//! Uses the GOG api as described [here](https://gogapidocs.readthedocs.io/en/latest/).
//!
//! # Example
//! ```
//! use gog::Gog;
//!
//! let mut http_client = Http::new();
//! let mut gog = Gog::new(&mut http_client);
//! gog.login();
//! gog.sync(download_folder);
//! ```

use configfiles::{ConfigFiles, ConfigError};
use http::{Http, HttpError};
use models;
use models::{Token, Game, Installer, Config};
use serde_json;
use serde_json::Value;
use std::collections::HashMap;
use std::fmt;
use std::fs;
use std::fs::File;
use std::io;
use std::io::Write;
use std::path::Path;

/// Wraps `ConfigError`, `HttpError`, `serde_json::Error`, and `io::Error`.
#[derive(Debug)]
pub enum GogError {
    Error(&'static str),
    ConfigError(ConfigError),
    HttpError(HttpError),
    SerdeError(serde_json::Error),
    IOError(io::Error),
}

impl fmt::Display for GogError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match *self {
            GogError::Error(ref err) => fmt::Display::fmt(err, f),
            GogError::ConfigError(ref err) => fmt::Display::fmt(err, f),
            GogError::HttpError(ref err) => fmt::Display::fmt(err, f),
            GogError::SerdeError(ref err) => fmt::Display::fmt(err, f),
            GogError::IOError(ref err) => fmt::Display::fmt(err, f),
        }
    }
}

impl From<ConfigError> for GogError {
    fn from(e: ConfigError) -> Self {
        GogError::ConfigError(e)
    }
}

impl From<HttpError> for GogError {
    fn from(e: HttpError) -> Self {
        GogError::HttpError(e)
    }
}

impl From<serde_json::Error> for GogError {
    fn from(e: serde_json::Error) -> Self {
        GogError::SerdeError(e)
    }
}

impl From<io::Error> for GogError {
    fn from(e: io::Error) -> Self {
        GogError::IOError(e)
    }
}

/// Wraps the GOG api.
/// At the moment Client ID and Client Secret are hardcoded to the galaxy client.
pub struct Gog<'a> {
    client_id: String,
    client_secret: String,
    redirect_uri: String,
    games_uri: String,
    http_client: &'a mut Http,
}

impl<'a> Gog<'a> {
    /// Create a new instance of `Gog`.
    pub fn new(http_client: &'a mut Http) -> Gog<'a> {
        Gog {
            client_id: String::from("46899977096215655"),
            client_secret: String::from("9d85c43b1482497dbbce61f6e4aa173a433796eeae2ca8c5f6129f2dc4de46d9"),
            redirect_uri: String::from("https://embed.gog.com/on_login_success?origin=client"),
            games_uri: String::from("https://embed.gog.com/user/data/games"),
            http_client: http_client,
        }
    }

    /// Logs into a gog account.
    /// If a token was already saved it should work automatically. Otherwise you
    /// will get an url which you have to open in a browser. There you have to
    /// login and copy the code parameter from the next page into the prompt.
    pub fn login(&mut self) -> Result<(), GogError> {
        let config = ConfigFiles::new();
        let mut token: Token = match config.load("token.json") {
            Ok(value) => value,
            Err(_) => {
                let code = self.get_code()?;
                self.get_token(code.as_str())?
            }
        };

        if token.is_expired() {
            token = self.refresh_token(token.refresh_token.as_str())?;
        }

        config.save("token.json", &token)?;

        let auth_header = format!("Authorization: Bearer {token}", token = token.access_token);
        self.http_client.add_header(auth_header.as_str())?;

        Ok(())
    }

    /// Syncs the contents of a gog account with a local folder.
    /// Uses a hash to figure out whether something has changed.
    pub fn sync(&mut self,
                storage_path: &str,
                storage_path_movies: &str,
                os_filters: &Vec<String>,
                language_filters: &Vec<String>)
                -> Result<(), GogError> {
        let configfiles = ConfigFiles::new();
        let mut config: Config = match configfiles.load("config.json") {
            Ok(value) => value,
            Err(_) => {
                error!("Configuration error, generating new one...");

                Config {
                    storage: String::from(storage_path),
                    movie_storage: String::from(storage_path_movies),
                    games: HashMap::new(),
                    installers: HashMap::new(),
                    extras: HashMap::new(),
                    os_filters: os_filters.clone(),
                    language_filters: language_filters.clone(),
                }
            }
        };

        let game_ids = self.get_game_ids()?;

        for game_id in game_ids {
            let game_hash_saved = match config.games.get(&game_id.to_string()) {
                Some(value) => value.clone(),
                None => u64::min_value(),
            };

            let game = match self.get_game(game_id, &os_filters, &language_filters) {
                Ok(value) => value,
                Err(error) => {
                    error!("{}", error);
                    break;
                }
            };

            let game_hash = models::get_hash(&game);

            if game_hash_saved == game_hash {
                info!("{} already up to date.", &game.title);
                continue;
            }

            let game_root = if game.is_movie {
                Path::new(storage_path_movies).join(&game.title)
            } else {
                Path::new(storage_path).join(&game.title)
            };

            fs::create_dir_all(&game_root)?;

            if !game.cd_key.is_empty() {
                let key_path = Path::new(game_root.as_os_str()).join("key.txt");
                let mut key_file = File::create(&key_path)?;
                key_file.write_all(game.cd_key.as_bytes())?
            }

            for installer in game.installers {
                let installer_hash_saved = match config.installers.get(&installer.manual_url) {
                    Some(value) => value.clone(),
                    None => u64::min_value(),
                };
                let installer_hash = models::get_hash(&installer);

                if installer_hash_saved == installer_hash {
                    info!("{} already up to date.", &installer.manual_url);
                    continue;
                }

                let installer_root = Path::new(&game_root).join(&installer.language);
                fs::create_dir_all(&installer_root)?;

                let installer_uri = format!("https://embed.gog.com{}", installer.manual_url);

                info!("downloading {} for {}...",
                      &installer.manual_url,
                      &game.title);
                self.http_client.download(installer_uri.as_str(), &installer_root)?;

                config.installers.insert(installer.manual_url, installer_hash);
                configfiles.save("config.json", &config)?;
            }

            for extra in game.extras {
                let extra_hash_saved = match config.extras.get(&extra.manual_url) {
                    Some(value) => value.clone(),
                    None => u64::min_value(),
                };

                let extra_hash = models::get_hash(&extra);

                if extra_hash_saved == extra_hash {
                    info!("{} already up to date.", &extra.manual_url);
                    continue;
                }

                let extra_uri = format!("https://embed.gog.com{}", extra.manual_url);

                info!("downloading {} for {}...", &extra.name, &game.title);
                self.http_client.download(extra_uri.as_str(), &game_root)?;

                config.extras.insert(extra.manual_url, extra_hash);
                configfiles.save("config.json", &config)?;
            }

            config.games.insert(game_id.to_string(), game_hash);
            configfiles.save("config.json", &config)?;
        }

        Ok(())
    }

    fn get_code(&self) -> Result<String, GogError> {
        let auth_uri = self.auth_uri(self.client_id.as_str(), self.redirect_uri.as_str());

        println!("Open the following url in a browser, login to your account and paste the \
                  resulting code parameter.");
        println!("{}", auth_uri);

        let mut code = String::new();

        print!("Code: ");
        io::stdout().flush()?;

        io::stdin()
            .read_line(&mut code)
            .expect("Failed to read line");

        Ok(code)
    }

    fn get_token(&mut self, code: &str) -> Result<Token, GogError> {
        let token_uri = self.token_uri(self.client_id.as_str(),
                                       self.client_secret.as_str(),
                                       code,
                                       self.redirect_uri.as_str());

        let token_response = match self.http_client.get(token_uri.as_str()) {
            Ok(value) => value,
            Err(error) => return Err(GogError::HttpError(error)),
        };

        match serde_json::from_str(&token_response) {
            Ok(value) => Ok(value),
            Err(error) => Err(GogError::SerdeError(error)),
        }
    }

    fn refresh_token(&mut self, refresh_token: &str) -> Result<Token, GogError> {
        let token_refresh_uri = self.token_refresh_uri(self.client_id.as_str(),
                                                       self.client_secret.as_str(),
                                                       refresh_token);

        let token_response = match self.http_client.get(token_refresh_uri.as_str()) {
            Ok(value) => value,
            Err(error) => return Err(GogError::HttpError(error)),
        };

        match serde_json::from_str(&token_response) {
            Ok(value) => Ok(value),
            Err(error) => Err(GogError::SerdeError(error)),
        }
    }

    fn get_game_ids(&mut self) -> Result<Vec<u64>, GogError> {
        let response = self.http_client.get(self.games_uri.as_str())?;
        let game_ids_raw: Value = serde_json::from_str(response.as_str())?;
        let game_ids_serde = &game_ids_raw["owned"];

        let mut game_ids: Vec<u64> = Vec::new();

        if !game_ids_serde.is_array() {
            return Err(GogError::Error("Error parsing game ids."));
        }

        for game_id in game_ids_serde.as_array().unwrap() {
            let game_id_parsed = game_id.as_u64().unwrap_or(0);

            if game_id_parsed == 0 {
                error!("Cant parse game id {}", game_id);
                continue;
            }

            // The numbers in this list are excluded because they refer to
            // favourites, promotions and such.
            if [1, 2, 3, 4, 5].contains(&game_id_parsed) {
                continue;
            }

            game_ids.push(game_id_parsed);
        }

        return Ok(game_ids);
    }

    fn get_game(&mut self,
                game_id: u64,
                os_filters: &Vec<String>,
                language_filters: &Vec<String>)
                -> Result<Game, GogError> {
        let game_uri = self.game_uri(game_id);

        let response = self.http_client.get(game_uri.as_str())?;

        let mut game: Game = serde_json::from_str(&response)?;

        let game_raw: Value = serde_json::from_str(response.as_str())?;
        let downloads = &game_raw["downloads"];

        if game_raw.is_object() && !game_raw.as_object().unwrap().contains_key("forumLink") {
            return Err(GogError::Error("No forumLink property"));
        }

        let is_movie = match game_raw["forumLink"].as_str() {
            Some(value) => value == "https://embed.gog.com/forum/movies",
            None => false,
        };

        game.is_movie = is_movie;

        for languages in downloads.as_array() {
            for language in languages {
                if !language.is_array() || language.as_array().unwrap().len() < 2 {
                    error!("Skipping a language for {}", game.title);
                    continue;
                }

                let installer_language = match language[0].as_str() {
                    Some(value) => value.to_lowercase(),
                    None => String::default(),
                };

                if installer_language.is_empty() {
                    error!("Skipping a language for {}", game.title);
                    continue;
                }

                if !is_movie && !language_filters.is_empty() &&
                   !language_filters.contains(&installer_language) {
                    info!("Skipping {} for {}", &installer_language, game.title);
                    continue;
                }

                for systems in language[1].as_object() {
                    for system in systems.keys() {
                        if is_movie && !os_filters.is_empty() && !os_filters.contains(system) {
                            info!("Skipping {} {} for {}",
                                  &installer_language,
                                  system,
                                  game.title);
                            continue;
                        }

                        for real_downloads in systems.get(system) {
                            for real_download in real_downloads.as_array() {
                                for download in real_download {
                                    if !download.is_object() ||
                                       !download.as_object().unwrap().contains_key("manualUrl") {
                                        error!("Skipping an installer for {}", game.title);
                                        continue;
                                    }

                                    let installer = Installer {
                                        manual_url: String::from(download["manualUrl"]
                                            .as_str()
                                            .unwrap()),
                                        version: String::from(download["version"]
                                            .as_str()
                                            .unwrap_or("")),
                                        os: system.clone(),
                                        language: installer_language.clone(),
                                    };

                                    game.installers.push(installer);
                                }
                            }
                        }
                    }
                }
            }
        }

        Ok(game)
    }

    fn auth_uri(&self, client_id: &str, redirect_uri: &str) -> String {
        format!("https://auth.gog.\
                 com/auth?client_id={client_id}&redirect_uri={redirect_uri}&response_type=code&layout=client2",
                client_id = client_id,
                redirect_uri = redirect_uri)
    }

    fn token_uri(&self,
                 client_id: &str,
                 client_secret: &str,
                 code: &str,
                 redirect_uri: &str)
                 -> String {
        format!("https://auth.gog.\
                 com/token?client_id={client_id}&client_secret={client_secret}&grant_type=authorization_code&code={code}&redirect_uri={redirect_uri}",
                client_id = client_id,
                client_secret = client_secret,
                code = code.trim(),
                redirect_uri = redirect_uri)
    }

    fn token_refresh_uri(&self,
                         client_id: &str,
                         client_secret: &str,
                         refresh_token: &str)
                         -> String {
        format!("https://auth.gog.\
                 com/token?client_id={client_id}&client_secret={client_secret}&grant_type=refresh_token&refresh_token={refresh_token}",
                client_id = client_id,
                client_secret = client_secret,
                refresh_token = refresh_token)
    }

    fn game_uri(&self, game_id: u64) -> String {
        format!("https://embed.gog.com/account/gameDetails/{game_id}.json",
                game_id = game_id)
    }
}