#![feature(allocator_api)]

use std::{
    alloc::Global,
    ffi::CString,
    io::{Write, stdin},
    iter::zip,
    str::FromStr,
};

use itertools::Itertools;
use password_hash::derive_encryption_key;
use spectre_api_sys::SpectreAlgorithm;

macro_rules! read_line {
    ($lines:expr, $label:expr) => {{
        print!("{}: ", $label);
        std::io::stdout().flush().unwrap();
        CString::from_str(
            &$lines
                .next()
                .transpose()
                .ok()
                .flatten()
                .unwrap_or_else(|| panic!("Expected {}.", $label)),
        )
        .unwrap()
    }};
}

fn main() {
    let mut lines = stdin().lines();
    let username = read_line!(lines, "username");
    let secret = read_line!(lines, "secret");

    let user_key = unsafe {
        &*spectre_api_sys::spectre_user_key(
            username.as_ptr(),
            secret.as_ptr(),
            SpectreAlgorithm::Current,
        )
    };
    let salt = username.as_bytes(); // TODO: Derive the same salt that spectre passes to scrypt.
    let encryption_key = derive_encryption_key(salt, secret.as_bytes(), Global);
    let mut encrypted_user_key = encryption_key;

    assert_eq!(encrypted_user_key.len(), user_key.bytes.len());

    for (dst_byte, user_byte) in zip(&mut encrypted_user_key, &user_key.bytes) {
        *dst_byte ^= *user_byte;
    }

    println!(
        "\nEncrypted User Key:\n{:02x}",
        encrypted_user_key.iter().format("")
    );
}