use std::fs;
//use std::fs::File;
//use std::io::prelude::*;
use std::error::Error;
use std::env;

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

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

    let results = if conf.insensitive {
        search(&conf.query, &contents)
    } else {
        search_insensitive(&conf.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
}

fn search_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
}

impl Config {
    pub fn new(args: &[String]) -> Result<Config, &'static str> {
        if args.len() < 3 {
            return Err("too few arguments")
        }

        Ok(Config {
            query: args[1].clone(),
            filename: args[2].clone(),
            insensitive: env::var("CASE_INSENSITIVE").is_err(),
        })
    }
}

#[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_insensitive(query, contents)
        );
    }
}