Tweak error handling a bit

Always get http headers of the response to be able
to handle issues more explicitly.
These headers also contain additional information
we will need later on.

Change-Id: I062e97726a473c16b29cd84be0aa37260bac4ed8
Reviewed-by: David Schulz <david.schulz@qt.io>

plugins/axivion/axivionresultparser.cpp

@@ -6,9 +6,69 @@
 #include <QJsonArray>
 #include <QJsonDocument>
 #include <QJsonObject>
+#include <QRegularExpression>
+
+#include <utility>
 
 namespace Axivion::Internal {
 
+static std::pair<QByteArray, QByteArray> splitHeaderAndBody(const QByteArray &input)
+{
+    QByteArray header;
+    QByteArray json;
+    int emptyLine = input.indexOf("\r\n\r\n"); // we always get \r\n as line separator
+    if (emptyLine != -1) {
+        header = input.left(emptyLine);
+        json = input.mid(emptyLine + 4);
+    } else {
+        json = input;
+    }
+    return {header, json};
+}
+
+static int httpStatus(const QByteArray &header)
+{
+    int firstHeaderEnd = header.indexOf("\r\n");
+    if (firstHeaderEnd == -1)
+        return 600; // unexpected header
+    const QString firstLine = QString::fromUtf8(header.first(firstHeaderEnd));
+    static const QRegularExpression regex(R"(^HTTP/\d\.\d (\d{3}) .*$)");
+    const QRegularExpressionMatch match = regex.match(firstLine);
+    return match.hasMatch() ? match.captured(1).toInt() : 601;
+}
+
+static std::pair<BaseResult, QJsonDocument> prehandleHeaderAndBody(const QByteArray &header,
+                                                                   const QByteArray &body)
+{
+    BaseResult result;
+    if (header.isEmpty()) {
+        result.error = QString::fromUtf8(body); // we likely had a curl problem
+        return {result, {}};
+    }
+    int status = httpStatus(header);
+    if ((status > 399) || (status > 299 && body.isEmpty())) { // FIXME handle some explicitly?
+        const QString statusStr = QString::number(status);
+        if (body.isEmpty() || body.startsWith('<')) // likely an html response or redirect
+            result.error = QLatin1String("(%1)").arg(statusStr);
+        else
+            result.error = QLatin1String("%1 (%2)").arg(QString::fromUtf8(body)).arg(statusStr);
+        return {result, {}};
+    }
+
+    QJsonParseError error;
+    const QJsonDocument doc = QJsonDocument::fromJson(body, &error);
+    if (error.error != QJsonParseError::NoError) {
+        result.error = error.errorString();
+        return {result, doc};
+    }
+
+    if (!doc.isObject()) {
+        result.error = "Not an object.";
+        return {result, {}};
+    }
+
+    return {result, doc};
+}
 
 namespace ResultParser {
 
@@ -16,18 +76,10 @@ DashboardInfo parseDashboardInfo(const QByteArray &input)
 {
     DashboardInfo result;
 
-    QJsonParseError error;
-    const QJsonDocument doc = QJsonDocument::fromJson(input, &error);
-    if (error.error != QJsonParseError::NoError) {
-        if (input.startsWith("Authentication failed:"))
-            result.error = QString::fromUtf8(input);
-        else
-            result.error = error.errorString();
-        return result;
-    }
-
-    if (!doc.isObject()) {
-        result.error = "Not an object.";
+    auto [header, body] = splitHeaderAndBody(input);
+    auto [error, doc] = prehandleHeaderAndBody(header, body);
+    if (!error.error.isEmpty()) {
+        result.error = error.error;
         return result;
     }
     const QJsonObject object = doc.object();