lib.rs

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

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

    #[test]
    fn case_sensitive() {
        let query = "duct";
        let content = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["safe, fast, productive."], search(query, content));
    }

    #[test]
    fn case_insensitive() {
        let query = "RUST";
        let content = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["Rust:"], search_case_insensitive(query, content));
    }
}

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

impl Config {
    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, &'static str> {
        args.next();

        let query = match args.next() {
            Some(q) => q,
            None => return Err("Didn't get the query string"),
        };

        let file_path = match args.next() {
            Some(fp) => fp,
            None => return Err("Didn't get the file path"),
        };
        let ignore_case = env::var("IGNORE_CASE").is_ok();

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

// Box<dyn Error> means the function can return an object
// that implements the Error trait.
//
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, content: &'a str) -> Vec<&'a str> {
    content
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}

pub fn search_case_insensitive<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
    content
        .lines()
        .filter(|line| line.to_lowercase().contains(&query.to_lowercase()))
        .collect()
}