my_grep 0.1.0

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

/// 运行搜索功能
///
/// # Examples
/// ```
/// mygrep::run(config)
/// ```
pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;

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

    for line in results {
        println!("查找的内容: {}", line)
    }

    Ok(())
}

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> {
        if args.len() < 3 {
            return Err("需要输入要搜索的内容与文件路径");
        }
        args.next();

        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("获取查询字符串出错"),
        };
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("获取查询文件出错"),
        };

        let case_sensitive = env::var("CASE_INSENSITIVE").unwrap_or_else(|_| String::from("0"));
        let case_sensitive = match &case_sensitive[..] {
            "0" => true,
            "1" => false,
            _ => true,
        };
        Ok(Config {
            query,
            filename,
            case_sensitive,
        })
    }
}

pub fn search_case_sensitive<'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_case_sensitive(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)
        );
    }
}