//
//  ZcashSDK.swift
//  ZcashLightClientKit
//
//  Created by Francisco Gindre on 7/22/21.
//

import Foundation
public protocol ZcashNetwork {
    var networkType: NetworkType { get }
    var constants: NetworkConstants.Type { get }
}

public enum NetworkType {
    case mainnet
    case testnet
    
    var networkId: UInt32 {
        switch self {
        case .mainnet:  return 1
        case .testnet:  return 0
        }
    }
}

extension NetworkType {
    static func forChainName(_ chainame: String) -> NetworkType? {
        switch chainame {
        case "test":    return .testnet
        case "main":    return .mainnet
        default:        return nil
        }
    }
    
    static func forNetworkId(_ id: UInt32) -> NetworkType? {
        switch id {
        case 1: return .mainnet
        case 0: return .testnet
        default: return nil
        }
    }
}

public enum ZcashNetworkBuilder {
    public static func network(for networkType: NetworkType) -> ZcashNetwork {
        switch networkType {
        case .mainnet:  return ZcashMainnet()
        case .testnet:  return ZcashTestnet()
        }
    }
}

class ZcashTestnet: ZcashNetwork {
    var networkType: NetworkType = .testnet
    var constants: NetworkConstants.Type = ZcashSDKTestnetConstants.self
}

class ZcashMainnet: ZcashNetwork {
    var networkType: NetworkType = .mainnet
    var constants: NetworkConstants.Type = ZcashSDKMainnetConstants.self
}

/**
Constants of ZcashLightClientKit. this constants don't
*/
public enum ZcashSDK {

    /// The number of zatoshi that equal 1 ZEC.
    public static var zatoshiPerZEC: BlockHeight = 100_000_000

    /// The theoretical maximum number of blocks in a reorg, due to other bottlenecks in the protocol design.
    public static var maxReorgSize = 100

    /// The amount of blocks ahead of the current height where new transactions are set to expire. This value is controlled
    /// by the rust backend but it is helpful to know what it is set to and should be kept in sync.
    public static var expiryOffset = 20

    // mark: Defaults

    /// Default size of batches of blocks to request from the compact block service. Which was used both for scanning and downloading.
    /// consider basing your code assumptions on `DefaultDownloadBatch` and `DefaultScanningBatch` instead.
    @available(*, deprecated, message: "this value is being deprecated in favor of `DefaultDownloadBatch` and `DefaultScanningBatch`")
    public static var DefaultBatchSize = 100

    /// Default batch size for downloading blocks for the compact block processor. This value was changed due to
    /// full blocks causing block download memory usage significantly and also timeouts on grpc calls.
    /// this value is subject to change in the future.
    public static var DefaultDownloadBatch = 10

    /// Default batch size for scanning blocks for the compact block processor
    public static var DefaultScanningBatch = 100

    /// Default amount of time, in in seconds, to poll for new blocks. Typically, this should be about half the average
    /// block time.
    public static var defaultPollInterval: TimeInterval = 20

    /// Default attempts at retrying.
    public static var defaultRetries: Int = 5

    /// The default maximum amount of time to wait during retry backoff intervals. Failed loops will never wait longer than
    /// this before retyring.
    public static var defaultMaxBackOffInterval: TimeInterval = 600

    /// Default number of blocks to rewind when a chain reorg is detected. This should be large enough to recover from the
    /// reorg but smaller than the theoretical max reorg size of 100.
    public static var defaultRewindDistance: Int = 10

    /// The number of blocks to allow before considering our data to be stale. This usually helps with what to do when
    /// returning from the background and is exposed via the Synchronizer's isStale function.
    public static var defaultStaleTolerance: Int = 10

    /// Default Name for LibRustZcash data.db
    public static var defaultDataDbName = "data.db"

    /// Default Name for Compact Block caches db
    public static var defaultCacheDbName = "caches.db"

    /// Default name for pending transactions db
    public static var defaultPendingDbName = "pending.db"

    /// File name for the sapling spend params
    public static var spendParamFilename = "sapling-spend.params"

    /// File name for the sapling output params
    public static var outputParamFilename = "sapling-output.params"

    /// The Url that is used by default in zcashd.
    /// We'll want to make this externally configurable, rather than baking it into the SDK but
    /// this will do for now, since we're using a cloudfront URL that already redirects.
    public static var cloudParameterURL = "https://z.cash/downloads/"
}

public protocol NetworkConstants {
    /// The height of the first sapling block. When it comes to shielded transactions, we do not need to consider any blocks
    /// prior to this height, at all.
    static var saplingActivationHeight: BlockHeight { get }

    /// Default Name for LibRustZcash data.db
    static var defaultDataDbName: String { get }

    /// Default Name for Compact Block caches db
    static var defaultCacheDbName: String { get }

    /// Default name for pending transactions db
    static var defaultPendingDbName: String { get }

    /// Default prefix for db filenames
    static var defaultDbNamePrefix: String { get }

    /// fixed height where the SDK considers that the ZIP-321 was deployed. This is a workaround
    /// for librustzcash not figuring out the tx fee from the tx itself.
    static var feeChangeHeight: BlockHeight { get }

    @available(*, deprecated, message: "This function will be removed soon. Use the one returning `Zatoshi` instead")
    static func defaultFee(for height: BlockHeight) -> Int64

    /// Returns the default fee according to the blockheight. see [ZIP-313](https://zips.z.cash/zip-0313)
    static func defaultFee(for height: BlockHeight) -> Zatoshi
}

public extension NetworkConstants {
    @available(*, deprecated, message: "This function will be removed soon. Use the one returning `Zatoshi` instead")
    static func defaultFee(for height: BlockHeight = BlockHeight.max) -> Int64 {
        guard height >= feeChangeHeight else { return 10_000 }
        
        return 1_000
    }

    static func defaultFee(for height: BlockHeight = BlockHeight.max) -> Zatoshi {
        guard height >= feeChangeHeight else { return Zatoshi(10_000) }

        return Zatoshi(1_000)
    }
}

public class ZcashSDKMainnetConstants: NetworkConstants {
    private init() {}

    /// The height of the first sapling block. When it comes to shielded transactions, we do not need to consider any blocks
    /// prior to this height, at all.
    public static var saplingActivationHeight: BlockHeight = 419_200

    /// Default Name for LibRustZcash data.db
    public static var defaultDataDbName = "data.db"

    /// Default Name for Compact Block caches db
    public static var defaultCacheDbName = "caches.db"

    /// Default name for pending transactions db
    public static var defaultPendingDbName = "pending.db"
    
    public static var defaultDbNamePrefix = "ZcashSdk_mainnet_"
    
    public static var feeChangeHeight: BlockHeight = 1_077_550
}

public class ZcashSDKTestnetConstants: NetworkConstants {
    private init() {}

    /// The height of the first sapling block. When it comes to shielded transactions, we do not need to consider any blocks
    /// prior to this height, at all.
    public static var saplingActivationHeight: BlockHeight = 280_000

    /// Default Name for LibRustZcash data.db
    public static var defaultDataDbName = "data.db"

    /// Default Name for Compact Block caches db
    public static var defaultCacheDbName = "caches.db"

    /// Default name for pending transactions db
    public static var defaultPendingDbName = "pending.db"
    
    public static var defaultDbNamePrefix = "ZcashSdk_testnet_"

    /// Estimated height where wallets are supposed to change the fee
    public static var feeChangeHeight: BlockHeight = 1_028_500
}
