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use std::env;
use std::error::Error;
use std::fs::File;
use std::io::prelude::*;

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 filename"),
      };
      let case_sensitive = env::var("CASE_INSENSITIVE").is_err();
      Ok(Config {
         query,
         filename,
         case_sensitive,
      })
   }
}

pub fn run(config: Config) -> Result<(), Box<Error>> {
   let mut f = File::open(config.filename)?;
   let mut contents = String::new();
   f.read_to_string(&mut contents)?;
   let results = if config.case_sensitive {
      search(&config.query, &contents)
   } else {
      search_case_insensitive(&config.query, &contents)
   };

   // if results.len() == 0 { println!("nothing found!");}
   for line in results {
      println!("{}", line);
   }

   Ok(())
}

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

pub fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
   contents
      .lines()
      .filter(|line| line.to_lowercase().contains(&query.to_lowercase()))
      .collect()
   // let mut res = Vec::new();
   //let query = query.to_lowercase();
   // for line in contents.lines() {
   //    if line.to_lowercase().contains(&query) {
   //       res.push(line);
   //    }
   // }
   // res
}

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

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

      assert_eq!(vec!["productive. Pick three."], search(query, contents));
   }

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

      assert_eq!(
         vec!["productive. Pick three."],
         search_case_insensitive(query, contents)
      );
   }
}