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/*
 * @Description: 
 * @Version: 2.0
 * @Autor: lotuscc
 * @Date: 2021-05-24 15:16:54
 * @LastEditors: lotuscc
 * @LastEditTime: 2021-05-25 20:27:31
 */

//! # My Crate
//!
//! `my_crate` is a collection of utilities to make performing certain
//! calculations more convenient.

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

pub struct Config{
    pub query: String,
    pub filename: String,
    pub case_sensitive: bool,
}

impl Config {
/// make the config
/// # Examples
/// ```
/// let args = env::args(); 
/// let config = Config::new(args).unwrap_or_else(|err| {
///     eprintln!("Problem parsing arguments: {}", err);
///     process::exit(1);
/// });
/// ```
/// 
        pub fn new(mut args: env::Args) -> Result<Config, &'static str> {
    
        // skip the name of the program. 
        args.next();
        
        // get the query string 
        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("Need a query string."),
        };

        // get the filename 
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("Need a file name."),
        };

        // get the case
        let mut case_sensitive = env::var("CASE_INSENSITIVE").is_err();
        
        // 判断是否使用了--case
        if case_sensitive == true{
            case_sensitive = match args.next() {
                Some(arg) => if arg == "--case" { false } else { true } ,
                None => true,
            }
        }

        Ok(Config { query, filename, case_sensitive})
    }
}

/// use the minigrep project with a config
/// # Examples
/// ```
/// if let Err(e) = minigrep::run(config) {
///     eprintln!("Application error: {}", e);
///     process::exit(1);
/// }
/// ```
/// 

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

    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()

}
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()
}

#[cfg(test)]
mod tests {
    use super::*;
   
    #[test]
    fn case_sensitive(){
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.
Trust me.";
        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));        
    }
}