First draft of modpack module

theseus/src/modpack/mod.rs

@@ -0,0 +1,68 @@
+//! Provides utilties for downloading and parsing modpacks
+
+use std::{convert::TryFrom, io, path::Path};
+use fs_extra::dir::CopyOptions;
+use tokio::fs;
+
+use self::manifest::Manifest;
+
+mod manifest;
+
+pub const MANIFEST_PATH: &'static str = "index.json";
+pub const OVERRIDES_PATH: &'static str = "overrides/";
+
+#[derive(thiserror::Error, Debug)]
+pub enum ModpackError {
+    #[error("I/O error while reading modpack: {0}")]
+    IOError(#[from] io::Error),
+
+    #[error("I/O error while reading modpack: {0}")]
+    FSExtraError(#[from] fs_extra::error::Error),
+
+    #[error("Invalid output directory: {0}")]
+    InvalidDirectory(String),
+
+    #[error("Error parsing manifest: {0}")]
+    ManifestError(String),
+
+    #[error("Daedalus error: {0}")]
+    DaedalusError(#[from] daedalus::Error),
+
+    #[error("Error parsing json: {0}")]
+    JsonError(#[from] serde_json::Error),
+
+    #[error("Error joining futures: {0}")]
+    JoinError(#[from] tokio::task::JoinError),
+}
+
+/// Realise a given modpack into an instance
+pub async fn realise_modpack(dir: &Path, dest: &Path, side: &manifest::ModpackSide) -> Result<(), ModpackError> {
+    if dest.is_file() {
+        return Err(ModpackError::InvalidDirectory(String::from("Output is not a directory")));
+    }
+    if dest.exists() && std::fs::read_dir(dest).map_or(false, |it| it.count() != 0) {
+        return Err(ModpackError::InvalidDirectory(String::from("Output directory is non-empty")));
+    }
+    if !dest.exists() {
+        fs::create_dir_all(dest).await?;
+    }
+
+    // Copy overrides
+    let overrides = Some(dir.join(OVERRIDES_PATH)).filter(|it| it.exists() && it.is_dir());
+    if let Some(overrides) = overrides {
+        fs_extra::dir::copy(overrides, dest, &CopyOptions::new())?;
+    }
+
+    // Parse manifest
+    // NOTE: I'm using standard files here, since Serde does not support async readers
+    let manifest_path = Some(dir.join(MANIFEST_PATH))
+        .filter(|it| it.exists() && it.is_file())
+        .ok_or(ModpackError::ManifestError(String::from("Manifest missing or is not a file")))?;
+    let manifest_file = std::fs::File::open(manifest_path)?;
+    let manifest_json: serde_json::Value = serde_json::from_reader(io::BufReader::new(manifest_file))?;
+    let manifest = Manifest::try_from(manifest_json)?;
+
+    // Realise manifest
+    manifest.download_files(dest, side).await?;
+    Ok(())
+}