"""
On-Chain Executor — Construct unsigned transactions for Mantle L2
=================================================================
Follows the mantle-agent-scaffold pattern: construct-only safety.
Never handles private keys. Returns unsigned transaction payloads
that must be signed externally (e.g., via ERC-4337 wallet).

Supported DEXes: Fluxion (primary), Agni, Merchant Moe
Supported Lending: Aave V3 (Lendle)
"""

import logging
import time
from dataclasses import dataclass, field
from enum import Enum
from typing import Any, Dict, List, Optional, Tuple

from eth_abi import encode as abi_encode
from eth_utils import function_signature_to_4byte_selector
import json

from config.constants import (
    MANTLE_CHAIN_ID,
    MANTLE_RPC_URL,
    Tokens,
    DEXRouters,
    LendingProtocols,
    ERC20_ABI,
    SWAP_ROUTER_ABI,
    AAVE_POOL_ABI,
    PortfolioConfig,
)

logger = logging.getLogger("executor")


@dataclass
class UnsignedTx:
    """
    Unsigned transaction payload — the executor's output.
    Must be signed by an external wallet (e.g., ERC-4337 bundler).
    
    Follows mantle-agent-scaffold's UnsignedTxResult pattern.
    """
    to: str
    data: str  # hex-encoded calldata
    value: str = "0x0"  # msg.value in hex
    chain_id: int = MANTLE_CHAIN_ID
    gas_limit: Optional[int] = None
    human_summary: str = ""
    
    def to_dict(self) -> Dict[str, Any]:
        d = {
            "to": self.to,
            "data": self.data,
            "value": self.value,
            "chainId": self.chain_id,
            "human_summary": self.human_summary,
        }
        if self.gas_limit:
            d["gasLimit"] = hex(self.gas_limit)
        return d


@dataclass
class RebalancePlan:
    """Complete rebalancing execution plan."""
    timestamp: float
    current_weights: List[float]
    target_weights: List[float]
    trades: List[UnsignedTx]
    approvals: List[UnsignedTx]
    estimated_gas_usd: float
    estimated_slippage_bps: int
    human_summary: str
    
    def to_dict(self) -> Dict:
        return {
            "timestamp": self.timestamp,
            "current_weights": self.current_weights,
            "target_weights": self.target_weights,
            "n_trades": len(self.trades),
            "n_approvals": len(self.approvals),
            "estimated_gas_usd": self.estimated_gas_usd,
            "estimated_slippage_bps": self.estimated_slippage_bps,
            "human_summary": self.human_summary,
            "trades": [t.to_dict() for t in self.trades],
            "approvals": [a.to_dict() for a in self.approvals],
        }


class SwapRoute(Enum):
    """Available swap routing options."""
    FLUXION = "fluxion"
    AGNI = "agni"
    MERCHANT_MOE = "merchant_moe"


# ─────────────────────── ABI Encoding Helpers ───────────────────────

def encode_function_call(sig: str, args: list) -> str:
    """Encode a Solidity function call to hex calldata."""
    selector = function_signature_to_4byte_selector(sig).hex()
    if not args:
        return "0x" + selector
    
    # Map signature to types
    param_str = sig[sig.index("(") + 1 : sig.index(")")]
    param_types = [t.strip() for t in param_str.split(",")] if param_str else []
    
    encoded = abi_encode(param_types, args).hex()
    return "0x" + selector + encoded


def encode_erc20_approve(spender: str, amount: int) -> str:
    """Encode ERC20 approve(spender, amount)."""
    return encode_function_call(
        "approve(address,uint256)",
        [bytes.fromhex(spender[2:]), amount]
    )


# ─────────────────────── Token Registry ─────────────────────────────

TOKEN_DECIMALS = {
    "USDY": 18,
    "mETH": 18,
    "MI4": 18,
    "USDC": 6,
    "USDT": 6,
    "WMNT": 18,
    "WETH": 18,
}

TOKEN_ADDRESSES = {
    "USDY": Tokens.USDY,
    "mETH": Tokens.METH,
    "USDC": Tokens.USDC,
    "USDT": Tokens.USDT,
    "WMNT": Tokens.WMNT,
    "WETH": Tokens.WETH,
}

# Fluxion fee tiers (Uni V3 compatible)
FEE_TIERS = [100, 500, 3000, 10000]  # 0.01%, 0.05%, 0.3%, 1%


# ─────────────────────── Executor ───────────────────────────────────

class OnChainExecutor:
    """
    Constructs unsigned transactions for portfolio rebalancing.
    
    Safety guarantees:
    - NEVER handles private keys
    - ONLY interacts with whitelisted contracts
    - ALL outputs are unsigned transaction payloads
    - Human-readable summaries for every action
    """
    
    WHITELISTED_CONTRACTS = {
        DEXRouters.FLUXION_SWAP_ROUTER,
        DEXRouters.AGNI_SWAP_ROUTER,
        DEXRouters.MERCHANT_MOE_ROUTER,
        LendingProtocols.AAVE_V3_POOL,
        Tokens.USDY,
        Tokens.METH,
        Tokens.USDC,
        Tokens.WMNT,
    }
    
    def __init__(
        self,
        wallet_address: str,
        portfolio_config: Optional[PortfolioConfig] = None,
        preferred_dex: SwapRoute = SwapRoute.FLUXION,
    ):
        self.wallet = wallet_address
        self.config = portfolio_config or PortfolioConfig()
        self.preferred_dex = preferred_dex
        
        # Execution history
        self.execution_log: List[Dict] = []
    
    def is_whitelisted(self, address: str) -> bool:
        """Check if contract address is in the whitelist."""
        return address.lower() in {a.lower() for a in self.WHITELISTED_CONTRACTS}
    
    def build_rebalance_plan(
        self,
        current_weights: List[float],
        target_weights: List[float],
        portfolio_value_usd: float,
        asset_prices: Dict[str, float],
        max_slippage_bps: Optional[int] = None,
    ) -> RebalancePlan:
        """
        Build a complete rebalancing plan from current to target weights.
        
        1. Compute required trades (sell overweight, buy underweight)
        2. Route through best DEX
        3. Generate approval + swap transactions
        4. Estimate gas costs
        
        Args:
            current_weights: [USDY_w, mETH_w, MI4_w]
            target_weights: [USDY_w, mETH_w, MI4_w]
            portfolio_value_usd: Total portfolio value
            asset_prices: {"USDY": 1.0, "mETH": 3200.0, "MI4": 100.0}
            max_slippage_bps: Override max slippage
            
        Returns:
            RebalancePlan with all unsigned transactions
        """
        slippage = max_slippage_bps or self.config.max_slippage_bps
        assets = ["USDY", "mETH", "MI4"]
        
        # Calculate weight deltas
        deltas = [target_weights[i] - current_weights[i] for i in range(3)]
        
        # Determine sells (negative delta) and buys (positive delta)
        sells = []
        buys = []
        for i, (asset, delta) in enumerate(zip(assets, deltas)):
            if abs(delta) < 0.005:  # skip if delta < 0.5%
                continue
            usd_amount = abs(delta) * portfolio_value_usd
            token_amount = usd_amount / max(asset_prices.get(asset, 1.0), 0.01)
            
            if delta < 0:
                sells.append((asset, token_amount, usd_amount))
            else:
                buys.append((asset, token_amount, usd_amount))
        
        # Build transactions
        approvals = []
        trades = []
        summary_parts = []
        
        # Process sells first (to get intermediate tokens for buys)
        for sell_asset, sell_amount, sell_usd in sells:
            # Route: sell_asset → USDC (intermediate)
            decimals = TOKEN_DECIMALS.get(sell_asset, 18)
            amount_raw = int(sell_amount * (10 ** decimals))
            
            # Build approval
            router = self._get_router_address()
            approval_tx = self._build_approval(
                token=TOKEN_ADDRESSES[sell_asset],
                spender=router,
                amount=amount_raw,
                summary=f"Approve {sell_amount:.4f} {sell_asset} for swap",
            )
            approvals.append(approval_tx)
            
            # Build swap
            swap_tx = self._build_swap(
                token_in=TOKEN_ADDRESSES[sell_asset],
                token_out=Tokens.USDC,
                amount_in=amount_raw,
                min_amount_out=int(sell_usd * (10 ** 6) * (1 - slippage / 10000)),
                fee=3000,
                summary=f"Sell {sell_amount:.4f} {sell_asset} (~${sell_usd:.2f}) → USDC",
            )
            trades.append(swap_tx)
            summary_parts.append(f"SELL {sell_amount:.4f} {sell_asset} (${sell_usd:.0f})")
        
        # Process buys
        for buy_asset, buy_amount, buy_usd in buys:
            decimals_in = TOKEN_DECIMALS["USDC"]
            amount_in_raw = int(buy_usd * (10 ** decimals_in))
            
            decimals_out = TOKEN_DECIMALS.get(buy_asset, 18)
            min_out = int(buy_amount * (10 ** decimals_out) * (1 - slippage / 10000))
            
            # Approve USDC
            router = self._get_router_address()
            approval_tx = self._build_approval(
                token=Tokens.USDC,
                spender=router,
                amount=amount_in_raw,
                summary=f"Approve {buy_usd:.2f} USDC for {buy_asset} purchase",
            )
            approvals.append(approval_tx)
            
            # Swap USDC → buy_asset
            swap_tx = self._build_swap(
                token_in=Tokens.USDC,
                token_out=TOKEN_ADDRESSES.get(buy_asset, Tokens.USDY),
                amount_in=amount_in_raw,
                min_amount_out=min_out,
                fee=3000,
                summary=f"Buy {buy_amount:.4f} {buy_asset} (~${buy_usd:.2f}) with USDC",
            )
            trades.append(swap_tx)
            summary_parts.append(f"BUY {buy_amount:.4f} {buy_asset} (${buy_usd:.0f})")
        
        # Estimate gas
        gas_per_swap = 250_000  # typical Uni V3 swap
        gas_per_approval = 50_000
        total_gas = len(trades) * gas_per_swap + len(approvals) * gas_per_approval
        gas_price_gwei = 0.02  # Mantle is cheap
        gas_cost_mnt = total_gas * gas_price_gwei / 1e9
        mnt_price = 0.70  # approximate
        gas_cost_usd = gas_cost_mnt * mnt_price
        
        plan = RebalancePlan(
            timestamp=time.time(),
            current_weights=current_weights,
            target_weights=target_weights,
            trades=trades,
            approvals=approvals,
            estimated_gas_usd=gas_cost_usd,
            estimated_slippage_bps=slippage,
            human_summary=(
                f"Rebalance: {' | '.join(summary_parts) or 'No trades needed'}\n"
                f"Trades: {len(trades)}, Approvals: {len(approvals)}, "
                f"Est. gas: ${gas_cost_usd:.4f}"
            ),
        )
        
        logger.info(f"Rebalance plan: {plan.human_summary}")
        self.execution_log.append(plan.to_dict())
        return plan
    
    def _get_router_address(self) -> str:
        """Get the router address for the preferred DEX."""
        if self.preferred_dex == SwapRoute.FLUXION:
            return DEXRouters.FLUXION_SWAP_ROUTER
        elif self.preferred_dex == SwapRoute.AGNI:
            return DEXRouters.AGNI_SWAP_ROUTER
        elif self.preferred_dex == SwapRoute.MERCHANT_MOE:
            return DEXRouters.MERCHANT_MOE_ROUTER
        return DEXRouters.FLUXION_SWAP_ROUTER
    
    def _build_approval(
        self, token: str, spender: str, amount: int, summary: str
    ) -> UnsignedTx:
        """Build ERC20 approve transaction."""
        if not self.is_whitelisted(token) or not self.is_whitelisted(spender):
            raise ValueError(f"Contract not whitelisted: token={token}, spender={spender}")
        
        # approve(address,uint256)
        selector = "095ea7b3"
        spender_padded = spender[2:].lower().zfill(64)
        amount_hex = hex(amount)[2:].zfill(64)
        calldata = "0x" + selector + spender_padded + amount_hex
        
        return UnsignedTx(
            to=token,
            data=calldata,
            human_summary=summary,
            gas_limit=60_000,
        )
    
    def _build_swap(
        self,
        token_in: str,
        token_out: str,
        amount_in: int,
        min_amount_out: int,
        fee: int = 3000,
        summary: str = "",
    ) -> UnsignedTx:
        """Build Uniswap V3-style exactInputSingle swap transaction."""
        router = self._get_router_address()
        
        if not self.is_whitelisted(router):
            raise ValueError(f"Router not whitelisted: {router}")
        
        # exactInputSingle((address,address,uint24,address,uint256,uint256,uint256,uint160))
        selector = "414bf389"
        deadline = int(time.time()) + 1800  # 30 min deadline
        
        # ABI encode the tuple
        params = (
            token_in[2:].lower().zfill(64) +
            token_out[2:].lower().zfill(64) +
            hex(fee)[2:].zfill(64) +
            self.wallet[2:].lower().zfill(64) +
            hex(deadline)[2:].zfill(64) +
            hex(amount_in)[2:].zfill(64) +
            hex(min_amount_out)[2:].zfill(64) +
            "0" * 64  # sqrtPriceLimitX96 = 0 (no limit)
        )
        
        calldata = "0x" + selector + params
        
        return UnsignedTx(
            to=router,
            data=calldata,
            human_summary=summary,
            gas_limit=300_000,
        )
    
    def build_aave_supply(
        self, asset: str, amount: int, asset_symbol: str = "USDY"
    ) -> List[UnsignedTx]:
        """Build Aave V3 supply transactions (approval + supply)."""
        pool = LendingProtocols.AAVE_V3_POOL
        
        # Approval
        approve_tx = self._build_approval(
            token=asset,
            spender=pool,
            amount=amount,
            summary=f"Approve {asset_symbol} for Aave V3 supply",
        )
        
        # supply(address,uint256,address,uint16)
        selector = "617ba037"
        calldata = "0x" + selector + (
            asset[2:].lower().zfill(64) +
            hex(amount)[2:].zfill(64) +
            self.wallet[2:].lower().zfill(64) +
            "0" * 64  # referralCode = 0
        )
        
        supply_tx = UnsignedTx(
            to=pool,
            data=calldata,
            human_summary=f"Supply {asset_symbol} to Aave V3 for additional yield",
            gas_limit=300_000,
        )
        
        return [approve_tx, supply_tx]
    
    def build_aave_withdraw(
        self, asset: str, amount: int, asset_symbol: str = "USDY"
    ) -> UnsignedTx:
        """Build Aave V3 withdraw transaction."""
        pool = LendingProtocols.AAVE_V3_POOL
        
        # withdraw(address,uint256,address)
        selector = "69328dec"
        calldata = "0x" + selector + (
            asset[2:].lower().zfill(64) +
            hex(amount)[2:].zfill(64) +
            self.wallet[2:].lower().zfill(64)
        )
        
        return UnsignedTx(
            to=pool,
            data=calldata,
            human_summary=f"Withdraw {asset_symbol} from Aave V3",
            gas_limit=250_000,
        )
    
    def get_execution_history(self) -> List[Dict]:
        """Return execution log."""
        return self.execution_log