1 files changed, 168 insertions, 0 deletions
diff --git a/src/embedded.rs b/src/embedded.rs
new file mode 100644
index 0000000..1dce46c
--- /dev/null
+++ b/src/embedded.rs
@@ -0,0 +1,168 @@
+use anyhow::{Context, Error, Result};
+use std::{
+    fs::{create_dir, OpenOptions},
+    io::{self, Write},
+};
+
+use crate::info_file::ExerciseInfo;
+
+/// Contains all embedded files.
+pub static EMBEDDED_FILES: EmbeddedFiles = rustlings_macros::include_files!();
+
+#[derive(Clone, Copy)]
+pub enum WriteStrategy {
+    IfNotExists,
+    Overwrite,
+}
+
+impl WriteStrategy {
+    fn write(self, path: &str, content: &[u8]) -> Result<()> {
+        let file = match self {
+            Self::IfNotExists => OpenOptions::new().create_new(true).write(true).open(path),
+            Self::Overwrite => OpenOptions::new()
+                .create(true)
+                .write(true)
+                .truncate(true)
+                .open(path),
+        };
+
+        file.with_context(|| format!("Failed to open the file `{path}` in write mode"))?
+            .write_all(content)
+            .with_context(|| format!("Failed to write the file {path}"))
+    }
+}
+
+// Files related to one exercise.
+struct ExerciseFiles {
+    // The content of the exercise file.
+    exercise: &'static [u8],
+    // The content of the solution file.
+    solution: &'static [u8],
+    // Index of the related `ExerciseDir` in `EmbeddedFiles::exercise_dirs`.
+    dir_ind: usize,
+}
+
+// A directory in the `exercises/` directory.
+pub struct ExerciseDir {
+    pub name: &'static str,
+    readme: &'static [u8],
+}
+
+impl ExerciseDir {
+    fn init_on_disk(&self) -> Result<()> {
+        // 20 = 10 + 10
+        // exercises/ + /README.md
+        let mut dir_path = String::with_capacity(20 + self.name.len());
+        dir_path.push_str("exercises/");
+        dir_path.push_str(self.name);
+
+        if let Err(e) = create_dir(&dir_path) {
+            if e.kind() == io::ErrorKind::AlreadyExists {
+                return Ok(());
+            }
+
+            return Err(
+                Error::from(e).context(format!("Failed to create the directory {dir_path}"))
+            );
+        }
+
+        let mut readme_path = dir_path;
+        readme_path.push_str("/README.md");
+
+        WriteStrategy::Overwrite.write(&readme_path, self.readme)
+    }
+}
+
+/// All embedded files.
+pub struct EmbeddedFiles {
+    /// The content of the `info.toml` file.
+    pub info_file: &'static str,
+    exercise_files: &'static [ExerciseFiles],
+    pub exercise_dirs: &'static [ExerciseDir],
+}
+
+impl EmbeddedFiles {
+    /// Dump all the embedded files of the `exercises/` directory.
+    pub fn init_exercises_dir(&self, exercise_infos: &[ExerciseInfo]) -> Result<()> {
+        create_dir("exercises").context("Failed to create the directory `exercises`")?;
+
+        WriteStrategy::IfNotExists.write(
+            "exercises/README.md",
+            include_bytes!("../exercises/README.md"),
+        )?;
+
+        for dir in self.exercise_dirs {
+            dir.init_on_disk()?;
+        }
+
+        for (exercise_info, exercise_files) in exercise_infos.iter().zip(self.exercise_files) {
+            WriteStrategy::IfNotExists.write(&exercise_info.path(), exercise_files.exercise)?;
+        }
+
+        Ok(())
+    }
+
+    pub fn write_exercise_to_disk(&self, exercise_ind: usize, path: &str) -> Result<()> {
+        let exercise_files = &self.exercise_files[exercise_ind];
+        let dir = &self.exercise_dirs[exercise_files.dir_ind];
+
+        dir.init_on_disk()?;
+        WriteStrategy::Overwrite.write(path, exercise_files.exercise)
+    }
+
+    /// Write the solution file to disk and return its path.
+    pub fn write_solution_to_disk(
+        &self,
+        exercise_ind: usize,
+        exercise_name: &str,
+    ) -> Result<String> {
+        let exercise_files = &self.exercise_files[exercise_ind];
+        let dir = &self.exercise_dirs[exercise_files.dir_ind];
+
+        // 14 = 10 + 1 + 3
+        // solutions/ + / + .rs
+        let mut solution_path = String::with_capacity(14 + dir.name.len() + exercise_name.len());
+        solution_path.push_str("solutions/");
+        solution_path.push_str(dir.name);
+        solution_path.push('/');
+        solution_path.push_str(exercise_name);
+        solution_path.push_str(".rs");
+
+        WriteStrategy::Overwrite.write(&solution_path, exercise_files.solution)?;
+
+        Ok(solution_path)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use serde::Deserialize;
+
+    use super::*;
+
+    #[derive(Deserialize)]
+    struct ExerciseInfo {
+        dir: String,
+    }
+
+    #[derive(Deserialize)]
+    struct InfoFile {
+        exercises: Vec<ExerciseInfo>,
+    }
+
+    #[test]
+    fn dirs() {
+        let exercises = toml_edit::de::from_str::<InfoFile>(EMBEDDED_FILES.info_file)
+            .expect("Failed to parse `info.toml`")
+            .exercises;
+
+        assert_eq!(exercises.len(), EMBEDDED_FILES.exercise_files.len());
+
+        for (exercise, exercise_files) in exercises.iter().zip(EMBEDDED_FILES.exercise_files) {
+            assert_eq!(
+                exercise.dir,
+                EMBEDDED_FILES.exercise_dirs[exercise_files.dir_ind].name,
+            );
+        }
+    }
+}