import {
  Connection,
  Keypair,
  Signer,
  PublicKey,
  Transaction,
  TransactionSignature,
  ConfirmOptions,
  sendAndConfirmRawTransaction,
  RpcResponseAndContext,
  SimulatedTransactionResponse,
  Commitment,
} from "@solana/web3.js";

/**
 * The network and wallet context used to send transactions paid for and signed
 * by the provider.
 */
export default class Provider {
  /**
   * @param connection The cluster connection where the program is deployed.
   * @param wallet     The wallet used to pay for and sign all transactions.
   * @param opts       Transaction confirmation options to use by default.
   */
  constructor(
    readonly connection: Connection,
    readonly wallet: Wallet,
    readonly opts: ConfirmOptions
  ) {}

  static defaultOptions(): ConfirmOptions {
    return {
      preflightCommitment: "recent",
      commitment: "recent",
    };
  }

  /**
   * Returns a `Provider` with a wallet read from the local filesystem.
   *
   * @param url  The network cluster url.
   * @param opts The default transaction confirmation options.
   *
   * (This api is for Node only.)
   */
  static local(url?: string, opts?: ConfirmOptions): Provider {
    opts = opts ?? Provider.defaultOptions();
    const connection = new Connection(
      url ?? "http://localhost:8899",
      opts.preflightCommitment
    );
    const wallet = NodeWallet.local();
    return new Provider(connection, wallet, opts);
  }

  /**
   * Returns a `Provider` read from the `ANCHOR_PROVIDER_URL` envirnment
   * variable
   *
   * (This api is for Node only.)
   */
  static env(): Provider {
    const process = require("process");
    const url = process.env.ANCHOR_PROVIDER_URL;
    if (url === undefined) {
      throw new Error("ANCHOR_PROVIDER_URL is not defined");
    }
    const options = Provider.defaultOptions();
    const connection = new Connection(url, options.commitment);
    const wallet = NodeWallet.local();

    return new Provider(connection, wallet, options);
  }

  /**
   * Sends the given transaction, paid for and signed by the provider's wallet.
   *
   * @param tx      The transaction to send.
   * @param signers The set of signers in addition to the provdier wallet that
   *                will sign the transaction.
   * @param opts    Transaction confirmation options.
   */
  async send(
    tx: Transaction,
    signers?: Array<Signer | undefined>,
    opts?: ConfirmOptions
  ): Promise<TransactionSignature> {
    if (signers === undefined) {
      signers = [];
    }
    if (opts === undefined) {
      opts = this.opts;
    }

    tx.feePayer = this.wallet.publicKey;
    tx.recentBlockhash = (
      await this.connection.getRecentBlockhash(opts.preflightCommitment)
    ).blockhash;

    await this.wallet.signTransaction(tx);
    signers
      .filter((s) => s !== undefined)
      .forEach((kp) => {
        tx.partialSign(kp);
      });

    const rawTx = tx.serialize();

    const txId = await sendAndConfirmRawTransaction(
      this.connection,
      rawTx,
      opts
    );

    return txId;
  }

  /**
   * Similar to `send`, but for an array of transactions and signers.
   */
  async sendAll(
    reqs: Array<SendTxRequest>,
    opts?: ConfirmOptions
  ): Promise<Array<TransactionSignature>> {
    if (opts === undefined) {
      opts = this.opts;
    }
    const blockhash = await this.connection.getRecentBlockhash(
      opts.preflightCommitment
    );

    let txs = reqs.map((r) => {
      let tx = r.tx;
      let signers = r.signers;

      if (signers === undefined) {
        signers = [];
      }

      tx.feePayer = this.wallet.publicKey;
      tx.recentBlockhash = blockhash.blockhash;

      signers
        .filter((s) => s !== undefined)
        .forEach((kp) => {
          tx.partialSign(kp);
        });

      return tx;
    });

    const signedTxs = await this.wallet.signAllTransactions(txs);

    const sigs = [];

    for (let k = 0; k < txs.length; k += 1) {
      const tx = signedTxs[k];
      const rawTx = tx.serialize();
      sigs.push(
        await sendAndConfirmRawTransaction(this.connection, rawTx, opts)
      );
    }

    return sigs;
  }

  /**
   * Simulates the given transaction, returning emitted logs from execution.
   *
   * @param tx      The transaction to send.
   * @param signers The set of signers in addition to the provdier wallet that
   *                will sign the transaction.
   * @param opts    Transaction confirmation options.
   */
  async simulate(
    tx: Transaction,
    signers?: Array<Signer | undefined>,
    opts?: ConfirmOptions
  ): Promise<RpcResponseAndContext<SimulatedTransactionResponse>> {
    if (signers === undefined) {
      signers = [];
    }
    if (opts === undefined) {
      opts = this.opts;
    }

    tx.feePayer = this.wallet.publicKey;
    tx.recentBlockhash = (
      await this.connection.getRecentBlockhash(
        opts.preflightCommitment ?? this.opts.preflightCommitment
      )
    ).blockhash;

    await this.wallet.signTransaction(tx);
    signers
      .filter((s) => s !== undefined)
      .forEach((kp) => {
        tx.partialSign(kp);
      });

    return await simulateTransaction(
      this.connection,
      tx,
      opts.commitment ?? this.opts.commitment
    );
  }
}

export type SendTxRequest = {
  tx: Transaction;
  signers: Array<Signer | undefined>;
};

/**
 * Wallet interface for objects that can be used to sign provider transactions.
 */
export interface Wallet {
  signTransaction(tx: Transaction): Promise<Transaction>;
  signAllTransactions(txs: Transaction[]): Promise<Transaction[]>;
  publicKey: PublicKey;
}

/**
 * Node only wallet.
 */
export class NodeWallet implements Wallet {
  constructor(readonly payer: Keypair) {}

  static local(): NodeWallet {
    const payer = Keypair.fromSecretKey(
      Buffer.from(
        JSON.parse(
          require("fs").readFileSync(
            require("os").homedir() + "/.config/solana/id.json",
            {
              encoding: "utf-8",
            }
          )
        )
      )
    );
    return new NodeWallet(payer);
  }

  async signTransaction(tx: Transaction): Promise<Transaction> {
    tx.partialSign(this.payer);
    return tx;
  }

  async signAllTransactions(txs: Transaction[]): Promise<Transaction[]> {
    return txs.map((t) => {
      t.partialSign(this.payer);
      return t;
    });
  }

  get publicKey(): PublicKey {
    return this.payer.publicKey;
  }
}

// Copy of Connection.simulateTransaction that takes a commitment parameter.
async function simulateTransaction(
  connection: Connection,
  transaction: Transaction,
  commitment: Commitment
): Promise<RpcResponseAndContext<SimulatedTransactionResponse>> {
  // @ts-ignore
  transaction.recentBlockhash = await connection._recentBlockhash(
    // @ts-ignore
    connection._disableBlockhashCaching
  );

  const signData = transaction.serializeMessage();
  // @ts-ignore
  const wireTransaction = transaction._serialize(signData);
  const encodedTransaction = wireTransaction.toString("base64");
  const config: any = { encoding: "base64", commitment };
  const args = [encodedTransaction, config];

  // @ts-ignore
  const res = await connection._rpcRequest("simulateTransaction", args);
  if (res.error) {
    throw new Error("failed to simulate transaction: " + res.error.message);
  }
  return res.result;
}

/**
 * Sets the default provider on the client.
 */
export function setProvider(provider: Provider) {
  _provider = provider;
}

/**
 * Returns the default provider being used by the client.
 */
export function getProvider(): Provider {
  if (_provider === null) {
    return Provider.local();
  }
  return _provider;
}

// Global provider used as the default when a provider is not given.
let _provider: Provider | null = null;