73 lines
2.2 KiB
Rust
73 lines
2.2 KiB
Rust
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use std::{iter, ops::Add};
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use crate::message::{self, Message};
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pub fn encrypt_message(message: &mut Message, circle_length: &usize) -> Vec<Circle> {
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fill_circles(
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&mut encode_circles(
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&mut triples_into_circles(&message.to_triples(), circle_length),
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&mut message.parts.start_shift,
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),
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circle_length
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)
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}
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fn caesar_shift(char: char, shift: u8) -> char {
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(char as u8 + shift) as char
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}
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type Circle = Vec<message::Triple>;
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fn triples_into_circles(triples: &Vec<message::Triple>, circle_length: &usize) -> Vec<Circle> {
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triples.chunks(*circle_length)
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.map(|chunk| {
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chunk.to_vec()
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}).collect()
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}
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fn encode_circles(circles: &mut Vec<Circle>, shift: &mut u8) -> Vec<Circle> {
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circles.iter_mut().enumerate().map(|(count, circle)| {
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let shift_delta = match count {
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count if count % 2 == 0 => count.add(1) as i8,
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_ => -(count.add(1) as i8)
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};
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let circle_iter = circle.iter_mut();
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let new_circle = match count {
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0 => circle_iter.skip(1),
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_ => circle_iter.skip(0),
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}.map(|triple| {
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triple.first = caesar_shift(triple.first, *shift);
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*shift = shift.wrapping_add_signed(shift_delta);
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triple.second = caesar_shift(triple.second, *shift);
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*shift = shift.wrapping_add_signed(shift_delta);
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triple.second = caesar_shift(triple.third, *shift);
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*shift = shift.wrapping_add_signed(shift_delta);
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triple.clone()
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}).collect::<Circle>();
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let new_circle = match count {
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0 => {
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let mut vec = vec![circle[0].clone()];
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vec.extend(new_circle);
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return vec;
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},
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_ => new_circle,
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};
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new_circle
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}).collect()
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}
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fn fill_circles(circles: &mut Vec<Circle>, circle_length: &usize) -> Vec<Circle> {
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circles.iter_mut().map(|circle| {
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circle.extend(iter::repeat(message::Triple::filler())
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.take(
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circle_length - circle.len()
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)
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);
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circle.clone()
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}).collect()
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}
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