clifton_minigrep 0.1.0

//! # minigrep
//!
//! minigrep is a utility for searching text files, like grep!
//!
//! ## options
//!
//! use `CASE_INSENSITIVE=1 minigrep` for case insensitive matching

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

pub struct Config {
    pub query: String,
    pub filename: String,
    pub case_sensitive: bool,
}

impl Config {
    pub fn new(mut args: std::env::Args) -> Result<Config, &'static str> {
        args.next();
        let query = match args.next() {
            Some(query) => query,
            None => return Err("didn't get a query string!"),
        };
        let filename = match args.next() {
            Some(filename) => filename,
            None => return Err("didn't get a filename"),
        };
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        Ok(Config {
            query,
            filename,
            case_sensitive,
        })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(&config.filename)?;
    for line in search(&config, &contents) {
        println!("{}", line);
    }
    Ok(())
}

fn search<'a>(config: &Config, contents: &'a str) -> Vec<&'a str> {
    let query = if config.case_sensitive {
        config.query.clone()
    } else {
        config.query.to_lowercase()
    };
    contents
        .lines()
        .filter(|line| {
            if config.case_sensitive {
                line.contains(&query)
            } else {
                line.to_lowercase().contains(&query)
            }
        })
        .collect()
}

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

    #[test]
    fn case_sensitive() {
        let query = String::from("duct");
        let filename = String::from("unused");
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape";
        let config = Config {
            query,
            filename,
            case_sensitive: true,
        };

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

    #[test]
    fn case_insensitive() {
        let query = String::from("RuSt");
        let filename = String::from("unused");
        let contents = "\
Rust:
safe, fast, productive.
Pick three
Trust me";
        let config = Config {
            query,
            filename,
            case_sensitive: false,
        };

        assert_eq!(vec!["Rust:", "Trust me"], search(&config, contents));
    }
}