mtgodot-poc/extension/src/pack/pack_mount.cpp

#include "pack_mount.h"

#include <algorithm>
#include <filesystem>

namespace fs = std::filesystem;

namespace mtpack {

std::string PackMount::norm(std::string s) {
	std::replace(s.begin(), s.end(), '\\', '/');
	// strip a leading "x:/" drive
	if (s.size() > 2 && s[1] == ':') {
		s = s.substr(2);
	}
	while (!s.empty() && s.front() == '/') {
		s.erase(s.begin());
	}
	std::transform(s.begin(), s.end(), s.begin(), [](unsigned char c) { return std::tolower(c); });
	// fold "//"
	std::string o;
	o.reserve(s.size());
	for (char c : s) {
		if (c == '/' && !o.empty() && o.back() == '/') {
			continue;
		}
		o.push_back(c);
	}
	return o;
}

bool PackMount::mount(const std::string &epk_path, std::string *err) {
	auto pk = std::make_shared<EterPack>();
	if (!pk->open(epk_path, err)) {
		return false;
	}
	const size_t pi = m_packs.size();
	m_packs.push_back(pk);
	for (const std::string &name : pk->names()) {
		std::string n = norm(name);
		m_by_norm[n] = {pi, name}; // later pack wins
		auto p = n.find("ymir work/");
		if (p != std::string::npos) {
			m_by_ymir[n.substr(p + 10)] = {pi, name};
		}
	}
	return true;
}

int PackMount::scan_dir(const std::string &dir, const std::string &patch_prefix) {
	std::error_code ec;
	if (!fs::is_directory(dir, ec)) {
		return 0;
	}
	std::vector<std::string> base, patch;
	for (const auto &e : fs::directory_iterator(dir, ec)) {
		if (!e.is_regular_file()) {
			continue;
		}
		const auto &p = e.path();
		if (p.extension() != ".epk") {
			continue;
		}
		if (!patch_prefix.empty() && p.filename().string().rfind(patch_prefix, 0) == 0) {
			patch.push_back(p.string());
		} else {
			base.push_back(p.string());
		}
	}
	std::sort(base.begin(), base.end());
	std::sort(patch.begin(), patch.end());

	int n = 0;
	for (const auto &v : {&base, &patch}) {
		for (const std::string &f : *v) {
			if (mount(f)) {
				++n;
			}
		}
	}
	return n;
}

bool PackMount::has(const std::string &vp) const {
	std::string n = norm(vp);
	if (m_by_norm.count(n)) {
		return true;
	}
	auto p = n.find("ymir work/");
	std::string suf = (p != std::string::npos) ? n.substr(p + 10) : n;
	return m_by_ymir.count(suf) != 0;
}

bool PackMount::read(const std::string &vp, std::vector<uint8_t> &out, std::string *err) const {
	std::string n = norm(vp);
	const Ref *r = nullptr;
	if (auto it = m_by_norm.find(n); it != m_by_norm.end()) {
		r = &it->second;
	} else {
		auto p = n.find("ymir work/");
		std::string suf = (p != std::string::npos) ? n.substr(p + 10) : n;
		if (auto it2 = m_by_ymir.find(suf); it2 != m_by_ymir.end()) {
			r = &it2->second;
		}
	}
	if (!r) {
		if (err) *err = "not mounted: " + vp;
		return false;
	}
	return m_packs[r->pack]->read(r->name, out, err);
}

} // namespace mtpack