mod dicts;

use num::pow::pow;
use num::{BigInt, Num, ToPrimitive};

use data_encoding::HEXLOWER;
use ring::digest::{Context, SHA256};
use std::io::Error;
use std::io::{BufReader, Read};

pub(crate) fn sha256_digest(string: String) -> Result<String, Error> {
    let mut reader = BufReader::new(string.as_bytes());
    let mut context = Context::new(&SHA256);
    let mut buffer = [0; 1024];

    loop {
        let count = reader.read(&mut buffer)?;
        if count == 0 {
            break;
        }
        context.update(&buffer[..count]);
    }

    let digest = context.finish();
    Ok(HEXLOWER.encode(digest.as_ref()))
}

pub fn generate_nickname(hex_str: &str) -> String {
    let max_num = 999;

    let num_adj = BigInt::from(dicts::ADJECTIVES.len());
    let num_nouns = BigInt::from(dicts::NOUNS.len());

    // Compute pool size by combinatorics
    let pool_size = max_num * num_nouns.clone() * num_adj;

    // Min-Max scale the hash relative to the pool size
    let max_int_hash = pow(BigInt::from(2), 256);

    // Perform multiplication
    let int_hash = BigInt::from_str_radix(hex_str, 16).unwrap();
    let nick_id = (int_hash * pool_size) / max_int_hash;

    // Compute adjective id
    let (adj, remainder) = {
        let adj_id: BigInt = &nick_id / (max_num * &num_nouns);
        let adj = dicts::ADJECTIVES[adj_id.to_u128().unwrap() as usize];
        let remainder = &nick_id - (&adj_id * max_num * num_nouns);
        (adj, remainder)
    };

    // Compute noun id
    let (noun_id, noun) = {
        let noun_id: BigInt = &remainder / max_num;
        let noun = dicts::NOUNS[noun_id.to_u128().unwrap() as usize];
        (noun_id, noun)
    };

    // Remainder is the numeric element
    let number = {
        let num_id: BigInt = remainder - noun_id * max_num;
        num_id.to_string()
    };

    let nick = format!("{}{}{}", adj, noun, number);

    nick
}

pub fn generate_short_nickname(hex_str: &str) -> Result<String, Error> {
    let max_iters = 10000;
    let max_length = 18;
    let mut i = 0;
    let mut hash = hex_str.to_owned();
    let mut nick = generate_nickname(&hash);
    while i < max_iters {
        if nick.len() <= max_length {
            return Ok(nick);
        } else {
            let string = hash.to_owned() + "42";
            hash = sha256_digest(string)?;
            nick = generate_nickname(&hash);
            i += 1;
        }
    }
    Ok(String::from(""))
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_adjective_dictionary() {
        // Checks a few randomly selected adjectives
        let adjective_4 = "Sweeping";
        let adjective_1683 = "Atomic";
        let adjective_4774 = "Satoshi";

        assert_eq!(dicts::ADJECTIVES[4], adjective_4);
        assert_eq!(dicts::ADJECTIVES[1683], adjective_1683);
        assert_eq!(dicts::ADJECTIVES[4774], adjective_4774);
    }

    #[test]
    fn test_nouns_dictionary() {
        // Checks a few randomly selected nouns
        let noun_118 = "Address";
        let noun_6540 = "Null";
        let noun_10937 = "Zombie";

        assert_eq!(dicts::NOUNS[118], noun_118);
        assert_eq!(dicts::NOUNS[6540], noun_6540);
        assert_eq!(dicts::NOUNS[10937], noun_10937);
    }

    #[test]
    fn test_sha256() {
        assert_eq!(
            sha256_digest(String::from("abc")).unwrap(),
            String::from("ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad")
        );
    }
    #[test]
    fn test_nickname_generator() {
        assert_eq!(
            generate_short_nickname(
                "23d022aa5dc633f2f115e48fc1f393f051ebdec3dfae41cfcd01bdac3577017f"
            )
            .unwrap(),
            "EntertainedWin410"
        );
        assert_eq!(
            generate_short_nickname(
                "e16b82646823b51bdda76a2eb2147afbe57b2100af46a61adc0671820a6dc991"
            )
            .unwrap(),
            "FrankVitro385"
        );
        assert_eq!(
            generate_short_nickname(
                "242bb123c13a7cb24708f16000fbabe1c4eae06b6912b47e6b0c2fa08307ec0a"
            )
            .unwrap(),
            "VernacularBoxer512"
        );
        assert_eq!(
            generate_short_nickname(
                "29c7e1d03d109bcb6af4057c84670702710a9261e16ca6b77a21f5f950644133"
            )
            .unwrap(),
            "SwimmingPuzzle724"
        );
        assert_eq!(
            generate_short_nickname(
                "70e2b8e0cc3daa4d2a0c622c46f30a5507b4f66feef3893e9eaccfce3f8ff0fc"
            )
            .unwrap(),
            "IrritatingLimp990"
        );
        assert_eq!(
            generate_short_nickname(
                "2f26321bf6cf99dea51a1664fc812ee3d3123313b9b7abcc79d4bbbaf6b9a470"
            )
            .unwrap(),
            "UnknownMap519"
        );
        assert_eq!(
            generate_short_nickname(
                "8d9531f05fde6f2e44961b113141e1625f20d17e25101c35071660f8e6a705f0"
            )
            .unwrap(),
            "UnworthyHymn429"
        );
        assert_eq!(
            generate_short_nickname(
                "29e6baf2d7442963517e93f2b4fe6a326a0474410ce916778ce800e7cb6524af"
            )
            .unwrap(),
            "LegibleTract390"
        );
        assert_eq!(
            generate_short_nickname(
                "672e48fd4a7d2a28923cb637ff9aca48ad398ff058ce39d48d1463ef5396ebd3"
            )
            .unwrap(),
            "FidgetyOverhaul213"
        );
        assert_eq!(
            generate_short_nickname(
                "f387da94931be5545e8b618640a27ec2cfc2fec99570f477a3f0057d7c8de597"
            )
            .unwrap(),
            "GeographicZeal110"
        );
        assert_eq!(
            generate_short_nickname(
                "0704bc96c5909c47d2461ad161db271f43649aa5331b514b7b484c0cecfd72f9"
            )
            .unwrap(),
            "HumorousOriginal57"
        );
        assert_eq!(
            generate_short_nickname(
                "44623105ab0e9b17674cf0aa4df81b5a8acba636f1cf2f4bf03c516b53853be3"
            )
            .unwrap(),
            "IrritatedApex167"
        );
        assert_eq!(
            generate_short_nickname(
                "72b1e55e5afce59d9f59f115d5ffcfebbb623d17fb4ed14793655fba854b26a2"
            )
            .unwrap(),
            "ComicalBicycle160"
        );
        assert_eq!(
            generate_short_nickname(
                "2e5fb21fdc3c628c29707d89b08b8cfa0f1ced10cf90aa3c42ad528cee0eca45"
            )
            .unwrap(),
            "StinkyFormation19"
        );
        assert_eq!(
            generate_short_nickname(
                "1057a3d72d96b643ebb924859705f1b385371210cfbfdf78eedc8e5f9c34c137"
            )
            .unwrap(),
            "InaptMajesty747"
        );
        assert_eq!(
            generate_short_nickname(
                "1e7ad4d15162c3f813c542d813ffae5f027aaa0c174a7cf3a9840fda20881824"
            )
            .unwrap(),
            "SolitaryWear892"
        );
        assert_eq!(
            generate_short_nickname(
                "5881365a9e19ed77f479d6aa28bbc0a4b2c879a8b75debaf87b327af377acc35"
            )
            .unwrap(),
            "ChivalrousOlive8"
        );
        assert_eq!(
            generate_short_nickname(
                "63c2b815132c79ef3a874f4138b6786c19acd94556d62f1170d55af40b3def92"
            )
            .unwrap(),
            "SurgicalStink272"
        );
        assert_eq!(
            generate_short_nickname(
                "682258198870f90832f0854a8bee08eb587438a1dd5b12ada901676907347d38"
            )
            .unwrap(),
            "ScarredOrganism49"
        );
        assert_eq!(
            generate_short_nickname(
                "efa4068f4e6825526ced61d8b77f6bd237f2f9d001672cad272e2fec8474b213"
            )
            .unwrap(),
            "SatinDiffidence476"
        );
        assert_eq!(
            generate_short_nickname(
                "735f64aa04f66be52aa32ad39344150a704b6142a03bb0248b8198a9e2374e1b"
            )
            .unwrap(),
            "TactualExhibit853"
        );
        assert_eq!(
            generate_short_nickname(
                "015a4b8ded8107c4bb37763d25b22f0e7be64be5587b7609744b76403ee963fa"
            )
            .unwrap(),
            "UnhealthyBuild495"
        );
        assert_eq!(
            generate_short_nickname(
                "006833a6d33c4e4d9d3785505f6d68a29b5e5e9b40d6767a5ae017dc6b3872d0"
            )
            .unwrap(),
            "OnerousMast982"
        );
        assert_eq!(
            generate_short_nickname(
                "d3f5e6c547af1c268bfc00bc92bbdbbbf80df2e30a8eaf5f2a199a07e0320cda"
            )
            .unwrap(),
            "PertToner606"
        );
        assert_eq!(
            generate_short_nickname(
                "3ee5dd464116bb1cbe225a07d4577b459cc49da215db0dec7e832d8cec3a6ec2"
            )
            .unwrap(),
            "BloomingProduce238"
        );
        assert_eq!(
            generate_short_nickname(
                "0c007605495eb709f5572fcdef6acec89e3fcccf3cd0d919ed305904771c0b4d"
            )
            .unwrap(),
            "CuriousAdhesive448"
        );
        assert_eq!(
            generate_short_nickname(
                "5716513f0e782df1fa1c7b4b2bfc5b74416a4e52251c8cecaf890413d32e3624"
            )
            .unwrap(),
            "ConvolutedOnset713"
        );
        assert_eq!(
            generate_short_nickname(
                "84424fd8f3b996448737b7b7e1649b8856d042fb63e739fd22c6e0a1a4d47a23"
            )
            .unwrap(),
            "GregariousMix774"
        );
        assert_eq!(
            generate_short_nickname(
                "3544ad1a5ce79496d3920c26aa5666f6c77222b18458a679543041c54c309ee7"
            )
            .unwrap(),
            "BrawnyEtiquette688"
        );
        assert_eq!(
            generate_short_nickname(
                "e1b9ebf74c15f82f9b94d9cc1b5de69000f61a98d3d456086436cf0a04ade2d1"
            )
            .unwrap(),
            "AdaptableBushel935"
        );
        assert_eq!(
            generate_short_nickname(
                "72914bdd87104d8edf5d375d1b2aa64aac4a0d930da925d65bc91dd9a0ec89a5"
            )
            .unwrap(),
            "FilteredMale710"
        );
        assert_eq!(
            generate_short_nickname(
                "da3764eb861e39c5c092b7c18c2f7b64dd29afe8b1ba7c0ba66d5d344709d5b1"
            )
            .unwrap(),
            "DetachedXylyl936"
        );
        assert_eq!(
            generate_short_nickname(
                "40dde35f9e54a568783152088dcb8867c4201aaef6282e8eac358600577fbcb7"
            )
            .unwrap(),
            "ThisHick743"
        );
        assert_eq!(
            generate_short_nickname(
                "92c64aa3ad5474072b5428f1900c0ecf7a404e7db824d789e68124d3124ddfc8"
            )
            .unwrap(),
            "FastHousehold302"
        );
        assert_eq!(
            generate_short_nickname(
                "023d51ba37e49ba8fd3c0d2256d52f8f24049923a7a87fa25d4051d9e8c0db65"
            )
            .unwrap(),
            "QuietExcise380"
        );
        assert_eq!(
            generate_short_nickname(
                "703d70855f2362a851dc50675b0f1e33b22cdf5550c4a47093b8ecad5084ef04"
            )
            .unwrap(),
            "VisceralSunspot235"
        );
        assert_eq!(
            generate_short_nickname(
                "344c8af920e3daea139b6b4f557ba2dc88b8c8e780751c50eec2bfc34cef9fb4"
            )
            .unwrap(),
            "TrainableStripe521"
        );
        assert_eq!(
            generate_short_nickname(
                "a5b28e037299321af4acca4b4800ff96812085610a9396daa2e72630831ca954"
            )
            .unwrap(),
            "ShriekingOzone191"
        );
        assert_eq!(
            generate_short_nickname(
                "6f8f86121107866dc1993d31901320425041edb22ae819086a72f513cec0a026"
            )
            .unwrap(),
            "EuphemisticRope564"
        );
        assert_eq!(
            generate_short_nickname(
                "9004e73f27dc2dbc2e7e2f94d1c1adb8f9e18774de9e384e6f3658678af86d49"
            )
            .unwrap(),
            "UntaintedHill937"
        );
        assert_eq!(
            generate_short_nickname(
                "e2c7a42525878575087b8bbb6315d9c171925dbe6322272e55e631ada1bb458f"
            )
            .unwrap(),
            "LeftHook809"
        );
        assert_eq!(
            generate_short_nickname(
                "52efa730b1259e501831fbe0e6f3d0544a6181d5ce39f16a484d347ca1eb6aa7"
            )
            .unwrap(),
            "MalleablePorch278"
        );
    }
}