// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.

import Foundation
import GRDB
import Curve25519Kit

public protocol GeneralCacheType {
    var encodedPublicKey: String? { get set }
    var recentReactionTimestamps: [Int64] { get set }
}

public enum General {
    public class Cache: GeneralCacheType {
        public var encodedPublicKey: String? = nil
        public var recentReactionTimestamps: [Int64] = []
    }
    
    public static var cache: Atomic<GeneralCacheType> = Atomic(Cache())
}

public enum GeneralError: Error {
    case keyGenerationFailed
}

public func getUserHexEncodedPublicKey(_ db: Database? = nil, dependencies: Dependencies = Dependencies()) -> String {
    if let cachedKey: String = dependencies.generalCache.wrappedValue.encodedPublicKey { return cachedKey }
    
    if let publicKey: Data = Identity.fetchUserPublicKey(db) { // Can be nil under some circumstances
        let sessionId: SessionId = SessionId(.standard, publicKey: publicKey.bytes)
        
        dependencies.generalCache.mutate { $0.encodedPublicKey = sessionId.hexString }
        return sessionId.hexString
    }
    
    return ""
}

/// Does nothing, but is never inlined and thus evaluating its argument will never be optimized away.
///
/// Useful for forcing the instantiation of lazy properties like globals.
@inline(never)
public func touch<Value>(_ value: Value) { /* Do nothing */ }

/// Returns `f(x!)` if `x != nil`, or `nil` otherwise.
public func given<T, U>(_ x: T?, _ f: (T) throws -> U) rethrows -> U? { return try x.map(f) }

public func with<T, U>(_ x: T, _ f: (T) throws -> U) rethrows -> U { return try f(x) }