minigrep_101 0.1.0

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

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

    let results = if config.ignore_case {
        search_case_insensitive(&config.query, &contents)
    } else {
        search_case_sensitive(&config.query, &contents)
    };

    results.into_iter().for_each(|line| {
        println!("{line}");
    });
    
    Ok(())
}

#[derive(Debug)]
pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool
}

impl Config {
    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Self, &'static str> {
        args.next();

        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a query string"),
        };

        let file_path = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a file path"),
        };

        let mut ignore_case = env::var("IGNORE_CASE").is_ok();

        if let Some(arg) = args.next() {
            if arg == "-i" {
                ignore_case = true;
            }
        }
        Ok(Config { query, file_path, ignore_case })
    }
}

pub fn search_case_sensitive<'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> {
    let query = query.to_lowercase();
    contents
        .lines()
        .filter(|line| line.to_lowercase().contains(&query))
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;
    
    #[test]
    fn case_sensitive_one_result() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape.";
        assert_eq!(vec!["safe, fast, productive."], search_case_sensitive(query, contents));
    }

    #[test]
    fn case_sensitive_two_results() {
        let query = "s";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Duct tape.";
        assert_eq!(vec!["Rust:", "safe, fast, productive."], search_case_sensitive(query, contents));
    }

    #[test]
    fn case_insensitive_two_results() {
        let query = "rUsT";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";

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