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

pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool,
}

impl Config {
    fn new(args: &[String]) -> Config {
        if args.len() < 3 {
            panic!("not enough arguments");
        }

        // let query = &args[1];
        // let file_path = &args[2];

        // (query, file_path)
        // (&args[1], &args[2])

        // In this case while learning rust, it is okay
        // to use clone() here while not managing lifetimes
        // and such.
        //
        // For rush, I will absolutely want to mess with
        // lifetimes and references for speed.
        // Gonna make this fast af
        // https://www.youtube.com/watch?v=y-5JFBEoU9c
        Config {
            query: args[1].clone(),
            file_path: args[2].clone(),
            ignore_case: false,
        }
    }

    // pub fn build(args: &[String]) -> Result<Config, &'static str> {
    //     if args.len() < 3 {
    //         return Err("not enough arguments");
    //     }

    //     Ok(Config {
    //         query: args[1].clone(),
    //         file_path: args[2].clone(),
    //         ignore_case: env::var("IGNORE_CASE").is_ok(),
    //     })
    // }

    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, &'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 ignore_case = env::var("IGNORE_CASE").is_ok();

        Ok(Config {
            query,
            file_path,
            ignore_case,
        })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    // Best to group configuration variables such as query, file_path,
    // and contents into one structure.
    let contents = fs::read_to_string(config.file_path)?;

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

    for line in search(&config.query, &contents) {
        println!("{line}");
    }

    // println!("With text:\n{contents}");

    Ok(())
}

pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    contents
        .lines()
        .filter(|line| line.contains(query))
        .collect()
    // let mut results = Vec::new();

    // for line in contents.lines() {
    //     if line.contains(query) {
    //         results.push(line);
    //     }
    // }

    // results
}

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);
        }
    }

    results
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn one_result() {
        let query = "duct";
        let contents = "\
Rust
safe, fast, productive.
Pick three.";

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

        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)
        );
    }
}