#include <cstdlib>
#include <cstring>
#include <sys/stat.h>
#include <string>
#include <nlohmann/json.hpp>

#include "log.h"
#include "misc.h"
#include "config.h"

static FILE* fopen_or_raise(const char* __restrict path, const char* __restrict mode, bool ignore_enoent) {
    FILE* file = fopen(path, mode);
    if (!file && !(ignore_enoent && errno == ENOENT)) {
        throw_system_error(std::string("fopen(") + quote(path) + ')');
    }
    return file;
}

static void fclose_and_log(FILE* file) {
    if (!fclose(file)) {
        return;
    }
    log(std::string("Failed to close a file: fclose(): ") + strerror(errno));
}


std::string get_config_folder() {
    const char* path;

    path = getenv("XDG_CONFIG_HOME");
    if (path) {
        return std::string(path) + "/logmeow";
    }
    path = getenv("HOME");
    if (path) {
        return std::string(path) + "/.config/logmeow";
    }

    throw std::runtime_error("cannot find suitable config folder, please set XDG_CONFIG_HOME or HOME");
}

std::string get_config_file_path() {
    return get_config_folder() + "/config.json";
}

// tries to create a directory with an empty string if it's just "/" but who cares
void create_config_folders_if_necessary() {
    std::string full_path = get_config_folder();
    std::string path;
    size_t pos = 0;

    while (pos != std::string::npos) {
        pos = full_path.find('/', pos);
        if (pos != std::string::npos) {
            pos++;
        }
        path = full_path.substr(0, pos);
        if (!mkdir(path.c_str(), 0600)) {
            continue;
        }
        if (errno == EEXIST) {
            continue;
        }
        throw_system_error(std::string("mkdir(") + quote(path) + ')');
    }
}


void from_json(const nlohmann::json& j, Config& config) {
    j.at("logcat_command").get_to(config.logcat_command);
    j.at("normal_font_size").get_to(config.normal_font_size);
    j.at("monospace_font_size").get_to(config.monospace_font_size);
    j.at("filters").get_to(config.filters);
    j.at("exclusions").get_to(config.exclusions);
}

Config load_config() {
    std::string config_file_path = get_config_file_path();
    std::unique_ptr<FILE, decltype(&fclose_and_log)> config_file(fopen_or_raise(config_file_path.c_str(), "r", true), fclose_and_log);

    if (!config_file) {
        return Config();
    }

    return nlohmann::json::parse(config_file.get()).get<Config>();
}


void to_json(nlohmann::json& j, const Config& config) {
    j["logcat_command"] = config.logcat_command;
    j["normal_font_size"] = config.normal_font_size;
    j["monospace_font_size"] = config.monospace_font_size;
    j["filters"] = config.filters;
    j["exclusions"] = config.exclusions;
}

void write_config(const Config& config) {
    std::string config_file_path = get_config_file_path();
    std::string tmp_config_file_path = config_file_path + ".tmp";

    std::unique_ptr<FILE, decltype(&fclose_and_log)> config_file(fopen_or_raise(tmp_config_file_path.c_str(), "w", false), fclose_and_log);
    std::string str_config = nlohmann::json(config).dump(4);
    fwrite(str_config.data(), sizeof(char), str_config.size(), config_file.get());
    config_file.reset();

    if (!rename(tmp_config_file_path.c_str(), config_file_path.c_str())) {
        return;
    }
    throw_system_error(std::string("rename(") + quote(tmp_config_file_path) + ", " + quote(config_file_path) + ')');
}