//! minigrep
//! search for string in a file
//!

use std::env;
use std::error::Error;
use std::fs;

#[derive(Debug)]
pub struct Config {
    pub filename: String,
    pub query: 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(query) => query,
            None => return Err("missing query"),
        };
        let filename = match args.next() {
            Some(v) => v,
            None => return Err("missing filename"),
        };
        let is_case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        Ok(Config {
            query: query,
            filename: filename,
            case_sensitive: is_case_sensitive,
        })
    }
}

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

    let matches = if config.case_sensitive {
        search(&config.query, &content)
    } else {
        search_case_insensitive(&config.query, &content)
    };

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

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

/// search case insensitive
///
/// # Example
///
/// ```
/// let query = "safe";
/// let content = "\n
/// Rust:
/// safe, fast, productive.
/// Pick three.";
/// let expected = vec!["safe, fast, productive."];
/// assert_eq!(expected, minigrep::search_case_insensitive(query,content));
/// ```
pub fn search_case_insensitive<'a>(query: &str, content: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();
    content
        .lines()
        .filter(|line| line.to_lowercase().contains(&query))
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;
    #[test]
    fn case_sensitive() {
        let query = "duct";
        let content = "\n
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["safe, fast, productive."], search(query, content));
    }

    #[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)
        );
    }
}