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|
use std::{
fs::File,
io::{Read, Seek, Write},
};
use serde::{Deserialize, Serialize};
use anyhow::{Context, Result};
use crate::diff::ContentChange;
#[derive(Serialize, Deserialize, Debug)]
pub struct FileHistory {
cursor: usize,
changes: Vec<FileChange>,
}
impl FileHistory {
pub fn from_file(file: &mut File) -> Result<FileHistory> {
let mut buffer = Vec::new();
file.read_to_end(&mut buffer)
.context("Failed reading file history.")?;
let file_history = serde_json::from_slice::<FileHistory>(&buffer);
file_history.context("Corrupted file history.")
}
pub fn write_to_file(&self, file: &mut File) -> anyhow::Result<()> {
let encoded: Vec<u8> = serde_json::to_vec(self)?;
file.rewind()?;
file.set_len(0)?;
file.write_all(encoded.as_ref())?;
Ok(())
}
pub fn cursor(&self) -> usize {
self.cursor
}
pub fn file_is_deleted(&self) -> bool {
match self.changes.last() {
Some(change) => match change {
FileChange::Deleted => true,
FileChange::Updated(_) => false,
},
None => false,
}
}
pub fn get_content(&self) -> Vec<u8> {
let mut buffer = Vec::new();
for file_change in self.changes.iter().take(self.cursor + 1) {
if let FileChange::Updated(ref updated) = file_change {
for change in updated.iter() {
change.apply(&mut buffer)
}
} else {
buffer.drain(0..);
}
}
buffer
}
pub fn set_cursor(&mut self, new_cursor: usize) {
if new_cursor < self.changes.len() {
self.cursor = new_cursor;
} else {
panic!(
"Out-of-bounds cursor for file history: {}, can be at most {}",
new_cursor,
self.changes.len() - 1
);
}
}
pub fn add_change(&mut self, change: FileChange) {
self.changes.push(change);
}
}
impl Default for FileHistory {
fn default() -> Self {
Self {
cursor: 0,
changes: Vec::new(),
}
}
}
#[derive(Serialize, Deserialize, Debug)]
pub enum FileChange {
Updated(Vec<ContentChange>),
Deleted,
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_get_content() {
let stages = &[
"",
"hiii!",
"yes hii? this is a test.",
"yes bye! this is not a test.",
];
let mut history = FileHistory::default();
history.add_change(FileChange::Updated(Vec::new()));
for old_index in 0..stages.len() - 1 {
let old = stages[old_index].as_bytes();
let new = stages[old_index + 1].as_bytes();
let stage_difference = ContentChange::diff(old, new);
history.add_change(FileChange::Updated(stage_difference));
}
for index in 0..stages.len() {
history.set_cursor(index);
assert_eq!(stages[index].as_bytes(), history.get_content());
}
}
}
|
