public/subjects/profanity_filter/README.md

## profanity filter

### Instructions

Sometimes it is more desirable to catch the failure of some parts of a program instead
of just calling panic.

For this exercise you will have to create a message blocker, where you must block the word `stupid`

You will have to create a structure called `Message`, this structure
must have the following elements:

- content: String
- user: String
- time_sent: String

The struct must also have a implementation of 2 functions associated to it:

- `new`, that initializes the structure
- `send_ms`, that only has its implementation type (**self**) as argument and returns an option.
  This function must return `None` if the content of the message is either **empty** or contains the
  word **stupid**. Otherwise it returns the content of the message.

You will have to create two more functions that aren't associated to any structure:

- `check_ms` that receives as parameters the reference to the structure `Message` and returns a tuple,
containing a `bool` and a `string`. This function will execute the function `send_ms` and if the result
of the option is `None` it should return (false, "ERROR: illegal"). Otherwise it returns `true` and the
content of the message sent.
- `date_format` that creates and formats the date and time that the message was sent, the format should
look like this: **Mon Oct  5 10:22:19 2020**

### Expected Function

```rust
pub struct Message {}

impl Message {
  pub fn new(ms: String, u: String, t: String) -> Message {}
  pub fn send_ms(&self) -> Option<&str> {}
}

pub fn check_ms(ms: &Message) -> (bool, &str) {}
pub fn format_date() -> String {}
```

### Usage

Here is a program to test your function

```rust
fn main() {
  let m0 = Message::new("hello there".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m0));

  let m1 = Message::new("".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m1));

  let m2 = Message::new("you are stupid".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m2));

  let m3 = Message::new("stupid".to_string(), "toby".to_string(), format_date());
  println!("{:?}", check_ms(&m3));
}
```

And its output:

```console
student@ubuntu:~/[[ROOT]]/test$ cargo run
(true, "hello there")
(false, "ERROR: illegal")
(false, "ERROR: illegal")
(false, "ERROR: illegal")
student@ubuntu:~/[[ROOT]]/test$
```

### Notions

- https://docs.rs/chrono/0.4.19/chrono/
- https://doc.rust-lang.org/stable/book/ch06-01-defining-an-enum.html?highlight=option#the-option-enum-and-its-advantages-over-null-values