feat: Quest loading

- Added config::Config::load_quests()
- Added quest::error::QuestError error type
- Updated documentation

src/quest/mod.rs

@@ -1,6 +1,11 @@
-//! Module for handling text-based quests and user answers
+//! Text-based quests and user solutions for them
+
+pub mod error;
+
+use std::path::PathBuf;
 
 use serde::{ Serialize, Deserialize };
+use error::QuestError;
 
 /// Difficulty of the quest
 #[derive(Serialize, Deserialize)]
@@ -60,3 +65,18 @@ pub struct Quest {
     #[serde(default = "default_answer")]
     pub answer: String,
 }
+
+impl Quest {
+    /// Parse quest TOML or return error
+    pub fn load(path: PathBuf) -> Result<Self, QuestError> {
+        match std::fs::read_to_string(path) {
+            Ok(string) => {
+                match toml::from_str::<Quest>(&string) {
+                    Ok(quest) => Ok(quest),
+                    Err(error) => Err(QuestError::TomlError(error))
+                }
+            },
+            Err(error) => Err(QuestError::IoError(error))
+        }
+    }
+}