use std::error::Error;
use std::fs;
use std::env;
use std::env::Args;
pub struct Config {
    pub query: String,
    pub filename: String,
    pub case_sensitive: bool,
}

/// # config
/// ```
/// config::new
impl Config {
    pub fn new(mut args: Args) -> Result<Config, &'static str> {
        args.next();
        let query = match args.next() {
            Some(e) => e,
            None => return Err("Didn't get a query string")
        };
        let filename = match args.next() {
            Some(e) => e,
            None => return Err("Did't get a file name")
        };
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        Ok(Config {query, filename, case_sensitive})
    }
}

pub fn run(config: &Config) -> Result<(), Box<Error>> {
    let content = fs::read_to_string(&config.filename)?;
    let results;
    if config.case_sensitive {
        results = search(&config.query, &content);
    } else {
        results = search_case_sensitive(&config.query, &content);
    }
    for line in results {
        println!("{}", line);
    }
    Ok(())
}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents.lines()
        .filter(|x| x.contains(query))
        .collect()
}

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

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

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

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