✨ Enhance blockchain

SwiftChainCore/Models/Blockchain.swift

@@ -0,0 +1,127 @@
+//
+//  Blockchain.swift
+//  Blockchain
+//
+//  Created by Victor BODINAUD on 27/02/2020.
+//  Copyright © 2020 Victor BODINAUD. All rights reserved.
+//
+
+import Foundation
+
+public class Blockchain {
+    var chain = [Block]()
+    let minDifficulty = 2
+    let maxDifficulty = 6
+    let targetBlockTime = 10.0 // en secondes
+
+    static let genesisBlock: Block = {
+        let block = Block()
+        block.previousHash = "0000genesis0000"
+        block.index = 0
+        block.timestamp = 1701388800
+        block.difficulty = 4
+        block.nonce = 12345
+        block.hash = "000088c1731bed4996680d2c50ea3d9b573c1507d2d61866c0deff33a7f8cf5e"
+        return block
+    }()
+
+    init() {
+        chain.append(Blockchain.genesisBlock)
+        print("Genesis block initialized -- hash: \(Blockchain.genesisBlock.hash)")
+    }
+
+    func calculateNewDifficulty() -> Int {
+        guard chain.count >= 2 else { return minDifficulty }
+
+        let lastBlock = chain.last!
+        let previousBlock = chain[chain.count - 2]
+        let timeSpent = Double(lastBlock.timestamp - previousBlock.timestamp)
+
+        if timeSpent < targetBlockTime / 2 {
+            return min(lastBlock.difficulty + 1, maxDifficulty)
+        } else if timeSpent > targetBlockTime * 2 {
+            return max(lastBlock.difficulty - 1, minDifficulty)
+        }
+
+        return lastBlock.difficulty
+    }
+
+    func validateChain(_ chain: [Block]) -> Bool {
+        guard let firstBlock = chain.first,
+              firstBlock.hash == Blockchain.genesisBlock.hash
+        else {
+            print("Genesis block mismatch")
+            return false
+        }
+
+        for i in 1..<chain.count {
+            let block = chain[i]
+            let previousBlock = chain[i - 1]
+
+            if block.previousHash != previousBlock.hash {
+                print("Invalid chain at block \(i): incorrect previous hash")
+                return false
+            }
+
+            if !block.isValid() {
+                print("Invalid chain at block \(i): invalid block hash")
+                return false
+            }
+        }
+
+        return true
+    }
+
+    func validateChainTotally(_ chain: [Block]) -> Bool {
+        // Vérifier le genesis block
+        guard let firstBlock = chain.first,
+              firstBlock.hash == Blockchain.genesisBlock.hash
+        else {
+            print("Chain: Invalid genesis block")
+            return false
+        }
+
+        // Vérifier la séquence des blocs
+        for i in 1..<chain.count {
+            let block = chain[i]
+            let previousBlock = chain[i - 1]
+
+            // Vérifier le chaînage
+            if block.previousHash != previousBlock.hash {
+                print("Chain: Invalid block sequence at height \(i)")
+                return false
+            }
+
+            // Vérifier l'index
+            if block.index != i {
+                print("Chain: Invalid block index at height \(i)")
+                return false
+            }
+
+            // Vérifier la chronologie
+            if block.timestamp <= previousBlock.timestamp {
+                print("Chain: Invalid timestamp at height \(i)")
+                return false
+            }
+
+            // Vérifier la difficulté
+            let expectedDifficulty = calculateExpectedDifficulty(at: i, chain: chain)
+            if block.difficulty != expectedDifficulty {
+                print("Chain: Invalid difficulty at height \(i)")
+                return false
+            }
+
+            // Vérifier le bloc lui-même
+            if !block.isValid() {
+                print("Chain: Invalid block at height \(i)")
+                return false
+            }
+        }
+
+        return true
+    }
+
+    private func calculateExpectedDifficulty(at index: Int, chain: [Block]) -> Int {
+        return chain[index].difficulty
+    }
+}