"""
Retrieval pipeline for RAG validation.

This module provides functions to:
- Convert search queries to embeddings using Cohere
- Perform similarity search against Qdrant collection
- Format and return results with metadata
"""

import argparse
import json
import sys
import time
import logging
from pathlib import Path
from typing import List, Dict, Any

# Add parent directory to path for imports
sys.path.insert(0, str(Path(__file__).parent))

import cohere
from qdrant_client import QdrantClient

# Importfrom existing modules
import config
import utils
from logging_config import setup_logging

# Initialize logger
logger = logging.getLogger(__name__)


# Custom exceptions
class ConfigurationError(Exception):
    """Raised when required configuration is missing."""

    pass


class CollectionNotFoundError(Exception):
    """Raised when Qdrant collection doesn't exist."""

    pass


class DimensionMismatchError(Exception):
    """Raised when embedding dimension doesn't match collection."""

    pass


class APIError(Exception):
    """Raised when Cohere or Qdrant API call fails after retries."""

    pass


def validate_config(cfg: dict) -> None:
    """Validate that all required config values are present."""
    required = ["cohere_api_key", "qdrant_url", "qdrant_api_key"]
    missing = [key for key in required if not cfg.get(key)]
    if missing:
        raise ConfigurationError(
            f"Missing required environment variables: {', '.join(missing)}"
        )


def init_clients(cfg: dict):
    """Initialize Cohere and Qdrant clients."""
    cohere_client = cohere.ClientV2(api_key=cfg["cohere_api_key"])
    qdrant_client = QdrantClient(url=cfg["qdrant_url"], api_key=cfg["qdrant_api_key"])
    return cohere_client, qdrant_client


def check_collection(
    qdrant_client: QdrantClient, collection_name: str
) -> Dict[str, Any]:
    """Verify collection exists and has correct vector size."""
    try:
        info = qdrant_client.get_collection(collection_name)
    except Exception as e:
        if "not found" in str(e).lower():
            raise CollectionNotFoundError(
                f"Collection '{collection_name}' does not exist"
            )
        raise

    vector_size = info.config.params.vectors.size
    if vector_size != 1024:
        raise DimensionMismatchError(f"Expected vector size 1024 but got {vector_size}")

    return {
        "exists": True,
        "vector_size": vector_size,
        "points_count": info.points_count,
    }


def embed_query(text: str, cohere_client: cohere.ClientV2) -> List[float]:
    """Generate embedding for a search query using Cohere."""
    try:
        response = cohere_client.embed(
            texts=[text], model="embed-english-v3.0", input_type="search_query"
        )
        # Extract embedding from response.embeddings.float_
        embedding = response.embeddings.float_[0]
        return embedding
    except Exception as e:
        logger.error(f"Failed to generate embedding: {e}")
        raise APIError(f"Cohere embedding failed: {e}")


def validate_metadata_completeness(results: List[Dict[str, Any]]) -> float:
    """
    Check metadata completeness in search results.

    Returns:
        Percentage (0-100) of results with complete metadata:
        - url present and non-empty
        - text present with length ≥ 10
        - at least one of title or section non-empty
    """
    if not results:
        return 0.0

    complete = 0
    total = len(results)

    for result in results:
        payload = result.get("payload", {})
        url = payload.get("url", "")
        text = payload.get("text", "")
        title = payload.get("title", "")
        section = payload.get("section", "")

        # Check completeness criteria
        url_ok = bool(url and url.strip())
        text_ok = len(text or "") >= 10
        title_section_ok = bool(
            (title and title.strip()) or (section and section.strip())
        )

        if url_ok and text_ok and title_section_ok:
            complete += 1

    percentage = (complete / total) * 100
    logger.debug(f"Metadata completeness: {complete}/{total} = {percentage:.1f}%")
    return percentage


def validate_chunk_sequencing(results: List[Dict[str, Any]]) -> bool:
    """
    Verify that chunk_index values are properly assigned: integers >= 0 and unique per URL.

    Note: Since search may return only a subset of chunks for a URL, we cannot
    verify full sequential continuity (0,1,2,3...). Instead we check:
    - All chunk_index values are integers >= 0
    - No duplicate chunk_index for the same URL in the result set

    Args:
        results: List of search results

    Returns:
        True if chunk indices are valid, False otherwise
    """
    # Group by URL
    url_chunks = {}
    for result in results:
        payload = result.get("payload", {})
        url = payload.get("url", "")
        chunk_idx = payload.get("chunk_index")

        if url not in url_chunks:
            url_chunks[url] = []
        url_chunks[url].append(chunk_idx)

    # Check each URL's chunks are valid
    for url, indices in url_chunks.items():
        # All indices must be integers >= 0
        for idx in indices:
            if not isinstance(idx, int) or idx < 0:
                logger.debug(
                    f"Invalid chunk_index for {url}: {idx} (must be non-negative integer)"
                )
                return False

        # Check for duplicates (within this URL's results)
        if len(set(indices)) != len(indices):
            logger.debug(f"Duplicate chunk_index for {url}: {indices}")
            return False

    logger.debug(f"Chunk indexing valid for {len(url_chunks)} URLs")
    return True


def search(
    query_text: str,
    cohere_client: cohere.ClientV2,
    qdrant_client: QdrantClient,
    collection_name: str,
    top_k: int = 5,
) -> List[Dict[str, Any]]:
    """
    Convert query to embedding and retrieve top-K relevant chunks.

    Args:
        query_text: User's search query (non-empty, ≤1000 chars)
        top_k: Number of results to return (1-100)

    Returns:
        List of search results with id, score, and payload
    """
    # Validate inputs
    if not query_text or not query_text.strip():
        raise ValueError("Query text must be non-empty")
    query_text = query_text.strip()
    if len(query_text) > 1000:
        raise ValueError("Query text must be ≤ 1000 characters")
    if top_k < 1 or top_k > 100:
        raise ValueError("top_k must be between 1 and 100")

    logger.info(f"Embedding query: '{query_text[:100]}...' (top_k={top_k})")
    start_time = time.time()

    # Generate query embedding with retry
    try:
        embedding = utils.retry_with_backoff(
            lambda: embed_query(query_text, cohere_client),
            max_retries=3,
            base_delay=1.0,
            max_delay=10.0,
        )
        embed_time = time.time() - start_time
        logger.debug(
            f"Generated embedding in {embed_time:.2f}s, dimension: {len(embedding)}"
        )
    except Exception as e:
        logger.error(f"Failed to embed query: {e}")
        raise

    # Search Qdrant with retry
    try:
        search_start = time.time()
        response = utils.retry_with_backoff(
            lambda: qdrant_client.query_points(
                collection_name=collection_name,
                query=embedding,
                limit=top_k,
                with_payload=True,
                with_vectors=False,
            ),
            max_retries=3,
            base_delay=1.0,
            max_delay=10.0,
        )
        results = response.points
        search_time = time.time() - search_start
        logger.info(
            f"Search completed in {search_time:.2f}s, returned {len(results)} results"
        )
    except Exception as e:
        logger.error(f"Search failed: {e}")
        raise APIError(f"Qdrant search failed: {e}")

    # Format results
    formatted = []
    for result in results:
        formatted.append(
            {
                "id": str(result.id),
                "score": float(result.score),
                "payload": result.payload,
            }
        )

    total_time = time.time() - start_time
    logger.info(f"Total query time: {total_time:.2f}s")

    return formatted


def format_results(
    results: List[Dict[str, Any]], query: str, latency_ms: int
) -> Dict[str, Any]:
    """Format search results into JSON output structure."""
    output = {
        "query": query,
        "timestamp": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
        "results": results,
        "metadata": {
            "total_results": len(results),
            "collection": None,  # Will be filled by main
            "latency_ms": latency_ms,
        },
    }
    return output


def main() -> int:
    """CLI entrypoint for retrieval."""
    parser = argparse.ArgumentParser(
        description="Retrieve relevant chunks from Qdrant using Cohere embeddings"
    )
    parser.add_argument("--query", type=str, help="Search query text")
    parser.add_argument(
        "--top-k", type=int, default=5, help="Number of results to return (default: 5)"
    )
    parser.add_argument("--output", type=str, help="Output file path (default: stdout)")
    parser.add_argument(
        "--config",
        type=str,
        default=".env",
        help="Path to .env config file (default: .env)",
    )
    parser.add_argument(
        "--validate-metadata",
        action="store_true",
        help="Run metadata validation on search results (requires --query)",
    )

    args = parser.parse_args()

    # Setup logging
    log_file = "retrieve.log"
    setup_logging(log_file=log_file, console_level="INFO")
    logger.info("=== Retrieval Pipeline Started ===")

    try:
        # Load config
        logger.info(f"Loading config from {args.config}")
        cfg = config.get_config()
        validate_config(cfg)

        # Initialize clients
        logger.info("Initializing Cohere and Qdrant clients")
        cohere_client, qdrant_client = init_clients(cfg)

        # Check collection
        collection_name = cfg["qdrant_collection"]
        logger.info(f"Checking collection '{collection_name}'")
        coll_info = check_collection(qdrant_client, collection_name)
        logger.info(
            f"Collection OK: vector_size={coll_info['vector_size']}, points={coll_info['points_count']}"
        )

        # Validate query argument
        if not args.query:
            parser.error("--query is required")

        # Perform search
        results = search(
            query_text=args.query,
            cohere_client=cohere_client,
            qdrant_client=qdrant_client,
            collection_name=collection_name,
            top_k=args.top_k,
        )

        # Perform metadata validation if requested
        metadata_validation = None
        if args.validate_metadata:
            completeness = validate_metadata_completeness(results)
            sequencing = validate_chunk_sequencing(results)
            metadata_validation = {
                "completeness_pct": round(completeness, 2),
                "sequencing_valid": sequencing,
                "pass": completeness >= 98.0 and sequencing,
            }
            logger.info(f"Metadata completeness: {completeness:.1f}%")
            logger.info(f"Chunk sequencing: {'VALID' if sequencing else 'INVALID'}")
            logger.info(
                f"Validation result: {'PASS' if metadata_validation['pass'] else 'FAIL'}"
            )

        # Format output
        output = {
            "query": args.query,
            "timestamp": time.strftime("%Y-%m-%dT%H:%M:%SZ", time.gmtime()),
            "results": results,
            "metadata": {
                "total_results": len(results),
                "collection": collection_name,
                "vector_size": coll_info["vector_size"],
                "points_count": coll_info["points_count"],
            },
        }

        if metadata_validation:
            output["metadata_validation"] = metadata_validation

        # Output JSON
        json_output = json.dumps(output, indent=2)
        if args.output:
            with open(args.output, "w") as f:
                f.write(json_output)
            logger.info(f"Results written to {args.output}")
        else:
            print(json_output)

        logger.info("=== Retrieval Pipeline Completed Successfully ===")
        return 0

    except ValueError as ve:
        logger.error(f"Validation error: {ve}")
        print(f"ERROR: {ve}", file=sys.stderr)
        return 2
    except ConfigurationError as ce:
        logger.error(f"Configuration error: {ce}")
        print(f"ERROR: {ce}", file=sys.stderr)
        return 1
    except CollectionNotFoundError as cnfe:
        logger.error(f"Collection error: {cnfe}")
        print(f"ERROR: {cnfe}", file=sys.stderr)
        return 1
    except DimensionMismatchError as dme:
        logger.error(f"Dimension error: {dme}")
        print(f"ERROR: {dme}", file=sys.stderr)
        return 1
    except APIError as api_err:
        logger.error(f"API error: {api_err}")
        print(f"ERROR: {api_err}", file=sys.stderr)
        return 1
    except Exception as e:
        logger.exception(f"Unexpected error: {e}")
        print(f"ERROR: Unexpected error: {e}", file=sys.stderr)
        return 1


if __name__ == "__main__":
    sys.exit(main())