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//! # Minigrep
//!
//! `minigrep` is based on a grep tutorial in the rust book.

use std::error::Error;
use std::fs;
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 })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)
        .expect("Something went wrong with reading the file");

    let results = match config.case_sensitive {
        true => search(&config.query, &contents),
        false => search_case_insensitive(&config.query, &contents),
    };

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

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.to_lowercase()
                )
            )
        .collect()
}

/// Finds string `query` in multi-line string `contents`, then returns an array of matches.
///
/// # Examples
/// ```
/// let query = "foo";
/// let contents = "foo\nbar\nfoobar";
/// let res = search(query, contents);
/// assert_eq!(res, ["foo", "foobar"]);
/// ```
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents.lines()
        .filter(|line| line.contains(query))
        .collect()
}



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

    #[test]
    fn one_result(){
        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 = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";

        assert_eq!(
            vec!["Rust:", "Trust me."],
            search_case_insensitive(query, contents)
        );
    }
}