"""Merge and persist region review state (FR-08)."""
from __future__ import annotations

import json
from datetime import datetime, timezone
from typing import Any, Dict, List, Optional

from sqlalchemy.orm import Session

from ..models import DetectionRun
from .models import RegionReview

VALID_REVIEW_STATUSES = {"pending", "confirmed", "false_positive", "submitted"}


def _utcnow() -> datetime:
    return datetime.now(timezone.utc)


def load_regions(run: DetectionRun) -> List[dict]:
    try:
        return json.loads(run.regions_json or "[]")
    except json.JSONDecodeError:
        return []


def save_regions(db: Session, run: DetectionRun, regions: List[dict]) -> None:
    run.regions_json = json.dumps(regions)
    run.regions_count = len(regions)
    db.commit()


def merge_reviews(db: Session, run_id: int, regions: List[dict]) -> List[dict]:
    """Attach reviewStatus / notes from RegionReview rows onto region dicts."""
    reviews = {
        r.region_id: r
        for r in db.query(RegionReview).filter(RegionReview.run_id == run_id).all()
    }
    out = []
    for region in regions:
        rid = int(region.get("id", 0))
        rev = reviews.get(rid)
        merged = dict(region)
        if rev:
            merged["reviewStatus"] = rev.status
            merged["reviewNotes"] = rev.notes or ""
            merged["reviewedAt"] = rev.reviewed_at.isoformat() if rev.reviewed_at else None
        else:
            merged.setdefault("reviewStatus", region.get("reviewStatus", "pending"))
        out.append(merged)
    return out


def get_or_create_review(db: Session, run_id: int, region_id: int) -> RegionReview:
    row = (
        db.query(RegionReview)
        .filter(RegionReview.run_id == run_id, RegionReview.region_id == region_id)
        .first()
    )
    if row:
        return row
    row = RegionReview(run_id=run_id, region_id=region_id, status="pending")
    db.add(row)
    db.commit()
    db.refresh(row)
    return row


def set_region_review(
    db: Session,
    run: DetectionRun,
    region_id: int,
    review_status: str,
    reviewer_id: int,
    notes: str = "",
) -> dict:
    if review_status not in ("confirmed", "false_positive", "pending"):
        raise ValueError(f"Invalid reviewStatus: {review_status}")

    regions = load_regions(run)
    region = next((r for r in regions if int(r.get("id", -1)) == region_id), None)
    if not region:
        raise LookupError("Region not found in run")

    row = get_or_create_review(db, run.id, region_id)
    if row.status == "submitted":
        raise PermissionError("Region already submitted — cannot change review")

    row.status = review_status
    row.reviewer_id = reviewer_id
    row.notes = (notes or "").strip()
    row.reviewed_at = _utcnow()
    db.commit()

    region["reviewStatus"] = review_status
    if notes:
        region["reviewNotes"] = notes
    save_regions(db, run, regions)
    return merge_reviews(db, run.id, [region])[0]


def filter_regions_by_review(regions: List[dict], status: str) -> List[dict]:
    return [r for r in regions if (r.get("reviewStatus") or "pending") == status]


def mark_confirmed_submitted(db: Session, run_id: int, region_ids: List[int]) -> int:
    q = db.query(RegionReview).filter(
        RegionReview.run_id == run_id,
        RegionReview.region_id.in_(region_ids),
        RegionReview.status == "confirmed",
    )
    now = _utcnow()
    count = 0
    for row in q.all():
        row.status = "submitted"
        row.submitted_at = now
        count += 1
    db.commit()
    return count


def review_summary(regions: List[dict]) -> Dict[str, int]:
    summary = {"pending": 0, "confirmed": 0, "false_positive": 0, "submitted": 0}
    for r in regions:
        st = r.get("reviewStatus") or "pending"
        summary[st] = summary.get(st, 0) + 1
    return summary