Add config system to read from file (#664)

Co-authored-by: Daniel Valentine <daniel@vielle.ws>

src/config.rs

@@ -0,0 +1,130 @@
+use once_cell::sync::Lazy;
+use std::{env::var, fs::read_to_string};
+
+// Waiting for https://github.com/rust-lang/rust/issues/74465 to land, so we
+// can reduce reliance on once_cell.
+//
+// This is the local static that is initialized at runtime (technically at
+// first request) and contains the instance settings.
+static CONFIG: Lazy<Config> = Lazy::new(Config::load);
+
+/// Stores the configuration parsed from the environment variables and the
+/// config file. `Config::Default()` contains None for each setting.
+#[derive(Default, serde::Deserialize)]
+pub struct Config {
+	#[serde(rename = "LIBREDDIT_SFW_ONLY")]
+	sfw_only: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_THEME")]
+	default_theme: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_FRONT_PAGE")]
+	default_front_page: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_LAYOUT")]
+	default_layout: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_WIDE")]
+	default_wide: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_COMMENT_SORT")]
+	default_comment_sort: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_POST_SORT")]
+	default_post_sort: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_SHOW_NSFW")]
+	default_show_nsfw: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_BLUR_NSFW")]
+	default_blur_nsfw: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_USE_HLS")]
+	default_use_hls: Option<String>,
+
+	#[serde(rename = "LIBREDDIT_DEFAULT_HIDE_HLS_NOTIFICATION")]
+	default_hide_hls_notification: Option<String>,
+}
+
+impl Config {
+	/// Load the configuration from the environment variables and the config file.
+	/// In the case that there are no environment variables set and there is no
+	/// config file, this function returns a Config that contains all None values.
+	pub fn load() -> Self {
+		// Read from libreddit.toml config file. If for any reason, it fails, the
+		// default `Config` is used (all None values)
+		let config: Config = toml::from_str(&read_to_string("libreddit.toml").unwrap_or_default()).unwrap_or_default();
+		// This function defines the order of preference - first check for
+		// environment variables with "LIBREDDIT", then check the config, then if
+		// both are `None`, return a `None` via the `map_or_else` function
+		let parse = |key: &str| -> Option<String> { var(key).ok().map_or_else(|| get_setting_from_config(key, &config), Some) };
+		Self {
+			sfw_only: parse("LIBREDDIT_SFW_ONLY"),
+			default_theme: parse("LIBREDDIT_DEFAULT_THEME"),
+			default_front_page: parse("LIBREDDIT_DEFAULT_FRONT_PAGE"),
+			default_layout: parse("LIBREDDIT_DEFAULT_LAYOUT"),
+			default_post_sort: parse("LIBREDDIT_DEFAULT_POST_SORT"),
+			default_wide: parse("LIBREDDIT_DEFAULT_WIDE"),
+			default_comment_sort: parse("LIBREDDIT_DEFAULT_COMMENT_SORT"),
+			default_show_nsfw: parse("LIBREDDIT_DEFAULT_SHOW_NSFW"),
+			default_blur_nsfw: parse("LIBREDDIT_DEFAULT_BLUR_NSFW"),
+			default_use_hls: parse("LIBREDDIT_DEFAULT_USE_HLS"),
+			default_hide_hls_notification: parse("LIBREDDIT_DEFAULT_HIDE_HLS"),
+		}
+	}
+}
+
+fn get_setting_from_config(name: &str, config: &Config) -> Option<String> {
+	match name {
+		"LIBREDDIT_SFW_ONLY" => config.sfw_only.clone(),
+		"LIBREDDIT_DEFAULT_THEME" => config.default_theme.clone(),
+		"LIBREDDIT_DEFAULT_FRONT_PAGE" => config.default_front_page.clone(),
+		"LIBREDDIT_DEFAULT_LAYOUT" => config.default_layout.clone(),
+		"LIBREDDIT_DEFAULT_COMMENT_SORT" => config.default_comment_sort.clone(),
+		"LIBREDDIT_DEFAULT_POST_SORT" => config.default_post_sort.clone(),
+		"LIBREDDIT_DEFAULT_SHOW_NSFW" => config.default_show_nsfw.clone(),
+		"LIBREDDIT_DEFAULT_BLUR_NSFW" => config.default_blur_nsfw.clone(),
+		"LIBREDDIT_DEFAULT_USE_HLS" => config.default_use_hls.clone(),
+		"LIBREDDIT_DEFAULT_HIDE_HLS_NOTIFICATION" => config.default_hide_hls_notification.clone(),
+		"LIBREDDIT_DEFAULT_WIDE" => config.default_wide.clone(),
+		_ => None,
+	}
+}
+
+/// Retrieves setting from environment variable or config file.
+pub(crate) fn get_setting(name: &str) -> Option<String> {
+	get_setting_from_config(name, &CONFIG)
+}
+
+#[cfg(test)]
+use {sealed_test::prelude::*, std::fs::write};
+
+#[test]
+#[sealed_test(env = [("LIBREDDIT_SFW_ONLY", "1")])]
+fn test_env_var() {
+	assert!(crate::utils::sfw_only())
+}
+
+#[test]
+#[sealed_test]
+fn test_config() {
+	let config_to_write = r#"LIBREDDIT_DEFAULT_COMMENT_SORT = "best""#;
+	write("libreddit.toml", config_to_write).unwrap();
+	assert_eq!(get_setting("LIBREDDIT_DEFAULT_COMMENT_SORT"), Some("best".into()));
+}
+
+#[test]
+#[sealed_test(env = [("LIBREDDIT_DEFAULT_COMMENT_SORT", "top")])]
+fn test_env_config_precedence() {
+	let config_to_write = r#"LIBREDDIT_DEFAULT_COMMENT_SORT = "best""#;
+	write("libreddit.toml", config_to_write).unwrap();
+	assert_eq!(get_setting("LIBREDDIT_DEFAULT_COMMENT_SORT"), Some("top".into()))
+}
+
+#[test]
+#[sealed_test(env = [("LIBREDDIT_DEFAULT_COMMENT_SORT", "top")])]
+fn test_alt_env_config_precedence() {
+	let config_to_write = r#"LIBREDDIT_DEFAULT_COMMENT_SORT = "best""#;
+	write("libreddit.toml", config_to_write).unwrap();
+	assert_eq!(get_setting("LIBREDDIT_DEFAULT_COMMENT_SORT"), Some("top".into()))
+}

src/main.rs

@@ -3,6 +3,7 @@
 #![allow(clippy::cmp_owned)]
 
 // Reference local files
+mod config;
 mod duplicates;
 mod post;
 mod search;

src/utils.rs

@@ -680,8 +680,8 @@ pub fn setting(req: &Request<Body>, name: &str) -> String {
 	req
 		.cookie(name)
 		.unwrap_or_else(|| {
-			// If there is no cookie for this setting, try receiving a default from an environment variable
-			if let Ok(default) = std::env::var(format!("LIBREDDIT_DEFAULT_{}", name.to_uppercase())) {
+			// If there is no cookie for this setting, try receiving a default from the config
+			if let Some(default) = crate::config::get_setting(&format!("LIBREDDIT_DEFAULT_{}", name.to_uppercase())) {
 				Cookie::new(name, default)
 			} else {
 				Cookie::named(name)
@@ -866,7 +866,7 @@ pub async fn error(req: Request<Body>, msg: impl ToString) -> Result<Response<Bo
 	Ok(Response::builder().status(404).header("content-type", "text/html").body(body.into()).unwrap_or_default())
 }
 
-/// Returns true if the environment variable `LIBREDDIT_SFW_ONLY` carries the
+/// Returns true if the config/env variable `LIBREDDIT_SFW_ONLY` carries the
 /// value `on`.
 ///
 /// If this variable is set as such, the instance will operate in SFW-only
@@ -874,9 +874,9 @@ pub async fn error(req: Request<Body>, msg: impl ToString) -> Result<Response<Bo
 /// subreddits or posts or userpages for users Reddit has deemed NSFW will
 /// be denied.
 pub fn sfw_only() -> bool {
-	match env::var("LIBREDDIT_SFW_ONLY") {
-		Ok(val) => val == "on",
-		Err(_) => false,
+	match crate::config::get_setting("LIBREDDIT_SFW_ONLY") {
+		Some(val) => val == "on",
+		None => false,
 	}
 }