from __future__ import annotations

"""Merge embedding-similar clusters in SQLite.

This is a maintenance script for the embedding-first clustering rollout.
It supports dry-run mode, reports candidate groups, and when run wet it merges
clusters within the same topic whose embeddings are similar enough.

Usage:
  ./.venv/bin/python scripts/merge_cluster_embeddings.py --dry-run --threshold 0.90
  ./.venv/bin/python scripts/merge_cluster_embeddings.py --threshold 0.88
"""

import argparse
import json
import sys
from collections import defaultdict
from pathlib import Path
from typing import Any

ROOT = Path(__file__).resolve().parents[1]
sys.path.insert(0, str(ROOT))

from news_mcp.config import DB_PATH
from news_mcp.dedup.embedding_support import cosine_similarity
from news_mcp.storage.sqlite_store import SQLiteClusterStore


def _embedding(cluster: dict[str, Any]) -> list[float] | None:
    emb = cluster.get("embedding")
    if isinstance(emb, list) and emb:
        try:
            return [float(x) for x in emb]
        except Exception:
            return None
    return None


def _avg_vectors(vectors: list[list[float]]) -> list[float] | None:
    if not vectors:
        return None
    size = len(vectors[0])
    if any(len(v) != size for v in vectors):
        return None
    out = [0.0] * size
    for v in vectors:
        for i, x in enumerate(v):
            out[i] += x
    n = float(len(vectors))
    return [x / n for x in out]


def _uniq_by_url(items: list[dict[str, Any]]) -> list[dict[str, Any]]:
    seen = set()
    out = []
    for item in items:
        key = item.get("url") or item.get("title")
        if key in seen:
            continue
        seen.add(key)
        out.append(item)
    return out


def _merge_payloads(clusters: list[dict[str, Any]]) -> dict[str, Any]:
    # Choose the most populated cluster as the base.
    base = max(clusters, key=lambda c: len(c.get("articles", []) or []))
    merged = dict(base)

    all_articles: list[dict[str, Any]] = []
    all_sources: list[str] = []
    all_entities: list[str] = []
    all_keywords: list[str] = []
    embeddings: list[list[float]] = []
    sent_scores: list[float] = []

    first_seen = None
    last_updated = None

    for c in clusters:
        all_articles.extend([a for a in (c.get("articles", []) or []) if isinstance(a, dict)])
        all_sources.extend([str(s) for s in (c.get("sources", []) or [])])
        all_entities.extend([str(e) for e in (c.get("entities", []) or [])])
        all_keywords.extend([str(k) for k in (c.get("keywords", []) or [])])

        emb = _embedding(c)
        if emb:
            embeddings.append(emb)

        if c.get("sentimentScore") is not None:
            try:
                sent_scores.append(float(c["sentimentScore"]))
            except Exception:
                pass

        fs = str(c.get("first_seen") or c.get("timestamp") or "")
        lu = str(c.get("last_updated") or c.get("timestamp") or "")
        if fs and (first_seen is None or fs < first_seen):
            first_seen = fs
        if lu and (last_updated is None or lu > last_updated):
            last_updated = lu

    merged["articles"] = _uniq_by_url(all_articles)
    merged["sources"] = list(dict.fromkeys(all_sources))
    merged["entities"] = list(dict.fromkeys(e for e in all_entities if e))
    merged["keywords"] = list(dict.fromkeys(k for k in all_keywords if k))
    merged["first_seen"] = first_seen or merged.get("first_seen")
    merged["last_updated"] = last_updated or merged.get("last_updated")
    merged["importance"] = max(float(c.get("importance", 0.0) or 0.0) for c in clusters)
    if sent_scores:
        merged["sentimentScore"] = sum(sent_scores) / len(sent_scores)
    merged["embedding"] = _avg_vectors(embeddings) or merged.get("embedding")
    merged["embedding_model"] = merged.get("embedding_model") or "ollama:nomic-embed-text"
    return merged


def main() -> None:
    parser = argparse.ArgumentParser(description="Merge embedding-similar news clusters")
    parser.add_argument("--db", type=Path, default=DB_PATH)
    parser.add_argument("--threshold", type=float, default=0.9)
    parser.add_argument("--dry-run", action="store_true")
    parser.add_argument("--limit", type=int, default=None, help="Optional maximum number of rows to scan")
    parser.add_argument("--top", type=int, default=50, help="Max groups to print in dry-run mode")
    args = parser.parse_args()

    store = SQLiteClusterStore(args.db)
    with store._conn() as conn:  # noqa: SLF001 - maintenance script
        rows = conn.execute("SELECT cluster_id, topic, payload FROM clusters ORDER BY updated_at ASC").fetchall()

    if args.limit is not None:
        rows = rows[: args.limit]

    by_topic: dict[str, list[dict[str, Any]]] = defaultdict(list)
    for cluster_id, topic, payload_json in rows:
        try:
            cluster = json.loads(payload_json)
        except Exception:
            continue
        emb = _embedding(cluster)
        if not emb:
            continue
        cluster["_topic_key"] = topic or cluster.get("topic", "other")
        by_topic[cluster["_topic_key"]].append(cluster)

    groups = []
    for topic, clusters in by_topic.items():
        if len(clusters) < 2:
            continue

        parent = list(range(len(clusters)))

        def find(x: int) -> int:
            while parent[x] != x:
                parent[x] = parent[parent[x]]
                x = parent[x]
            return x

        def union(a: int, b: int) -> None:
            ra, rb = find(a), find(b)
            if ra != rb:
                parent[rb] = ra

        for i in range(len(clusters)):
            ei = _embedding(clusters[i])
            if not ei:
                continue
            for j in range(i + 1, len(clusters)):
                ej = _embedding(clusters[j])
                if not ej:
                    continue
                if cosine_similarity(ei, ej) >= args.threshold:
                    union(i, j)

        buckets: dict[int, list[dict[str, Any]]] = defaultdict(list)
        for idx, c in enumerate(clusters):
            buckets[find(idx)].append(c)

        for bucket in buckets.values():
            if len(bucket) < 2:
                continue
            bucket = sorted(bucket, key=lambda c: str(c.get("updated_at") or c.get("last_updated") or ""), reverse=True)
            groups.append((topic, bucket))

    print({"threshold": args.threshold, "merge_groups": len(groups), "dry_run": args.dry_run})

    if args.dry_run:
        for topic, bucket in groups[: args.top]:
            print(json.dumps({
                "topic": topic,
                "size": len(bucket),
                "cluster_ids": [c.get("cluster_id") for c in bucket],
                "headlines": [c.get("headline") for c in bucket],
            }, ensure_ascii=False))
        return

    with store._conn() as conn:  # noqa: SLF001
        for topic, bucket in groups:
            merged = _merge_payloads(bucket)
            cluster_id = merged.get("cluster_id")
            payload = json.dumps(merged, ensure_ascii=False)
            conn.execute(
                "INSERT INTO clusters(cluster_id, topic, payload, updated_at) VALUES(?,?,?,?) "
                "ON CONFLICT(cluster_id) DO UPDATE SET topic=excluded.topic, payload=excluded.payload, updated_at=excluded.updated_at",
                (cluster_id, topic, payload, merged.get("last_updated") or merged.get("updated_at") or ""),
            )
            # Delete absorbed duplicates; keep the representative row.
            dup_ids = [c.get("cluster_id") for c in bucket if c.get("cluster_id") != cluster_id]
            for cid in dup_ids:
                conn.execute("DELETE FROM clusters WHERE cluster_id=?", (cid,))
        conn.commit()

    print({"merged_groups": len(groups), "threshold": args.threshold})


if __name__ == "__main__":
    main()