Add initial support for PHP7 (#97)

* Add initial support for PHP7

* Update PHP env with now an PSR3 logger (Monolog). Now you can also create a handler function with PSR7 Http message and PSR3 logger in parameter.

* Add examples for PHP7 environement

* For development you can create a function in this path /app/userfuncdev.php it will be loaded

* Switch to alpine base image

* handler now receive an array with request, response and logger object

examples/php7/hello.php

@@ -0,0 +1,3 @@
+<?php
+echo "Hello from PHP";
+$logger->warning("Hello logger");

examples/php7/hellopsr.php

@@ -0,0 +1,12 @@
+<?php
+function handler($context){
+    /** @var \Psr\Http\Message\ResponseInterface $response */
+    $response = $context["response"];
+    /** @var \Psr\Http\Message\ServerRequestInterface $request */
+    $request = $context["request"];
+    /** @var \Psr\Log\LoggerInterface $logger */
+    $logger = $context["logger"];
+    
+    $response->getBody()->write("Hello from handler PHP");
+    $logger->warning("Hello logger");
+}

examples/php7/stock.php

@@ -0,0 +1,47 @@
+<?php
+use \Psr\Http\Message\ResponseInterface;
+use \Psr\Http\Message\ServerRequestInterface;
+use \Psr\Log\LoggerInterface;
+
+function sendError($response,$message){
+    $response = $response->withStatus(500);
+    $response->getBody()->write($message);
+    return $response;
+}
+
+function handler($context){
+    /** @var ResponseInterface $response */
+    $response = $context["response"];
+    /** @var ServerRequestInterface $request */
+    $request = $context["request"];
+    /** @var LoggerInterface $logger */
+    $logger = $context["logger"];
+    
+    $logger->debug("Request : ",$request->getParsedBody());
+    if($request->getMethod() != "POST")
+        return sendError($response,"You must use POST method");
+
+    $body = $request->getParsedBody();
+    if(!isset($body["currency"]))
+        return sendError($response,"'currency' is not present in the POST request");
+
+    $allowedCurrency = ["ltc","btc"];
+    if(!in_array($body["currency"],$allowedCurrency))
+        return sendError($response,"'currency' is non allowed. Use one of them : ".implode(",",$allowedCurrency));
+
+    $curl = curl_init();
+    curl_setopt_array($curl, array(
+        CURLOPT_RETURNTRANSFER => 1,
+        CURLOPT_URL => 'https://api.cryptonator.com/api/ticker/'.$body["currency"].'-usd'
+    ));
+    $result = curl_exec($curl);
+    curl_close($curl);
+
+    $result = json_decode($result,true);
+    if($result){
+        $logger->debug("Response API",$result);
+        $response->getBody()->write(json_encode(array("text"=>sprintf("%s-USB = %02f",$body["currency"],$result["ticker"]["price"]))));
+    }else
+        return sendError($response,"Cryptonator API not available");
+
+}