//! # Minigrep
//!
//! A library mimic `grep` utility

pub use self::config::Config;
pub use self::utilities::run;
pub use self::utilities::search;
pub use self::utilities::search_case_insensitive;

pub mod config {
    use std::env;

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

    impl Config {
        /// Create Config struct from command line arguments
        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("Did not get a query string")
            };
            let filename = match args.next() {
                Some(arg) => arg,
                None => return Err("Did not get a file name")
            };

            let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
            Ok(Config { query, filename, case_sensitive })
        }
    }
}

pub mod utilities {
    use std::error::Error;
    use std::fs;

    use super::Config;

    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(())
    }

    /// Find all lines that match `query`
    ///
    /// # Example
    /// ```
    /// use minigrep_tutorial::search;
    /// let query = "duct";
    /// let contents = "\nRust:\nsafe, fast, productive.\nPick three";
    /// 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()
    }

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

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

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

    #[test]
    fn case_insensitive() {
        let query = "rUsT";
        let contents = "Rust:\nsafe, fast\nTrust me!";
        assert_eq!(vec!["Rust:", "Trust me!"], search_case_insensitive(query, contents))
    }
}