Use readers/writers more extensively.

src/habitmgr.rs

@@ -17,15 +17,14 @@
  */
 
 use std::path::PathBuf;
-use std::fs::{File, OpenOptions};
-use std::io::{BufReader, BufRead, Write};
+use std::fs::OpenOptions;
+use std::io::{BufReader, BufWriter};
 
 use crate::habit::Habit;
 
 pub struct HabitMgr
 {
 	habits:Vec<Habit>,
-	//data_dir:PathBuf,
 	habits_path:PathBuf,
 }
 
@@ -34,56 +33,65 @@ impl HabitMgr
 	pub fn new(data_dir:&PathBuf) -> Self
 	{
 		let habits_path:PathBuf = data_dir.clone().join("active_habits.json");
+		/*
+		 * There may be a way of simplifying this, but the idea is that if we try
+		 * to read the file without any JSON code in it then we'll get an error.
+		 * This code avoids said error.
+		 */
 		if !habits_path.is_file()
 		{
-			File::create(&habits_path)
+			println!("First launch: creating files.");
+			let habits_file = OpenOptions::new()
+				.create(true)
+				.write(true)
+				.open(&habits_path)
 				.unwrap_or_else(|e| {
 					panic!("Error creating file {}:\n{}",
 								 habits_path.display(), e);
 				});
+			let habit_writer = BufWriter::new(&habits_file);
+			serde_json::to_writer(habit_writer, &Vec::<Habit>::new())
+				.unwrap_or_else(|e| {
+					panic!("Error writing to file {}:\n{}",
+								 habits_path.display(), e);
+				});
 		}
 		Self
 		{
 			habits: Vec::new(),
-			//data_dir: data_dir.clone(),
 			habits_path,
 		}
 	}
 
 	fn import_habits(&mut self)
 	{
-		let habits_file = File::open(&self.habits_path)
+		let habits_file = OpenOptions::new()
+			.read(true)
+			.open(&self.habits_path)
 			.unwrap_or_else(|e| {
 				panic!("Error opening file {}:\n{}", self.habits_path.display(), e);
 			});
-		let reader = BufReader::new(&habits_file);
-		// TODO: figure out a way to do this with from_reader() instead to simplify
-		//habits = serde_json::from_reader(reader).unwrap();
-
-		for (_i, line) in reader.lines().enumerate()
-		{
-			let habit:Habit = serde_json::from_str(line.unwrap().as_str()).unwrap();
-			self.habits.push(habit);
-		}
+		let habits_reader = BufReader::new(&habits_file);
+		self.habits = serde_json::from_reader(habits_reader).unwrap();
 	}
 
 	pub fn add(&mut self, name:String, bad:bool, weight:u8, _days:String)
 	{
-		// TODO: Refractor so perhaps we import habits first and then export them
-		let mut habits_file = OpenOptions::new()
-			.append(true)
+		self.import_habits();
+		let habits_file = OpenOptions::new()
+			.truncate(true)
+			.write(true)
 			.open(&self.habits_path)
 			.unwrap_or_else(|e| {
 				panic!("Error opening file {}:\n{}", self.habits_path.display(), e);
 			});
 
-		let habit = Habit::new(name.clone(), bad, weight);
-		let mut habit_string = serde_json::to_string(&habit).unwrap();
-		habit_string.push_str("\n");
-		habits_file.write_all(habit_string.as_bytes())
+		self.habits.push(Habit::new(name.clone(), bad, weight));
+		let habits_writer = BufWriter::new(habits_file);
+		serde_json::to_writer(habits_writer, &self.habits)
 			.unwrap_or_else(|e| {
-				panic!("Error writing to file {}:\n{}",
-							 self.habits_path.display(), e);
+					panic!("Error writing to file {}:\n{}",
+								 self.habits_path.display(), e);
 			});
 
 		println!("New habit {} added.", &name);