Simplify docs of the configuration object

Making sure the majority of snippets will work after being copied from
the site.

Signed-off-by: Luís Cobucci <lcobucci@gmail.com>

docs/configuration.md

@@ -9,118 +9,244 @@ It's meant for:
 * Providing custom implementation for the [extension points](extending-the-library.md)
 * Retrieving components (encoder, decoder, parser, validator, and builder)
 
-## Usage
-
-In order to use it, you must:
-
-1. Initialise the configuration object
-1. Customise the configuration object
-1. Retrieve components
-
-### Configuration initialisation
+## Initialisation
 
 The `Lcobucci\JWT\Signer\Key\InMemory` object is used for symmetric/asymmetric signature.
 
 To initialise it, you can pass the key content as a plain text:
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Signer\Key\InMemory;
 
+require 'vendor/autoload.php';
+
 $key = InMemory::plainText('my-key-as-plaintext');
 ```
 
 Provide a base64 encoded string:
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Signer\Key\InMemory;
 
-$key = InMemory::base64Encoded('YSB2ZXJ5IGxvbmcgYSB2ZXJ5IHVsdHJhIHNlY3VyZSBrZXkgZm9yIG15IGFtYXppbmcgdG9rZW5z');
+require 'vendor/autoload.php';
+
+$key = InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=');
 ```
 
 Or provide a file path:
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Signer\Key\InMemory;
 
-$key = InMemory::file(__DIR__ . '/path-to-my-key-stored-in-a-file.pem'); // this reads the file and keeps its contents in memory
+require 'vendor/autoload.php';
+
+// this reads the file and keeps its contents in memory
+$key = InMemory::file(__DIR__ . '/path-to-my-key-stored-in-a-file.pem');
 ```
 
-#### For symmetric algorithms
+### For symmetric algorithms
 
-Symmetric algorithms use the same key for both signature creation and verification.
+[Symmetric algorithms](supported-algorithms.md#symmetric-algorithms) use the same key for both signature creation and verification.
 This means that it's really important that your key **remains secret**.
 
 !!! Tip
     It is recommended that you use a key with lots of entropy, preferably generated using a cryptographically secure pseudo-random number generator (CSPRNG).
     You can use the [CryptoKey](https://github.com/AndrewCarterUK/CryptoKey) tool to do this for you.
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Configuration;
-use Lcobucci\JWT\Signer\Hmac\Sha256;
+use Lcobucci\JWT\Signer;
 use Lcobucci\JWT\Signer\Key\InMemory;
 
+require 'vendor/autoload.php';
+
 $configuration = Configuration::forSymmetricSigner(
-    // You may use any HMAC variations (256, 384, and 512)
-    new Sha256(),
+    new Signer\Hmac\Sha256(),
     // replace the value below with a key of your own!
     InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
-    // You may also override the JOSE encoder/decoder if needed by providing extra arguments here
+    // You may also override the JOSE encoder/decoder if needed
+    // by providing extra arguments here
 );
 ```
 
-#### For asymmetric algorithms
+### For asymmetric algorithms
 
-Asymmetric algorithms use a **private key** for signature creation and a **public key** for verification.
+[Asymmetric algorithms](supported-algorithms.md#asymmetric-algorithms) use a **private key** for signature creation and a **public key** for verification.
 This means that it's fine to distribute your **public key**. However, the **private key** should **remain secret**.
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Configuration;
 use Lcobucci\JWT\Signer;
 use Lcobucci\JWT\Signer\Key\InMemory;
 
+require 'vendor/autoload.php';
+
 $configuration = Configuration::forAsymmetricSigner(
-    // You may use RSA or ECDSA and all their variations (256, 384, and 512) and EdDSA over Curve25519
     new Signer\Rsa\Sha256(),
     InMemory::file(__DIR__ . '/my-private-key.pem'),
     InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
-    // You may also override the JOSE encoder/decoder if needed by providing extra arguments here
+    // You may also override the JOSE encoder/decoder if needed
+    // by providing extra arguments here
 );
 ```
 
 !!! Important
     The implementation of ECDSA algorithms have a constructor dependency.
     Use the `create()` named constructor to avoid having to handle it (e.g.: `Lcobucci\JWT\Signer\Ecdsa\Sha256::create()`).
 
-#### For no algorithm
+### For no algorithm
 
 !!! Warning
     This configuration type is **NOT** recommended for production environments.
     It's only provided to allow people to have a simpler and faster setup for tests, avoiding any kind of signature creation/verification.
 
 ```php
+<?php
+declare(strict_types=1);
+
 use Lcobucci\JWT\Configuration;
 
+require 'vendor/autoload.php';
+
 $configuration = Configuration::forUnsecuredSigner(
-    // You may also override the JOSE encoder/decoder if needed by providing extra arguments here
+    // You may also override the JOSE encoder/decoder if needed by providing
+    // extra arguments here
 );
 ```
 
-### Customisation
+## Customisation
 
 By using the setters of the `Lcobucci\JWT\Configuration` you may customise the setup of this library.
 
 !!! Important
     If you want to use a customised configuration, please make sure you call the setters before of invoking any getter.
     Otherwise, the default implementations will be used.
 
-These are the available setters:
+### Builder factory
+
+It configures how the token builder should be created.
+It's useful when you want to provide a [custom Builder](extending-the-library.md#builder).
+
+```php
+<?php
+declare(strict_types=1);
+
+use Lcobucci\JWT\Builder;
+use Lcobucci\JWT\ClaimsFormatter;
+use Lcobucci\JWT\Configuration;
+use Lcobucci\JWT\Encoding\JoseEncoder;
+use Lcobucci\JWT\Signer;
+use Lcobucci\JWT\Signer\Key\InMemory;
+
+require 'vendor/autoload.php';
+
+$configuration = Configuration::forSymmetricSigner(
+    new Signer\Hmac\Sha256(),
+    InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
+);
+
+$configuration->setBuilderFactory(
+    static function (ClaimsFormatter $formatter): Builder {
+        // This assumes `MyCustomBuilder` is an existing class 
+        return new MyCustomBuilder(new JoseEncoder(), $formatter);
+    }
+);
+```
+
+### Parser
+
+It configures how the token parser should be created.
+It's useful when you want to provide a [custom Parser](extending-the-library.md#parser).
+
+```php
+<?php
+declare(strict_types=1);
+
+use Lcobucci\JWT\Configuration;
+use Lcobucci\JWT\Signer;
+use Lcobucci\JWT\Signer\Key\InMemory;
+
+require 'vendor/autoload.php';
+
+$configuration = Configuration::forSymmetricSigner(
+    new Signer\Hmac\Sha256(),
+    InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
+);
+
+// This assumes `MyParser` is an existing class 
+$configuration->setParser(new MyParser());
+```
+
+### Validator
+
+It configures how the token validator should be created.
+It's useful when you want to provide a [custom Validator](extending-the-library.md#validator).
+
+```php
+<?php
+declare(strict_types=1);
+
+use Lcobucci\JWT\Configuration;
+use Lcobucci\JWT\Signer;
+use Lcobucci\JWT\Signer\Key\InMemory;
+
+require 'vendor/autoload.php';
+
+$configuration = Configuration::forSymmetricSigner(
+    new Signer\Hmac\Sha256(),
+    InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
+);
+
+// This assumes `MyValidator` is an existing class
+$configuration->setValidator(new MyValidator());
+```
+
+### Validation constraints
 
-* `Lcobucci\JWT\Configuration#setBuilderFactory()`: configures how the token builder should be created
-* `Lcobucci\JWT\Configuration#setParser()`: configures a custom token parser
-* `Lcobucci\JWT\Configuration#setValidator()`: configures a custom validator
-* `Lcobucci\JWT\Configuration#setValidationConstraints()`: configures the default set of validation constraints
+It configures which are the base constraints to be used during validation.
+
+```php
+<?php
+declare(strict_types=1);
+
+use Lcobucci\Clock\SystemClock;
+use Lcobucci\JWT\Configuration;
+use Lcobucci\JWT\Signer;
+use Lcobucci\JWT\Signer\Key\InMemory;
+use Lcobucci\JWT\Validation\Constraint\IssuedBy;
+use Lcobucci\JWT\Validation\Constraint\SignedWith;
+use Lcobucci\JWT\Validation\Constraint\StrictValidAt;
+
+require 'vendor/autoload.php';
+
+$configuration = Configuration::forSymmetricSigner(
+    new Signer\Hmac\Sha256(),
+    InMemory::base64Encoded('mBC5v1sOKVvbdEitdSBenu59nfNfhwkedkJVNabosTw=')
+);
+
+$configuration->setValidationConstraints(
+    new SignedWith($configuration->signer(), $configuration->signingKey()),
+    new StrictValidAt(SystemClock::fromUTC()),
+    new IssuedBy('https://api.my-awesome-company.com')
+);
+```
 
-### Retrieve components
+## Retrieve components
 
 Once you've made all the necessary configuration you can pass the configuration object around your code and use the getters to retrieve the components: