"""Polygon blockchain client with connection pooling and caching.

This module provides a Polygon client for wallet data queries with:
- Connection pooling for concurrent requests
- Redis caching to avoid redundant RPC calls
- Retry logic with exponential backoff
- Rate limiting to respect provider limits
- Failover to secondary RPC URL
"""

import asyncio
import json
import logging
import time
from collections.abc import Sequence
from dataclasses import dataclass
from datetime import datetime
from decimal import Decimal
from typing import Any, cast

from redis.asyncio import Redis
from web3 import AsyncWeb3
from web3.exceptions import Web3Exception
from web3.providers import AsyncHTTPProvider

from polymarket_insider_tracker.profiler.models import Transaction, WalletInfo

logger = logging.getLogger(__name__)

# Default configuration
DEFAULT_CACHE_TTL_SECONDS = 300  # 5 minutes
DEFAULT_MAX_REQUESTS_PER_SECOND = 25
DEFAULT_MAX_RETRIES = 3
DEFAULT_RETRY_DELAY_SECONDS = 1.0
DEFAULT_CONNECTION_POOL_SIZE = 10
DEFAULT_REQUEST_TIMEOUT = 30


class PolygonClientError(Exception):
    """Base exception for Polygon client errors."""


class RPCError(PolygonClientError):
    """Raised when RPC call fails."""


class RateLimitError(PolygonClientError):
    """Raised when rate limit is exceeded."""


@dataclass
class RateLimiter:
    """Token bucket rate limiter."""

    max_tokens: float
    refill_rate: float  # tokens per second
    tokens: float
    last_refill: float

    @classmethod
    def create(cls, max_requests_per_second: float) -> "RateLimiter":
        """Create a rate limiter with specified max requests per second."""
        return cls(
            max_tokens=max_requests_per_second,
            refill_rate=max_requests_per_second,
            tokens=max_requests_per_second,
            last_refill=time.monotonic(),
        )

    def _refill(self) -> None:
        """Refill tokens based on elapsed time."""
        now = time.monotonic()
        elapsed = now - self.last_refill
        self.tokens = min(self.max_tokens, self.tokens + elapsed * self.refill_rate)
        self.last_refill = now

    async def acquire(self, tokens: float = 1.0) -> None:
        """Acquire tokens, waiting if necessary."""
        while True:
            self._refill()
            if self.tokens >= tokens:
                self.tokens -= tokens
                return
            # Wait for tokens to refill
            wait_time = (tokens - self.tokens) / self.refill_rate
            await asyncio.sleep(wait_time)


class PolygonClient:
    """Polygon blockchain client with caching and rate limiting.

    Provides efficient access to wallet data with:
    - Connection pooling for concurrent requests
    - Redis caching with configurable TTL
    - Rate limiting to respect provider limits
    - Retry logic with exponential backoff
    - Failover to secondary RPC

    Example:
        ```python
        redis = Redis.from_url("redis://localhost:6379")
        client = PolygonClient(
            rpc_url="https://polygon-rpc.com",
            fallback_rpc_url="https://polygon-bor.publicnode.com",
            redis=redis,
        )

        # Get single wallet info
        nonce = await client.get_transaction_count("0x...")

        # Batch query multiple wallets
        nonces = await client.get_transaction_counts(["0x...", "0x..."])
        ```
    """

    def __init__(
        self,
        rpc_url: str,
        *,
        fallback_rpc_url: str | None = None,
        redis: Redis | None = None,
        cache_ttl_seconds: int = DEFAULT_CACHE_TTL_SECONDS,
        max_requests_per_second: float = DEFAULT_MAX_REQUESTS_PER_SECOND,
        max_retries: int = DEFAULT_MAX_RETRIES,
        retry_delay_seconds: float = DEFAULT_RETRY_DELAY_SECONDS,
    ) -> None:
        """Initialize the Polygon client.

        Args:
            rpc_url: Primary Polygon RPC endpoint URL.
            fallback_rpc_url: Optional fallback RPC URL for failover.
            redis: Optional Redis client for caching.
            cache_ttl_seconds: Cache TTL in seconds.
            max_requests_per_second: Rate limit for RPC calls.
            max_retries: Maximum retry attempts on failure.
            retry_delay_seconds: Initial delay between retries.
        """
        self._rpc_url = rpc_url
        self._fallback_rpc_url = fallback_rpc_url
        self._redis = redis
        self._cache_ttl = cache_ttl_seconds
        self._max_retries = max_retries
        self._retry_delay = retry_delay_seconds

        # Create web3 instances
        self._w3 = AsyncWeb3(AsyncHTTPProvider(rpc_url))
        self._w3_fallback: AsyncWeb3[AsyncHTTPProvider] | None = None
        if fallback_rpc_url:
            self._w3_fallback = AsyncWeb3(AsyncHTTPProvider(fallback_rpc_url))

        # Rate limiter
        self._rate_limiter = RateLimiter.create(max_requests_per_second)

        # Track primary RPC health
        self._primary_healthy = True
        self._last_primary_check = 0.0
        self._primary_recovery_interval = 60.0  # Try primary again after 60s

        # Cache key prefix
        self._cache_prefix = "polygon:"

    def _cache_key(self, key_type: str, address: str) -> str:
        """Generate a cache key."""
        return f"{self._cache_prefix}{key_type}:{address.lower()}"

    async def _get_cached(self, key: str) -> str | None:
        """Get value from cache."""
        if not self._redis:
            return None
        try:
            value = await self._redis.get(key)
            if isinstance(value, bytes):
                return value.decode()
            return str(value) if value is not None else None
        except Exception as e:
            logger.warning("Cache get failed: %s", e)
            return None

    async def _set_cached(self, key: str, value: str, ttl: int | None = None) -> None:
        """Set value in cache."""
        if not self._redis:
            return
        try:
            await self._redis.set(key, value, ex=ttl or self._cache_ttl)
        except Exception as e:
            logger.warning("Cache set failed: %s", e)

    def _should_try_primary(self) -> bool:
        """Check if we should try the primary RPC."""
        if self._primary_healthy:
            return True
        # Periodically retry primary
        now = time.monotonic()
        if now - self._last_primary_check > self._primary_recovery_interval:
            self._last_primary_check = now
            return True
        return False

    async def _execute_with_retry(
        self,
        func_name: str,
        *args: Any,
        **kwargs: Any,
    ) -> Any:
        """Execute an RPC call with retry and failover logic.

        Args:
            func_name: Name of the web3.eth method to call.
            *args: Positional arguments for the method.
            **kwargs: Keyword arguments for the method.

        Returns:
            Result from the RPC call.

        Raises:
            RPCError: If all retries and failover fail.
        """
        await self._rate_limiter.acquire()

        last_error: Exception | None = None
        delay = self._retry_delay

        # Try primary RPC
        if self._should_try_primary():
            for attempt in range(self._max_retries):
                try:
                    method = getattr(self._w3.eth, func_name)
                    result = await method(*args, **kwargs)
                    self._primary_healthy = True
                    return result
                except Web3Exception as e:
                    last_error = e
                    logger.warning(
                        "Primary RPC %s failed (attempt %d/%d): %s",
                        func_name,
                        attempt + 1,
                        self._max_retries,
                        e,
                    )
                    if attempt < self._max_retries - 1:
                        await asyncio.sleep(delay)
                        delay *= 2  # Exponential backoff

            # Mark primary as unhealthy
            self._primary_healthy = False
            self._last_primary_check = time.monotonic()

        # Try fallback RPC
        if self._w3_fallback:
            delay = self._retry_delay
            for attempt in range(self._max_retries):
                try:
                    method = getattr(self._w3_fallback.eth, func_name)
                    result = await method(*args, **kwargs)
                    logger.info("Fallback RPC succeeded for %s", func_name)
                    return result
                except Web3Exception as e:
                    last_error = e
                    logger.warning(
                        "Fallback RPC %s failed (attempt %d/%d): %s",
                        func_name,
                        attempt + 1,
                        self._max_retries,
                        e,
                    )
                    if attempt < self._max_retries - 1:
                        await asyncio.sleep(delay)
                        delay *= 2

        raise RPCError(f"RPC call {func_name} failed after all retries: {last_error}")

    async def get_transaction_count(self, address: str) -> int:
        """Get wallet transaction count (nonce).

        Args:
            address: Wallet address.

        Returns:
            Transaction count.
        """
        cache_key = self._cache_key("nonce", address)

        # Check cache
        cached = await self._get_cached(cache_key)
        if cached is not None:
            return int(cached)

        # Query blockchain
        count = await self._execute_with_retry(
            "get_transaction_count",
            AsyncWeb3.to_checksum_address(address),
        )

        # Cache result
        await self._set_cached(cache_key, str(count))

        return int(count)

    async def get_transaction_counts(
        self,
        addresses: Sequence[str],
    ) -> dict[str, int]:
        """Batch get transaction counts for multiple addresses.

        Args:
            addresses: List of wallet addresses.

        Returns:
            Dictionary mapping address to transaction count.
        """
        if not addresses:
            return {}

        results: dict[str, int] = {}
        uncached: list[str] = []

        # Check cache for each address
        for address in addresses:
            cache_key = self._cache_key("nonce", address)
            cached = await self._get_cached(cache_key)
            if cached is not None:
                results[address.lower()] = int(cached)
            else:
                uncached.append(address)

        # Query uncached addresses concurrently
        if uncached:
            tasks = [self.get_transaction_count(addr) for addr in uncached]
            counts = await asyncio.gather(*tasks, return_exceptions=True)

            for addr, count in zip(uncached, counts, strict=True):
                if isinstance(count, BaseException):
                    logger.warning("Failed to get nonce for %s: %s", addr, count)
                    results[addr.lower()] = 0
                else:
                    results[addr.lower()] = count

        return results

    async def get_balance(self, address: str) -> Decimal:
        """Get wallet MATIC balance in Wei.

        Args:
            address: Wallet address.

        Returns:
            Balance in Wei as Decimal.
        """
        cache_key = self._cache_key("balance", address)

        # Check cache
        cached = await self._get_cached(cache_key)
        if cached is not None:
            return Decimal(cached)

        # Query blockchain
        balance = await self._execute_with_retry(
            "get_balance",
            AsyncWeb3.to_checksum_address(address),
        )

        # Cache result
        await self._set_cached(cache_key, str(balance))

        return Decimal(balance)

    async def get_token_balance(
        self,
        address: str,
        token_address: str,
    ) -> Decimal:
        """Get ERC20 token balance.

        Args:
            address: Wallet address.
            token_address: ERC20 token contract address.

        Returns:
            Token balance in smallest unit as Decimal.
        """
        cache_key = self._cache_key(f"token:{token_address.lower()}", address)

        # Check cache
        cached = await self._get_cached(cache_key)
        if cached is not None:
            return Decimal(cached)

        # ERC20 balanceOf ABI
        erc20_abi = [
            {
                "constant": True,
                "inputs": [{"name": "_owner", "type": "address"}],
                "name": "balanceOf",
                "outputs": [{"name": "balance", "type": "uint256"}],
                "type": "function",
            }
        ]

        await self._rate_limiter.acquire()

        try:
            w3 = self._w3 if self._primary_healthy else (self._w3_fallback or self._w3)
            contract = w3.eth.contract(
                address=AsyncWeb3.to_checksum_address(token_address),
                abi=erc20_abi,
            )
            balance = await contract.functions.balanceOf(
                AsyncWeb3.to_checksum_address(address)
            ).call()
        except Web3Exception as e:
            raise RPCError(f"Failed to get token balance: {e}") from e

        # Cache result
        await self._set_cached(cache_key, str(balance))

        return Decimal(balance)

    async def get_block(self, block_number: int) -> dict[str, Any]:
        """Get block by number.

        Args:
            block_number: Block number.

        Returns:
            Block data dictionary.
        """
        cache_key = f"{self._cache_prefix}block:{block_number}"

        # Check cache
        cached = await self._get_cached(cache_key)
        if cached is not None:
            return cast(dict[str, Any], json.loads(cached))

        block = await self._execute_with_retry("get_block", block_number)

        # Convert to serializable dict
        block_dict = dict(block)
        block_dict["timestamp"] = int(block_dict["timestamp"])

        # Cache result (blocks are immutable, use longer TTL)
        await self._set_cached(cache_key, json.dumps(block_dict), ttl=3600)

        return dict(block_dict)

    async def get_first_transaction(self, address: str) -> Transaction | None:
        """Get the first transaction for a wallet.

        This is useful for determining wallet age. Note: This is an expensive
        operation as it may require scanning transaction history.

        Args:
            address: Wallet address.

        Returns:
            First transaction or None if no transactions.
        """
        cache_key = self._cache_key("first_tx", address)

        # Check cache
        cached = await self._get_cached(cache_key)
        if cached is not None:
            if cached == "null":
                return None
            data = json.loads(cached)
            return Transaction(
                hash=data["hash"],
                block_number=data["block_number"],
                timestamp=datetime.fromisoformat(data["timestamp"]),
                from_address=data["from_address"],
                to_address=data["to_address"],
                value=Decimal(data["value"]),
                gas_used=data["gas_used"],
                gas_price=Decimal(data["gas_price"]),
            )

        # Check if wallet has any transactions
        nonce = await self.get_transaction_count(address)
        if nonce == 0:
            await self._set_cached(cache_key, "null", ttl=60)  # Short TTL for empty
            return None

        # Note: Getting the actual first transaction requires using an indexer
        # or scanning blocks, which is expensive. For now, we'll return None
        # and recommend using an indexer service for production.
        logger.warning(
            "get_first_transaction requires an indexer service for %s (nonce=%d)",
            address,
            nonce,
        )
        return None

    async def get_wallet_info(self, address: str) -> WalletInfo:
        """Get aggregated wallet information.

        Args:
            address: Wallet address.

        Returns:
            WalletInfo with transaction count, balance, and first transaction.
        """
        # Fetch data concurrently
        nonce_task = self.get_transaction_count(address)
        balance_task = self.get_balance(address)
        first_tx_task = self.get_first_transaction(address)

        nonce, balance, first_tx = await asyncio.gather(nonce_task, balance_task, first_tx_task)

        return WalletInfo(
            address=address.lower(),
            transaction_count=nonce,
            balance_wei=balance,
            first_transaction=first_tx,
        )

    async def health_check(self) -> bool:
        """Check if the client can connect to the RPC.

        Returns:
            True if healthy, False otherwise.
        """
        try:
            await self._execute_with_retry("block_number")
            return True
        except RPCError:
            return False