# -*- coding:utf-8 -*-
"""Hybrid retrieval: vector search + graph expansion + RRF fusion."""
from typing import List, Dict

def rrf_fusion(results_list: List[List[Dict]], k: int = 60) -> List[Dict]:
    """Reciprocal Rank Fusion - merge multiple ranked lists."""
    scores = {}
    
    for results in results_list:
        for rank, item in enumerate(results):
            doc_id = item.get("id", item.get("node_id", str(rank)))
            rrf_score = 1.0 / (k + rank + 1)
            
            if doc_id not in scores:
                scores[doc_id] = {"item": item, "score": 0}
            scores[doc_id]["score"] += rrf_score
    
    sorted_items = sorted(scores.values(), key=lambda x: -x["score"])
    
    for item in sorted_items:
        item["item"]["rrf_score"] = round(item["score"], 6)
    
    return [item["item"] for item in sorted_items]


def vector_search(query_embedding: List[float], vdb_plugin: Dict, 
                  collection: str = "knowledge", top_k: int = 20) -> List[Dict]:
    """Search VDB for similar vectors."""
    from plugins.registry import call_plugin
    
    endpoint = vdb_plugin.get("endpoint")
    if not endpoint:
        return []
    
    result = call_plugin(endpoint, "/v1/query", {
        "colname": collection,
        "vector": query_embedding,
        "pagerows": top_k,
        "page": 1
    })
    
    if "error" in result or result.get("status") != "SUCCEEDED":
        return []
    
    # VDB returns {"status": "SUCCEEDED", "data": {"rows": [...]}}
    data = result.get("data", {})
    return data.get("rows", []) if isinstance(data, dict) else []


def graph_expand(entity_ids: List[str], graph_plugin: Dict, 
                 graph_name: str = "knowledge", hops: int = 2) -> List[Dict]:
    """Expand entities via graph neighbors."""
    from plugins.registry import call_plugin
    
    endpoint = graph_plugin.get("endpoint")
    if not endpoint or graph_plugin.get("type") == "none":
        return []
    
    all_neighbors = []
    seen = set()
    
    for entity_id in entity_ids:
        # Graph uses entity_{name} format from ingest
        node_id = f"entity_{entity_id}".replace(" ", "_")
        result = call_plugin(endpoint, "/api/graph/neighbors", {
            "graph": graph_name,
            "node_id": node_id,
            "depth": hops
        })
        
        if "error" not in result:
            for neighbor in result.get("neighbors", []):
                nid = neighbor.get("node_id", "")
                if nid and nid not in seen:
                    seen.add(nid)
                    neighbor["source_entity"] = entity_id
                    neighbor["id"] = nid
                    all_neighbors.append(neighbor)
    
    return all_neighbors


def hybrid_retrieve(query_embedding: List[float], 
                    extracted_entities: List[str],
                    pipeline: Dict,
                    collection: str = "knowledge",
                    graph_name: str = "knowledge") -> List[Dict]:
    """Hybrid retrieval: vector + graph + RRF fusion."""
    plugins = pipeline.get("plugins", {})
    retriever_config = plugins.get("retriever", {})
    
    vector_top_k = retriever_config.get("vector_top_k", 20)
    graph_hops = retriever_config.get("graph_hops", 2)
    retriever_type = retriever_config.get("type", "hybrid")
    
    results_lists = []
    
    # Vector search
    vdb_plugin = plugins.get("vdb", {})
    vector_results = vector_search(query_embedding, vdb_plugin, collection, vector_top_k)
    if vector_results:
        results_lists.append(vector_results)
    
    # Graph expansion (only if hybrid mode and graph enabled)
    if retriever_type == "hybrid" and extracted_entities:
        graph_plugin = plugins.get("graph", {})
        graph_results = graph_expand(extracted_entities, graph_plugin, graph_name, graph_hops)
        if graph_results:
            results_lists.append(graph_results)
    
    if not results_lists:
        return []
    
    if len(results_lists) == 1:
        return results_lists[0]
    
    return rrf_fusion(results_lists)


def rerank_results(query: str, results: List[Dict], reranker_plugin: Dict, 
                   top_k: int = 5) -> List[Dict]:
    """Rerank results using BGE-Reranker."""
    from plugins.registry import call_plugin
    
    if not results or reranker_plugin.get("type") == "none":
        return results[:top_k]
    
    endpoint = reranker_plugin.get("endpoint")
    if not endpoint:
        return results[:top_k]
    
    # Prepare documents for reranking
    documents = []
    for r in results:
        doc = r.get("text", "") or r.get("description", "") or r.get("transcript", "")
        if not doc:
            doc = str(r.get("name", "")) + " " + str(r.get("attrs", {}))
        documents.append(doc)
    
    if not documents:
        return results[:top_k]
    
    rerank_result = call_plugin(endpoint, "/api/rerank", {
        "query": query,
        "documents": documents,
        "top_k": top_k
    })
    
    if "error" in rerank_result:
        return results[:top_k]
    
    # Map reranked docs back to original results
    ranked = []
    for rd in rerank_result.get("ranked_docs", []):
        doc_text = rd.get("doc", "")
        for orig in results:
            orig_text = orig.get("text", "") or orig.get("description", "") or str(orig.get("name", ""))
            if doc_text == orig_text or doc_text in orig_text or orig_text in doc_text:
                orig["rerank_score"] = rd.get("score", 0)
                ranked.append(orig)
                break
    
    return ranked if ranked else results[:top_k]