3 files changed, 195 insertions, 0 deletions
diff --git a/src/launcher/jre.rs b/src/launcher/jre.rs
new file mode 100644
index 0000000..2979c52
--- /dev/null
+++ b/src/launcher/jre.rs
@@ -0,0 +1,101 @@
+use std::error::Error;
+use std::fmt::{Display, Formatter};
+use std::path::{Path, PathBuf};
+use log::{debug, info, warn};
+use tokio::{fs, io};
+
+mod arch;
+mod manifest;
+
+use arch::JRE_ARCH;
+use manifest::JavaRuntimesManifest;
+use crate::launcher::jre::manifest::JavaRuntimeManifest;
+use super::constants;
+
+pub struct JavaRuntimeRepository {
+    home: PathBuf,
+    manifest: JavaRuntimesManifest
+}
+
+impl JavaRuntimeRepository {
+    pub async fn new(home: impl AsRef<Path>) -> Result<Self, JavaRuntimeError> {
+        info!("Java runtime architecture is \"{}\".", JRE_ARCH);
+
+        fs::create_dir_all(&home).await.map_err(|e| JavaRuntimeError::IO { what: "creating home directory", error: e })?;
+
+        let manifest: JavaRuntimesManifest = reqwest::get(constants::URL_JRE_MANIFEST).await
+            .map_err(|e| JavaRuntimeError::Download {
+                what: "runtime manifest (all.json)",
+                error: e
+            })?.json().await
+            .map_err(|e| JavaRuntimeError::Download {
+                what: "runtime manifest (all.json)",
+                error: e
+            })?;
+
+        Ok(JavaRuntimeRepository {
+            home: home.as_ref().to_path_buf(),
+            manifest
+        })
+    }
+
+    pub async fn choose_runtime(&self, component: &str) -> Result<JavaRuntimeManifest, JavaRuntimeError> {
+        let Some(runtime_components) = self.manifest.get(JRE_ARCH) else {
+            return Err(JavaRuntimeError::UnsupportedArch(JRE_ARCH));
+        };
+
+        let Some(runtime_component) = runtime_components.get(component) else {
+            return Err(JavaRuntimeError::UnsupportedComponent { arch: JRE_ARCH, component: component.to_owned() });
+        };
+
+        let Some(runtime) = runtime_component.iter().filter(|r| r.availability.progress == 100).next() else {
+            if !runtime_components.is_empty() {
+                warn!("Weird: the only java runtimes in {JRE_ARCH}.{component} has a progress of less than 100!");
+            }
+
+            return Err(JavaRuntimeError::UnsupportedComponent { arch: JRE_ARCH, component: component.to_owned() });
+        };
+
+        let Some(ref url) = runtime.manifest.url else {
+            return Err(JavaRuntimeError::MalformedManifest);
+        };
+
+        debug!("Ensuring manifest for runtime {JRE_ARCH}.{component}: {url}");
+
+
+        // hmm maybe
+
+        todo!()
+    }
+}
+
+#[derive(Debug)]
+pub enum JavaRuntimeError {
+    IO { what: &'static str, error: io::Error },
+    Download { what: &'static str, error: reqwest::Error },
+    UnsupportedArch(&'static str),
+    UnsupportedComponent { arch: &'static str, component: String },
+    MalformedManifest
+}
+
+impl Display for JavaRuntimeError {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            JavaRuntimeError::IO { what, error } => write!(f, "i/o error ({}): {}", what, error),
+            JavaRuntimeError::Download { what, error } => write!(f, "error downloading {}: {}", what, error),
+            JavaRuntimeError::UnsupportedArch(arch) => write!(f, r#"unsupported architecture "{arch}""#),
+            JavaRuntimeError::UnsupportedComponent { arch, component } => write!(f, r#"unsupported component "{component}" for architecture "{arch}""#),
+            JavaRuntimeError::MalformedManifest => f.write_str("malformed runtime manifest (launcher bug?)"),
+        }
+    }
+}
+
+impl Error for JavaRuntimeError {
+    fn source(&self) -> Option<&(dyn Error + 'static)> {
+        match self {
+            JavaRuntimeError::IO { error, .. } => Some(error),
+            JavaRuntimeError::Download { error, .. } => Some(error),
+            _ => None
+        }
+    }
+}
diff --git a/src/launcher/jre/arch.rs b/src/launcher/jre/arch.rs
new file mode 100644
index 0000000..e984171
--- /dev/null
+++ b/src/launcher/jre/arch.rs
@@ -0,0 +1,45 @@
+use cfg_if::cfg_if;
+
+macro_rules! define_arch {
+    ($arch:expr) => {
+        pub const JRE_ARCH: &str = $arch;
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_os = "windows")] {
+        cfg_if! {
+            if #[cfg(target_arch = "x86_64")] {
+                define_arch!("windows-x64");
+            } else if #[cfg(target_arch = "x86")] {
+                define_arch!("windows-x86");
+            } else if #[cfg(target_arch = "aarch64")] {
+                define_arch!("windows-arm64");
+            } else {
+                define_arch!("gamecore");
+            }
+        }
+    } else if #[cfg(target_os = "linux")] {
+        cfg_if! {
+            if #[cfg(target_arch = "x86_64")] {
+                define_arch!("linux");
+            } else if #[cfg(target_arch = "x86")] {
+                define_arch!("linux-i386");
+            } else {
+                define_arch!("gamecore");
+            }
+        }
+    } else if #[cfg(target_os = "macos")] {
+        cfg_if! {
+            if #[cfg(target_arch = "aarch64")] {
+                define_arch!("mac-os-arm64");
+            } else if #[cfg(target_arch = "x86_64")] {
+                define_arch!("mac-os");
+            } else {
+                define_arch!("gamecore");
+            }
+        }
+    } else {
+        define_arch!("gamecore");
+    }
+}
diff --git a/src/launcher/jre/manifest.rs b/src/launcher/jre/manifest.rs
new file mode 100644
index 0000000..9b84377
--- /dev/null
+++ b/src/launcher/jre/manifest.rs
@@ -0,0 +1,49 @@
+use std::collections::HashMap;
+use serde::Deserialize;
+use crate::version::DownloadInfo;
+
+#[derive(Debug, Deserialize)]
+pub struct Availability {
+    pub group: u32,   // unknown meaning
+    pub progress: u32 // unknown meaning
+}
+
+#[derive(Debug, Deserialize)]
+pub struct Version {
+    pub name: String,
+    pub version: String
+}
+
+#[derive(Debug, Deserialize)]
+pub struct JavaRuntimeInfo {
+    // I don't see how half of this information is useful with how the JRE system currently functions -figboot
+    pub availability: Availability,
+    pub manifest: DownloadInfo,
+    pub version: Version
+}
+
+pub type JavaRuntimesManifest = HashMap<String, HashMap<String, Vec<JavaRuntimeInfo>>>;
+
+#[derive(Debug, Deserialize, Clone, Copy, Eq, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum FileType {
+    File,
+    Directory,
+    Link
+}
+
+#[derive(Debug, Deserialize)]
+pub struct JavaRuntimeFile {
+    #[serde(rename = "type")]
+    pub file_type: FileType,
+    #[serde(default)]
+    pub executable: bool,
+
+    pub lzma: DownloadInfo,
+    pub raw: DownloadInfo
+}
+
+#[derive(Debug, Deserialize)]
+pub struct JavaRuntimeManifest {
+    pub files: HashMap<String, JavaRuntimeFile>
+}