import asyncio
import os
import re
import json
import redis.asyncio as redis
import numpy as np

from redis.commands.search.query import Query as RediSearchQuery
from redis.commands.search.indexDefinition import IndexDefinition, IndexType
from redis.commands.search.field import (
    TagField,
    TextField,
    NumericField,
    VectorField,
)
from loguru import logger
from typing import Dict, List, Optional
from datastore.datastore import DataStore
from models.models import (
    DocumentChunk,
    DocumentMetadataFilter,
    DocumentChunkWithScore,
    DocumentMetadataFilter,
    QueryResult,
    QueryWithEmbedding,
)
from services.date import to_unix_timestamp

# Read environment variables for Redis
REDIS_HOST = os.environ.get("REDIS_HOST", "localhost")
REDIS_PORT = int(os.environ.get("REDIS_PORT", 6379))
REDIS_PASSWORD = os.environ.get("REDIS_PASSWORD")
REDIS_INDEX_NAME = os.environ.get("REDIS_INDEX_NAME", "index")
REDIS_DOC_PREFIX = os.environ.get("REDIS_DOC_PREFIX", "doc")
REDIS_DISTANCE_METRIC = os.environ.get("REDIS_DISTANCE_METRIC", "COSINE")
REDIS_INDEX_TYPE = os.environ.get("REDIS_INDEX_TYPE", "FLAT")
assert REDIS_INDEX_TYPE in ("FLAT", "HNSW")

# OpenAI Ada Embeddings Dimension
VECTOR_DIMENSION = 1536

# RediSearch constants
REDIS_REQUIRED_MODULES = [
    {"name": "search", "ver": 20600},
    {"name": "ReJSON", "ver": 20404}
]

REDIS_DEFAULT_ESCAPED_CHARS = re.compile(r"[,.<>{}\[\]\\\"\':;!@#$%^&()\-+=~\/ ]")

# Helper functions
def unpack_schema(d: dict):
    for v in d.values():
        if isinstance(v, dict):
            yield from unpack_schema(v)
        else:
            yield v

async def _check_redis_module_exist(client: redis.Redis, modules: List[dict]):
    installed_modules = (await client.info()).get("modules", [])
    installed_modules = {module["name"]: module for module in installed_modules}
    for module in modules:
        if module["name"] not in installed_modules or int(installed_modules[module["name"]]["ver"]) < int(module["ver"]):
            error_message = "You must add the RediSearch (>= 2.6) and ReJSON (>= 2.4) modules from Redis Stack. " \
                "Please refer to Redis Stack docs: https://redis.io/docs/stack/"
            logger.error(error_message)
            raise AttributeError(error_message)


class RedisDataStore(DataStore):
    def __init__(self, client: redis.Redis, redisearch_schema: dict):
        self.client = client
        self._schema = redisearch_schema
        # Init default metadata with sentinel values in case the document written has no metadata
        self._default_metadata = {
            field: (0 if field == "created_at" else "_null_") for field in redisearch_schema["metadata"]
        }

    ### Redis Helper Methods ###

    @classmethod
    async def init(cls, **kwargs):
        """
        Setup the index if it does not exist.
        """
        try:
            # Connect to the Redis Client
            logger.info("Connecting to Redis")
            client = redis.Redis(
                host=REDIS_HOST, port=REDIS_PORT, password=REDIS_PASSWORD
            )
        except Exception as e:
            logger.error(f"Error setting up Redis: {e}")
            raise e

        await _check_redis_module_exist(client, modules=REDIS_REQUIRED_MODULES)

        dim = kwargs.get("dim", VECTOR_DIMENSION)
        redisearch_schema = {
            "metadata": {
                "document_id": TagField("$.metadata.document_id", as_name="document_id"),
                "source_id": TagField("$.metadata.source_id", as_name="source_id"),
                "source": TagField("$.metadata.source", as_name="source"),
                "author": TextField("$.metadata.author", as_name="author"),
                "created_at": NumericField("$.metadata.created_at", as_name="created_at"),
            },
            "embedding": VectorField(
                "$.embedding",
                REDIS_INDEX_TYPE,
                {
                    "TYPE": "FLOAT64",
                    "DIM": dim,
                    "DISTANCE_METRIC": REDIS_DISTANCE_METRIC,
                },
                as_name="embedding",
            ),
        }
        try:
            # Check for existence of RediSearch Index
            await client.ft(REDIS_INDEX_NAME).info()
            logger.info(f"RediSearch index {REDIS_INDEX_NAME} already exists")
        except:
            # Create the RediSearch Index
            logger.info(f"Creating new RediSearch index {REDIS_INDEX_NAME}")
            definition = IndexDefinition(
                prefix=[REDIS_DOC_PREFIX], index_type=IndexType.JSON
            )
            fields = list(unpack_schema(redisearch_schema))
            logger.info(f"Creating index with fields: {fields}")
            await client.ft(REDIS_INDEX_NAME).create_index(
                fields=fields, definition=definition
            )
        return cls(client, redisearch_schema)

    @staticmethod
    def _redis_key(document_id: str, chunk_id: str) -> str:
        """
        Create the JSON key for document chunks in Redis.

        Args:
            document_id (str): Document Identifier
            chunk_id (str): Chunk Identifier

        Returns:
            str: JSON key string.
        """
        return f"doc:{document_id}:chunk:{chunk_id}"

    @staticmethod
    def _escape(value: str) -> str:
        """
        Escape filter value.

        Args:
            value (str): Value to escape.

        Returns:
            str: Escaped filter value for RediSearch.
        """

        def escape_symbol(match) -> str:
            value = match.group(0)
            return f"\\{value}"

        return REDIS_DEFAULT_ESCAPED_CHARS.sub(escape_symbol, value)

    def _get_redis_chunk(self, chunk: DocumentChunk) -> dict:
        """
        Convert DocumentChunk into a JSON object for storage
        in Redis.

        Args:
            chunk (DocumentChunk): Chunk of a Document.

        Returns:
            dict: JSON object for storage in Redis.
        """
        # Convert chunk -> dict
        data = chunk.__dict__
        metadata = chunk.metadata.__dict__
        data["chunk_id"] = data.pop("id")

        # Prep Redis Metadata
        redis_metadata = dict(self._default_metadata)
        if metadata:
            for field, value in metadata.items():
                if value:
                    if field == "created_at":
                        redis_metadata[field] = to_unix_timestamp(value)  # type: ignore
                    else:
                        redis_metadata[field] = value
        data["metadata"] = redis_metadata
        return data

    def _get_redis_query(self, query: QueryWithEmbedding) -> RediSearchQuery:
        """
        Convert a QueryWithEmbedding into a RediSearchQuery.

        Args:
            query (QueryWithEmbedding): Search query.

        Returns:
            RediSearchQuery: Query for RediSearch.
        """
        filter_str: str = ""

        # RediSearch field type to query string
        def _typ_to_str(typ, field, value) -> str:  # type: ignore
            if isinstance(typ, TagField):
                return f"@{field}:{{{self._escape(value)}}} "
            elif isinstance(typ, TextField):
                return f"@{field}:{value} "
            elif isinstance(typ, NumericField):
                num = to_unix_timestamp(value)
                match field:
                    case "start_date":
                        return f"@{field}:[{num} +inf] "
                    case "end_date":
                        return f"@{field}:[-inf {num}] "

        # Build filter
        if query.filter:
            redisearch_schema = self._schema
            for field, value in query.filter.__dict__.items():
                if not value:
                    continue
                if field in redisearch_schema:
                    filter_str += _typ_to_str(redisearch_schema[field], field, value)
                elif field in redisearch_schema["metadata"]:
                    if field == "source":  # handle the enum
                        value = value.value
                    filter_str += _typ_to_str(
                        redisearch_schema["metadata"][field], field, value
                    )
                elif field in ["start_date", "end_date"]:
                    filter_str += _typ_to_str(
                        redisearch_schema["metadata"]["created_at"], field, value
                    )

        # Postprocess filter string
        filter_str = filter_str.strip()
        filter_str = filter_str if filter_str else "*"

        # Prepare query string
        query_str = (
            f"({filter_str})=>[KNN {query.top_k} @embedding $embedding as score]"
        )
        return (
            RediSearchQuery(query_str)
            .sort_by("score")
            .paging(0, query.top_k)
            .dialect(2)
        )

    async def _redis_delete(self, keys: List[str]):
        """
        Delete a list of keys from Redis.

        Args:
            keys (List[str]): List of keys to delete.
        """
        # Delete the keys
        await asyncio.gather(*[self.client.delete(key) for key in keys])

    #######

    async def _upsert(self, chunks: Dict[str, List[DocumentChunk]]) -> List[str]:
        """
        Takes in a list of list of document chunks and inserts them into the database.
        Return a list of document ids.
        """
        # Initialize a list of ids to return
        doc_ids: List[str] = []

        # Loop through the dict items
        for doc_id, chunk_list in chunks.items():

            # Append the id to the ids list
            doc_ids.append(doc_id)

            # Write chunks in a pipelines
            async with self.client.pipeline(transaction=False) as pipe:
                for chunk in chunk_list:
                    key = self._redis_key(doc_id, chunk.id)
                    data = self._get_redis_chunk(chunk)
                    await pipe.json().set(key, "$", data)
                await pipe.execute()

        return doc_ids

    async def _query(
        self,
        queries: List[QueryWithEmbedding],
    ) -> List[QueryResult]:
        """
        Takes in a list of queries with embeddings and filters and
        returns a list of query results with matching document chunks and scores.
        """
        # Prepare query responses and results object
        results: List[QueryResult] = []

        # Gather query results in a pipeline
        logger.info(f"Gathering {len(queries)} query results")
        for query in queries:

            logger.debug(f"Query: {query.query}")
            query_results: List[DocumentChunkWithScore] = []

            # Extract Redis query
            redis_query: RediSearchQuery = self._get_redis_query(query)
            embedding = np.array(query.embedding, dtype=np.float64).tobytes()

            # Perform vector search
            query_response = await self.client.ft(REDIS_INDEX_NAME).search(
                redis_query, {"embedding": embedding}
            )

            # Iterate through the most similar documents
            for doc in query_response.docs:
                # Load JSON data
                doc_json = json.loads(doc.json)
                # Create document chunk object with score
                result = DocumentChunkWithScore(
                    id=doc_json["metadata"]["document_id"],
                    score=doc.score,
                    text=doc_json["text"],
                    metadata=doc_json["metadata"]
                )
                query_results.append(result)

            # Add to overall results
            results.append(QueryResult(query=query.query, results=query_results))

        return results

    async def _find_keys(self, pattern: str) -> List[str]:
        return [key async for key in self.client.scan_iter(pattern)]

    async def delete(
        self,
        ids: Optional[List[str]] = None,
        filter: Optional[DocumentMetadataFilter] = None,
        delete_all: Optional[bool] = None,
    ) -> bool:
        """
        Removes vectors by ids, filter, or everything in the datastore.
        Returns whether the operation was successful.
        """
        # Delete all vectors from the index if delete_all is True
        if delete_all:
            try:
                logger.info(f"Deleting all documents from index")
                await self.client.ft(REDIS_INDEX_NAME).dropindex(True)
                logger.info(f"Deleted all documents successfully")
                return True
            except Exception as e:
                logger.error(f"Error deleting all documents: {e}")
                raise e

        # Delete by filter
        if filter:
            # TODO - extend this to work with other metadata filters?
            if filter.document_id:
                try:
                    keys = await self._find_keys(
                        f"{REDIS_DOC_PREFIX}:{filter.document_id}:*"
                    )
                    await self._redis_delete(keys)
                    logger.info(f"Deleted document {filter.document_id} successfully")
                except Exception as e:
                    logger.error(f"Error deleting document {filter.document_id}: {e}")
                    raise e

        # Delete by explicit ids (Redis keys)
        if ids:
            try:
                logger.info(f"Deleting document ids {ids}")
                keys = []
                # find all keys associated with the document ids
                for document_id in ids:
                    doc_keys = await self._find_keys(
                        pattern=f"{REDIS_DOC_PREFIX}:{document_id}:*"
                    )
                    keys.extend(doc_keys)
                # delete all keys
                logger.info(f"Deleting {len(keys)} keys from Redis")
                await self._redis_delete(keys)
            except Exception as e:
                logger.error(f"Error deleting ids: {e}")
                raise e

        return True
