Added image filename implementation

main.cpp

@@ -1,3 +1,6 @@
+// Start using chrono when C++20 becomes available
+// #include <chrono>
+#include <filesystem>
 #include <iostream>
 #include <list>
 #include <map>
@@ -8,7 +11,13 @@
 #include <utility>
 #include <vector>
 
+#include <stdio.h>
 #include <stdint.h>
+#include <time.h>
+
+// Stop using these when C++20 becomes available
+#include <fcntl.h>
+#include <sys/stat.h>
 
 #include "httplib.h"
 #include "json.hpp"
@@ -19,6 +28,7 @@
 using nlohmann::json;
 
 using namespace std;
+namespace fs = std::filesystem;
 
 constexpr int API_KEY_LENGHT = 16;
 constexpr char DEFAULT_IMAGE_URL[] = "https://trmnl.com/images/setup/setup-logo.bmp";
@@ -92,6 +102,54 @@ bool reload_container(TRMNLContainer& container, const string& filename)
 	return true;
 }
 
+string get_timestamp_from_filename(const string& filepath)
+{
+	char result[128] = "";
+
+	struct stat status;
+	stat(filepath.c_str(), &status);
+
+	// Time of last modification
+	time_t file_time = status.st_mtim.tv_sec;
+
+	tm* file_tm;
+	file_tm = gmtime(&file_time);
+
+	snprintf(result, sizeof(result) - 1, "%04d-%02d-%02dT%02d:%02d:%02d",
+		file_tm->tm_year + 1900,
+		file_tm->tm_mon + 1,
+		file_tm->tm_mday,
+		file_tm->tm_hour,
+		file_tm->tm_min,
+		file_tm->tm_sec
+	);
+
+	return result;
+}
+
+// Use this when C++20 becomes available
+#if 0
+string get_timestamp_from_file_time(const fs::file_time_type& ftime)
+{
+	char result[128] = "";
+	time_t file_time = std::chrono::system_clock::to_time_t(std::chrono::file_clock::to_sys(ftime));
+
+	tm* file_tm;
+	file_tm = gmtime(&file_time);
+
+	snprintf(result, sizeof(result) - 1, "%04d-%02d-%02dT%02d:%02d:%02d",
+		file_tm->tm_year + 1900,
+		file_tm->tm_mon + 1,
+		file_tm->tm_mday,
+		file_tm->tm_hour,
+		file_tm->tm_min,
+		file_tm->tm_sec
+	);
+
+	return result;
+}
+#endif
+
 // First string is image filename for URL
 // Second string is timestamp for TRMNL filename
 pair<string, string> find_image_for_friendly(const string& folder_images, const string& friendly_id)
@@ -99,7 +157,22 @@ pair<string, string> find_image_for_friendly(const string& folder_images, const
 	pair<string, string> result = {"", ""};
 	set<string> permitted_extensions = { ".bmp", ".png" };
 
-	// TODO: Implement
+	if (!fs::is_directory(folder_images))
+	{
+		return result;
+	}
+
+	for (const fs::directory_entry& entry : fs::directory_iterator(folder_images))
+	{
+		if ((entry.path().stem() == friendly_id) &&
+			(0 != permitted_extensions.count(entry.path().extension())))
+		{
+			result.first = entry.path().filename();
+			result.second = get_timestamp_from_filename(entry.path());
+			// Change to this when C++20 becomes available
+			// result.second = get_timestamp_from_file_time(entry.last_write_time());
+		}
+	}
 
 	return result;
 }
@@ -170,6 +243,12 @@ int main(int argc, char **argv)
 		return -1;
 	}
 
+	if (!fs::is_directory(folder_images))
+	{
+		cout << "filepath for images is not a folder" << endl;
+		return -1;
+	}
+
 	if (!cert_file.empty() && !key_file.empty())
 	{
 		// TODO: Implement SSL Server Properly