Refactor Library

The launcher code was in a position ripe for sphagetti, so this rewrites it in a more robust way.
In addition to cleaner code, this provides the following changes:
- Removal of obsolete Mojang authentication
- The rebasing of some internal state into a Sled database
- Tweaks which make some internal mechanisms more robust (e.g. profiles which fail to load can be removed)
- Additional tooling integration such as direnv
- Distinct public API to avoid messing with too much internal code
- Unified error handling in the form of `theseus::Error` and `theseus::Result`

theseus/src/state/dirs.rs

@@ -0,0 +1,129 @@
+//! Theseus directory information
+use std::path::PathBuf;
+use tokio::fs;
+
+#[derive(Debug)]
+pub struct DirectoryInfo {
+    pub config_dir: PathBuf,
+    pub working_dir: PathBuf,
+}
+
+impl DirectoryInfo {
+    /// Get all paths needed for Theseus to operate properly
+    pub async fn init() -> crate::Result<Self> {
+        // Working directory
+        let working_dir = std::env::current_dir().map_err(|err| {
+            crate::Error::FSError(format!(
+                "Could not open working directory: {err}"
+            ))
+        })?;
+
+        // Config directory
+        let config_dir = Self::env_path("THESEUS_CONFIG_DIR")
+            .or_else(|| Some(dirs::config_dir()?.join("theseus")))
+            .ok_or(crate::Error::FSError(
+                "Could not find valid config dir".to_string(),
+            ))?;
+
+        fs::create_dir_all(&config_dir).await.map_err(|err| {
+            crate::Error::FSError(format!(
+                "Error creating Theseus config directory: {err}"
+            ))
+        })?;
+
+        Ok(Self {
+            config_dir,
+            working_dir,
+        })
+    }
+
+    /// Get the Minecraft instance metadata directory
+    #[inline]
+    pub fn metadata_dir(&self) -> PathBuf {
+        self.config_dir.join("meta")
+    }
+
+    /// Get the Minecraft versions metadata directory
+    #[inline]
+    pub fn versions_dir(&self) -> PathBuf {
+        self.metadata_dir().join("versions")
+    }
+
+    /// Get the metadata directory for a given version
+    #[inline]
+    pub fn version_dir(&self, version: &str) -> PathBuf {
+        self.versions_dir().join(version)
+    }
+
+    /// Get the Minecraft libraries metadata directory
+    #[inline]
+    pub fn libraries_dir(&self) -> PathBuf {
+        self.metadata_dir().join("libraries")
+    }
+
+    /// Get the Minecraft assets metadata directory
+    #[inline]
+    pub fn assets_dir(&self) -> PathBuf {
+        self.metadata_dir().join("assets")
+    }
+
+    /// Get the assets index directory
+    #[inline]
+    pub fn assets_index_dir(&self) -> PathBuf {
+        self.assets_dir().join("indexes")
+    }
+
+    /// Get the assets objects directory
+    #[inline]
+    pub fn objects_dir(&self) -> PathBuf {
+        self.assets_dir().join("objects")
+    }
+
+    /// Get the directory for a specific object
+    #[inline]
+    pub fn object_dir(&self, hash: &str) -> PathBuf {
+        self.objects_dir().join(&hash[..2]).join(hash)
+    }
+
+    /// Get the Minecraft legacy assets metadata directory
+    #[inline]
+    pub fn legacy_assets_dir(&self) -> PathBuf {
+        self.metadata_dir().join("resources")
+    }
+
+    /// Get the Minecraft legacy assets metadata directory
+    #[inline]
+    pub fn natives_dir(&self) -> PathBuf {
+        self.metadata_dir().join("natives")
+    }
+
+    /// Get the natives directory for a version of Minecraft
+    #[inline]
+    pub fn version_natives_dir(&self, version: &str) -> PathBuf {
+        self.natives_dir().join(version)
+    }
+
+    /// Get the directory containing instance icons
+    #[inline]
+    pub fn icon_dir(&self) -> PathBuf {
+        self.config_dir.join("icons")
+    }
+
+    /// Get the file containing the global database
+    #[inline]
+    pub fn database_file(&self) -> PathBuf {
+        self.config_dir.join("data.bin")
+    }
+
+    /// Get the settings file for Theseus
+    #[inline]
+    pub fn settings_file(&self) -> PathBuf {
+        self.config_dir.join("settings.json")
+    }
+
+    /// Get path from environment variable
+    #[inline]
+    fn env_path(name: &str) -> Option<PathBuf> {
+        std::env::var_os(name).map(PathBuf::from)
+    }
+}