smolgrep/src/parser.rs

use std::{
    fs::File,
    io::{BufRead, BufReader},
};

use anyhow::Context;
use regex::Regex;

use crate::matches::{self, Match, Matches};

pub fn read_lines(
    file_path: &str,
) -> anyhow::Result<impl Iterator<Item = std::io::Result<String>>, anyhow::Error> {
    if file_path.is_empty() {
        return Err(anyhow::anyhow!("File path cannot be empty"));
    }

    let file =
        File::open(file_path).with_context(|| format!("failed to open file: {file_path}"))?;
    let reader = BufReader::new(file);

    Ok(reader.lines())
}

fn get_file_name_from_path(file_path: &str) -> String {
    match file_path.rsplit('/').next() {
        Some(name) => name.into(),
        None => file_path.into(),
    }
}

pub fn match_pattern(
    iter: impl Iterator<Item = std::io::Result<String>>,
    pattern: &str,
    file_path: &str,
) -> anyhow::Result<Matches, anyhow::Error> {
    let reg = Regex::new(pattern).with_context(|| format!("invalid regex: {:?}", pattern))?;
    let mut matches = Vec::new();

    for (idx, line) in iter.enumerate() {
        let line = line?;

        if reg.is_match(&line) {
            let m = Match {
                line_number: idx,
                text: line,
                file_name: get_file_name_from_path(file_path),
            };

            matches.push(m);
        }
    }

    Ok(Matches { items: matches, pattern: String::from(pattern) })
}