1 files changed, 123 insertions, 0 deletions

diff --git a/src/readline.rs b/src/readline.rs
new file mode 100644
index 0000000..d689f95
--- /dev/null
+++ b/src/readline.rs
@@ -0,0 +1,123 @@
+use std::borrow::Cow::{self, Owned};
+use std::path::PathBuf;
+
+use rustyline::completion::{Completer, FilenameCompleter, Pair};
+use rustyline::config::{Builder, ColorMode, CompletionType, EditMode};
+use rustyline::error::ReadlineError;
+use rustyline::highlight::Highlighter;
+use rustyline::hint::{Hinter, HistoryHinter};
+use rustyline::{Context, Editor, Helper};
+
+use directories::ProjectDirs;
+
+use regex::Regex;
+
+use crate::error::CalcError;
+use crate::eval_math_expression;
+
+pub struct RLHelper {
+    completer: FilenameCompleter,
+    highlighter: LineHighlighter,
+    hinter: HistoryHinter,
+}
+
+struct LineHighlighter {}
+impl Highlighter for LineHighlighter {
+    fn highlight_hint<'h>(&self, hint: &'h str) -> Cow<'h, str> {
+        Owned(format!("\x1b[90m{}\x1b[0m", hint))
+    }
+    fn highlight<'l>(&self, line: &'l str, _: usize) -> Cow<'l, str> {
+        use std::fs::OpenOptions;
+        use std::io::{BufRead, BufReader};
+
+        let eva_dirs = ProjectDirs::from("com", "NerdyPepper", "eva").unwrap();
+        let eva_data_dir = eva_dirs.data_dir();
+        let mut previous_ans_path = PathBuf::from(eva_data_dir);
+        previous_ans_path.push("previous_ans.txt");
+
+        let file = OpenOptions::new()
+            .create(true)
+            .read(true)
+            .append(true)
+            .open(&previous_ans_path)
+            .unwrap();
+
+        let rdr = BufReader::new(file);
+        let lines = rdr.lines().map(|l| l.unwrap());
+        let prev_ans = match lines.last() {
+            Some(val) => val.parse::<f64>().ok(),
+            None => None,
+        };
+        let op = eval_math_expression(line, prev_ans);
+        match op {
+            Ok(_) => {
+                let constants = ["e", "pi"];
+                let functions = [
+                    "sin", "cos", "tan", "csc", "sec", "cot", "sinh", "cosh", "tanh", "ln", "log",
+                    "sqrt", "ceil", "floor", "rad", "deg", "abs", "asin", "acos", "atan", "acsc",
+                    "asec", "acot",
+                ];
+                let ops = Regex::new(r"(?P<o>[\+-/\*%\^!])").unwrap();
+                let mut coloured: String = ops.replace_all(line, "\x1b[35m$o\x1b[0m").into();
+
+                for c in &constants {
+                    coloured = coloured.replace(c, &format!("\x1b[33m{}\x1b[0m", c));
+                }
+                for f in &functions {
+                    coloured = coloured.replace(f, &format!("\x1b[34m{}\x1b[0m", f));
+                }
+                Owned(coloured)
+            }
+            Err(CalcError::Help) => Owned(line.replace("help", "\x1b[36mhelp\x1b[0m")),
+            Err(_) => Owned(format!("\x1b[31m{}\x1b[0m", line)),
+        }
+    }
+}
+
+impl Highlighter for RLHelper {
+    fn highlight_hint<'h>(&self, hint: &'h str) -> Cow<'h, str> {
+        self.highlighter.highlight_hint(hint)
+    }
+    fn highlight<'l>(&self, line: &'l str, pos: usize) -> Cow<'l, str> {
+        self.highlighter.highlight(line, pos)
+    }
+}
+
+impl Completer for RLHelper {
+    type Candidate = Pair;
+    fn complete(
+        &self,
+        line: &str,
+        pos: usize,
+        ctx: &Context<'_>,
+    ) -> Result<(usize, Vec<Pair>), ReadlineError> {
+        self.completer.complete(line, pos, ctx)
+    }
+}
+
+impl Hinter for RLHelper {
+    fn hint(&self, line: &str, a: usize, b: &Context) -> Option<String> {
+        self.hinter.hint(line, a, b)
+    }
+}
+
+impl Helper for RLHelper {}
+
+pub fn create_readline() -> Editor<RLHelper> {
+    let config_builder = Builder::new();
+    let config = config_builder
+        .color_mode(ColorMode::Enabled)
+        .edit_mode(EditMode::Emacs)
+        .history_ignore_space(true)
+        .completion_type(CompletionType::Circular)
+        .max_history_size(1000)
+        .build();
+    let mut rl = Editor::with_config(config);
+    let h = RLHelper {
+        completer: FilenameCompleter::new(),
+        highlighter: LineHighlighter {},
+        hinter: HistoryHinter {},
+    };
+    rl.set_helper(Some(h));
+    rl
+}