use blockchain::blocks::loans::UnsignedLoanContractTransaction;
use blockchain::common::cli_prompts::{prompt_hidden_nonempty, prompt_visible};
use blockchain::common::types::LENDER_FEE;
use blockchain::json;
use blockchain::records::wallet_registry::resolve_local_input_short_address;
use blockchain::wallets::structures::Wallet;
use blockchain::File;
use blockchain::{create_dir_all, AsyncWriteExt};
use blockchain::{Local, LocalResult, NaiveDate, NaiveTime, TimeZone};

fn pad_to_width(input: &str, width: usize) -> String {
    // Asset names are fixed-width fields in the loan transaction bytes.
    let mut result = String::with_capacity(width);
    let _ = std::fmt::write(&mut result, format_args!("{input:<width$}"));
    result
}

fn display_fee(value: u64) -> f64 {
    // Fees are stored as atomic units and displayed as whole-coin decimals for the CLI.
    value as f64 / 100_000_000.0
}

fn normalize_short_address_input(address: &str) -> Result<String, String> {
    // Accept local vanity/short input and resolve it into the real short address.
    resolve_local_input_short_address(address.trim())
}

fn parse_start_date(input: &str) -> Result<u32, String> {
    // Loan start dates are entered as calendar dates and stored as local midnight timestamps.
    let date = NaiveDate::parse_from_str(input.trim(), "%Y-%m-%d")
        .map_err(|_| "Please enter the date in YYYY-MM-DD format.".to_string())?;
    let datetime = date.and_time(NaiveTime::from_hms_opt(0, 0, 0).unwrap());
    let timestamp = match Local.from_local_datetime(&datetime) {
        LocalResult::Single(dt) => dt.timestamp(),
        LocalResult::Ambiguous(dt, _) => dt.timestamp(),
        LocalResult::None => {
            return Err("Loan start date could not be resolved in local time.".to_string());
        }
    };
    if timestamp < 0 || timestamp > u32::MAX as i64 {
        return Err("Loan start date is out of range.".to_string());
    }
    Ok(timestamp as u32)
}

#[tokio::main]
async fn main() {
    // Loan contracts use transaction type 7 and are first signed by the lender.
    let txtype = 7;

    // Coin/token and collateral names are padded to fixed-width transaction fields.
    let loan_coin_name = prompt_visible("What coin or token will you be lending out? ").await;
    let loan_coin_name = loan_coin_name.trim().to_lowercase();
    let loan_coin = pad_to_width(&loan_coin_name, 15);

    let loan_amount_string = prompt_visible("How many coins or tokens will you be lending? ").await;
    let loan_amount_f64: f64 = loan_amount_string
        .trim()
        .parse()
        .expect("Please enter a valid amount");
    let loan_amount = (loan_amount_f64 * 100_000_000.0).round() as u64;

    // Payment cadence is stored as a compact one-letter code.
    let payment_period =
        prompt_visible("Would you like each payment period to be daily, weekly, or monthly? ")
            .await;
    let payment_period = match payment_period.trim().to_lowercase().as_str() {
        "daily" | "d" => "d".to_string(),
        "weekly" | "w" => "w".to_string(),
        "monthly" | "m" => "m".to_string(),
        _ => {
            println!("Payment period must be daily, weekly, or monthly.");
            return;
        }
    };

    let payment_number_string =
        prompt_visible("How many payments do you expect until the loan is considered paid? ").await;
    let payment_number: u8 = payment_number_string
        .trim()
        .parse()
        .expect("Please enter a valid number");

    let payment_amount_string = prompt_visible("What should be the amount of each payment? ").await;
    let payment_amount_f64: f64 = payment_amount_string
        .trim()
        .parse()
        .expect("Please enter a valid amount");
    let payment_amount = (payment_amount_f64 * 100_000_000.0).round() as u64;

    let grace_period_string =
        prompt_visible("How many payments can be missed before you will claim the collateral? ")
            .await;
    let grace_period: u8 = grace_period_string
        .trim()
        .parse()
        .expect("Please enter a valid number");

    let max_late_value_string = prompt_visible(
        "How far behind in value can the borrower be before you will claim the collateral? ",
    )
    .await;
    let max_late_value_f64: f64 = max_late_value_string
        .trim()
        .parse()
        .expect("Please enter a valid amount");
    let max_late_value = (max_late_value_f64 * 100_000_000.0).round() as u64;

    // Collateral can be a coin, token, or NFT name; NFT collateral uses amount 1.
    let collateral_name =
        prompt_visible("What collateral coin, token, or NFT will you be accepting for this loan? ")
            .await;
    let collateral_name = collateral_name.trim().to_lowercase();
    let collateral = pad_to_width(&collateral_name, 15);

    let collateral_amount_string = prompt_visible("How many collateral coins or tokens will you be accepting for this loan (enter 1 for NFT collateral)? ").await;
    let collateral_amount_f64: f64 = collateral_amount_string
        .trim()
        .parse()
        .expect("Please enter a valid amount");
    let collateral_amount = (collateral_amount_f64 * 100_000_000.0).round() as u64;

    let start_date =
        prompt_visible("What is the date this loan should begin? (YYYY-MM-DD): ").await;
    let timestamp = match parse_start_date(&start_date) {
        Ok(timestamp) => timestamp,
        Err(err) => {
            println!("{err}");
            return;
        }
    };

    // Resolve the borrower input before writing it into the loan offer.
    let borrower = prompt_visible("What is the wallet address of the borrower? ").await;
    let borrower = match normalize_short_address_input(borrower.trim()) {
        Ok(address) => address,
        Err(_) => {
            println!("borrower wallet invalid");
            return;
        }
    };

    let txfee_prompt = format!(
        "Enter the txfee you will be paying for this transaction (minimum: {:.8})",
        display_fee(LENDER_FEE)
    );
    let txfee_string = prompt_visible(&format!("{txfee_prompt}: ")).await;
    let txfee_f64: f64 = txfee_string
        .trim()
        .parse()
        .expect("Please enter a valid fee");
    let txfee = (txfee_f64 * 100_000_000.0).round() as u64;

    // Load the lender wallet that creates the first loan-contract signature.
    let decryption_key = prompt_hidden_nonempty(
        "What is your wallet decryption key? ",
        "Wallet key cannot be empty. Please try again.",
    )
    .await;

    let wallet = match Wallet::try_obtain_wallet(decryption_key, None).await {
        Ok(wallet) => wallet,
        Err(err) => {
            eprintln!("Wallet decryption failed: {err}");
            return;
        }
    };
    let private_key = &wallet.saved.private_key;
    let lender = &wallet.saved.short_address;

    // The lender must sign with a valid current-network short address.
    if !Wallet::short_address_validation(lender.trim_matches('"')) {
        println!("lender wallet invalid: {lender}");
        return;
    }

    // Build the unsigned loan so both lender and borrower sign the exact same hash.
    let unsigned_loan = UnsignedLoanContractTransaction::new(
        txtype,
        timestamp,
        &loan_coin,
        loan_amount,
        lender.trim_matches('"'),
        &collateral,
        collateral_amount,
        &borrower,
        &payment_period,
        payment_number,
        payment_amount,
        grace_period,
        max_late_value,
        txfee,
    )
    .await;

    // This first signature is the lender's offer; the borrower adds signature2 later.
    let (hash, signature1) = match unsigned_loan.hash_and_sign(private_key).await {
        Ok(value) => value,
        Err(err) => {
            eprintln!("Failed to sign loan contract: {err}");
            return;
        }
    };

    // Save the partially signed loan JSON for the borrower to review and sign.
    let output = json!({
        "txtype": txtype,
        "timestamp": timestamp,
        "loan_coin": loan_coin,
        "loan_amount": loan_amount,
        "lender": lender.trim_matches('"'),
        "collateral": collateral,
        "collateral_amount": collateral_amount,
        "borrower": borrower,
        "payment_period": payment_period,
        "payment_number": payment_number,
        "payment_amount": payment_amount,
        "grace_period": grace_period,
        "max_late_value": max_late_value,
        "txfee": txfee,
        "hash": hash,
        "signature1": signature1,
    });
    let output_str = serde_json::to_string_pretty(&output).expect("Failed to serialize JSON");

    // Transaction creation tools all write into ./transactions using the transaction hash.
    let dir_path = "./transactions";
    if let Err(e) = create_dir_all(&dir_path).await {
        eprintln!("Failed to create directory: {e}");
        return;
    }

    let file_path = format!(
        "{}/{}.json",
        dir_path,
        output["hash"].as_str().unwrap_or_default()
    );
    let mut file = File::create(&file_path)
        .await
        .expect("Failed to create file");
    if let Err(e) = file.write_all(output_str.as_bytes()).await {
        eprintln!("Failed to write file: {e}");
        return;
    }

    println!("transaction: {output_str}");
}