perf: Cache environment variables at startup

5 files changed, 85 insertions, 56 deletions

diff --git a/src/environment.rs b/src/environment.rs
new file mode 100644
index 0000000..dd10171
--- /dev/null
+++ b/src/environment.rs
@@ -0,0 +1,56 @@
+use std::sync::LazyLock;
+
+pub static ENVIRONMENT: LazyLock<Environment> =
+  LazyLock::new(Environment::from_environment);
+
+pub struct Environment {
+  pub root:                       String,
+  pub css_external:               Option<String>,
+  pub primary_colour:             Option<String>,
+  pub favicon_external:           Option<String>,
+  pub mathjax:                    bool,
+  pub head:                       Option<String>,
+  pub header:                     Option<String>,
+  pub plain_text_route:           Option<String>,
+  pub condense_links:             Vec<String>,
+  pub condense_links_at_headings: Vec<String>,
+  pub proxy_by_default:           bool,
+  pub keep_gemini:                Option<Vec<String>>,
+  pub embed_images:               Option<String>,
+}
+
+impl Environment {
+  fn from_environment() -> Self {
+    Self {
+      root:                       std::env::var("ROOT").unwrap_or_else(|_| {
+        log::warn!(
+          "could not use ROOT from environment variables, proceeding with \
+           default root: gemini://fuwn.me"
+        );
+        "gemini://fuwn.me".to_string()
+      }),
+      css_external:               std::env::var("CSS_EXTERNAL").ok(),
+      primary_colour:             std::env::var("PRIMARY_COLOUR").ok(),
+      favicon_external:           std::env::var("FAVICON_EXTERNAL").ok(),
+      mathjax:                    std::env::var("MATHJAX")
+        .map(|v| v.to_lowercase() == "true")
+        .unwrap_or(true),
+      head:                       std::env::var("HEAD").ok(),
+      header:                     std::env::var("HEADER").ok(),
+      plain_text_route:           std::env::var("PLAIN_TEXT_ROUTE").ok(),
+      condense_links:             std::env::var("CONDENSE_LINKS")
+        .map(|s| s.split(',').map(String::from).collect())
+        .unwrap_or_default(),
+      condense_links_at_headings: std::env::var("CONDENSE_LINKS_AT_HEADINGS")
+        .map(|s| s.split(',').map(String::from).collect())
+        .unwrap_or_default(),
+      proxy_by_default:           std::env::var("PROXY_BY_DEFAULT")
+        .map(|v| v.to_lowercase() == "true")
+        .unwrap_or(true),
+      keep_gemini:                std::env::var("KEEP_GEMINI")
+        .ok()
+        .map(|s| s.split(',').map(String::from).collect()),
+      embed_images:               std::env::var("EMBED_IMAGES").ok(),
+    }
+  }
+}
diff --git a/src/html.rs b/src/html.rs
index ae79489..11ad698 100644
--- a/src/html.rs
+++ b/src/html.rs
@@ -1,7 +1,7 @@
 use {
-  crate::url::matches_pattern,
+  crate::{environment::ENVIRONMENT, url::matches_pattern},
   germ::ast::Node,
-  std::{env::var, fmt::Write},
+  std::fmt::Write,
   url::Url,
 };
 
@@ -47,26 +47,14 @@ pub fn from_gemini(
   let mut title = String::new();
   let mut previous_link = false;
   let mut previous_link_count = 0;
-  let condense_links = {
-    let links = var("CONDENSE_LINKS").map_or_else(
-      |_| vec![],
-      |condense_links| {
-        condense_links
-          .split(',')
-          .map(std::string::ToString::to_string)
-          .collect()
-      },
-    );
-
-    links.contains(&url.path().to_string()) || links.contains(&"*".to_string())
-  };
-  let condensible_headings_value =
-    var("CONDENSE_LINKS_AT_HEADINGS").unwrap_or_default();
-  let condensible_headings = if condensible_headings_value.is_empty() {
-    vec![]
-  } else {
-    condensible_headings_value.split(',').collect::<Vec<_>>()
-  };
+  let condense_links =
+    ENVIRONMENT.condense_links.contains(&url.path().to_string())
+      || ENVIRONMENT.condense_links.contains(&"*".to_string());
+  let condensible_headings = ENVIRONMENT
+    .condense_links_at_headings
+    .iter()
+    .map(String::as_str)
+    .collect::<Vec<_>>();
   let mut in_condense_links_flag_trap = !condensible_headings.is_empty();
 
   for node in ast {
@@ -154,10 +142,7 @@ pub fn from_gemini(
           href = link_from_host_href(url, &href)?;
         }
 
-        if var("PROXY_BY_DEFAULT")
-          .unwrap_or_else(|_| "true".to_string())
-          .to_lowercase()
-          == "true"
+        if ENVIRONMENT.proxy_by_default
           && href.contains("gemini://")
           && !surface
         {
@@ -190,9 +175,7 @@ pub fn from_gemini(
           }
         }
 
-        if let Ok(keeps) = var("KEEP_GEMINI") {
-          let patterns = keeps.split(',').collect::<Vec<_>>();
-
+        if let Some(patterns) = &ENVIRONMENT.keep_gemini {
           if (href.starts_with('/') || !href.contains("://")) && !surface {
             let temporary_href = link_from_host_href(url, &href)?;
             let should_exclude = patterns
@@ -213,7 +196,7 @@ pub fn from_gemini(
           }
         }
 
-        if let Ok(embed_images) = var("EMBED_IMAGES") {
+        if let Some(embed_images) = &ENVIRONMENT.embed_images {
           if let Some(extension) = std::path::Path::new(&href).extension() {
             if extension == "png"
               || extension == "jpg"
diff --git a/src/main.rs b/src/main.rs
index 56402c9..a39e83e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,6 +10,7 @@
 #![recursion_limit = "128"]
 #![allow(clippy::cast_precision_loss)]
 
+mod environment;
 mod html;
 mod response;
 mod url;
diff --git a/src/response.rs b/src/response.rs
index 68c1690..5a3f204 100644
--- a/src/response.rs
+++ b/src/response.rs
@@ -1,9 +1,12 @@
 pub mod configuration;
 
 use {
-  crate::url::{from_path as url_from_path, matches_pattern},
+  crate::{
+    environment::ENVIRONMENT,
+    url::{from_path as url_from_path, matches_pattern},
+  },
   actix_web::{Error, HttpResponse},
-  std::{env::var, fmt::Write, time::Instant},
+  std::{fmt::Write, time::Instant},
 };
 
 const CSS: &str = include_str!("../default.css");
@@ -142,11 +145,8 @@ pub async fn default(
     );
   }
 
-  if let Ok(css) = var("CSS_EXTERNAL") {
-    let stylesheets =
-      css.split(',').filter(|s| !s.is_empty()).collect::<Vec<_>>();
-
-    for stylesheet in stylesheets {
+  if let Some(css) = &ENVIRONMENT.css_external {
+    for stylesheet in css.split(',').filter(|s| !s.is_empty()) {
       let _ = write!(
         &mut html_context,
         "<link rel=\"stylesheet\" type=\"text/css\" href=\"{stylesheet}\">",
@@ -158,7 +158,7 @@ pub async fn default(
       r#"<link rel="stylesheet" href="https://latex.vercel.app/style.css"><style>{CSS}</style>"#
     );
 
-    if let Ok(primary) = var("PRIMARY_COLOUR") {
+    if let Some(primary) = &ENVIRONMENT.primary_colour {
       let _ = write!(
         &mut html_context,
         "<style>:root {{ --primary: {primary} }}</style>"
@@ -171,16 +171,14 @@ pub async fn default(
     }
   }
 
-  if let Ok(favicon) = var("FAVICON_EXTERNAL") {
+  if let Some(favicon) = &ENVIRONMENT.favicon_external {
     let _ = write!(
       &mut html_context,
       "<link rel=\"icon\" type=\"image/x-icon\" href=\"{favicon}\">",
     );
   }
 
-  if var("MATHJAX").unwrap_or_else(|_| "true".to_string()).to_lowercase()
-    == "true"
-  {
+  if ENVIRONMENT.mathjax {
     html_context.push_str(
       r#"<script type="text/javascript" id="MathJax-script" async
         src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js">
@@ -188,15 +186,15 @@ pub async fn default(
     );
   }
 
-  if let Ok(head) = var("HEAD") {
-    html_context.push_str(&head);
+  if let Some(head) = &ENVIRONMENT.head {
+    html_context.push_str(head);
   }
 
   let _ = write!(&mut html_context, "<title>{gemini_title}</title>");
   let _ = write!(&mut html_context, "</head><body>");
 
   if !http_request.path().starts_with("/proxy") {
-    if let Ok(header) = var("HEADER") {
+    if let Some(header) = &ENVIRONMENT.header {
       let _ = write!(
         &mut html_context,
         "<big><blockquote>{header}</blockquote></big>"
@@ -260,7 +258,7 @@ pub async fn default(
     env!("VERGEN_GIT_SHA").get(0..5).unwrap_or("UNKNOWN"),
   );
 
-  if let Ok(plain_texts) = var("PLAIN_TEXT_ROUTE") {
+  if let Some(plain_texts) = &ENVIRONMENT.plain_text_route {
     if plain_texts.split(',').any(|r| {
       matches_pattern(r, http_request.path())
         || matches_pattern(r, http_request.path().trim_end_matches('/'))
diff --git a/src/url.rs b/src/url.rs
index 56858e6..0c95eb0 100644
--- a/src/url.rs
+++ b/src/url.rs
@@ -42,16 +42,7 @@ pub fn from_path(
   } else {
     format!(
       "{}{}{}",
-      {
-        std::env::var("ROOT").unwrap_or_else(|_| {
-          warn!(
-            "could not use ROOT from environment variables, proceeding with \
-             default root: gemini://fuwn.me"
-          );
-
-          "gemini://fuwn.me".to_string()
-        })
-      },
+      &crate::environment::ENVIRONMENT.root,
       path,
       if fallback { "/" } else { "" }
     )