module config.downloaderconfig;

/++
+ This struct represents the config of this
+ programm and is used by the other classes
+ to configure stuff
+/
struct Config
{
    /++
    + This variable holds the folder/path into which
    + mangas are downloaded by default
    +/
    string standard_download_folder;

    /++
    + This variable determins if mangas should be downloaded
    + again even if they already are downloaded
    +/
    bool   redownload_mangas_regardless;

    /++
    + This variable determins if the downloader should output debug infos
    +/
    bool   enable_debug_output;
}

/++
+ This class handles reading and creating the config files
+/
class DownloaderConfig
{
static private:
    import std.stdio : writeln;
    import std.json  : JSONValue, parseJSON;
    import std.file  : exists, mkdir, readText, copy;
    import std.stdio : toFile;
    import std.string: strip;
    import std.array : replace;

    /++
    + This specifies the default path to the config
    +/
    string default_config_path = "/.config/hentai_downloader/config.json";

    /++
    + This specifies the default path to the template file config file
    +/
    immutable string default_config_template_path = "./default_config_template.json";

    /++
    + This holds the text of the `default_config_template.json` file in case it
    + doesn't exist in the default path anymore
    +/
    immutable string default_config_template_text =
    `
    {
        "standard_download_folder"      : "~/Downloads/Lewds/",
        "redownload_mangas_regardless"  : false,
        "enable_debug_output"           : false
    }
    `;

    /++
    + This function checks the config in `config_path` exists
    +/
    bool configExists(string config_path)
    {
        return exists(config_path);
    }

    /++
    + This function creates a new default config at `config_path`
    +/
    void createNewConfig(string config_path)
    {
        writeln("[*] Creating new config file in ", config_path);

        // The folder that holds the config file
        immutable string config_dir = "/home/" ~ getUsername() ~ "/.config/hentai_downloader";

        /* writeln("Config folder:", config_dir); */

        // if the folder ~/.config/hentai_downloader doesnt exist
        if(!exists(config_dir))
            mkdir(config_dir); // Create it

        /* writeln("Config file: ", config_path); */

        // Write to template file into the config folder
        if(!exists(config_path))
        {
            /* writeln("Saving default config to file: ", config_path); */
            default_config_template_text.toFile(config_path);
        }
    }

    /++
    + Turns a relative path e.g. "~/.config" into an absolute path "/home/user/.config"
    +/
    string makeRelativePathAbsolute(string path)
    {
        return path.replace("~", "/home/"~getUsername());
    }

    /++
    + This function checks if the folder specified in the config file exists
    + and if not creates it
    +/
    void checkStandardFolder(Config config)
    {
        // FIXME: nested folders break me

        // Replace the relative path
        string absolutePath = makeRelativePathAbsolute(config.standard_download_folder);

        if(!exists(absolutePath))
        {
            // If the `standard_download_folder` doesnt exist, create it!
            absolutePath.mkdir();
        }
    }

    /++
    + Gets the username of the current user
    +/
    string getUsername()
    {
        import std.process : executeShell;
        import core.stdc.stdlib : exit, EXIT_FAILURE;
        // Execute whoami to get the current username
        auto whoami = executeShell(`whoami`);
        if(whoami.status != 0)
        {
            // If whoami fails exit the program
            // FIXME: raise an exception or something
            writeln("[!] Failed to get the current username");
            exit(EXIT_FAILURE);
        }
        // Return the stripped username
        return whoami.output.strip();
    }

    /++
    + Get the users .config path
    +/
    string getUserConfigPath()
    {
        // Return the combined path to the .config folder of the user
        return "/home/" ~ getUsername() ~ default_config_path;
    }

    /++
    + This function trys to parse the config file
    + given in `config_path`, and return a Config struct
    +/
    Config parseConfig(string config_path)
    {
        import std.conv : to;

        // Read the config file
        string config_text = to!string(readText(config_path));

        // Parse the config as JSON
        auto config_json = parseJSON(config_text);

        // Create a new config
        Config _config;

        // Assign the values that were parsed from the config file
        _config.standard_download_folder     = config_json["standard_download_folder"].str();
        _config.redownload_mangas_regardless = config_json["redownload_mangas_regardless"].boolean();
        _config.enable_debug_output          = config_json["enable_debug_output"].boolean();

        // Adjust the foler path
        _config.standard_download_folder = makeRelativePathAbsolute(_config.standard_download_folder);

        return _config;
    }

    /++
    + Loads and checks the given config
    +/
    Config loadMyConfig(string config_path)
    {
        // Get the cofig path for this user
        config_path = getUserConfigPath();

        // Check if the given config exists
        if(!configExists(config_path))
            createNewConfig(config_path); // If it doesn't, create it!

        // Parse the config
        Config _config = parseConfig(config_path);

        // Check the download folder
        checkStandardFolder(_config);

        return _config;
    }


public:
    /++
    + This loads and parses the default config at `default_config_path`
    + into a `Config` struct
    +/
    static Config loadConfig()
    {
        return loadMyConfig(this.default_config_path);
    }

    /++
    + This loads and parses a custom config from `custom_config_path`
    + into a `Config` struct
    +/
    static Config loadConfig(string custom_config_path)
    {
        return loadMyConfig(custom_config_path);
    }
}