class SHA256 {
  private static K = [
    0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
    0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da, 0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
    0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
    0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
  ];

  static hash(message: string): string {
    const msg = this.preprocess(message);
    const chunks = this.chunkMessage(msg);

    let h0 = 0x6a09e667;
    let h1 = 0xbb67ae85;
    let h2 = 0x3c6ef372;
    let h3 = 0xa54ff53a;
    let h4 = 0x510e527f;
    let h5 = 0x9b05688c;
    let h6 = 0x1f83d9ab;
    let h7 = 0x5be0cd19;

    for (const chunk of chunks) {
      const w = this.createMessageSchedule(chunk);
      let [a, b, c, d, e, f, g, h] = [h0, h1, h2, h3, h4, h5, h6, h7];

      for (let i = 0; i < 64; i += 1) {
        const s1 = this.rightRotate(e, 6) ^ this.rightRotate(e, 11) ^ this.rightRotate(e, 25);
        const ch = (e & f) ^ (~e & g);
        const temp1 = (h + s1 + ch + this.K[i] + w[i]) >>> 0;
        const s0 = this.rightRotate(a, 2) ^ this.rightRotate(a, 13) ^ this.rightRotate(a, 22);
        const maj = (a & b) ^ (a & c) ^ (b & c);
        const temp2 = (s0 + maj) >>> 0;

        h = g;
        g = f;
        f = e;
        e = (d + temp1) >>> 0;
        d = c;
        c = b;
        b = a;
        a = (temp1 + temp2) >>> 0;
      }

      h0 = (h0 + a) >>> 0;
      h1 = (h1 + b) >>> 0;
      h2 = (h2 + c) >>> 0;
      h3 = (h3 + d) >>> 0;
      h4 = (h4 + e) >>> 0;
      h5 = (h5 + f) >>> 0;
      h6 = (h6 + g) >>> 0;
      h7 = (h7 + h) >>> 0;
    }

    return [h0, h1, h2, h3, h4, h5, h6, h7].map((h) => h.toString(16).padStart(8, '0')).join('');
  }

  private static preprocess(message: string): number[] {
    const bytes = [];
    for (let i = 0; i < message.length; i += 1) {
      const code = message.charCodeAt(i);
      if (code < 0x80) {
        bytes.push(code);
      } else if (code < 0x800) {
        bytes.push(0xc0 | (code >> 6));
        bytes.push(0x80 | (code & 0x3f));
      } else {
        bytes.push(0xe0 | (code >> 12));
        bytes.push(0x80 | ((code >> 6) & 0x3f));
        bytes.push(0x80 | (code & 0x3f));
      }
    }

    const msgLen = bytes.length;
    bytes.push(0x80);

    while (bytes.length % 64 !== 56) {
      bytes.push(0);
    }

    const lengthBits = msgLen * 8;
    for (let i = 7; i >= 0; i -= 1) {
      bytes.push((lengthBits >>> (i * 8)) & 0xff);
    }

    return bytes;
  }

  private static chunkMessage(bytes: number[]): number[][] {
    const chunks = [];
    for (let i = 0; i < bytes.length; i += 64) {
      chunks.push(bytes.slice(i, i + 64));
    }
    return chunks;
  }

  private static createMessageSchedule(chunk: number[]): number[] {
    const w = [];
    for (let i = 0; i < 16; i += 1) {
      w[i] = (chunk[i * 4] << 24) | (chunk[i * 4 + 1] << 16) | (chunk[i * 4 + 2] << 8) | chunk[i * 4 + 3];
    }

    for (let i = 16; i < 64; i += 1) {
      const s0 = this.rightRotate(w[i - 15], 7) ^ this.rightRotate(w[i - 15], 18) ^ (w[i - 15] >>> 3);
      const s1 = this.rightRotate(w[i - 2], 17) ^ this.rightRotate(w[i - 2], 19) ^ (w[i - 2] >>> 10);
      w[i] = (w[i - 16] + s0 + w[i - 7] + s1) >>> 0;
    }

    return w;
  }

  private static rightRotate(value: number, amount: number): number {
    return ((value >>> amount) | (value << (32 - amount))) >>> 0;
  }
}

class ProofOfWork {
  private difficulty: number;

  constructor(difficulty: number = 4) {
    this.difficulty = difficulty;
  }

  mine(blockData: string): { nonce: number; hash: string } {
    let nonce = 0;
    let hash = '';

    do {
      nonce += 1;
      hash = SHA256.hash(blockData + nonce);
    } while (!this.isValidHash(hash));

    return { nonce, hash };
  }

  isValidHash(hash: string): boolean {
    return hash.startsWith('0'.repeat(this.difficulty));
  }
}

class MerkleTree {
  private leaves: string[];
  private tree: string[][];

  constructor(leaves: string[]) {
    this.leaves = leaves.map((leaf) => SHA256.hash(leaf));
    this.buildTree();
  }

  private buildTree(): void {
    this.tree = [this.leaves];

    while (this.tree[this.tree.length - 1].length > 1) {
      const currentLevel = this.tree[this.tree.length - 1];
      const nextLevel: string[] = [];

      for (let i = 0; i < currentLevel.length; i += 2) {
        const left = currentLevel[i];
        const right = i + 1 < currentLevel.length ? currentLevel[i + 1] : left;
        nextLevel.push(SHA256.hash(left + right));
      }

      this.tree.push(nextLevel);
    }
  }

  getRoot(): string {
    return this.tree[this.tree.length - 1][0];
  }

  getProof(index: number): { hash: string; isLeft: boolean }[] {
    const proof: { hash: string; isLeft: boolean }[] = [];
    let currentIndex = index;

    for (let level = 0; level < this.tree.length - 1; level += 1) {
      const isLeft = currentIndex % 2 === 0;
      const siblingIndex = isLeft ? currentIndex + 1 : currentIndex - 1;

      if (siblingIndex < this.tree[level].length) {
        proof.push({
          hash: this.tree[level][siblingIndex],
          isLeft: !isLeft,
        });
      }

      currentIndex = Math.floor(currentIndex / 2);
    }

    return proof;
  }

  verifyProof(leaf: string, proof: { hash: string; isLeft: boolean }[], root: string): boolean {
    let hash = SHA256.hash(leaf);

    for (const { hash: siblingHash, isLeft } of proof) {
      if (isLeft) {
        hash = SHA256.hash(siblingHash + hash);
      } else {
        hash = SHA256.hash(hash + siblingHash);
      }
    }

    return hash === root;
  }
}

interface BlockData {
  index: number;
  timestamp: number;
  data: string;
  previousHash: string;
}

class Block {
  index: number;
  timestamp: number;
  data: string;
  previousHash: string;
  hash: string;
  nonce: number;

  constructor(data: BlockData) {
    this.index = data.index;
    this.timestamp = data.timestamp;
    this.data = data.data;
    this.previousHash = data.previousHash;
    this.nonce = 0;
    this.hash = this.calculateHash();
  }

  calculateHash(): string {
    return SHA256.hash(this.index + this.timestamp + this.data + this.previousHash + this.nonce);
  }

  mineBlock(difficulty: number): void {
    const pow = new ProofOfWork(difficulty);
    const result = pow.mine(this.index + this.timestamp + this.data + this.previousHash);
    this.nonce = result.nonce;
    this.hash = result.hash;
  }
}

class Blockchain {
  private chain: Block[];
  private difficulty: number;

  constructor(difficulty: number = 4) {
    this.chain = [this.createGenesisBlock()];
    this.difficulty = difficulty;
  }

  private createGenesisBlock(): Block {
    return new Block({
      index: 0,
      timestamp: Date.now(),
      data: 'Genesis Block',
      previousHash: '0',
    });
  }

  getLatestBlock(): Block {
    return this.chain[this.chain.length - 1];
  }

  addBlock(data: string): void {
    const newBlock = new Block({
      index: this.getLatestBlock().index + 1,
      timestamp: Date.now(),
      data,
      previousHash: this.getLatestBlock().hash,
    });

    newBlock.mineBlock(this.difficulty);
    this.chain.push(newBlock);
  }

  isChainValid(): boolean {
    for (let i = 1; i < this.chain.length; i += 1) {
      const currentBlock = this.chain[i];
      const previousBlock = this.chain[i - 1];

      if (currentBlock.hash !== currentBlock.calculateHash()) {
        return false;
      }

      if (currentBlock.previousHash !== previousBlock.hash) {
        return false;
      }
    }

    return true;
  }
}