/*
Copyright 2019 ETCDEV GmbH
Copyright 2020 EmeraldPay, Inc

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
pub use crate::crypto::util::{keccak256, KECCAK256_BYTES};
use byteorder::{BigEndian, ReadBytesExt, WriteBytesExt};
use chrono::prelude::Utc;
use hex::FromHex;
use std::io::Cursor;

pub fn none_if_empty(s: &str) -> Option<String> {
    if s.is_empty() {
        None
    } else {
        Some(s.to_string())
    }
}

/// Convert byte array into `u64`
///
/// # Arguments
///
/// * `v` - array to be converted
///
pub fn to_u64(v: &[u8]) -> u64 {
    let data = align_bytes(v, 8);
    let mut buf = Cursor::new(&data);

    buf.read_u64::<BigEndian>().unwrap()
}

/// Trix hex prefix `0x`
///
/// # Arguments
///
/// * `val` - string to be trimmed
///
pub fn trim_hex(val: &str) -> &str {
    if !val.starts_with("0x") {
        return val;
    }

    let (_, s) = val.split_at(2);
    s
}

/// Convert a slice into array
///
/// # Arguments
///
/// * `slice` - slice to be converted
///
pub fn to_arr<A, T>(slice: &[T]) -> A
where
    A: AsMut<[T]> + Default,
    T: Clone,
{
    let mut arr = Default::default();
    <A as AsMut<[T]>>::as_mut(&mut arr).clone_from_slice(slice);
    arr
}

/// Padding high bytes with `O` to fit `len` bytes
///
/// # Arguments
///
/// * `data` - data to be aligned
/// * `len` - length of required array
///
pub fn align_bytes(data: &[u8], len: usize) -> Vec<u8> {
    if data.len() >= len {
        return data.to_vec();
    }

    let mut v = vec![0u8; len - data.len()];
    v.extend_from_slice(data);
    v
}

/// Padding hex string with `O` to get even length
///
/// # Arguments
///
/// * `data` - data to be aligned
///
pub fn to_even_str(data: &str) -> String {
    if data.len() % 2 == 0 {
        return String::from(data);
    }

    let mut v = String::from("0");
    v.push_str(data);
    v
}

/// Trim all high zero bytes
///
/// # Arguments
///
/// * `data` - value to be trimmed
///
pub fn trim_bytes(data: &[u8]) -> &[u8] {
    let mut n = 0;
    for b in data {
        if *b != 0u8 {
            break;
        }
        n += 1;
    }
    &data[n..data.len()]
}

/// Counts bytes required to hold `x` value
///
/// # Arguments
///
/// * `x` - value to find size
///
pub fn bytes_count(x: usize) -> u8 {
    match x {
        _ if x > 0xff => 1 + bytes_count(x >> 8),
        _ if x > 0 => 1,
        _ => 0,
    }
}

/// Converts `unsigned` value to byte array
///
/// # Arguments
///
/// * `x` - a value to be converted into byte vector
/// * `len` - size of value
///
pub fn to_bytes(x: u64, len: u8) -> Vec<u8> {
    let mut buf = vec![];
    match len {
        1 => buf.push(x as u8),
        2 => buf.write_u16::<BigEndian>(x as u16).unwrap(),
        4 => buf.write_u32::<BigEndian>(x as u32).unwrap(),
        8 => buf.write_u64::<BigEndian>(x).unwrap(),
        _ => (),
    }
    buf
}

/// Time stamp in format `yyy-mm-ddThh-mm-ss`
pub fn timestamp() -> String {
    // `2017-05-01T20:21:10.163281100+00:00` -> `2017-05-01T20-21-10`
    str::replace(&Utc::now().to_rfc3339(), ":", "-")
        .split('.')
        .next()
        .unwrap()
        .to_string()
}

///
pub fn to_16bytes(hex: &str) -> [u8; 16] {
    to_arr(Vec::from_hex(&hex).unwrap().as_slice())
}

///
pub fn to_20bytes(hex: &str) -> [u8; 20] {
    to_arr(Vec::from_hex(&hex).unwrap().as_slice())
}

///
pub fn to_32bytes(hex: &str) -> [u8; 32] {
    let parsed = Vec::from_hex(&hex).unwrap();
    if parsed.len() != 32 {
        let aligned = align_bytes(parsed.as_slice(), 32);
        to_arr(aligned.as_slice())
    } else {
        to_arr(parsed.as_slice())
    }
}

#[cfg(test)]
pub use self::tests::*;

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

    #[test]
    fn should_convert_zero_string_into_16bytes() {
        assert_eq!(to_16bytes("00000000000000000000000000000000"), [0u8; 16]);
    }

    #[test]
    fn should_convert_address_into_20bytes() {
        assert_eq!(
            to_20bytes("3f4e0668c20e100d7c2a27d4b177ac65b2875d26"),
            [
                0x3f, 0x4e, 0x06, 0x68, 0xc2, 0x0e, 0x10, 0x0d, 0x7c, 0x2a, 0x27, 0xd4, 0xb1, 0x77,
                0xac, 0x65, 0xb2, 0x87, 0x5d, 0x26,
            ]
        );
    }

    #[test]
    fn should_convert_key_into_32bytes() {
        assert_eq!(
            to_32bytes("fa384e6fe915747cd13faa1022044b0def5e6bec4238bec53166487a5cca569f",),
            [
                0xfa, 0x38, 0x4e, 0x6f, 0xe9, 0x15, 0x74, 0x7c, 0xd1, 0x3f, 0xaa, 0x10, 0x22, 0x04,
                0x4b, 0x0d, 0xef, 0x5e, 0x6b, 0xec, 0x42, 0x38, 0xbe, 0xc5, 0x31, 0x66, 0x48, 0x7a,
                0x5c, 0xca, 0x56, 0x9f,
            ]
        );
    }

    #[test]
    fn should_align_empty_bytes() {
        assert_eq!(align_bytes(&[], 8), vec![0, 0, 0, 0, 0, 0, 0, 0]);
    }

    #[test]
    fn should_align_some_zero_bytes() {
        assert_eq!(align_bytes(&[0, 0, 0], 8), vec![0, 0, 0, 0, 0, 0, 0, 0]);
    }

    #[test]
    fn should_align_all_zero_bytes() {
        assert_eq!(
            align_bytes(&[0, 0, 0, 0, 0, 0, 0, 0], 8),
            vec![0, 0, 0, 0, 0, 0, 0, 0]
        );
    }

    #[test]
    fn should_align_some_bytes() {
        assert_eq!(align_bytes(&[0, 1, 2, 3], 8), vec![0, 0, 0, 0, 0, 1, 2, 3]);
    }

    #[test]
    fn should_align_full_bytes() {
        assert_eq!(
            align_bytes(&[1, 2, 3, 4, 5, 6, 7, 8], 8),
            vec![1, 2, 3, 4, 5, 6, 7, 8]
        );
    }

    #[test]
    fn should_skip_smaller_length() {
        assert_eq!(
            align_bytes(&[1, 2, 3, 4, 5, 6, 7, 8], 6),
            vec![1, 2, 3, 4, 5, 6, 7, 8]
        );
    }

    #[test]
    fn should_align_to_even_str() {
        assert_eq!(to_even_str("100"), String::from("0100"));
    }

    #[test]
    fn should_skip_already_even_str() {
        assert_eq!(to_even_str("100012"), String::from("100012"));
    }

    #[test]
    fn should_trim_empty_bytes() {
        assert_eq!(trim_bytes(&[]), &[] as &[u8]);
    }

    #[test]
    fn should_trim_zero_bytes() {
        assert_eq!(trim_bytes(&[0, 0, 0]), &[] as &[u8]);
    }

    #[test]
    fn should_trim_some_bytes() {
        assert_eq!(trim_bytes(&[0, 0, 0, 0, 0, 1, 2, 3]), &[1, 2, 3]);
    }

    #[test]
    fn should_trim_hex_prefix() {
        assert_eq!("12345", trim_hex("0x12345"))
    }

    #[test]
    fn should_skip_trim_hex_prefix() {
        assert_eq!("12345", trim_hex("12345"))
    }

    #[test]
    fn should_count_bytes_for_rlp() {
        assert_eq!(bytes_count(0x00), 0);
        assert_eq!(bytes_count(0x01), 1);
        assert_eq!(bytes_count(0xff), 1);
        assert_eq!(bytes_count(0xff01), 2);
        assert_eq!(bytes_count(0xffff01), 3);
    }

    #[test]
    fn should_convert_u8_to_bytes() {
        assert_eq!([1], to_bytes(1, 1).as_slice());
        assert_eq!([2], to_bytes(2, 1).as_slice());
        assert_eq!([127], to_bytes(127, 1).as_slice());
        assert_eq!([128], to_bytes(128, 1).as_slice());
        assert_eq!([255], to_bytes(255, 1).as_slice());
    }

    #[test]
    fn should_convert_u16_to_bytes() {
        assert_eq!([0, 1], to_bytes(1, 2).as_slice());
        assert_eq!([0, 2], to_bytes(2, 2).as_slice());
        assert_eq!([0, 255], to_bytes(255, 2).as_slice());
        assert_eq!([1, 0], to_bytes(256, 2).as_slice());
        assert_eq!([0x12, 0x34], to_bytes(0x1234, 2).as_slice());
        assert_eq!([0xff, 0xff], to_bytes(0xffff, 2).as_slice());
    }

    #[test]
    fn should_convert_u32_to_bytes() {
        assert_eq!([0, 0, 0, 1], to_bytes(1, 4).as_slice());
        assert_eq!([0x12, 0x34, 0x56, 0x78], to_bytes(0x12345678, 4).as_slice());
        assert_eq!([0xff, 0x0, 0x0, 0x0], to_bytes(0xff000000, 4).as_slice());
        assert_eq!([0x00, 0xff, 0x0, 0x0], to_bytes(0x00ff0000, 4).as_slice());
    }

    #[test]
    fn should_convert_u64_to_bytes() {
        assert_eq!([0, 0, 0, 0, 0, 0, 0, 1], to_bytes(1, 8).as_slice());
        assert_eq!(
            [0x12, 0x34, 0x56, 0x78, 0x90, 0xab, 0xcd, 0xef],
            to_bytes(0x1234567890abcdef, 8).as_slice()
        );
        assert_eq!(
            [0xff, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0],
            to_bytes(0xff00000000000000, 8).as_slice()
        );
        assert_eq!(
            [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff],
            to_bytes(0xffffffffffffffff, 8).as_slice()
        );
    }

    #[test]
    fn should_generate_timestamp() {
        let re = Regex::new(r"^\d{4}-\d{2}-\d{2}[T]\d{2}-\d{2}-\d{2}").unwrap();

        assert!(re.is_match(&timestamp()));
    }
}