package net.rustnotmc.client;

import net.minecraft.client.Minecraft;
import net.minecraft.client.gui.GuiChat;
import net.minecraft.client.gui.GuiIngameMenu;
import net.minecraft.client.gui.GuiMainMenu;
import net.minecraft.client.gui.GuiOptions;
import net.minecraft.client.gui.GuiScreen;
import net.minecraft.client.gui.GuiWorldSelection;
import net.minecraft.client.gui.achievement.GuiStats;
import net.minecraft.client.gui.advancements.GuiScreenAdvancements;
import net.minecraft.client.gui.inventory.GuiContainer;
import net.minecraft.client.settings.KeyBinding;
import net.rustnotmc.api.client.ClientServices;
import net.rustnotmc.api.client.Commands;
import net.rustnotmc.api.client.Input;
import net.rustnotmc.api.client.Screen;
import net.rustnotmc.api.client.ScreenKind;
import org.lwjgl.input.Mouse;

/**
 * The client's implementation of the mod API.
 *
 * Everything here reads presentation state the client already has: what screen
 * is open, what the window measures, which key is held. Nothing reaches into
 * the world, a player or a packet, because the server owns those and a client
 * mod is not allowed to decide them.
 *
 * The values are recomputed per call rather than cached. A mod may ask once a
 * frame, and a stale answer would be worse than a cheap one.
 *
 * Lives in game-fork/src-overlay; src is regenerated on every build.
 */
public final class RsxClientServices implements ClientServices {

    private final Minecraft minecraft;
    private final RsxScreen screen = new RsxScreen();
    private final RsxInput input = new RsxInput();
    private final RsxCommands commands = new RsxCommands();

    private long tick;
    private long frame;

    public RsxClientServices(Minecraft minecraft) {
        this.minecraft = minecraft;
    }

    /** Called once per frame by the bootstrap, before anything is asked. */
    public void advanceFrame() {
        this.frame++;
    }

    /** Called once per tick by the bootstrap. */
    public void advanceTick() {
        this.tick++;
    }

    boolean dispatchCommand(String line, String sender) {
        return this.commands.dispatch(line, sender);
    }

    @Override
    public Screen screen() {
        return this.screen;
    }

    @Override
    public Input input() {
        return this.input;
    }

    @Override
    public Commands commands() {
        return this.commands;
    }

    @Override
    public long tick() {
        return this.tick;
    }

    @Override
    public long frame() {
        return this.frame;
    }

    @Override
    public net.rustnotmc.api.client.FrameStats frameStats() {
        return RsxFrameStats.latest();
    }

    private final class RsxScreen implements Screen {

        @Override
        public ScreenKind kind() {
            GuiScreen current = minecraft.currentScreen;
            if (current == null) {
                return minecraft.world == null ? ScreenKind.UNKNOWN : ScreenKind.IN_GAME;
            }
            if (current instanceof GuiChat) {
                return ScreenKind.CHAT;
            }
            if (current instanceof GuiIngameMenu) {
                return ScreenKind.PAUSED;
            }
            if (current instanceof GuiMainMenu) {
                return ScreenKind.MAIN_MENU;
            }
            if (current instanceof GuiWorldSelection) {
                return ScreenKind.WORLD_SELECTION;
            }
            if (current instanceof GuiOptions) {
                return ScreenKind.OPTIONS;
            }
            if (current instanceof GuiContainer) {
                return ScreenKind.INVENTORY;
            }
            if (current instanceof GuiScreenAdvancements || current instanceof GuiStats) {
                return ScreenKind.ADVANCEMENTS;
            }
            // a screen this build has no name for, over a loaded world or not
            return minecraft.world == null ? ScreenKind.UNKNOWN : ScreenKind.PAUSED;
        }

        @Override
        public int width() {
            return minecraft.displayWidth / Math.max(1, scaleFactor());
        }

        @Override
        public int height() {
            return minecraft.displayHeight / Math.max(1, scaleFactor());
        }

        @Override
        public float scale() {
            return (float) scaleFactor();
        }

        @Override
        public int windowWidth() {
            return minecraft.displayWidth;
        }

        @Override
        public int windowHeight() {
            return minecraft.displayHeight;
        }

        private int scaleFactor() {
            int gui = minecraft.gameSettings == null ? 2 : minecraft.gameSettings.guiScale;
            if (gui <= 0) {
                // auto: the client picks the largest scale that keeps the
                // interface at least this wide
                int width = minecraft.displayWidth;
                gui = 1;
                while (width / (gui + 1) >= 320 && gui < 4) {
                    gui++;
                }
            }
            return gui;
        }
    }

    private final class RsxInput implements Input {

        @Override
        public boolean keyDown(String keyId) {
            if (keyId == null || minecraft.gameSettings == null) {
                return false;
            }
            KeyBinding[] bindings = minecraft.gameSettings.keyBindings;
            if (bindings == null) {
                return false;
            }
            for (int i = 0; i < bindings.length; i++) {
                if (keyId.equals(bindings[i].getKeyDescription()) && bindings[i].isKeyDown()) {
                    return true;
                }
            }
            return false;
        }

        @Override
        public boolean anyKeyDown() {
            KeyBinding[] bindings = minecraft.gameSettings == null
                    ? null : minecraft.gameSettings.keyBindings;
            if (bindings == null) {
                return false;
            }
            for (int i = 0; i < bindings.length; i++) {
                if (bindings[i].isKeyDown()) {
                    return true;
                }
            }
            return false;
        }

        @Override
        public boolean focused() {
            return minecraft.inGameHasFocus;
        }

        @Override
        public int mouseX() {
            return scaled(Mouse.getX());
        }

        @Override
        public int mouseY() {
            return scaled(Mouse.getY());
        }

        @Override
        public int mouseButtons() {
            int buttons = 0;
            if (Mouse.isButtonDown(0)) {
                buttons |= 1;
            }
            if (Mouse.isButtonDown(1)) {
                buttons |= 2;
            }
            if (Mouse.isButtonDown(2)) {
                buttons |= 4;
            }
            return buttons;
        }

        @Override
        public boolean mouseDown(int button) {
            return button >= 0 && button <= 2 && Mouse.isButtonDown(button);
        }

        private int scaled(int windowCoord) {
            return windowCoord / Math.max(1, screen.scaleFactor());
        }
    }
}