From 142e787a9cdc585453e38eda26da7388ecfbec7f Mon Sep 17 00:00:00 2001
From: sabrina-shanman <sabrina@highfidelity.io>
Date: Thu, 29 Nov 2018 16:46:08 -0800
Subject: [PATCH] Create MIMETypeLibrary for general MIME type detection

---
 .../shared/src/shared/MIMETypeLibrary.cpp     | 85 +++++++++++++++++
 libraries/shared/src/shared/MIMETypeLibrary.h | 91 +++++++++++++++++++
 2 files changed, 176 insertions(+)
 create mode 100644 libraries/shared/src/shared/MIMETypeLibrary.cpp
 create mode 100644 libraries/shared/src/shared/MIMETypeLibrary.h

diff --git a/libraries/shared/src/shared/MIMETypeLibrary.cpp b/libraries/shared/src/shared/MIMETypeLibrary.cpp
new file mode 100644
index 0000000000..4f12f373fe
--- /dev/null
+++ b/libraries/shared/src/shared/MIMETypeLibrary.cpp
@@ -0,0 +1,85 @@
+//
+//  MIMETypeLibrary.cpp
+//  libraries/shared/src/shared
+//
+//  Created by Sabrina Shanman on 2018/11/29.
+//  Copyright 2018 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#include "MIMETypeLibrary.h"
+
+MIMETypeLibrary::ID MIMETypeLibrary::registerMIMEType(const MIMEType& mimeType) {
+    ID id;
+    withWriteLock([&](){
+        id = nextID++;
+        _mimeTypes.emplace_back(id, mimeType);
+    });
+    return id;
+}
+
+void MIMETypeLibrary::unregisterMIMEType(const MIMETypeLibrary::ID& id) {
+    withWriteLock([&](){
+        for (auto it = _mimeTypes.begin(); it != _mimeTypes.end(); it++) {
+            if ((*it).id == id) {
+                _mimeTypes.erase(it);
+                break;
+            }
+        }
+    });
+}
+
+MIMEType MIMETypeLibrary::getMIMEType(const MIMETypeLibrary::ID& id) const {
+    return resultWithReadLock<MIMEType>([&](){
+        for (auto& supportedFormat : _mimeTypes) {
+            if (supportedFormat.id == id) {
+                return supportedFormat.mimeType;
+            }
+        }
+        return MIMEType::NONE;
+    });
+}
+
+MIMETypeLibrary::ID MIMETypeLibrary::findMatchingMIMEType(const hifi::ByteArray& data, const hifi::VariantHash& mapping, const hifi::URL& url, const std::string& webMediaType) const {
+    return resultWithReadLock<MIMETypeLibrary::ID>([&](){
+        // Check file contents
+        for (auto& mimeType : _mimeTypes) {
+            for (auto& fileSignature : mimeType.mimeType.fileSignatures) {
+                auto testBytes = data.mid(fileSignature.byteOffset, (int)fileSignature.bytes.size()).toStdString();
+                if (testBytes == fileSignature.bytes) {
+                    return mimeType.id;
+                }
+            }
+        }
+
+        // Check file extension
+        std::string urlString = url.path().toStdString();
+        std::size_t extensionSeparator = urlString.rfind('.');
+        if (extensionSeparator != std::string::npos) {
+            std::string detectedExtension = urlString.substr(extensionSeparator + 1);
+            for (auto& supportedFormat : _mimeTypes) {
+                for (auto& extension : supportedFormat.mimeType.extensions) {
+                    if (extension == detectedExtension) {
+                        return supportedFormat.id;
+                    }
+                }
+            }
+        }
+
+        // Check web media type
+        if (webMediaType != "") {
+            for (auto& supportedFormat : _mimeTypes) {
+                for (auto& candidateWebMediaType : supportedFormat.mimeType.webMediaTypes) {
+                    if (candidateWebMediaType == webMediaType) {
+                        return supportedFormat.id;
+                    }
+                }
+            }
+        }
+
+        // Supported file type not found.
+        return INVALID_ID;
+    });
+}
diff --git a/libraries/shared/src/shared/MIMETypeLibrary.h b/libraries/shared/src/shared/MIMETypeLibrary.h
new file mode 100644
index 0000000000..62bc28cdad
--- /dev/null
+++ b/libraries/shared/src/shared/MIMETypeLibrary.h
@@ -0,0 +1,91 @@
+//
+//  MIMETypeLibrary.h
+//  libraries/shared/src/shared
+//
+//  Created by Sabrina Shanman on 2018/11/28.
+//  Copyright 2018 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+#ifndef hifi_MIMETypeLibrary_h
+#define hifi_MIMETypeLibrary_h
+
+#include <vector>
+#include <string>
+#include <functional>
+#include <mutex>
+
+#include "HifiTypes.h"
+
+#include "ReadWriteLockable.h"
+
+// A short sequence of bytes, typically at the beginning of the file, which identifies the file format
+class FileSignature {
+public:
+    FileSignature(const std::string& bytes, int byteOffset) :
+        bytes(bytes),
+        byteOffset(byteOffset) {
+    }
+    FileSignature(const FileSignature& fileSignature) :
+        bytes(fileSignature.bytes),
+        byteOffset(fileSignature.byteOffset) {
+    }
+
+    std::string bytes;
+    int byteOffset;
+};
+
+// A named file extension with a list of known ways to positively identify the file type
+class MIMEType {
+public:
+    MIMEType(const std::string& name) :
+        name(name) {
+    }
+    MIMEType() {};
+    MIMEType(const MIMEType& mimeType) :
+        name(mimeType.name),
+        extensions(mimeType.extensions),
+        webMediaTypes(mimeType.webMediaTypes),
+        fileSignatures(mimeType.fileSignatures) {
+    }
+
+    static MIMEType NONE;
+
+    std::string name;
+    std::vector<std::string> extensions;
+    std::vector<std::string> webMediaTypes;
+    std::vector<FileSignature> fileSignatures;
+};
+
+MIMEType MIMEType::NONE = MIMEType("");
+
+class MIMETypeLibrary : ReadWriteLockable {
+public:
+    using ID = unsigned int;
+    static const ID INVALID_ID { 0 };
+
+    ID registerMIMEType(const MIMEType& mimeType);
+    void unregisterMIMEType(const ID& id);
+
+    MIMEType getMIMEType(const ID& id) const;
+    ID findMatchingMIMEType(const hifi::ByteArray& data, const hifi::VariantHash& mapping, const hifi::URL& url, const std::string& webMediaType) const;
+
+protected:
+    ID nextID { 1 };
+    
+    class Entry {
+    public:
+        Entry(const ID& id, const MIMEType& mimeType) :
+            id(id),
+            mimeType(mimeType) {
+        }
+        ID id;
+        MIMEType mimeType;
+    };
+
+    std::vector<Entry> _mimeTypes;
+};
+
+#endif // hifi_MIMETypeLibrary_h