Implement Rust-based emote database and REST API

src/config.rs

@@ -0,0 +1,72 @@
+use config::{Config, ConfigError, Environment, File};
+use serde::Deserialize;
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct S3Config {
+    pub endpoint: String,
+    pub region: String,
+    pub bucket: String,
+    pub access_key: String,
+    pub secret_key: String,
+    /// Public base URL used to build emote image URLs returned in API responses.
+    /// Example: "https://s3.eu-central-1.wasabisys.com/open3dlab-emoji"
+    pub public_url: String,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct DatabaseConfig {
+    /// Database URL.
+    /// SQLite example:  "sqlite://mikebase.db"
+    /// PostgreSQL example: "postgresql://user:pass@localhost/mikebase"
+    pub url: String,
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct ServerConfig {
+    #[serde(default = "default_host")]
+    pub host: String,
+    #[serde(default = "default_port")]
+    pub port: u16,
+}
+
+fn default_host() -> String {
+    "0.0.0.0".to_string()
+}
+
+fn default_port() -> u16 {
+    3000
+}
+
+#[derive(Debug, Deserialize, Clone)]
+pub struct AppConfig {
+    pub s3: S3Config,
+    pub database: DatabaseConfig,
+    #[serde(default)]
+    pub server: ServerConfig,
+}
+
+impl Default for ServerConfig {
+    fn default() -> Self {
+        Self {
+            host: default_host(),
+            port: default_port(),
+        }
+    }
+}
+
+impl AppConfig {
+    pub fn load() -> Result<Self, ConfigError> {
+        let cfg = Config::builder()
+            // Optional config file (config.toml)
+            .add_source(File::with_name("config").required(false))
+            // Environment variables with prefix APP (e.g. APP__S3__BUCKET)
+            .add_source(
+                Environment::with_prefix("APP")
+                    .separator("__")
+                    .try_parsing(true),
+            )
+            .build()?;
+
+        cfg.try_deserialize()
+    }
+}