history is now separated from ps.rs, create valid_pbuf.rs to be used across different modules

src/history.rs

@@ -0,0 +1,48 @@
+use std::{fs::{File, OpenOptions}, io::{BufRead, BufReader, Write}, path::PathBuf};
+
+use crate::{rc::{self}, shell_error, valid_pbuf::IsValid, MapDisplay};
+
+pub struct History {
+	history_file: PathBuf,
+	checked_empty: bool
+}
+impl History {
+	pub fn init() -> Option<Self> {
+		rc::config_dir().map(|mut config| {
+			config.push(".history");
+			config.is_valid_file_or_create(b"");
+			Self {
+				history_file: config,
+				checked_empty: false
+			}
+		})
+	}
+
+	pub fn is_empty(&mut self) -> bool {
+		match self.checked_empty {
+			true => true,
+			false => self.read().map_or(false, |history_l| {
+				self.checked_empty = true;
+				history_l.is_empty()
+			})
+		}
+	}
+
+	pub fn write<S: AsRef<str>>(&mut self, content: S) {
+		OpenOptions::new().append(true).open(self.history_file.as_path()).map_or_display(|mut file| {
+			let write_data = match self.is_empty() {
+			    true => content.as_ref().to_owned(),
+			    false => format!("\n{}", content.as_ref()),
+			};
+			if let Err(write_err) = file.write_all(write_data.as_bytes()) {
+				shell_error(write_err);
+			};
+		});
+	}
+
+	pub fn read(&self) -> Option<Vec<String>> {
+		File::open(&self.history_file).map_or_display_none(|file| {
+			Some(BufReader::new(file).lines().map_while(Result::ok).collect::<Vec<String>>())
+		})
+	}
+}