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//! This is the amazing Minigrep that's going to take the world by storm

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

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(arg) => arg,
            None => return Err("Didn't get a query string")
        };
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a file name")
        };

        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();

        Ok(Config {
            query,
            filename,
            case_sensitive
        })
    }
}
///This function is the primary runner for Minigrep, which receives a Config object to know what to do
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

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

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

    Ok(())
}

///This function searches for a string in a given string
/// # Examples
///
/// ```
/// let query = "duct";
/// let contents = "\
/// Rust:
/// safe, fast, productive.
/// Pick three.
/// Duct tape.";
/// 
/// assert_eq!(vec!["safe, fast, productive."], search(query,contents));
/// ```
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
}

///This function searches for a string in a given string, without regard to the case of either
/// # Examples
///
/// ```
/// let query = "duct";
/// let contents = "\
/// Rust:
/// safe, fast, productive.
/// Pick three.
/// Duct tape.";
/// 
/// assert_eq!(vec!["safe, fast, productive."], search(query,contents));
/// ```
pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();
    contents
        .lines()
        .filter(|line| line.to_lowercase().contains(&query))
        .collect()
}







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

    #[test]
    fn one_result() {
        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));
    }
}