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//! # Minigrep
//! 
//! `minigrep`is a mock reimplementation of grep


use std::{ fs, error::Error, env };


pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

    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(())
}  

#[derive(Debug)]
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> {
        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 query string"),
        };
    
        let case_sensitive = env::var("CASE_INSENSITIVE").is_err();

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

/// Search func
/// 
/// # Examples
/// 
/// ```
/// use minigrep::search;
/// let query = "duct";
/// let contents = "\
/// Rust:
/// safe, fast, productive. 
/// Pick 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))
        .map(|line| line.trim())
        .collect()
}

pub 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.trim());
        }
    }

    results
}

#[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 = "rUst";
        let contents = "\
            Rust:
            safe, fast, productive.
            Pick three.
            Trust me.";

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