#pragma once

#include <filesystem>
#include <fstream>

namespace LXC::Util
{
	// Error returned when Util::ReadFile runs into errors //
	struct FileReadError final
	{
		// Different reasons why the error can occur //
		enum Reason
		{
			FileNotFound,
			PermissionDenied,
			NotAFile
		};

		// Constructor to pass arguments to the struct //
		FileReadError(const std::filesystem::path& _path, Reason _reason)
			: path(_path), reason(_reason)
		{}

		// Error information //
		const std::filesystem::path path;
		const Reason reason;

		// Turns the error into a c-string //
		inline static const char* const ReasonStr(Reason reason)
		{
			static const char* reasons[] =
			{
				"File cannot be found",
				"File reading permissions are denied",
				"Not a file"
			};

			return reasons[reason];
		}
	};

	// Util function to read a file as quick as possible with error handling //
	inline ReturnVal<std::string, FileReadError> ReadFile(const std::filesystem::path& filepath)
	{
		// Checks the file exists //
		if (!std::filesystem::exists(filepath))
			return FunctionFail<FileReadError>(std::filesystem::absolute(filepath), FileReadError::FileNotFound);

		// Checks it is a regular file //
		if (!std::filesystem::is_regular_file(filepath))
			return FunctionFail<FileReadError>(std::filesystem::absolute(filepath), FileReadError::NotAFile);

		// Checks it can open the file //
		std::ifstream file(filepath, std::ios::binary | std::ios::ate);
		if (!file)
			return FunctionFail<FileReadError>(std::filesystem::absolute(filepath), FileReadError::PermissionDenied);

		// Copies the file to the output string //
		const std::streamsize len = file.tellg();
		file.seekg(0, std::ios::beg);

		std::string contents(len, '\0');
		file.read(&contents[0], len);

		return contents;
	}
}