minigrep_xiangzeng 0.1.0

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

pub fn run(config: Config) -> Result<(), Box<dyn Error>> {
    let contents = fs::read_to_string(config.filename)?;
    let result = if config.case_sensitive {
        search(&config.query, &contents)
    } else {
        search_case_insensitive(&config.query, &contents)
    };
    for line in result {
        println!("{}", line);
    }
    Ok(())
}

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

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

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

impl Config {
    pub fn new<T>(mut args: T) -> Result<Config, &'static str>
    where
        T: Iterator<Item = String>,
    {
        args.next();

        let query = match args.next() {
            Some(a) => a,
            None => return Err("didn't read query"),
        };
        let filename = match args.next() {
            Some(a) => a,
            None => return Err("didn't read filename"),
        };

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

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

    #[test]
    fn test_config_new() {
        let args = ["app", "query", "path"].iter().map(|s| s.to_string());
        assert_eq!("query".to_string(), Config::new(args).expect("").query);
    }

    #[test]
    fn case_sensitive() {
        let query = "duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(vec!["safe, fast, productive."], search(query, contents));
    }

    #[test]
    fn case_insensitive() {
        let query = "Duct";
        let contents = "\
Rust:
safe, fast, productive.
Pick three.";
        assert_eq!(
            vec!["safe, fast, productive."],
            search_case_insensitive(query, contents)
        );
    }
}