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use std::fs::File;
use std::io::prelude::*;
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: env::Args) -> Result<Config, &'static str> {
        // ignore the command itself
        args.next();

        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("didn't get query string")
        };
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("didn't get query string")
        };
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();

        Ok(Config{
            query: query,
            filename: filename,
            case_sensitive: case_sensitive,
        })
    }
}

pub fn run(config: Config) -> Result<(), Box<Error>> {
    let mut f = File::open(&config.filename)?;

    let mut contents = String::new();
    f.read_to_string(&mut contents)?;

    // println!("Searching for \"{}\"", &config.query);
    // println!("In file {}", &config.filename);
    // println!("\nWith text:\n{}", contents);

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

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

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
    contents.lines().filter(|line| line.contains(query)).collect()
}

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
    contents.lines().filter(|line| line.to_lowercase().contains(&query)).collect()
}

#[cfg(test)]
mod test {
    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)
        );
    }
}