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use anyhow::{bail, Context, Result};
use serde::{Deserialize, Serialize};
use std::fs;
use crate::exercise::Exercise;
#[derive(Serialize, Deserialize)]
pub struct StateFile {
next_exercise_ind: usize,
progress: Vec<bool>,
}
const BAD_INDEX_ERR: &str = "The next exercise index is higher than the number of exercises";
impl StateFile {
fn read(exercises: &[Exercise]) -> Option<Self> {
let file_content = fs::read(".rustlings-state.json").ok()?;
let slf: Self = serde_json::de::from_slice(&file_content).ok()?;
if slf.progress.len() != exercises.len() || slf.next_exercise_ind >= exercises.len() {
return None;
}
Some(slf)
}
pub fn read_or_default(exercises: &[Exercise]) -> Self {
Self::read(exercises).unwrap_or_else(|| Self {
next_exercise_ind: 0,
progress: vec![false; exercises.len()],
})
}
fn write(&self) -> Result<()> {
// TODO: Capacity
let mut buf = Vec::with_capacity(1024);
serde_json::ser::to_writer(&mut buf, self).context("Failed to serialize the state")?;
fs::write(".rustlings-state.json", buf)
.context("Failed to write the state file `.rustlings-state.json`")?;
Ok(())
}
#[inline]
pub fn next_exercise_ind(&self) -> usize {
self.next_exercise_ind
}
pub fn set_next_exercise_ind(&mut self, ind: usize) -> Result<()> {
if ind >= self.progress.len() {
bail!(BAD_INDEX_ERR);
}
self.next_exercise_ind = ind;
self.write()
}
#[inline]
pub fn progress(&self) -> &[bool] {
&self.progress
}
pub fn reset(&mut self, ind: usize) -> Result<()> {
let done = self.progress.get_mut(ind).context(BAD_INDEX_ERR)?;
*done = false;
self.write()
}
}
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