#![allow(unused_variables)]
use std::env;
use std::error::Error;
use std::fs;

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,
        })
    }
}

/// Execute search with the given patern
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(())
}

/// Search a string in the text (case sensitive).
///
/// # Example
///
/// ```
/// let text = r#"I'm nobody! Who are you?
/// Are you nobody, too?
/// Then there's a pair of us - don't tell!
/// They'd banish us, you know.
///
/// How dreary to be somebody!
/// How public, like a frog
/// To tell your name the livelong day
/// To an admiring bog!
/// "#;
///
/// for line in search_case_insensitive("fro", text) {
///     println!("{}", line);
/// }
/// ```
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents.lines().filter(|l| l.contains(query)).collect()
}

/// Search a string in the text (case insensitive).
///
/// # Example
///
/// ```
/// let text = r#"I'm nobody! Who are you?
/// Are you nobody, too?
/// Then there's a pair of us - don't tell!
/// They'd banish us, you know.
///
/// How dreary to be somebody!
/// How public, like a frog
/// To tell your name the livelong day
/// To an admiring bog!
/// "#;
///
/// for line in search_case_insensitive("FrO", text) {
///     println!("{}", line);
/// }
/// ```
pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();
    contents
        .lines()
        .filter(|l| l.to_lowercase().contains(&query))
        .collect()
}