From b736068ee7b82e05c2ede8bc48ace7ffa4709e29 Mon Sep 17 00:00:00 2001
From: Chris Xiong <chirs241097@gmail.com>
Date: Wed, 24 Jul 2024 23:40:11 -0400
Subject: Initial commit.

---
 backend/src/config.rs | 82 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 backend/src/config.rs

(limited to 'backend/src/config.rs')

diff --git a/backend/src/config.rs b/backend/src/config.rs
new file mode 100644
index 0000000..a1085ba
--- /dev/null
+++ b/backend/src/config.rs
@@ -0,0 +1,82 @@
+use std::collections::hash_map::HashMap;
+use std::fs::File;
+use std::io::Read;
+use std::fmt::{Display, Formatter, Error};
+
+#[derive(Clone)]
+pub enum ConfigValue {
+    Str(String),
+    UInt(usize)
+}
+
+impl Display for ConfigValue {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error> {
+        match self {
+            ConfigValue::Str(s) => write!(f, "{}", s),
+            ConfigValue::UInt(u) => write!(f, "{}", u)
+        }
+    }
+}
+
+struct ConfigItem {
+    default_value: ConfigValue,
+    parse_func: Box<dyn Fn(String) -> Option<ConfigValue>>,
+}
+
+pub struct Config {
+    v: HashMap<String, ConfigValue>,
+}
+
+fn stripped_str(s: String) -> Option<ConfigValue> {
+    Some(ConfigValue::Str(String::from(s.trim())))
+}
+
+fn parse_usize(s: String) -> Option<ConfigValue> {
+    if let Ok(r) = usize::from_str_radix(&s, 10) {
+        Some(ConfigValue::UInt(r))
+    } else { None }
+}
+
+pub fn split_at_first<'a, 'b>(s: &'a str, sp: &'b str) -> (&'a str, &'a str) {
+    if let Some(p) = s.find(sp) {
+        (&s[.. p], &s[p + sp.len()..])
+    } else { (s, "") }
+}
+
+impl Config {
+    fn items() -> HashMap<&'static str, ConfigItem> {
+        HashMap::from([
+            ("SERVED_DATA_ROOT", ConfigItem{default_value: ConfigValue::Str(String::from("")), parse_func: Box::new(stripped_str)}),
+            ("POSTS_PER_PAGE", ConfigItem{default_value: ConfigValue::UInt(20), parse_func: Box::new(parse_usize)}),
+            ("DISPLAY_TIMEZONE", ConfigItem{default_value: ConfigValue::Str(String::from("UTC")), parse_func: Box::new(stripped_str)}),
+            ("VERSION_STRING", ConfigItem{default_value: ConfigValue::Str(String::from("1.0")), parse_func: Box::new(stripped_str)}),
+        ])
+    }
+    pub fn parse_config(filename: &str) -> Config {
+        let mut v = HashMap::from_iter(
+            Config::items().iter()
+            .map(|(k, v)| {(String::from(*k), v.default_value.clone())})
+        );
+        let mut f = File::open(filename).unwrap();
+        let mut s = String::new();
+        if let Ok(_) = f.read_to_string(&mut s) {
+            for l in s.split("\n") {
+                let (sname, svalue) = split_at_first(l, "=");
+                if let Some(ConfigItem{default_value: _, parse_func}) = Config::items().get(sname) {
+                    if let Some(value) = parse_func(String::from(svalue)) {
+                        v.insert(String::from(sname), value);
+                    }
+                }
+            }
+        }
+        Config { v }
+    }
+    pub fn get(&self, key: &str) -> ConfigValue {
+        self.v.get(&String::from(key)).unwrap().clone()
+    }
+    pub fn get_str(&self, key: &str) -> String {
+        if let ConfigValue::Str(s) = self.get(key) {
+            s
+        } else { String::from("") }
+    }
+}
-- 
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