"""
Blockchain Service - Bridge between H2H Backend and Smart Contracts

This service provides a Web3 integration layer for interacting with BetEscrow
and BetOracle smart contracts. It handles transaction building, signing, and
submission to the blockchain.

NOTE: This is pseudocode/skeleton showing the architecture.
In production, you would use web3.py library.
"""

from decimal import Decimal
from typing import Dict, Any, Optional
import asyncio


class BlockchainService:
    """
    Main service for blockchain interactions.

    Responsibilities:
    - Connect to blockchain RPC endpoint
    - Load contract ABIs and addresses
    - Build and sign transactions
    - Estimate gas costs
    - Submit transactions and wait for confirmation
    """

    def __init__(
        self,
        rpc_url: str,
        bet_escrow_address: str,
        bet_oracle_address: str,
        private_key: str
    ):
        """
        Initialize blockchain service.

        Args:
            rpc_url: Blockchain RPC endpoint (e.g., Infura, Alchemy)
            bet_escrow_address: Deployed BetEscrow contract address
            bet_oracle_address: Deployed BetOracle contract address
            private_key: Private key for backend signer account
        """
        # Pseudocode: Initialize Web3 connection
        # self.web3 = Web3(HTTPProvider(rpc_url))
        # self.account = Account.from_key(private_key)

        # Load contract ABIs and create contract instances
        # self.bet_escrow_contract = self.web3.eth.contract(
        #     address=bet_escrow_address,
        #     abi=load_abi("BetEscrow")
        # )
        # self.bet_oracle_contract = self.web3.eth.contract(
        #     address=bet_oracle_address,
        #     abi=load_abi("BetOracle")
        # )

        self.rpc_url = rpc_url
        self.bet_escrow_address = bet_escrow_address
        self.bet_oracle_address = bet_oracle_address
        self.signer_address = "DERIVED_FROM_PRIVATE_KEY"

    async def create_bet_on_chain(
        self,
        stake_amount: Decimal,
        creator_odds: float,
        opponent_odds: float,
        event_timestamp: int,
        event_id: str
    ) -> Dict[str, Any]:
        """
        Create a bet on the blockchain.

        This function:
        1. Builds the createBet transaction
        2. Estimates gas cost
        3. Signs the transaction with backend wallet
        4. Submits to blockchain
        5. Waits for confirmation
        6. Parses event logs to get bet ID

        Args:
            stake_amount: Amount each party stakes (in ETH or tokens)
            creator_odds: Odds multiplier for creator (e.g., 1.5)
            opponent_odds: Odds multiplier for opponent (e.g., 2.0)
            event_timestamp: Unix timestamp when event occurs
            event_id: External event identifier for oracle

        Returns:
            Dict containing:
                - bet_id: On-chain bet ID
                - tx_hash: Transaction hash
                - block_number: Block number where bet was created
                - gas_used: Actual gas consumed
        """
        # Pseudocode implementation:
        #
        # # Convert stake to wei
        # stake_wei = self.web3.toWei(stake_amount, 'ether')
        #
        # # Build transaction
        # tx = self.bet_escrow_contract.functions.createBet(
        #     stake_wei,
        #     int(creator_odds * 100),  # Scale to avoid decimals
        #     int(opponent_odds * 100),
        #     event_timestamp,
        #     self.web3.toBytes(text=event_id)
        # ).buildTransaction({
        #     'from': self.account.address,
        #     'gas': 200000,
        #     'gasPrice': await self.web3.eth.gas_price,
        #     'nonce': await self.web3.eth.get_transaction_count(self.account.address)
        # })
        #
        # # Sign transaction
        # signed_tx = self.web3.eth.account.sign_transaction(tx, self.account.key)
        #
        # # Send transaction
        # tx_hash = await self.web3.eth.send_raw_transaction(signed_tx.rawTransaction)
        #
        # # Wait for receipt
        # receipt = await self.web3.eth.wait_for_transaction_receipt(tx_hash)
        #
        # # Parse BetCreated event
        # event_log = self.bet_escrow_contract.events.BetCreated().processReceipt(receipt)
        # bet_id = event_log[0]['args']['betId']
        #
        # return {
        #     'bet_id': bet_id,
        #     'tx_hash': tx_hash.hex(),
        #     'block_number': receipt['blockNumber'],
        #     'gas_used': receipt['gasUsed']
        # }

        # Placeholder return for pseudocode
        await asyncio.sleep(0.1)  # Simulate async operation
        return {
            'bet_id': 42,
            'tx_hash': '0xabc123...',
            'block_number': 12345,
            'gas_used': 150000
        }

    async def prepare_accept_bet_transaction(
        self,
        bet_id: int,
        user_address: str,
        stake_amount: Decimal
    ) -> Dict[str, Any]:
        """
        Prepare acceptBet transaction for user to sign in frontend.

        This returns an unsigned transaction that the frontend will
        send to MetaMask for the user to sign.

        Args:
            bet_id: On-chain bet ID
            user_address: User's wallet address (from MetaMask)
            stake_amount: Stake amount to send with transaction

        Returns:
            Unsigned transaction dict ready for MetaMask
        """
        # Pseudocode:
        #
        # stake_wei = self.web3.toWei(stake_amount, 'ether')
        #
        # tx = self.bet_escrow_contract.functions.acceptBet(bet_id).buildTransaction({
        #     'from': user_address,
        #     'value': stake_wei,
        #     'gas': 300000,
        #     'gasPrice': await self.web3.eth.gas_price,
        #     'nonce': await self.web3.eth.get_transaction_count(user_address)
        # })
        #
        # return tx  # Frontend will sign this with MetaMask

        await asyncio.sleep(0.1)
        return {
            'to': self.bet_escrow_address,
            'from': user_address,
            'value': int(stake_amount * 10**18),  # wei
            'gas': 300000,
            'gasPrice': 50000000000,  # 50 gwei
            'data': '0x...'  # Encoded function call
        }

    async def request_settlement(
        self,
        bet_id: int
    ) -> str:
        """
        Request oracle settlement for a bet.

        Called after the real-world event has occurred.
        This triggers the oracle network to fetch results and settle.

        Args:
            bet_id: On-chain bet ID

        Returns:
            Transaction hash
        """
        # Pseudocode:
        #
        # tx = self.bet_escrow_contract.functions.requestSettlement(bet_id).buildTransaction({
        #     'from': self.account.address,
        #     'gas': 100000,
        #     'gasPrice': await self.web3.eth.gas_price,
        #     'nonce': await self.web3.eth.get_transaction_count(self.account.address)
        # })
        #
        # signed_tx = self.web3.eth.account.sign_transaction(tx, self.account.key)
        # tx_hash = await self.web3.eth.send_raw_transaction(signed_tx.rawTransaction)
        #
        # return tx_hash.hex()

        await asyncio.sleep(0.1)
        return '0xdef456...'

    async def settle_bet_via_oracle(
        self,
        request_id: int,
        bet_id: int,
        winner_address: str,
        result_data: bytes,
        signatures: list
    ) -> str:
        """
        Submit oracle settlement to blockchain.

        Called by oracle aggregator after consensus is reached.

        Args:
            request_id: Oracle request ID
            bet_id: On-chain bet ID
            winner_address: Winner's wallet address
            result_data: Raw API result data
            signatures: Signatures from oracle nodes

        Returns:
            Transaction hash
        """
        # Pseudocode:
        #
        # tx = self.bet_oracle_contract.functions.fulfillSettlement(
        #     request_id,
        #     bet_id,
        #     winner_address,
        #     result_data,
        #     signatures
        # ).buildTransaction({
        #     'from': self.account.address,
        #     'gas': 250000,
        #     'gasPrice': await self.web3.eth.gas_price,
        #     'nonce': await self.web3.eth.get_transaction_count(self.account.address)
        # })
        #
        # signed_tx = self.web3.eth.account.sign_transaction(tx, self.account.key)
        # tx_hash = await self.web3.eth.send_raw_transaction(signed_tx.rawTransaction)
        #
        # return tx_hash.hex()

        await asyncio.sleep(0.1)
        return '0xghi789...'

    async def get_bet_from_chain(self, bet_id: int) -> Dict[str, Any]:
        """
        Fetch bet details from blockchain.

        Calls the getBet view function on BetEscrow contract.

        Args:
            bet_id: On-chain bet ID

        Returns:
            Dict with bet details:
                - bet_id
                - creator (address)
                - opponent (address)
                - stake_amount
                - status (enum value)
                - winner (address)
                - created_at (timestamp)
        """
        # Pseudocode:
        #
        # bet = await self.bet_escrow_contract.functions.getBet(bet_id).call()
        #
        # return {
        #     'bet_id': bet[0],
        #     'creator': bet[1],
        #     'opponent': bet[2],
        #     'stake_amount': self.web3.fromWei(bet[3], 'ether'),
        #     'status': bet[4],  # Enum value (0=OPEN, 1=MATCHED, etc.)
        #     'creator_odds': bet[5] / 100.0,
        #     'opponent_odds': bet[6] / 100.0,
        #     'created_at': bet[7],
        #     'event_timestamp': bet[8],
        #     'event_id': bet[9],
        #     'winner': bet[10],
        #     'settled_at': bet[11]
        # }

        await asyncio.sleep(0.1)
        return {
            'bet_id': bet_id,
            'creator': '0xAlice...',
            'opponent': '0xBob...',
            'stake_amount': Decimal('100'),
            'status': 1,  # MATCHED
            'winner': None
        }

    async def get_user_escrow(self, user_address: str) -> Decimal:
        """
        Get total amount user has locked in escrow across all bets.

        Args:
            user_address: User's wallet address

        Returns:
            Total escrow amount in ETH
        """
        # Pseudocode:
        #
        # escrow_wei = await self.bet_escrow_contract.functions.getUserEscrow(
        #     user_address
        # ).call()
        #
        # return self.web3.fromWei(escrow_wei, 'ether')

        await asyncio.sleep(0.1)
        return Decimal('75.00')

    async def estimate_gas(
        self,
        transaction_type: str,
        **kwargs
    ) -> Dict[str, Any]:
        """
        Estimate gas cost for a transaction.

        Args:
            transaction_type: Type of transaction (create_bet, accept_bet, etc.)
            **kwargs: Transaction-specific parameters

        Returns:
            Dict with:
                - gas_limit: Estimated gas units
                - gas_price: Current gas price in wei
                - cost_eth: Total cost in ETH
                - cost_usd: Total cost in USD (fetched from price oracle)
        """
        # Pseudocode:
        #
        # # Build unsigned transaction
        # if transaction_type == "create_bet":
        #     tx = self.bet_escrow_contract.functions.createBet(...).buildTransaction(...)
        # elif transaction_type == "accept_bet":
        #     tx = self.bet_escrow_contract.functions.acceptBet(...).buildTransaction(...)
        #
        # # Estimate gas
        # gas_limit = await self.web3.eth.estimate_gas(tx)
        # gas_price = await self.web3.eth.gas_price
        #
        # cost_wei = gas_limit * gas_price
        # cost_eth = self.web3.fromWei(cost_wei, 'ether')
        #
        # # Fetch ETH price from oracle
        # eth_price_usd = await self.get_eth_price_usd()
        # cost_usd = float(cost_eth) * eth_price_usd
        #
        # return {
        #     'gas_limit': gas_limit,
        #     'gas_price': gas_price,
        #     'cost_eth': cost_eth,
        #     'cost_usd': cost_usd
        # }

        await asyncio.sleep(0.1)

        # Gas estimates for different operations
        estimates = {
            'create_bet': 120000,
            'accept_bet': 180000,
            'settle_bet': 150000
        }

        gas_limit = estimates.get(transaction_type, 100000)
        gas_price = 50000000000  # 50 gwei
        cost_wei = gas_limit * gas_price
        cost_eth = Decimal(cost_wei) / Decimal(10**18)

        return {
            'gas_limit': gas_limit,
            'gas_price': gas_price,
            'cost_eth': cost_eth,
            'cost_usd': float(cost_eth) * 2000  # Assume $2000/ETH
        }

    async def get_transaction_receipt(self, tx_hash: str) -> Optional[Dict[str, Any]]:
        """
        Get transaction receipt (confirmation status).

        Args:
            tx_hash: Transaction hash

        Returns:
            Receipt dict or None if not yet mined
        """
        # Pseudocode:
        #
        # try:
        #     receipt = await self.web3.eth.get_transaction_receipt(tx_hash)
        #     return {
        #         'status': receipt['status'],  # 1 = success, 0 = failed
        #         'block_number': receipt['blockNumber'],
        #         'gas_used': receipt['gasUsed'],
        #         'logs': receipt['logs']
        #     }
        # except TransactionNotFound:
        #     return None

        await asyncio.sleep(0.1)
        return {
            'status': 1,
            'block_number': 12345,
            'gas_used': 150000,
            'logs': []
        }


# Singleton instance
_blockchain_service: Optional[BlockchainService] = None


def get_blockchain_service() -> BlockchainService:
    """
    Get singleton blockchain service instance.

    In production, this would load config from environment variables.
    """
    global _blockchain_service

    if _blockchain_service is None:
        # Pseudocode: Load from config
        # from app.blockchain.config import BLOCKCHAIN_CONFIG
        #
        # _blockchain_service = BlockchainService(
        #     rpc_url=BLOCKCHAIN_CONFIG['rpc_url'],
        #     bet_escrow_address=BLOCKCHAIN_CONFIG['bet_escrow_address'],
        #     bet_oracle_address=BLOCKCHAIN_CONFIG['bet_oracle_address'],
        #     private_key=BLOCKCHAIN_CONFIG['backend_private_key']
        # )

        # Placeholder for pseudocode
        _blockchain_service = BlockchainService(
            rpc_url="https://eth-mainnet.alchemyapi.io/v2/YOUR-API-KEY",
            bet_escrow_address="0x1234567890abcdef...",
            bet_oracle_address="0xfedcba0987654321...",
            private_key="BACKEND_PRIVATE_KEY"
        )

    return _blockchain_service
