From 834cfad50233ded3439a2b7f8f6d293318b35196 Mon Sep 17 00:00:00 2001
From: Ted John <ted@brambles.org>
Date: Fri, 30 Mar 2018 20:57:05 +0100
Subject: [PATCH] Create new FileWatcher class

---
 src/openrct2/core/FileWatcher.cpp | 102 ++++++++++++++++++++++++++++++
 src/openrct2/core/FileWatcher.h   |  33 ++++++++++
 2 files changed, 135 insertions(+)
 create mode 100644 src/openrct2/core/FileWatcher.cpp
 create mode 100644 src/openrct2/core/FileWatcher.h

diff --git a/src/openrct2/core/FileWatcher.cpp b/src/openrct2/core/FileWatcher.cpp
new file mode 100644
index 0000000000..7429ea8c97
--- /dev/null
+++ b/src/openrct2/core/FileWatcher.cpp
@@ -0,0 +1,102 @@
+#include <array>
+#include <stdexcept>
+
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+#else
+#include <fcntl.h>
+#include <sys/inotify.h>
+#include <sys/types.h>
+#include <unistd.h>
+#endif
+
+#include "../core/String.hpp"
+#include "FileWatcher.h"
+
+FileWatcher::FileWatcher(const std::string &directoryPath)
+{
+#ifdef _WIN32
+    _directoryHandle = CreateFileA(directoryPath.c_str(), FILE_LIST_DIRECTORY, FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, nullptr);
+    if (_directoryHandle == INVALID_HANDLE_VALUE)
+    {
+        throw std::runtime_error("Unable to open directory '" + directoryPath + "'");
+    }
+#else
+    auto fd = inotify_init();
+    if (fd >= 0)
+    {
+        auto wd = inotify_add_watch(fd, directoryPath.c_str(), IN_CLOSE_WRITE);
+        if (wd >= 0)
+        {
+            _fileDesc = fd;
+            _watchDesc = wd;
+        }
+        else
+        {
+            close(fd);
+            throw std::runtime_error("Unable to watch directory '" + directoryPath + "'");
+        }
+    }
+#endif
+    _watchThread = std::thread(std::bind(&FileWatcher::WatchDirectory, this));
+}
+
+FileWatcher::~FileWatcher()
+{
+#ifdef _WIN32
+    CancelIoEx(_directoryHandle, nullptr);
+    CloseHandle(_directoryHandle);
+#else
+    inotify_rm_watch(_fileDesc, _watchDesc);
+    close(_fileDesc);
+#endif
+    _watchThread.join();
+}
+
+void FileWatcher::WatchDirectory()
+{
+#ifdef _WIN32
+    std::array<char, 1024> eventData;
+    DWORD bytesReturned;
+    while (ReadDirectoryChangesW(_directoryHandle, eventData.data(), (DWORD)eventData.size(), TRUE, FILE_NOTIFY_CHANGE_LAST_WRITE, &bytesReturned, nullptr, nullptr))
+    {
+        auto onFileChanged = OnFileChanged;
+        if (onFileChanged)
+        {
+            FILE_NOTIFY_INFORMATION * notifyInfo;
+            size_t offset = 0;
+            do
+            {
+                notifyInfo = (FILE_NOTIFY_INFORMATION*)(eventData.data() + offset);
+                offset += notifyInfo->NextEntryOffset;
+
+                std::wstring fileNameW(notifyInfo->FileName, notifyInfo->FileNameLength / sizeof(wchar_t));
+                auto fileName = String::ToUtf8(fileNameW);
+                onFileChanged(fileName);
+            }
+            while (notifyInfo->NextEntryOffset != 0);
+        }
+    }
+#else
+    std::array<char, 1024> eventData;
+    auto length = read(_fileDesc, eventData.data(), eventData.size());
+    if (length >= 0)
+    {
+        auto onFileChanged = OnFileChanged;
+        if (onFileChanged)
+        {
+            int offset = 0;
+            while (offset < length)
+            {
+                auto e = (inotify_event*)(eventData.data() + offset);
+                if ((e->mask & IN_CLOSE_WRITE) && !(e->mask & IN_ISDIR))
+                {
+                    onFileChanged(e->name);
+                }
+                offset += sizeof(inotify_event) + e->len;
+            }
+        }
+    }
+#endif
+}
diff --git a/src/openrct2/core/FileWatcher.h b/src/openrct2/core/FileWatcher.h
new file mode 100644
index 0000000000..9f923e9e15
--- /dev/null
+++ b/src/openrct2/core/FileWatcher.h
@@ -0,0 +1,33 @@
+#pragma once
+
+#include <functional>
+#include <string>
+#include <thread>
+
+#ifdef _WIN32
+typedef void * HANDLE;
+#endif
+
+/**
+ * Creates a new thread that watches a directory tree for file modifications.
+ */
+class FileWatcher
+{
+private:
+    std::thread _watchThread;
+#ifdef _WIN32
+    HANDLE _directoryHandle{};
+#else
+    int _fileDesc{};
+    int _watchDesc{};
+#endif
+
+public:
+    std::function<void(const std::string &path)> OnFileChanged;
+
+    FileWatcher(const std::string &directoryPath);
+    ~FileWatcher();
+
+private:
+    void WatchDirectory();
+};