"""Rebuild the migrated Milvus collection from saved vector chunks."""

from __future__ import annotations

import argparse
import json
from pathlib import Path

from pymilvus import Collection, CollectionSchema, DataType, FieldSchema, connections, utility


DEFAULT_COLLECTION = "regulations_dense_1024_v2"
DEFAULT_DIM = 1024


def build_collection(name: str, dim: int) -> Collection:
    """Create the migrated Milvus collection from scratch."""
    if utility.has_collection(name):
        utility.drop_collection(name)

    schema = CollectionSchema(
        fields=[
            FieldSchema(name="id", dtype=DataType.VARCHAR, max_length=128, is_primary=True, auto_id=False),
            FieldSchema(name="doc_id", dtype=DataType.VARCHAR, max_length=64),
            FieldSchema(name="doc_title", dtype=DataType.VARCHAR, max_length=256),
            FieldSchema(name="chunk_id", dtype=DataType.VARCHAR, max_length=128),
            FieldSchema(name="chunk_index", dtype=DataType.INT64),
            FieldSchema(name="piece_index", dtype=DataType.INT64),
            FieldSchema(name="text", dtype=DataType.VARCHAR, max_length=65535),
            FieldSchema(name="embedding_text", dtype=DataType.VARCHAR, max_length=65535),
            FieldSchema(name="embedding", dtype=DataType.FLOAT_VECTOR, dim=dim),
            FieldSchema(name="semantic_id", dtype=DataType.VARCHAR, max_length=128),
            FieldSchema(name="chunk_type", dtype=DataType.VARCHAR, max_length=64),
            FieldSchema(name="page_start", dtype=DataType.INT64),
            FieldSchema(name="page_end", dtype=DataType.INT64),
            FieldSchema(name="section_level", dtype=DataType.INT64),
            FieldSchema(name="source_ids", dtype=DataType.VARCHAR, max_length=4096),
            FieldSchema(name="section_path", dtype=DataType.VARCHAR, max_length=4096),
            FieldSchema(name="section_title", dtype=DataType.VARCHAR, max_length=512),
            FieldSchema(name="metadata_json", dtype=DataType.VARCHAR, max_length=65535),
            FieldSchema(name="created_at", dtype=DataType.INT64),
        ],
        description="Dense-only regulations index",
        enable_dynamic_field=False,
    )
    collection = Collection(name=name, schema=schema)
    collection.create_index(
        field_name="embedding",
        index_params={
            "metric_type": "COSINE",
            "index_type": "IVF_FLAT",
            "params": {"nlist": 128},
        },
    )
    return collection


def load_chunks(payload_path: Path) -> list[dict]:
    """Load vector chunks emitted by the Aliyun parser pipeline."""
    payload = json.loads(payload_path.read_text(encoding="utf-8"))
    if isinstance(payload, dict):
        chunks = payload.get("vector_chunks", [])
    else:
        chunks = payload
    if not isinstance(chunks, list):
        raise ValueError("vector chunk payload must be a list or a dict containing vector_chunks")
    return chunks


def main() -> None:
    """Rebuild the target collection from a vector chunk payload."""
    parser = argparse.ArgumentParser(description="Rebuild the migrated Milvus collection.")
    parser.add_argument("--host", default="127.0.0.1", help="Milvus host")
    parser.add_argument("--port", default="19530", help="Milvus port")
    parser.add_argument("--collection", default=DEFAULT_COLLECTION, help="Milvus collection name")
    parser.add_argument("--dim", type=int, default=DEFAULT_DIM, help="Embedding dimension")
    parser.add_argument("--payload", required=True, help="Path to vector_chunks.json or a compatible JSON file")
    args = parser.parse_args()

    connections.connect("default", host=args.host, port=args.port)
    collection = build_collection(args.collection, args.dim)
    chunks = load_chunks(Path(args.payload))
    if not chunks:
        print("No vector chunks found; collection was created but remains empty.")
        return

    data = [
        [chunk["chunk_id"] for chunk in chunks],
        [chunk["doc_id"] for chunk in chunks],
        [chunk["doc_title"] for chunk in chunks],
        [chunk["chunk_id"] for chunk in chunks],
        [int(chunk.get("chunk_index", 0) or 0) for chunk in chunks],
        [int(chunk.get("piece_index", 0) or 0) for chunk in chunks],
        [str(chunk.get("text", ""))[:65535] for chunk in chunks],
        [str(chunk.get("embedding_text", chunk.get("text", "")))[:65535] for chunk in chunks],
        [chunk["embedding"] for chunk in chunks],
        [str(chunk.get("semantic_id", "")) for chunk in chunks],
        [str(chunk.get("chunk_type", "")) for chunk in chunks],
        [int(chunk.get("page_start", 0) or 0) for chunk in chunks],
        [int(chunk.get("page_end", 0) or 0) for chunk in chunks],
        [int(chunk.get("section_level", 0) or 0) for chunk in chunks],
        [json.dumps(chunk.get("source_ids", []), ensure_ascii=False) for chunk in chunks],
        [json.dumps(chunk.get("section_path", []), ensure_ascii=False) for chunk in chunks],
        [str(chunk.get("section_title", "")) for chunk in chunks],
        [json.dumps(chunk, ensure_ascii=False) for chunk in chunks],
        [int(chunk.get("created_at", 0) or 0) for chunk in chunks],
    ]
    collection.insert(data)
    collection.flush()
    collection.load()
    print(f"Rebuilt collection {args.collection} with {len(chunks)} chunks.")


if __name__ == "__main__":
    main()