1 files changed, 74 insertions, 7 deletions
diff --git a/src/dev/check.rs b/src/dev/check.rs
index 5910a75..bc8e459 100644
--- a/src/dev/check.rs
+++ b/src/dev/check.rs
@@ -1,16 +1,83 @@
+use anyhow::{bail, Context, Result};
 use std::fs;
 
-use anyhow::{Context, Result};
+use crate::{
+    info_file::{ExerciseInfo, InfoFile},
+    DEVELOPING_OFFIFICAL_RUSTLINGS,
+};
 
-use crate::{info_file::InfoFile, init::cargo_toml};
+pub fn bins_start_end_ind(cargo_toml: &str) -> Result<(usize, usize)> {
+    let start_ind = cargo_toml
+        .find("bin = [")
+        .context("Failed to find the start of the `bin` list (`bin = [`)")?
+        + 7;
+    let end_ind = start_ind
+        + cargo_toml
+            .get(start_ind..)
+            .and_then(|slice| slice.as_bytes().iter().position(|c| *c == b']'))
+            .context("Failed to find the end of the `bin` list (`]`)")?;
+
+    Ok((start_ind, end_ind))
+}
+
+pub fn append_bins(
+    buf: &mut Vec<u8>,
+    exercise_infos: &[ExerciseInfo],
+    exercise_path_prefix: &[u8],
+) {
+    buf.push(b'\n');
+    for exercise_info in exercise_infos {
+        buf.extend_from_slice(b"  { name = \"");
+        buf.extend_from_slice(exercise_info.name.as_bytes());
+        buf.extend_from_slice(b"\", path = \"");
+        buf.extend_from_slice(exercise_path_prefix);
+        buf.extend_from_slice(b"exercises/");
+        if let Some(dir) = &exercise_info.dir {
+            buf.extend_from_slice(dir.as_bytes());
+            buf.push(b'/');
+        }
+        buf.extend_from_slice(exercise_info.name.as_bytes());
+        buf.extend_from_slice(b".rs\" },\n");
+    }
+}
+
+fn check_cargo_toml(
+    exercise_infos: &[ExerciseInfo],
+    current_cargo_toml: &str,
+    exercise_path_prefix: &[u8],
+) -> Result<()> {
+    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+
+    let old_bins = &current_cargo_toml.as_bytes()[bins_start_ind..bins_end_ind];
+    let mut new_bins = Vec::with_capacity(1 << 13);
+    append_bins(&mut new_bins, exercise_infos, exercise_path_prefix);
+
+    if old_bins != new_bins {
+        bail!("`Cargo.toml` is outdated. Run `rustlings dev update` to update it");
+    }
+
+    Ok(())
+}
+
+pub fn check() -> Result<()> {
+    let info_file = InfoFile::parse()?;
 
-pub fn check(info_file: InfoFile) -> Result<()> {
     // TODO: Add checks
 
-    // TODO: Keep dependencies!
-    fs::write("Cargo.toml", cargo_toml(&info_file.exercises))
-        .context("Failed to update the file `Cargo.toml`")?;
-    println!("Updated `Cargo.toml`");
+    if DEVELOPING_OFFIFICAL_RUSTLINGS {
+        check_cargo_toml(
+            &info_file.exercises,
+            include_str!("../../dev/Cargo.toml"),
+            b"../",
+        )
+        .context("The file `dev/Cargo.toml` is outdated. Please run `cargo run -- dev update` to update it")?;
+    } else {
+        let current_cargo_toml =
+            fs::read_to_string("Cargo.toml").context("Failed to read the file `Cargo.toml`")?;
+        check_cargo_toml(&info_file.exercises, &current_cargo_toml, b"").context(
+            "The file `Cargo.toml` is outdated. Please run `rustlings dev update` to update it",
+        )?;
+    }
 
     println!("\nEverything looks fine!");