#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <fstream>

#include "config.h"

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

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

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

Config parse_config(FILE* file) {
    size_t line_capacity_size = 128 * sizeof(char);
    char* line = static_cast<char*>(malloc(line_capacity_size));
    if (line == nullptr) {
        throw std::bad_alloc();
    }
    Config config;

    while (true) {
        errno = 0;
        if (getline(&line, &line_capacity_size, file) < 0) {
            int errsv = errno;
            free(line);
            if (errsv == ENOMEM) {
                throw std::bad_alloc();
            } else if (errsv != 0) {
                throw std::system_error(errsv, std::generic_category(), "getline()");
            } else {
                break;
            }
        }
        if (line_capacity_size == 0 || line[0] == '\0' || line[0] == '#') {
            continue;
        }
        if (char* newline = strchr(line, '\n')) {
            *newline = '\0';
        }

        if (strncmp(line, "logcat_command=", 15 * sizeof(char)) == 0) {
            config.logcat_command = &line[16];
        } else {
            std::invalid_argument e = std::invalid_argument(std::string("unknown config line: ") + line);
            free(line);
            throw e;
        }
    }

    return config;
}

void write_config(std::ofstream& file, const Config& config) {
    file << "# This is an auto-generated file, comments made will be lost\n"
         << "# This is a poor man's config file \"format\", there are only three legal lines:\n"
         << "#     # a comment, only available at the start of a line\n"
         << "#     (an empty line, no whitespace)\n"
         << "#     key=value pairs, no spaces around the delimiter, and no unknown keys\n\n"
         << "logcat_command=" << config.logcat_command;
}