src/lib.rs

use std::fs; 
use std::env;
use std::error::Error;

pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool,
}

impl Config {
    pub fn build(args: &[String]) -> Result<Config, &'static str>  {
         if args.len() < 3 {
            return Err("not enough arguments");
        }

        let query = args[1].clone();
        let file_path = args[2].clone();

        let ignore_case = env::var("IGNORE_CASE").is_ok();

        Ok(Config { query, file_path, ignore_case })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.file_path)?;

    let results = if config.ignore_case {
      search_case_insensitive(&config.query, &contents)
    } else {
      search(&config.query, &contents)
    };



    for line in results {
      println!("{line}");
    }

    Ok(())

}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let mut results = Vec::new();

    for line in contents.lines() {
      if line.contains(query) {
            results.push(line);
      }
    }

    results

}

pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
  let query = query.to_lowercase();
  let mut results = Vec::new();

  for line in contents.lines() {
    if line.to_lowercase().contains(&query) {
      results.push(line);
    }
  }

  results

}


#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn case_sensitive() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape.";

        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }


    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";

        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        );
    }

}