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


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

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

        let query = match args.next() {
            Some(val) => val,
            None => return Err("Missing query")
        };

        let file_path = match args.next() {
            Some(val ) => val,
            None => return Err("Missing file path")
        };
        
        let mut ignore_case: bool = false;
        if env::var("IGNORE_CASE").is_ok() {
            ignore_case = true;
        }

        let next = args.next().unwrap_or(String::from(""));
        if next.contains("-i") || next.contains("--ignore-case") {
            ignore_case = true;
        }

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

pub fn case_insensitive_search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
    let query = query.to_lowercase();

    contents
        .lines()
        .filter(|line| {
            line.to_lowercase().contains(&query)
        })
        .collect()
}



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


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

    let result: Vec<&str>;

    if args.ignore_case {
        result = case_insensitive_search(&args.query, &contents);
    } else {
        result = search(&args.query, &contents);
    }
    for line in result {
        println!("{line}");
    }
    Ok(())
}

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

    #[test]
    fn one_result() {
        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: &str = "RuSt";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";

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

}