#include "task.h"

#include <iostream>
#include <fstream>

#include "libcppbuild.h"
#include "settings.h"

namespace
{
std::string readFile(const std::string &fileName)
{
	std::ifstream ifs(fileName.c_str(), std::ios::in | std::ios::binary | std::ios::ate);

	std::ifstream::pos_type fileSize = ifs.tellg();
	ifs.seekg(0, std::ios::beg);

	std::vector<char> bytes(fileSize);
	ifs.read(bytes.data(), fileSize);

	return std::string(bytes.data(), fileSize);
}

std::vector<std::string> readDeps(const std::string& depFile)
{
	if(!std::filesystem::exists(depFile))
	{
		return {};
	}

	auto str = readFile(depFile);

	std::vector<std::string> output;
	std::string tmp;
	bool start{false};
	bool in_whitespace{false};
	for(const auto& c : str)
	{
		if(c == '\\' || c == '\n')
		{
			continue;
		}

		if(c == ':')
		{
			start = true;
			continue;
		}

		if(!start)
		{
			continue;
		}

		if(c == ' ' || c == '\t')
		{
			if(in_whitespace)
			{
				continue;
			}

			if(!tmp.empty())
			{
				output.push_back(tmp);
			}
			tmp.clear();
			in_whitespace = true;
		}
		else
		{
			in_whitespace = false;
			tmp += c;
		}
	}

	if(!tmp.empty())
	{
		output.push_back(tmp);
	}

	return output;
}
} // namespace ::

Task::Task(const BuildConfiguration& config, const Settings& settings,
           const std::string& source)
{
	sourceFile = source;
	targetFile = settings.builddir / sourceFile.stem();
	targetFile += ".o";
	depsFile = settings.builddir / sourceFile.stem();
	depsFile += ".d";
}

void Task::start()
{
	future =
		std::async(std::launch::async,
		 [&]()
		 {
			 if(!std::filesystem::exists(sourceFile))
			 {
				 std::cout << "Missing source file: " << std::string(sourceFile) << "\n";
				 return 1;
			 }

			 bool recompile{false};

			 if(!recompile &&
			    !std::filesystem::exists(targetFile))
			 {
				 recompile = true;
				 std::cout << "Missing targetFile\n";
			 }

			 if(!recompile &&
			    !std::filesystem::exists(depsFile))
			 {
				 recompile = true;
				 std::cout << "Missing depsFile\n";
			 }

			 if(!recompile &&
			    std::filesystem::last_write_time(sourceFile) >
			    std::filesystem::last_write_time(depsFile))
			 {
				 recompile = true;
				 std::cout << "The sourceFile newer than depsFile\n";
			 }

			 if(!recompile)
			 {
				 auto depList = readDeps(depsFile);
				 for(const auto& dep : depList)
				 {
					 if(!std::filesystem::exists(dep) ||
					    std::filesystem::last_write_time(targetFile) <
					    std::filesystem::last_write_time(dep))
					 {
						 recompile = true;
						 std::cout << "The targetFile older than dep\n";
						 break;
					 }
				 }
			 }

			 if(!recompile &&
			    std::filesystem::last_write_time(sourceFile) >
			    std::filesystem::last_write_time(targetFile))
			 {
				 recompile = true;
				 std::cout << "The targetFile older than sourceFile\n";
			 }

			 if(recompile)
			 {
				 std::string cmd =
				 "g++ -MMD -c " + std::string(sourceFile) +
				 " -o " + std::string(targetFile);
				 std::cout << cmd << "\n";

				 if(system(cmd.data()))
				 {
					 return 1;
				 }
				 return 0;
			 }

			 return 0;
		 });
}

int Task::wait()
{
	future.wait();
	return future.get();
}

int Task::clean()
{
	if(std::filesystem::exists(targetFile))
	{
		std::cout << "Removing " << std::string(targetFile) << "\n";
		std::filesystem::remove(targetFile);
	}

	if(std::filesystem::exists(depsFile))
	{
		std::cout << "Removing " << std::string(depsFile) << "\n";
		std::filesystem::remove(depsFile);
	}

	return 0;
}

std::vector<std::string> Task::depends()
{
	return {};
}