/* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2023 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use std::{
    fs::{read_dir, read_to_string},
    io::{stdin, Read},
};

use anyhow::Result;
use clap::{Parser, Subcommand};
use darkfi::{
    blockchain::{BlockInfo, Blockchain, BlockchainOverlay},
    cli_desc,
    tx::Transaction,
    util::{
        path::expand_path,
        time::{TimeKeeper, Timestamp},
    },
    validator::{utils::genesis_txs_total, verification::verify_genesis_block},
};
use darkfi_contract_test_harness::vks;
use darkfi_serial::{deserialize, serialize};

#[derive(Parser)]
#[command(about = cli_desc!())]
struct Args {
    #[command(subcommand)]
    command: Subcmd,
}

#[derive(Subcommand)]
enum Subcmd {
    /// Read a Darkfi genesis block from stdin and display it
    Display,

    /// Generate a Darkfi genesis block and write it to stdin
    Generate {
        #[arg(short, long, default_value = "genesis_txs")]
        /// Path to folder containing the genesis transactions
        txs_folder: String,

        #[arg(short, long)]
        /// Genesis timestamp to use, instead of current one
        genesis_timestamp: Option<u64>,
    },

    /// Read a Darkfi genesis block from stdin and verify it
    Verify,
}

/// Auxiliary function to read a bs58 genesis block from stdin
fn read_block() -> Result<BlockInfo> {
    eprintln!("Reading genesis block from stdin...");
    let mut buf = String::new();
    stdin().read_to_string(&mut buf)?;
    let bytes = bs58::decode(&buf.trim()).into_vec()?;
    let block = deserialize(&bytes)?;
    Ok(block)
}

#[async_std::main]
async fn main() -> Result<()> {
    // Parse arguments
    let args = Args::parse();

    // Execute a subcommand
    match args.command {
        Subcmd::Display => {
            let genesis_block = read_block()?;
            println!("{genesis_block:#?}");
            Ok(())
        }

        Subcmd::Generate { txs_folder, genesis_timestamp } => {
            // Grab genesis transactions from folder
            let txs_folder = expand_path(&txs_folder).unwrap();
            let mut genesis_txs: Vec<Transaction> = vec![];
            for file in read_dir(txs_folder)? {
                let bytes = bs58::decode(&read_to_string(file?.path())?.trim()).into_vec()?;
                let tx = deserialize(&bytes)?;
                genesis_txs.push(tx);
            }

            // Generate the genesis block
            let mut genesis_block = BlockInfo::default();

            // Update timestamp if one was provided
            if let Some(timestamp) = genesis_timestamp {
                genesis_block.header.timestamp = Timestamp(timestamp);
            }

            // Append genesis transactions
            if !genesis_txs.is_empty() {
                // Retrieve genesis producer transaction
                let producer_tx = genesis_block.txs.pop().unwrap();

                // Append genesis transactions and calculate their total
                genesis_block.txs.append(&mut genesis_txs);
                genesis_block.txs.push(producer_tx);
                let genesis_txs_total = genesis_txs_total(&genesis_block.txs)?;
                genesis_block.slots[0].total_tokens = genesis_txs_total;
            }

            // Write generated genesis block to stdin
            let encoded = bs58::encode(&serialize(&genesis_block)).into_string();
            println!("{}", encoded);

            Ok(())
        }

        Subcmd::Verify => {
            let genesis_block = read_block()?;
            let hash = genesis_block.hash()?;

            println!("Verifying genesis block: {hash}");

            // Initialize a temporary sled database
            let sled_db = sled::Config::new().temporary(true).open()?;
            let (_, vks) = vks::read_or_gen_vks_and_pks()?;
            vks::inject(&sled_db, &vks)?;

            // Create an overlay over whole blockchain
            let blockchain = Blockchain::new(&sled_db)?;
            let overlay = BlockchainOverlay::new(&blockchain)?;

            // Generate a dummy time keeper
            let time_keeper = TimeKeeper::new(genesis_block.header.timestamp, 10, 90, 0);

            // Grab block txs total
            let genesis_txs_total = genesis_txs_total(&genesis_block.txs)?;

            verify_genesis_block(&overlay, &time_keeper, &genesis_block, genesis_txs_total).await?;

            println!("Genesis block {hash} verified successfully!");

            Ok(())
        }
    }
}