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//! 此IO程序测试了一些命令行里的查找文件的功能，使用了迭代器等功能
use std::error::Error;



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(a) => a,
            None => return Err("dont get a query string"),
        };
        let filename = match args.next() {
            Some(a) => a,
            None => return Err("dont get a filename"),
        };
        let case_sensitive = std::env::var("CASE_INSENSITIVE").is_err();

        Ok(Config { query, filename, case_sensitive })
    }
}
/// # run
/// ```
/// let config = Config::new(...);
/// run(config);
/// ```
///
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let context = std::fs::read_to_string(config.filename)?;

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

    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> {
    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() {
        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)
        );
    }

    #[test]
    fn iter_test() {
        let arr = vec![1, 2, 4, 5];
        let res: u32 = arr.iter().sum();
        assert_eq!(res, 12);
    }
}

pub mod pr {
    use std::time::Instant;

    /// #nth_prime
    /// ```
    /// let result =nth_prime(300000);
    /// assert_eq!(result,425623);
   pub fn nth_prime(mut n: u32) -> u32 {
        let mut i = 3;
        let mut j = 1;
        loop {
            j = j + 2;
            if j * j > i {
                n = n - 1;
                if n == 1 {
                    break;
                }
                i = i + 2;
                j = 1;
            } else if i % j == 0 {
                i = i + 2;
                j = 1;
            }
        }
        return i;
    }

    #[test]
    fn test_pr() {
        let now = Instant::now();
        let result = nth_prime(300000);
        let du = now.elapsed().as_millis();
        println!("答案是:{},耗时:{}ms", result, du);
    }
}