rengrep 0.1.0

use std::{
    env::{self},
    error::Error as ErrorTrait,
    fs,
    io::{Error, ErrorKind},
};

pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool,
    pub with_line_number: bool,
}

impl Config {
    pub fn build(mut args: impl Iterator<Item = String>) -> Result<Config, Error> {
        args.next();

        let query = match args.next() {
            Some(value) => value.clone(),
            None => return Err(Error::new(ErrorKind::NotFound, "Query is empty!")),
        };
        let file_path = match args.next() {
            Some(value) => value.clone(),
            None => return Err(Error::new(ErrorKind::NotFound, "File path is empty!")),
        };

        let ignore_case = env::var("IGNORE_CASE").is_ok();

        let with_line_number = String::from("-l") == args.next().unwrap_or(String::new());

        Ok(Config {
            query,
            file_path,
            ignore_case,
            with_line_number,
        })
    }
}

pub fn run(config: Config) -> Result<(), Box<dyn ErrorTrait>> {
    let Config {
        query,
        file_path,
        ignore_case,
        with_line_number,
    } = config;
    let contents = fs::read_to_string(&file_path)?;

    let results = if ignore_case {
        search_case_insensitive(&query, &contents)
    } else {
        search(&query, &contents)
    };

    for (line_number, line_content) in results {
        if with_line_number {
            println!("{line_number}| {line_content}")
        } else {
            println!("{line_content}")
        }
    }

    Ok(())
}

fn search<'a>(query: &str, contents: &'a str) -> Vec<(usize, &'a str)> {
    let mut results = Vec::new();

    for line_info in contents.lines().into_iter().enumerate() {
        if line_info.1.contains(query) {
            results.push((line_info.0 + 1, line_info.1));
        }
    }

    results
}

fn search_case_insensitive<'a>(query: &str, contents: &'a str) -> Vec<(usize, &'a str)> {
    let mut results = Vec::new();

    for line_info in contents.lines().into_iter().enumerate() {
        if line_info.1.to_lowercase().contains(&query.to_lowercase()) {
            results.push((line_info.0 + 1, line_info.1));
        }
    }

    results
}

#[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![(2, "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![(1, "Rust:"), (4, "Trust me.")],
            search_case_insensitive(query, contents)
        )
    }
}