#include "build.h"

#include <fstream>
#include <sstream>
#include <mutex>
#include <unordered_set>

#include "sys.h"
#include "parallel.h"
#include "toolchain.h"
#include "logger.h"

namespace build {

static void findSourcesInDir(std::string dir, std::vector<SourceFile> &sources,
		BBParser::Variables vars);

static void findSources(std::string dir, std::string name,
		std::vector<SourceFile> &sources, BBParser::Variables vars) {
	std::string path = dir + "/" + name;
	sys::FileInfo finfo = sys::fileInfo(path);

	if (finfo.isDir) {
		// We don't want to send 'files'
		BBParser::Variables subvars = vars;
		subvars.erase("files");
		findSourcesInDir(path, sources, std::move(subvars));
	} else {
		SourceFile::FileType type = SourceFile::fileTypeFrom(name);
		if (type != SourceFile::FileType::UNKNOWN) {
			sources.emplace_back(dir, name, type, vars);
		}
	}
}

static void findSourcesInDir(std::string dir, std::vector<SourceFile> &sources,
		BBParser::Variables vars) {
	std::ifstream buildFile(dir + "/build.bb");
	std::vector<std::string> files;
	bool hasFiles = false;

	// Parse $dir/build.bb, see if it specifies a 'files' value.
	if (buildFile.good()) {
		BBParser parser(buildFile, BBParser::FLAG_NONE);
		parser.parse(vars);

		auto it = vars.find("files");
		if (it != vars.end()) {
			files = it->second;
			hasFiles = true;
		}
	}

	// If build.bb didn't specify 'files', we have to readdir
	if (!hasFiles) {
		sys::readDir(dir, files);
	}

	// Go through files
	for (auto &ent: files) {
		std::string path = dir + "/" + ent;
		BBParser::Variables subvars = vars;
		findSources(dir, ent, sources, vars);
	}
}

static std::string findTargetName(const BuildConf &conf) {
	auto it = conf.variables.find("target");
	if (it != conf.variables.end() && it->second.size() != 0) {
		return it->second[0];
	}

	for (auto &source: conf.sources) {
		const std::vector<std::string> *ptr = source.variable("target");
		if (ptr != nullptr && ptr->size() != 0) {
			return (*ptr)[0];
		}
	}

	return "target";
}

BuildConf readBuildConf(std::string outDir, int numJobs, const std::vector<std::string> &args) {
	BuildConf conf;
	conf.outDir = outDir;
	conf.numJobs = numJobs;

	// Read config from file
	if (sys::fileExists("build.bb")) {
		std::ifstream stream("build.bb");
		BBParser parser(stream, BBParser::FLAG_NONE);
		parser.parse(conf.variables);
	}

	// Read variables from args
	for (auto &arg: args) {
		std::istringstream stream(arg);
		BBParser parser(stream, BBParser::FLAG_ONE_LINE);
		parser.parse(conf.variables);
	}

	// Find source dirs
	std::vector<std::string> sourceDirs;
	{
		auto it = conf.variables.find("files");
		if (it == conf.variables.end()) {
			sys::readDir(".", sourceDirs);
		} else {
			sourceDirs = it->second;
		}
	}

	// Read configs from source dirs
	for (std::string &dir: sourceDirs) {
		findSources(".", dir, conf.sources, conf.variables);
	}

	conf.targetName = findTargetName(conf);

	return conf;
}

bool compile(const BuildConf &conf) {
	bool compiled = false;
	std::mutex mut;
	parallel::parallel(conf.numJobs, conf.sources, [&](const SourceFile &source) {
		if (source.needsRecompile(conf.outDir)) {
			source.compile(conf.outDir);
			mut.lock();
			compiled = true;
			mut.unlock();
		}
	});

	return compiled;
}

void link(const BuildConf &conf, toolchain::TargetType targetType) {
	logger::log("Link " + conf.outDir + '/' + conf.targetName);

	std::vector<std::string> ldFlags;
	std::unordered_set<std::string> ldFlagsSet;
	std::vector<std::string> ldLibs;
	std::unordered_set<std::string> ldLibsSet;
	std::vector<std::string> objects;

	SourceFile::FileType type = SourceFile::FileType::C;

	// Gather ldflags, ldlibs and objects from sources
	std::vector<std::string> flags;
	for (auto &source: conf.sources) {
		if (source.type() != SourceFile::FileType::C) {
			type = source.type();
		}

		flags = source.ldFlags();
		for (auto &flag: flags) {
			if (flag[0] == '-' && flag[1] == 'l') {
				std::cerr << "Warning: -l flags should go in ldlibs "
					<< "(at " << source.path() << ": " << flag << ")\n";
			}

			auto it = ldFlagsSet.find(flag);
			if (it == ldFlagsSet.end()) {
				ldFlagsSet.emplace(flag);
				ldFlags.push_back(std::move(flag));
			}
		}

		flags = source.ldLibs();
		for (auto &flag: flags) {
			auto it = ldLibsSet.find(flag);
			if (it == ldLibsSet.end()) {
				ldLibsSet.emplace(flag);
				ldLibs.push_back(std::move(flag));
			}
		}

		objects.push_back(std::move(source.objectPath(conf.outDir)));
	}

	flags.clear();

	toolchain::link(conf.targetName, ldFlags, ldLibs, type, targetType, objects, conf.outDir);
}

void writeCompileCommands(const BuildConf &conf) {
	sys::mkdirp(conf.outDir);
	std::string cwd = sys::cwd();
	std::ofstream os(conf.outDir + "/compile_commands.json");

	os << "[\n\t";
	bool first = true;
	for (auto &source: conf.sources) {
		std::string command;
		for (auto arg: source.compileCommand(conf.outDir)) {
			command += arg + ' ';
		}
		command.pop_back();

		if (!first) {
			os << ", ";
		}

		os << "{\n"
			<< "\t\t\"directory\": \"" << cwd << "\"\n"
			<< "\t\t\"command\": \"" << command << "\"\n"
			<< "\t\t\"file\": \"" << source.path() << "\"\n"
			<< "\t}";

		first = false;
	}

	os << "\n]\n";

	sys::symlink(conf.outDir + "/compile_commands.json", "compile_commands.json");
}

}