Throw exceptions about le-acme2-php

[fbett]

Ok, so there is a new commit that should satisfy.

About the referenced examples:

1. RateLimit
   There was a hope to find a way to handle rate limits within this library. This was not fully implemented as described in README.md. But is see, that the way to throw a RateLimitReachedException is currently a good idea.

2. Null response of Account::create and others
   A situation, i was also not happy with. An InvalidResponseException will be thrown now.

3. PHP functions like file_put_contents
   I'm not a fan of to handle system errors, if it is not necessary. In the case of file_put_contents, PHP will raise a message, if a problem occurs. These php messages could be handled by an exception handler.
   Additionally in case of your referenced example, nothing is lost:
   If file_put_contents fails only the cache file is not written.
   So i've not added here some error handling.

[fbett]

Thanks for your feedback.

Isn't it on the implementor to decide how to handle the thrown exceptions? I though, it would be very easy to implement a try/catch block while calling the methods like in the http example.

Remember, all the current exceptions are thrown on hard problems:

• Connection problems
• Wrong responses
• System errors (read/write)
• Wrong workflow
• System requirements (PHP Version, RSA support)
• Implementation problems (regex pattern)
  Because of that, currently only RuntimeExceptions are thrown.

I would suggest everyone to try it again from beginning, if an exception is thrown because of connection problems.

At what kind of situation did you thought?

Of course, all PRs are welcome.

[hayleyxyz]

I guess this is just a difference in coding styles, but personally I don't find plain RuntimeExceptions enough to build a rock-solid application. Uniquley typed exceptions lets the implementor handle each failure case differently, if needed

For example: https://github.com/fbett/le-acme2-php/blob/master/src/LE_ACME2/Response/AbstractResponse.php#L52
I would expect this to throw a RateLimitReachedException, then as an implementor I know to sleep my application for a period of time

Furthermore, functions that can commonly fail should have their return value checked, and throw an exception on failure

Example: https://github.com/fbett/le-acme2-php/blob/master/src/LE_ACME2/Connector/Storage.php#L97
file_put_contents() can fail for multiple reasons; permissions, fd exhaustion, no space on device
If this threw an IOException, as an implementor I would probably exit out here and report the exception so a human can come in an sort out the problem, since the application can't fix it itself

A less important example is here: https://github.com/fbett/le-acme2-php/blob/master/src/LE_ACME2/Account.php#L49
The function returns null on failure, so I can detect that, however an exception that tells me the explicit reason why would be nice