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/settings.rs

@@ -0,0 +1,119 @@
+//! Theseus settings file
+use serde::{Deserialize, Serialize};
+use std::{
+    collections::HashSet,
+    path::{Path, PathBuf},
+};
+use tokio::fs;
+
+// TODO: convert to semver?
+const CURRENT_FORMAT_VERSION: u32 = 1;
+
+// Types
+/// Global Theseus settings
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(default)]
+pub struct Settings {
+    pub memory: MemorySettings,
+    pub game_resolution: WindowSize,
+    pub custom_java_args: Vec<String>,
+    pub java_8_path: Option<PathBuf>,
+    pub java_17_path: Option<PathBuf>,
+    pub hooks: Hooks,
+    pub max_concurrent_downloads: usize,
+    pub version: u32,
+}
+
+impl Default for Settings {
+    fn default() -> Self {
+        Self {
+            memory: MemorySettings::default(),
+            game_resolution: WindowSize::default(),
+            custom_java_args: Vec::new(),
+            java_8_path: None,
+            java_17_path: None,
+            hooks: Hooks::default(),
+            max_concurrent_downloads: 64,
+            version: CURRENT_FORMAT_VERSION,
+        }
+    }
+}
+
+impl Settings {
+    pub async fn init(file: &Path) -> crate::Result<Self> {
+        if file.exists() {
+            fs::read(&file)
+                .await
+                .map_err(|err| {
+                    crate::Error::FSError(format!(
+                        "Error reading settings file: {err}"
+                    ))
+                })
+                .and_then(|it| {
+                    serde_json::from_slice::<Settings>(&it)
+                        .map_err(crate::Error::from)
+                })
+        } else {
+            Ok(Settings::default())
+        }
+    }
+
+    pub async fn sync(&self, to: &Path) -> crate::Result<()> {
+        fs::write(to, serde_json::to_vec_pretty(self)?)
+            .await
+            .map_err(|err| {
+                crate::Error::FSError(format!(
+                    "Error saving settings to file: {err}"
+                ))
+            })
+    }
+}
+
+/// Minecraft memory settings
+#[derive(Serialize, Deserialize, Debug, Clone, Copy)]
+pub struct MemorySettings {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub minimum: Option<u32>,
+    pub maximum: u32,
+}
+
+impl Default for MemorySettings {
+    fn default() -> Self {
+        Self {
+            minimum: None,
+            maximum: 2048,
+        }
+    }
+}
+
+/// Game window size
+#[derive(Serialize, Deserialize, Debug, Clone, Copy)]
+pub struct WindowSize(pub u16, pub u16);
+
+impl Default for WindowSize {
+    fn default() -> Self {
+        Self(854, 480)
+    }
+}
+
+/// Game initialization hooks
+#[derive(Serialize, Deserialize, Debug, Clone)]
+#[serde(default)]
+pub struct Hooks {
+    #[serde(skip_serializing_if = "HashSet::is_empty")]
+    pub pre_launch: HashSet<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub wrapper: Option<String>,
+    #[serde(skip_serializing_if = "HashSet::is_empty")]
+    pub post_exit: HashSet<String>,
+}
+
+impl Default for Hooks {
+    fn default() -> Self {
+        Self {
+            pre_launch: HashSet::<String>::new(),
+            wrapper: None,
+            post_exit: HashSet::<String>::new(),
+        }
+    }
+}