1 files changed, 146 insertions, 0 deletions
diff --git a/src/cargo_toml.rs b/src/cargo_toml.rs
new file mode 100644
index 0000000..445b6b5
--- /dev/null
+++ b/src/cargo_toml.rs
@@ -0,0 +1,146 @@
+use anyhow::{Context, Result};
+use std::path::Path;
+
+use crate::info_file::ExerciseInfo;
+
+/// Initial capacity of the bins buffer.
+pub const BINS_BUFFER_CAPACITY: usize = 1 << 14;
+
+/// Return the start and end index of the content of the list `bin = […]`.
+/// bin = [xxxxxxxxxxxxxxxxx]
+///        |start_ind       |
+///                         |end_ind
+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))
+}
+
+/// Generate and append the content of the `bin` list in `Cargo.toml`.
+/// The `exercise_path_prefix` is the prefix of the `path` field of every list entry.
+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");
+
+        let sol_path = exercise_info.sol_path();
+        if !Path::new(&sol_path).exists() {
+            continue;
+        }
+
+        buf.extend_from_slice(b"  { name = \"");
+        buf.extend_from_slice(exercise_info.name.as_bytes());
+        buf.extend_from_slice(b"_sol");
+        buf.extend_from_slice(b"\", path = \"");
+        buf.extend_from_slice(exercise_path_prefix);
+        buf.extend_from_slice(b"solutions/");
+        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");
+    }
+}
+
+/// Update the `bin` list and leave everything else unchanged.
+pub fn updated_cargo_toml(
+    exercise_infos: &[ExerciseInfo],
+    current_cargo_toml: &str,
+    exercise_path_prefix: &[u8],
+) -> Result<Vec<u8>> {
+    let (bins_start_ind, bins_end_ind) = bins_start_end_ind(current_cargo_toml)?;
+
+    let mut updated_cargo_toml = Vec::with_capacity(BINS_BUFFER_CAPACITY);
+    updated_cargo_toml.extend_from_slice(current_cargo_toml[..bins_start_ind].as_bytes());
+    append_bins(
+        &mut updated_cargo_toml,
+        exercise_infos,
+        exercise_path_prefix,
+    );
+    updated_cargo_toml.extend_from_slice(current_cargo_toml[bins_end_ind..].as_bytes());
+
+    Ok(updated_cargo_toml)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_bins_start_end_ind() {
+        assert_eq!(bins_start_end_ind("").ok(), None);
+        assert_eq!(bins_start_end_ind("[]").ok(), None);
+        assert_eq!(bins_start_end_ind("bin = [").ok(), None);
+        assert_eq!(bins_start_end_ind("bin = ]").ok(), None);
+        assert_eq!(bins_start_end_ind("bin = []").ok(), Some((7, 7)));
+        assert_eq!(bins_start_end_ind("bin= []").ok(), None);
+        assert_eq!(bins_start_end_ind("bin =[]").ok(), None);
+        assert_eq!(bins_start_end_ind("bin=[]").ok(), None);
+        assert_eq!(bins_start_end_ind("bin = [\nxxx\n]").ok(), Some((7, 12)));
+    }
+
+    #[test]
+    fn test_bins() {
+        let exercise_infos = [
+            ExerciseInfo {
+                name: String::from("1"),
+                dir: None,
+                test: true,
+                strict_clippy: true,
+                hint: String::new(),
+                skip_check_unsolved: false,
+            },
+            ExerciseInfo {
+                name: String::from("2"),
+                dir: Some(String::from("d")),
+                test: false,
+                strict_clippy: false,
+                hint: String::new(),
+                skip_check_unsolved: false,
+            },
+        ];
+
+        let mut buf = Vec::with_capacity(128);
+        append_bins(&mut buf, &exercise_infos, b"");
+        assert_eq!(
+            buf,
+            br#"
+  { name = "1", path = "exercises/1.rs" },
+  { name = "2", path = "exercises/d/2.rs" },
+"#,
+        );
+
+        assert_eq!(
+            updated_cargo_toml(&exercise_infos, "abc\nbin = [xxx]\n123", b"../").unwrap(),
+            br#"abc
+bin = [
+  { name = "1", path = "../exercises/1.rs" },
+  { name = "2", path = "../exercises/d/2.rs" },
+]
+123"#,
+        );
+    }
+}