use bloomfilter::Bloom;
use clap::{arg, Parser};
use std::error::Error;
use std::fs::File;
use std::io::{BufRead, BufReader, Write};
use std::path::PathBuf;

#[derive(Parser, Debug)]
#[command(author, version, about, long_about = None)]
struct Opts {
    #[arg(short, long, help = "Input file", default_value = "addresses.txt")]
    input_file: PathBuf,

    #[arg(short, long, help = "Output file", default_value = "bloom.dump")]
    output_file: PathBuf,

    #[arg(
        long,
        help = "Bloom filter: number of items",
        default_value_t = 1_180_626_779
    )]
    num_items: usize,

    #[arg(
        long,
        help = "Bloom filter: wanted rate of false positives",
        default_value_t = 0.000_000_001
    )]
    fp_rate: f64,
}

fn main() -> Result<(), Box<dyn Error>> {
    let opts: Opts = Opts::parse();

    let mut bloom = Bloom::new_for_fp_rate(opts.num_items, opts.fp_rate);

    let file = File::open(&opts.input_file)?;
    // buffer capacity in bytes, up from default 8K bytes
    // this only results in a very minor speedup, if any
    BufReader::with_capacity(1_000_000, file)
        .lines()
        .map(|l| l.unwrap())
        .for_each(|line| bloom.set(&line));

    // prepare output file
    let path = PathBuf::from(opts.output_file);
    let mut outfile = File::create(path)?;

    // write metadata
    outfile.write_all(&bloom.number_of_bits().to_be_bytes())?;
    outfile.write_all(&bloom.number_of_hash_functions().to_be_bytes())?;
    outfile.write_all(&bloom.sip_keys()[0].0.to_be_bytes())?;
    outfile.write_all(&bloom.sip_keys()[0].1.to_be_bytes())?;
    outfile.write_all(&bloom.sip_keys()[1].0.to_be_bytes())?;
    outfile.write_all(&bloom.sip_keys()[1].1.to_be_bytes())?;

    // write bitmap
    outfile.write_all(&bloom.bitmap())?;

    outfile.flush()?;

    Ok(())
}