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//! # Minigrep
//!
//! `minigrep` is an application to search text in a file.
//!

use std::{env, fs};
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> {
        // if args.len() < 3 {
        //     return Err("This program expects two arguments <query> <file>");
        // }
        args.next();
        let query = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn´t get a query string")
        };
        let filename = match args.next() {
            Some(arg) => arg,
            None => return Err("Didn´t get a filename")
        };

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

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(())
}
/// Search for a substring (query - first parameter) in the content (contents - second parameter)
///
/// # Example
///
/// ```
/// let query = "you";
/// let contents = "How are you doing?\nI'm doing well. Thanks for asking.";
/// let result = minigrep::search(&query, &contents);
/// assert_eq!(result,&["How are you doing?"])
/// ```
///# Panic
/// The scenarios in which the function being documented could panic. Callers of the function who don’t want their programs to panic should make sure they don’t call the function in these situations.
///# Errors:
///   If the function returns a Result, describing the kinds of errors that might occur and what conditions might cause those errors to be returned can be helpful to callers so they can write code to handle the different kinds of errors in different ways.
///# Safety
///  If the function is unsafe to call (we discuss unsafety in Chapter 19), there should be a section explaining why the function is unsafe and covering the invariants that the function expects callers to uphold.
pub fn search<'a>(query: &str, contents: &'a str) -> Vec<&'a str> {
//    let mut results = Vec::new();
    contents.lines().filter(|line| line.contains(query))
        .map(|line| line.trim()).collect()
    /*    for line in contents.lines() {
            if line.contains(query) {
                results.push(line.trim());
            }
        }
        results
    */
}

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()))
        .map(|line| line.trim()).collect()

    /*    let mut results = Vec::new();
        // contents.lines().filter_map(|line| line.contains(query));
        let query = query.to_lowercase();
        for line in contents.lines() {
            if line.to_lowercase().contains(&query) {
                results.push(line.trim());
            }
        }
        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!["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)
        );
    }
}