#include <filesystem>
#include <string>
#include <set>

#include "coders/gzip.hpp"
#include "engine.hpp"
#include "files/engine_paths.hpp"
#include "files/files.hpp"
#include "util/stringutil.hpp"
#include "api_lua.hpp"
#include "../lua_engine.hpp"

namespace fs = std::filesystem;
using namespace scripting;

static fs::path resolve_path(const std::string& path) {
    return engine->getPaths()->resolve(path);
}

static fs::path resolve_path_soft(const std::string& path) {
    if (path.find(':') == std::string::npos) {
        return fs::u8path("");
    }
    return engine->getPaths()->resolve(path, false);
}

static int l_find(lua::State* L) {
    auto path = lua::require_string(L, 1);
    try {
        return lua::pushstring(L, engine->getResPaths()->findRaw(path));
    } catch (const std::runtime_error& err) {
        return 0;
    }
}

static int l_resolve(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    return lua::pushstring(L, path.u8string());
}

static int l_read(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    if (fs::is_regular_file(path)) {
        return lua::pushstring(L, files::read_string(path));
    }
    throw std::runtime_error(
        "file does not exists " + util::quote(path.u8string())
    );
}

static std::set<std::string> writeable_entry_points {
    "world", "export", "config"
};

static fs::path get_writeable_path(lua::State* L) {
    std::string rawpath = lua::require_string(L, 1);
    fs::path path = resolve_path(rawpath);
    auto entryPoint = rawpath.substr(0, rawpath.find(':'));
    if (writeable_entry_points.find(entryPoint) == writeable_entry_points.end()) {
        if (lua::getglobal(L, "__vc_warning")) {
            lua::pushstring(L, "writing to read-only entry point");
            lua::pushstring(L, entryPoint);
            lua::pushinteger(L, 1);
            lua::call_nothrow(L, 3);
        }
    }
    return path;
}

static int l_write(lua::State* L) {
    fs::path path = get_writeable_path(L);
    std::string text = lua::require_string(L, 2);
    files::write_string(path, text);
    return 1;
}

static int l_remove(lua::State* L) {
    std::string rawpath = lua::require_string(L, 1);
    fs::path path = resolve_path(rawpath);
    auto entryPoint = rawpath.substr(0, rawpath.find(':'));
    if (writeable_entry_points.find(entryPoint) == writeable_entry_points.end()) {
        throw std::runtime_error("access denied");
    }
    return lua::pushboolean(L, fs::remove(path));
}

static int l_remove_tree(lua::State* L) {
    std::string rawpath = lua::require_string(L, 1);
    fs::path path = resolve_path(rawpath);
    auto entryPoint = rawpath.substr(0, rawpath.find(':'));
    if (writeable_entry_points.find(entryPoint) == writeable_entry_points.end()) {
        throw std::runtime_error("access denied");
    }
    return lua::pushinteger(L, fs::remove_all(path));
}

static int l_exists(lua::State* L) {
    fs::path path = resolve_path_soft(lua::require_string(L, 1));
    return lua::pushboolean(L, fs::exists(path));
}

static int l_isfile(lua::State* L) {
    fs::path path = resolve_path_soft(lua::require_string(L, 1));
    return lua::pushboolean(L, fs::is_regular_file(path));
}

static int l_isdir(lua::State* L) {
    fs::path path = resolve_path_soft(lua::require_string(L, 1));
    return lua::pushboolean(L, fs::is_directory(path));
}

static int l_length(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    if (fs::exists(path)) {
        return lua::pushinteger(L, fs::file_size(path));
    } else {
        return lua::pushinteger(L, -1);
    }
}

static int l_mkdir(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    return lua::pushboolean(L, fs::create_directory(path));
}

static int l_mkdirs(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    return lua::pushboolean(L, fs::create_directories(path));
}

static int l_read_bytes(lua::State* L) {
    fs::path path = resolve_path(lua::require_string(L, 1));
    if (fs::is_regular_file(path)) {
        size_t length = static_cast<size_t>(fs::file_size(path));

        auto bytes = files::read_bytes(path, length);

        lua::createtable(L, length, 0);
        int newTable = lua::gettop(L);

        for (size_t i = 0; i < length; i++) {
            lua::pushinteger(L, bytes[i]);
            lua::rawseti(L, i + 1, newTable);
        }
        return 1;
    }
    throw std::runtime_error(
        "file does not exists " + util::quote(path.u8string())
    );
}

static void read_bytes_from_table(
    lua::State* L, int tableIndex, std::vector<ubyte>& bytes
) {
    if (!lua::istable(L, tableIndex)) {
        throw std::runtime_error("table expected");
    } else {
        size_t size = lua::objlen(L, tableIndex);
        for (size_t i = 0; i < size; i++) {
            lua::rawgeti(L, i + 1, tableIndex);
            const int byte = lua::tointeger(L, -1);
            lua::pop(L);
            if (byte < 0 || byte > 255) {
                throw std::runtime_error(
                    "invalid byte '" + std::to_string(byte) + "'"
                );
            }
            bytes.push_back(byte);
        }
    }
}

static int l_write_bytes(lua::State* L) {
    fs::path path = get_writeable_path(L);

    if (auto bytearray = lua::touserdata<lua::LuaBytearray>(L, 2)) {
        auto& bytes = bytearray->data();
        return lua::pushboolean(
            L, files::write_bytes(path, bytes.data(), bytes.size())
        );
    }

    std::vector<ubyte> bytes;
    read_bytes_from_table(L, 2, bytes);
    return lua::pushboolean(
        L, files::write_bytes(path, bytes.data(), bytes.size())
    );
}

static int l_list_all_res(lua::State* L, const std::string& path) {
    auto files = engine->getResPaths()->listdirRaw(path);
    lua::createtable(L, files.size(), 0);
    for (size_t i = 0; i < files.size(); i++) {
        lua::pushstring(L, files[i]);
        lua::rawseti(L, i + 1);
    }
    return 1;
}

static int l_list(lua::State* L) {
    std::string dirname = lua::require_string(L, 1);
    if (dirname.find(':') == std::string::npos) {
        return l_list_all_res(L, dirname);
    }
    fs::path path = resolve_path(dirname);
    if (!fs::is_directory(path)) {
        throw std::runtime_error(
            util::quote(path.u8string()) + " is not a directory"
        );
    }
    lua::createtable(L, 0, 0);
    size_t index = 1;
    for (auto& entry : fs::directory_iterator(path)) {
        auto name = entry.path().filename().u8string();
        auto file = dirname + "/" + name;
        lua::pushstring(L, file);
        lua::rawseti(L, index);
        index++;
    }
    return 1;
}

static int l_gzip_compress(lua::State* L) {
    std::vector<ubyte> bytes;

    read_bytes_from_table(L, 1, bytes);
    auto compressed_bytes = gzip::compress(bytes.data(), bytes.size());
    int newTable = lua::gettop(L);

    for (size_t i = 0; i < compressed_bytes.size(); i++) {
        lua::pushinteger(L, compressed_bytes.data()[i]);
        lua::rawseti(L, i + 1, newTable);
    }
    return 1;
}

static int l_gzip_decompress(lua::State* L) {
    std::vector<ubyte> bytes;

    read_bytes_from_table(L, 1, bytes);
    auto decompressed_bytes = gzip::decompress(bytes.data(), bytes.size());
    int newTable = lua::gettop(L);

    for (size_t i = 0; i < decompressed_bytes.size(); i++) {
        lua::pushinteger(L, decompressed_bytes.data()[i]);
        lua::rawseti(L, i + 1, newTable);
    }
    return 1;
}

static int l_read_combined_list(lua::State* L) {
    std::string path = lua::require_string(L, 1);
    if (path.find(':') != std::string::npos) {
        throw std::runtime_error("entry point must not be specified");
    }
    return lua::pushvalue(L, engine->getResPaths()->readCombinedList(path));
}

static int l_read_combined_object(lua::State* L) {
    std::string path = lua::require_string(L, 1);
    if (path.find(':') != std::string::npos) {
        throw std::runtime_error("entry point must not be specified");
    }
    return lua::pushvalue(L, engine->getResPaths()->readCombinedObject(path));
}

const luaL_Reg filelib[] = {
    {"exists", lua::wrap<l_exists>},
    {"find", lua::wrap<l_find>},
    {"isdir", lua::wrap<l_isdir>},
    {"isfile", lua::wrap<l_isfile>},
    {"length", lua::wrap<l_length>},
    {"list", lua::wrap<l_list>},
    {"mkdir", lua::wrap<l_mkdir>},
    {"mkdirs", lua::wrap<l_mkdirs>},
    {"read_bytes", lua::wrap<l_read_bytes>},
    {"read", lua::wrap<l_read>},
    {"remove", lua::wrap<l_remove>},
    {"remove_tree", lua::wrap<l_remove_tree>},
    {"resolve", lua::wrap<l_resolve>},
    {"write_bytes", lua::wrap<l_write_bytes>},
    {"write", lua::wrap<l_write>},
    {"gzip_compress", lua::wrap<l_gzip_compress>},
    {"gzip_decompress", lua::wrap<l_gzip_decompress>},
    {"read_combined_list", lua::wrap<l_read_combined_list>},
    {"read_combined_object", lua::wrap<l_read_combined_object>},
    {NULL, NULL}};