package gui.backend;

import java.io.File;
import java.io.IOException;

import java.awt.GraphicsEnvironment;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontFormatException;

/**
 * A class solely to store user settings relating to default behaviors,
 * difficulty, filepaths, and more.
 *
 * These user settings are stored in a settings file that must be stored
 * either in "~/.config/sudoku/settings.json" or 
 * "%APPDATA%/Local/Sudoku/settings.json" depending on the user's operating
 * system.
 * 
 * (Currently) Configurable settings include:
 *      - Default puzzles directory for .sdku files;
 *      - New file Properties;
 *      - Font;
 *      - Window size;
 *      - Window resizing (experimental);
 *      - Cell start mode, meaning if a cell is blank and selected, input
 *          is either going to the notes or entering a value;
 *      - Application default open behavior;
 *      - Theme, specifically by providing a default.theme file formatted for JSON;
 *      - Auto-fill notes with possible values;
 *      - Auto-check user-entered values with the correct values;
 *      - Auto-save and auto-save frequency;
 */
public class Settings {
    private final String os;

    // The directory where the settings file is located.
    private String appDirectory; 

    // The default directory for .sdku files.
    private String defaultDirectory; 

    // The properties for creating a new .sdku file.
    private int newFileProperties;

    // The font to be used throughout the application.
    private Font font;

    // The default dimension of the application window.
    private Dimension dimension;

    // The default dimension of the cells in the application window.
    private Dimension cellDimension;

    // Resizable setting
    private boolean resizable;

    // Cell GUI Start Mode
    private boolean cellGUIStartMode;

    // Default open state for the application.
    private int defaultOpenState;

    // Theme object storing the colors for the GUI components.
    private Theme theme;

    // Auto-fill notes
    private boolean autoFillNotes;

    // Auto check values
    private boolean autoCheckValues;

    // Auto-save whenever a new note or value is changed.
    private boolean autoSave;

    // Auto-save frequency
    private int autoSaveFrequency;

    /**
     * Create a new Settings object, initializing the default settings
     * or reading in the settings from settings file if it exists.
     * 
     * While the defaultDirectory can be modified, it will not change where
     * the settings file is located. The settings file is always located in
     * either "~/.config/sudoku/" or "%APPDATA%/Local/Sudoku/", depending
     * on the user's operating system.
     * 
     * The settings file is settings.json.
     */
    public Settings() {
        os = System.getProperty("os.name").toLowerCase();
        if(os.startsWith("windows"))
            appDirectory = System.getProperty("user.home") + 
                            "\\AppData\\Local\\Sudoku\\";
        else
            appDirectory = System.getProperty("user.home") + 
                            "/.config/sudoku/";

        File dir = new File(appDirectory);
        
        // If the app directory does not exist, create it and populate a
        // settings.json file with the default settings.
        if (!dir.exists() || !dir.isDirectory()) {
            dir.mkdirs();
            defaultSettings();
            updateSettingsFile();

        } else readSettings();
    }

    /**
     * Set the default settings for the application and write them to the
     * settings file.
     */
    private void defaultSettings() {
        // Setup the default directory for .sdku puzzle files.
        defaultDirectory = appDirectory + "puzzles";
        File dir = new File(defaultDirectory);

        // Create the puzzles directory.
        if(!dir.exists() || !dir.isDirectory())
            dir.mkdirs();

        // Load the font from the system directory.
        if(loadFont("HackNerdFont-Regular") == 0)
            font = new Font("Hack Nerd Font", Font.PLAIN, 16);

        // If the font does not exist, use Arial as the default font.
        else 
            font = new Font("Arial", Font.PLAIN, 16);

        // Set other default settings.
        newFileProperties = 0;
        dimension = new Dimension(600, 800);
        resizable = false;
        cellGUIStartMode = true;
        defaultOpenState = 0;
        theme = new Theme(new File(appDirectory + "default.theme"));
        autoFillNotes = false;
        autoCheckValues = true;
        autoSave = false;
        autoSaveFrequency = 0;
        setCellDimensions();

        // Write the default settings to the settings.json file.
        updateSettingsFile();
    }

    /**
     * Open and write the settings to the settings file.
     * 
     * This method is called whenever a setting is updated.
     */
    private void updateSettingsFile() {
        // TODO: Write the settings to the settings file.
    }

    /**
     * Read the settings from the settings file.
     * 
     * If the settings file does not exist, the default settings will be used
     * to populate the Settings file.
     */
     private void readSettings() {
        File settingsFile = new File(appDirectory + "/settings.json");
        if (!settingsFile.exists() && !settingsFile.isDirectory()) {
            defaultSettings();
            return;
        }

        // TODO: Read the settings from the settings file.
     }

    /**
     * Load the font from the resources folder in the user's system directory.
     * 
     * @return int 0 if successful, 1 if the file does not exist.
     */
    private int loadFont(String fontName) {
        // Load the font from the system directory.
        String fontFilepath;
        if(os.startsWith("windows"))
            fontFilepath = System.getProperty("user.home") + 
                            "\\AppData\\Local\\Microsoft\\Windows\\Fonts\\" +
                            fontName + ".ttf";
        else if(os.startsWith("mac"))
            fontFilepath = "/Library/Fonts/" + fontName + ".ttf";
        else {
            fontName = "HackNerdFontMono-Regular";
            fontFilepath = "/usr/share/fonts/TTF/" + fontName + ".ttf";
        }
        // Register the font with the GraphicsEnvironment.
        try {
            GraphicsEnvironment ge = GraphicsEnvironment.
                getLocalGraphicsEnvironment();

            ge.registerFont(Font.createFont(
                Font.TRUETYPE_FONT,
                new File(fontFilepath)
            ));

            return 0;

        } catch(IOException | FontFormatException e) {
            System.out.println("Filepath of font not found: " +
                                fontFilepath + " does not exist.");
            return 1;
        }
    }

    /**
     * The Default Directory is a configurable setting, where the user can
     * specify a default directory to store .sdku files. This is useful for
     * eliminating the need for user input for file operations.
     *
     * By default, the default directory is either "~/.config/sudoku/puzzles"
     * or "%APPDATA%/Local/Sudoku/Puzzles", depending on the user's operating
     * system.
     * 
     * @return String
     */
    public String getDefaultDirectory() {
        return defaultDirectory;
    }

    /**
     * Set the default directory and write it to the settings file.
     * 
     * @param defaultDirectory
     */
    public void setDefaultDirectory(String defaultDirectory) {
        this.defaultDirectory = defaultDirectory;
        updateSettingsFile();
    }

    /**
     * New File Properties is a configurable setting, where the following
     * values are allowable:
     *      0 - Create a new, blank .sdku file
     *      1 - Create a new, random .sdku file
     * 
     * Integer is being used instead of boolean since additional properties
     * may be added in the future.
     *
     * @return int
     */
    public int getNewFileProperties() {
        return newFileProperties;
    }

    /**
     * Set the new file properties and write them to the settings file.
     * 
     * @param newFileProperties
     */
    public void setNewFileProperties(int newFileProperties) {
        this.newFileProperties = newFileProperties;
        updateSettingsFile();
    }

    /**
     * The Font is a configurable setting, where the user can specify a
     * font to be used throughout the application.
     * 
     * Fonts are loaded from the system directory. In Windows, the font
     * is loaded from C:\Windows\Fonts\. In MacOS, the font is loaded 
     * from /Library/Fonts/. In Linux, the font is loaded from 
     * /usr/share/fonts/.
     * 
     * @return Font
     */
    public Font getFont() {
        return font;
    }

    /**
     * Set the font and write it to the settings file.
     * 
     * @param font
     */
    public void setFont(Font font) {
        this.font = font;
        updateSettingsFile();
    }

    /**
     * The default dimension of the application window.
     * 
     * The user can specify both the starting width and height of the app,
     * and the app will remember the last used dimensions as well.
     * 
     * @return Dimension
     */
    public Dimension getDimension() {
        return dimension;
    }

    /**
     * Set the default dimension and write it to the settings file.
     * 
     * @param dimension
     */
    public void setDimension(Dimension dimension) {
        this.dimension = dimension;
        updateSettingsFile();
    }

    /**
     * The resizable setting for the application window.
     * 
     * By default, the application window is not resizable and is considered
     * an experimental feature. Dynamic layout is not yet supported.
     * 
     * @return boolean
     */
    public boolean getResizable() {
        return resizable;
    }

    /**
     * Set the resizable setting and write it to the settings file.
     *
     * @param resizable
     */
    public void setResizable(boolean resizable) {
        this.resizable = resizable;
        updateSettingsFile();
    }

    /**
     * The Cell GUI Start Mode is a configurable setting, where the user can
     * specify whether the cell GUI should start in notes mode or value mode.
     * 
     * By default, the cell GUI starts in value mode, ie. returns false.
     * Set to true to start in notes mode.
     * 
     * @return boolean
     */
    public boolean getCellGUIStartMode() {
        return cellGUIStartMode;
    }

    /**
     * Set the cell GUI start mode and write it to the settings file.
     * 
     * @param cellGUIStartMode
     */
    public void setCellGUIStartMode(boolean cellGUIStartMode) {
        this.cellGUIStartMode = cellGUIStartMode;
        updateSettingsFile();
    }

    /**
     * The default open state for the application. The following values
     * are accepted:
     *     0 - Open the default easy.sdku file, default behavior;
     *     1 - Open the last opened .sdku file;
     *     2 - Open a new, blank .sdku file; and 
     *     3 - Open a new, random .sdku file.
     * 
     * NOTE: The value 2 is not yet supported. 
     * 
     * @return
     */
    public int getDefaultOpenState() {
        return defaultOpenState;
    }

    /**
     * Set the default open state for the application and write it to the
     * settings file.
     * 
     * @param defaultOpenState
     */
    public void setDefaultOpenState(int defaultOpenState) {
        this.defaultOpenState = defaultOpenState;
        updateSettingsFile();
    }

    /**
     * The Theme object stores the colors for the GUI components.
     * 
     * The available colors for customization are:
     *      - primaryBackground
     *      - secondaryBackground
     *      - primaryText
     *      - secondaryText
     *      - primaryHighlight
     *      - secondaryHighlight
     *      - primaryBorder
     *      - secondaryBorder
     *      - primaryButton
     *      - secondaryButton
     *      - primaryButtonHighlight
     *      - secondaryButtonHighlight
     *      - primaryButtonBorder
     *      - secondaryButtonBorder
     *
     * @see Theme
     * @return
     */
    public Theme getTheme() {
        return theme;
    }

    /**
     * Set the theme and write it to the settings file.
     * 
     * @param theme
     */
    public void setTheme(Theme theme) {
        this.theme = theme;
        updateSettingsFile();
    }

    /**
     * The Auto-fill notes setting is a configurable setting, where the user
     * can specify whether notes should be automatically filled in when a
     * value is placed in a cell.
     * 
     * By default, the auto-fill notes setting is set to false.
     * 
     * @return boolean
     */
    public boolean getAutoFillNotes() {
        return autoFillNotes;
    }

    /**
     * Set the auto-fill notes setting and write it to the settings file.
     * 
     * @param autoFillNotes
     */
    public void setAutoFillNotes(boolean autoFillNotes) {
        this.autoFillNotes = autoFillNotes;
        setCellGUIStartMode(autoFillNotes);
        updateSettingsFile();
    }

    /**
     * The Auto-check values setting is a configurable setting, where the user
     * can specify whether values should be automatically checked when placed
     * in a cell.
     * 
     * By default, the auto-check values setting is set to false.
     * 
     * @return
     */
    public boolean getAutoCheckValues() {
        return autoCheckValues;
    }

    /**
     * Set the auto-check values setting and write it to the settings file.
     * 
     * @param autoCheckValues
     */
    public void setAutoCheckValues(boolean autoCheckValues) {
        this.autoCheckValues = autoCheckValues;
        updateSettingsFile();
    }

    /**
     * The default dimensions of the cells in the application window.
     * 
     * The default dimensions are set to 50x50 pixels.
     * 
     * @return
     */
    public Dimension getCellDimensions() {
        return cellDimension;
    }

    private void setCellDimensions() {
        int height;
        int width;

        if(dimension.height < 500) height = 50;
        else height = dimension.height / 10;

        if(dimension.width < 500) width = 50;
        else width = dimension.width / 10;

        cellDimension = new Dimension(width, height);
    }

    /**
     * Auto-save is a user-configurable setting to automatically save the
     * puzzle anytime they make a change. Additionally, auto-save will 
     * result in the file being automatically saved every 60 seconds, to
     * preserve the elapsed time tracking.
     * 
     * @return boolean
     */
    public boolean getAutoSave() {
        return autoSave;
    }

    /**
     * Set the auto-save feature to a specified state.
     * 
     * @param autoSave
     */
    public void setAutoSave(boolean autoSave) {
        this.autoSave = autoSave;
        updateSettingsFile();
    }

    /**
     * The auto save frequnecy, in seconds.
     * 
     * By default, auto-save will save whenever the user makes changes on the
     * puzzle. However, since elapsed time and other future features are not
     * user-controlled events, the frequency is used to specify in a separate
     * thread how often the .sdku file should be saved.
     * 
     * For performance and realistic necessity for preserving this kind of
     * information, the frequency should (not required) be following:
     *      - 0: off;
     *      - 5: 5 second intervals;
     *      - 30: 30 second intervals;
     *      - 60: 60 second intervals.
     * 
     * If auto-save is off, then this value is 0 automatically. When auto-save
     * is turned on, by default the value is 30.
     * 
     * @return auto-save frequency
     */
    public int getAutoSaveFrequency() {
        return autoSaveFrequency;
    }

    /**
     * Set the auto-save frequency, in seconds.
     * 
     * @param autoSaveFrequency
     */
    public void setAutoSaveFrequency(int autoSaveFrequency) {
        this.autoSaveFrequency = autoSaveFrequency;
        updateSettingsFile();
    }
}