//
//  Network.swift
//  OS Vault
//
//  Author: Simon-Pierre Boucher
//  Mail: contact@spboucher.ai
//

import Foundation
import BigInt

/// The EVM chains OS Vault can talk to. Fully data-driven: adding a chain is
/// a new case + ChainConfig entry. Every chain id and RPC below was verified
/// live before being listed (see docs/RESEARCH-MULTICHAIN.md). Non-EVM chains
/// (Bitcoin, Solana, Tron, TON, XRPL…) use their own adapters.
public enum Network: String, CaseIterable, Codable, Identifiable, Sendable {
    case baseSepolia        // testnet — safe default for development
    case baseMainnet
    case ethereum
    case arbitrum
    case optimism
    case polygon
    case bnb
    case avalanche
    case gnosis
    case linea
    case scroll

    public var id: String { rawValue }

    /// How transaction fees actually work on this chain — the research
    /// finding is that "EIP-1559" hides four distinct realities.
    public enum FeeModel: Sendable {
        /// Standard: maxFee = 2×baseFee + tip.
        case eip1559
        /// BNB Chain (BEP-226): baseFee is 0; price via eth_gasPrice.
        case zeroBaseFee
        /// OP-stack (Base, Optimism): L2 fee + L1 data fee from the
        /// GasPriceOracle predeploy at 0x42…0F, deducted silently.
        case opStackL1Fee
        /// Scroll: same idea, oracle at 0x5300…0002.
        case scrollL1Fee
        /// Arbitrum: estimateGas already folds the L1 buffer into gasLimit;
        /// suggested tip is 0.
        case arbitrumInclusive
        /// Linea: base fee pinned at 7 wei; real cost rides in the tip.
        case lineaPinnedBase
    }

    public struct ChainConfig: Sendable {
        public let chainID: BigUInt
        public let displayName: String
        public let nativeSymbol: String
        public let nativeName: String
        /// Ordered keyless endpoints: primary first, chain id verified live.
        public let rpcs: [URL]
        public let explorerBase: URL
        public let feeModel: FeeModel
        public let isTestnet: Bool
    }

    public var config: ChainConfig {
        switch self {
        case .baseSepolia:
            return ChainConfig(
                chainID: 84532, displayName: "Base Sepolia",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://sepolia.base.org")!,
                       URL(string: "https://base-sepolia-rpc.publicnode.com")!],
                explorerBase: URL(string: "https://sepolia.basescan.org")!,
                feeModel: .opStackL1Fee, isTestnet: true
            )
        case .baseMainnet:
            return ChainConfig(
                chainID: 8453, displayName: "Base",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://base-rpc.publicnode.com")!,
                       URL(string: "https://mainnet.base.org")!],
                explorerBase: URL(string: "https://basescan.org")!,
                feeModel: .opStackL1Fee, isTestnet: false
            )
        case .ethereum:
            return ChainConfig(
                chainID: 1, displayName: "Ethereum",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://ethereum-rpc.publicnode.com")!,
                       URL(string: "https://cloudflare-eth.com")!,
                       URL(string: "https://eth.merkle.io")!],
                explorerBase: URL(string: "https://etherscan.io")!,
                feeModel: .eip1559, isTestnet: false
            )
        case .arbitrum:
            return ChainConfig(
                chainID: 42161, displayName: "Arbitrum One",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://arbitrum-one-rpc.publicnode.com")!,
                       URL(string: "https://arb1.arbitrum.io/rpc")!],
                explorerBase: URL(string: "https://arbiscan.io")!,
                feeModel: .arbitrumInclusive, isTestnet: false
            )
        case .optimism:
            return ChainConfig(
                chainID: 10, displayName: "OP Mainnet",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://optimism-rpc.publicnode.com")!,
                       URL(string: "https://mainnet.optimism.io")!],
                explorerBase: URL(string: "https://optimistic.etherscan.io")!,
                feeModel: .opStackL1Fee, isTestnet: false
            )
        case .polygon:
            return ChainConfig(
                chainID: 137, displayName: "Polygon",
                nativeSymbol: "POL", nativeName: "Polygon Ecosystem Token",
                rpcs: [URL(string: "https://polygon-bor-rpc.publicnode.com")!,
                       URL(string: "https://polygon.drpc.org")!],
                explorerBase: URL(string: "https://polygonscan.com")!,
                feeModel: .eip1559, isTestnet: false
            )
        case .bnb:
            return ChainConfig(
                chainID: 56, displayName: "BNB Chain",
                nativeSymbol: "BNB", nativeName: "BNB",
                rpcs: [URL(string: "https://bsc-rpc.publicnode.com")!,
                       URL(string: "https://bsc-dataseed.bnbchain.org")!],
                explorerBase: URL(string: "https://bscscan.com")!,
                feeModel: .zeroBaseFee, isTestnet: false
            )
        case .avalanche:
            return ChainConfig(
                chainID: 43114, displayName: "Avalanche C-Chain",
                nativeSymbol: "AVAX", nativeName: "Avalanche",
                rpcs: [URL(string: "https://avalanche-c-chain-rpc.publicnode.com")!,
                       URL(string: "https://api.avax.network/ext/bc/C/rpc")!],
                explorerBase: URL(string: "https://snowtrace.io")!,
                feeModel: .eip1559, isTestnet: false
            )
        case .gnosis:
            return ChainConfig(
                chainID: 100, displayName: "Gnosis",
                nativeSymbol: "xDAI", nativeName: "xDAI (dollar-pegged)",
                rpcs: [URL(string: "https://gnosis-rpc.publicnode.com")!,
                       URL(string: "https://rpc.gnosischain.com")!],
                explorerBase: URL(string: "https://gnosisscan.io")!,
                feeModel: .eip1559, isTestnet: false
            )
        case .linea:
            return ChainConfig(
                chainID: 59144, displayName: "Linea",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://linea-rpc.publicnode.com")!,
                       URL(string: "https://rpc.linea.build")!],
                explorerBase: URL(string: "https://lineascan.build")!,
                feeModel: .lineaPinnedBase, isTestnet: false
            )
        case .scroll:
            return ChainConfig(
                chainID: 534352, displayName: "Scroll",
                nativeSymbol: "ETH", nativeName: "Ether",
                rpcs: [URL(string: "https://scroll-rpc.publicnode.com")!,
                       URL(string: "https://rpc.scroll.io")!],
                explorerBase: URL(string: "https://scrollscan.com")!,
                feeModel: .scrollL1Fee, isTestnet: false
            )
        }
    }

    /// L1 data-fee oracle for rollups that charge one (`getL1Fee(bytes)`).
    public var l1FeeOracle: String? {
        switch config.feeModel {
        case .opStackL1Fee: return "0x420000000000000000000000000000000000000F"
        case .scrollL1Fee: return "0x5300000000000000000000000000000000000002"
        default: return nil
        }
    }

    /// Active RPC endpoints, user override (Settings) first.
    public var rpcURLs: [URL] {
        var urls = config.rpcs
        if let raw = UserDefaults.standard.string(forKey: rpcOverrideKey),
           !raw.isEmpty, let url = URL(string: raw), url.scheme?.hasPrefix("http") == true {
            urls.insert(url, at: 0)
        }
        return urls
    }

    public var rpcOverrideKey: String { "osvault.rpcOverride.\(rawValue)" }

    public func explorerTxURL(_ hash: String) -> URL {
        config.explorerBase.appendingPathComponent("tx/\(hash)")
    }

    public func explorerAddressURL(_ address: String) -> URL {
        config.explorerBase.appendingPathComponent("address/\(address)")
    }
}