str | None = None
    latest: str | None = None
    ingested_count: int


# ---------------------------------------------------------------------------
# A. /headlines — raw rows
# ---------------------------------------------------------------------------

@router.get(
    "/headlines",
    response_model=HeadlinesResponse,
    summary="Raw multi-source news headlines",
    description=(
        "Multi-source raw headline rows. Filter by symbols, time window, and "
        "source. Sources: `alpaca_benzinga`, `stocktwits`, `finnhub`, `gdelt`."
    ),
)
@with_cache(
    namespace="news_v2:headlines",
    ttl=300,
    key_params=["symbols", "start", "end", "sources", "limit", "cursor"],
)
async def get_headlines(
    response: Response,
    symbols: Optional[str] = Query(None, description="CSV ticker list, max 50 (e.g. AAPL,MSFT)"),
    start: Optional[datetime] = Query(None, description="Start time (UTC ISO)"),
    end: Optional[datetime] = Query(None, description="End time (UTC ISO)"),
    sources: Optional[str] = Query(None, description=f"CSV source filter, subset of {sorted(_VALID_SOURCES)}"),
    limit: int = Query(100, ge=1, le=500),
    cursor: Optional[str] = Query(None, description="published_at_lt cursor (ISO datetime)"),
    force_refresh: bool = Query(False),
    db: AsyncSession = Depends(get_db),
):
    sym_list = _csv_to_list(symbols, max_items=50, kind="symbols")
    src_list = _csv_to_list(sources, max_items=10, kind="sources")
    if src_list:
        bad = [s for s in src_list if s not in _VALID_SOURCES]
        if bad:
            raise HTTPException(400, f"Unknown sources: {bad}")

    cursor_dt = _parse_cursor(cursor)

    try:
        await asyncio.wait_for(_HEADLINES_SEMAPHORE.acquire(), timeout=_SEMAPHORE_WAIT_TIMEOUT)
    except asyncio.TimeoutError:
        raise HTTPException(429, "Server busy — try again later")
    try:
        stmt = select(NewsHeadline).order_by(NewsHeadline.published_at.desc()).limit(limit)
        if sym_list:
            stmt = stmt.where(NewsHeadline.ticker.in_([s.upper() for s in sym_list]))
        if start is not None:
            stmt = stmt.where(NewsHeadline.published_at >= _ensure_utc(start))
        if end is not None:
            stmt = stmt.where(NewsHeadline.published_at < _ensure_utc(end))
        if src_list:
            stmt = stmt.where(NewsHeadline.source.in_(src_list))
        if cursor_dt is not None:
            stmt = stmt.where(NewsHeadline.published_at < cursor_dt)

        result = await db.execute(stmt)
        rows = result.scalars().all()
    finally:
        _HEADLINES_SEMAPHORE.release()

    items = [_row_to_item(r) for r in rows]
    next_cursor = items[-1].published_at if len(items) == limit else None
    return HeadlinesResponse(items=items, next_cursor=next_cursor)


# ---------------------------------------------------------------------------
# B. /session_aggregate — single ticker
# ---------------------------------------------------------------------------

@router.get(
    "/session_aggregate",
    response_model=SessionAggregateItem,
    summary="Session-aggregated news for one ticker",
)
@with_cache(
    namespace="news_v2:session_agg",
    ttl=600,
    key_params=["symbol", "session_date", "window", "sources"],
)
async def get_session_aggregate(
    response: Response,
    symbol: str = Query(..., description="Ticker symbol"),
    session_date: date = Query(..., description="ET session date (YYYY-MM-DD)"),
    window: str = Query("premarket", description=f"One of {sorted(_VALID_WINDOWS)}"),
    sources: Optional[str] = Query(None, description=f"CSV source filter, subset of {sorted(_VALID_SOURCES)}"),
    force_refresh: bool = Query(False),
    db: AsyncSession = Depends(get_db),
):
    if window not in _VALID_WINDOWS:
        raise HTTPException(400, f"window must be one of {sorted(_VALID_WINDOWS)}")

    src_list = _csv_to_list(sources, max_items=10, kind="sources")
    if src_list:
        bad = [s for s in src_list if s not in _VALID_SOURCES]
        if bad:
            raise HTTPException(400, f"Unknown sources: {bad}")

    try:
        await asyncio.wait_for(_AGG_SEMAPHORE.acquire(), timeout=_SEMAPHORE_WAIT_TIMEOUT)
    except asyncio.TimeoutError:
        raise HTTPException(429, "Server busy — try again later")
    try:
        try:
            agg = await aggregate_session(
                db=db,
                ticker=symbol,
                session_date=session_date,
                window=window,  # type: ignore[arg-type]
                sources=src_list,
            )
        except ValueError as e:
            raise HTTPException(400, str(e))
    finally:
        _AGG_SEMAPHORE.release()

    return SessionAggregateItem(**agg.to_dict())


# ---------------------------------------------------------------------------
# C. POST /session_aggregate/batch — many tickers
# ---------------------------------------------------------------------------

@router.post(
    "/session_aggregate/batch",
    response_model=SessionAggregateBatchResponse,
    summary="Session-aggregated news for many tickers in one call",
    description=(
        "Batch variant. Caching is intentionally NOT applied at this layer — "
        "fithia2 maintains a client-side disk cache as the primary defense; "
        "Oracle absorbs only burst load. Use the GET single endpoint for "
        "Redis-cached single-ticker reads."
    ),
)
async def post_session_aggregate_batch(
    payload: SessionAggregateBatchRequest = Body(...),
    db: AsyncSession = Depends(get_db),
):
    src_list = payload.sources or None
    if src_list:
        bad = [s for s in src_list if s not in _VALID_SOURCES]
        if bad:
            raise HTTPException(400, f"Unknown sources: {bad}")

    try:
        await asyncio.wait_for(_AGG_SEMAPHORE.acquire(), timeout=_SEMAPHORE_WAIT_TIMEOUT)
    except asyncio.TimeoutError:
        raise HTTPException(429, "Server busy — try again later")
    try:
        try:
            results = await aggregate_session_batch(
                db=db,
                tickers=payload.symbols,
                session_date=payload.session_date,
                window=payload.window,  # type: ignore[arg-type]
                sources=src_list,
            )
        except ValueError as e:
            raise HTTPException(400, str(e))
    finally:
        _AGG_SEMAPHORE.release()

    return SessionAggregateBatchResponse(
        items={t: SessionAggregateItem(**a.to_dict()) for t, a in results.items()}
    )


# ---------------------------------------------------------------------------
# D. /coverage — per-source ingest depth
# ---------------------------------------------------------------------------

@router.get(
    "/coverage",
    response_model=CoverageResponse,
    summary="Per-source ingest coverage probe",
)
@with_cache(
    namespace="news_v2:coverage",
    ttl=300,
    key_params=["source", "symbol"],
)
async def get_coverage(
    response: Response,
    source: str = Query(..., description=f"One of {sorted(_VALID_SOURCES)}"),
    symbol: Optional[str] = Query(None, description="Optional ticker filter"),
    force_refresh: bool = Query(False),
    db: AsyncSession = Depends(get_db),
):
    if source not in _VALID_SOURCES:
        raise HTTPException(400, f"Unknown source: {source}")

    stmt = select(
        func.min(NewsHeadline.published_at),
        func.max(NewsHeadline.published_at),
        func.count(NewsHeadline.id),
    ).where(NewsHeadline.source == source)
    if symbol:
        stmt = stmt.where(NewsHeadline.ticker == symbol.strip().upper())

    result = await db.execute(stmt)
    row = result.one()
    earliest, latest, count = row

    return CoverageResponse(
        source=source,
        symbol=symbol.strip().upper() if symbol else None,
        earliest=earliest.isoformat() if earliest else None,
        latest=latest.isoformat() if latest else None,
        ingested_count=int(count or 0),
    )


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------

def _csv_to_list(s: str | None, *, max_items: int, kind: str) -> list[str]:
    if not s:
        return []
    items = [x.strip() for x in s.split(",") if x.strip()]
    if len(items) > max_items:
        raise HTTPException(400, f"{kind} max {max_items} per request")
    return items


def _parse_cursor(cursor: str | None) -> datetime | None:
    if not cursor:
        return None
    try:
        if cursor.endswith("Z"):
            cursor = cursor[:-1] + "+00:00"
        dt = datetime.fromisoformat(cursor)
        if dt.tzinfo is None:
            dt = dt.replace(tzinfo=timezone.utc)
        return dt
    except Exception:
        raise HTTPException(400, "cursor must be ISO datetime")


def _ensure_utc(dt: datetime) -> datetime:
    if dt.tzinfo is None:
        return dt.replace(tzinfo=timezone.utc)
    return dt.astimezone(timezone.utc)


def _row_to_item(r: NewsHeadline) -> HeadlineItem:
    return HeadlineItem(
        source=r.source,
        source_id=r.source_id,
        ticker=r.ticker,
        tickers_all=list(r.tickers_all) if r.tickers_all else None,
        published_at=_ensure_utc(r.published_at).isoformat(),
        headline=r.headline,
        summary=r.summary,
        url=r.url,
        language=r.language,
        vendor_categories=list(r.vendor_categories) if r.vendor_categories else None,
        categories=list(r.categories) if r.categories else None,
        raw_sentiment=r.raw_sentiment,
        is_primary=bool(r.is_primary),
        ingested_at=_ensure_utc(r.ingested_at).isoformat(),
    )