/*
 * mygram-droid: Android TV client for Foldergram.
 * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
 * for more details.
 */


package mygram.droid;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.os.Handler;
import android.os.Looper;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.Space;
import android.widget.TextView;

import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.load.DataSource;
import com.bumptech.glide.load.engine.GlideException;
import com.bumptech.glide.request.RequestListener;
import com.bumptech.glide.request.target.Target;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ThreadLocalRandom;

/** Top bar, rotating blurred background, and the Home, Liked and Folders tabs. */
public final class MainActivity extends Activity {
	private static final int HOME = 0, LIKED = 1, FOLDERS = 2;
	private static final ViewGroup.LayoutParams FILL = new ViewGroup.LayoutParams(
			ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);

	private final Handler handler = new Handler(Looper.getMainLooper());
	private final Runnable rotate = this::rotateBackground;
	private FrameLayout content;
	/** Two layers that swap, so a new background fades in over the old one. */
	private final ImageView[] layers = new ImageView[2];
	private int front;
	private List<Post> backgrounds = new ArrayList<>();
	private RecyclerView homeList;
	private HomeRows homeRows;
	private int tab = HOME;
	private boolean ready, resumed, homeLoading, connecting;
	private LinearLayout homeButton, likedButton, foldersButton;

	@Override
	protected void onCreate(Bundle state) {
		super.onCreate(state);
		if (Prefs.server() == null) {
			startActivity(new Intent(this, SetupActivity.class));
			finish();
			return;
		}
		FrameLayout root = new FrameLayout(this);
		root.setBackgroundColor(Color.BLACK);
		FrameLayout layerBox = new FrameLayout(this); // bringToFront() stays inside it
		for (int i = 0; i < 2; i++) {
			layers[i] = new ImageView(this);
			layers[i].setScaleType(ImageView.ScaleType.CENTER_CROP);
			Ui.blur(layers[i], 60);
			layerBox.addView(layers[i], FILL);
		}
		root.addView(layerBox, FILL);
		View dim = new View(this);
		dim.setBackgroundColor(0xAA000000);
		root.addView(dim, FILL);
		LinearLayout column = new LinearLayout(this);
		column.setOrientation(LinearLayout.VERTICAL);
		column.addView(topBar());
		content = new FrameLayout(this);
		column.addView(content, new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, 0, 1));
		root.addView(column, FILL);
		setContentView(root);
		// connect() runs from onResume once the splash has let the user in.
	}

	/** [logo]  [Reels] [Liked] [Folders]  [Settings]; the current view is marked. */
	private View topBar() {
		LinearLayout bar = new LinearLayout(this);
		bar.setGravity(Gravity.CENTER_VERTICAL);
		int p = Ui.dp(this, 16);
		bar.setPadding(p * 2, p, p * 2, 0);
		homeButton = Ui.iconButton(this, R.drawable.ic_launcher, "Home", v -> show(HOME));
		bar.addView(homeButton);
		bar.addView(new Space(this), new LinearLayout.LayoutParams(0, 1, 1));
		bar.addView(Ui.iconButton(this, R.drawable.ic_reels, "Reels", v -> Playlist.openReels(this)));
		likedButton = Ui.iconButton(this, R.drawable.ic_favorite, "Liked", v -> show(LIKED));
		bar.addView(likedButton);
		foldersButton = Ui.iconButton(this, R.drawable.ic_folder, "Folders", v -> show(FOLDERS));
		bar.addView(foldersButton);
		bar.addView(new Space(this), new LinearLayout.LayoutParams(0, 1, 1));
		bar.addView(Ui.iconButton(this, R.drawable.ic_settings, "Settings",
				v -> startActivity(new Intent(this, SettingsActivity.class))));
		return bar;
	}

	private void connect() {
		if (connecting)
			return;
		message("Connecting…");
		connecting = true;
		Api.async(() -> {
			if (!Prefs.password().isEmpty())
				Api.login(Prefs.server(), Prefs.password());
			Likes.load();
			return Api.randomFeed();
		}, posts -> {
			connecting = false;
			if (isDestroyed())
				return;
			ready = true;
			backgrounds = posts;
			handler.removeCallbacks(rotate);
			rotateBackground();
			show(tab);
		}, e -> {
			connecting = false;
			if (!isDestroyed())
				failed(e);
		});
	}

	private void failed(Exception e) {
		LinearLayout box = Ui.column(this);
		box.addView(Ui.text(this, "Cannot reach the instance: " + e.getMessage(), 18));
		LinearLayout row = Ui.row(this);
		row.addView(Ui.iconButton(this, R.drawable.ic_refresh, "Retry", v -> connect()));
		row.addView(Ui.iconButton(this, R.drawable.ic_swap, "Change instance",
				v -> startActivity(new Intent(this, SetupActivity.class))));
		box.addView(row);
		setContent(box);
		row.getChildAt(0).requestFocus();
	}

	private void show(int t) {
		if (!ready)
			return;
		tab = t;
		Ui.markCurrent(homeButton, t == HOME);
		Ui.markCurrent(likedButton, t == LIKED);
		Ui.markCurrent(foldersButton, t == FOLDERS);
		if (t == HOME) {
			if (homeList != null) {
				setContent(homeList);
				return;
			}
			message("Loading…");
			if (homeLoading)
				return; // the request in flight shows the list when it lands
			homeLoading = true;
			Api.async(Api::folders, folders -> {
				homeLoading = false;
				homeRows = new HomeRows(this, folders);
				homeList = Ui.list(this, RecyclerView.VERTICAL);
				homeList.setAdapter(homeRows);
				if (tab == HOME)
					setContent(homeList);
			}, e -> {
				homeLoading = false;
				if (tab == t)
					failed(e);
			});
		} else if (t == LIKED) {
			message("Loading…");
			Api.async(Api::likes, posts -> {
				if (tab == LIKED)
					setContent(posts.isEmpty() ? centered("No liked posts yet")
							: Ui.grid(this, Ui.postTiles(this, posts), Ui.POST_W, Ui.POST_H, 6));
			}, e -> {
				if (tab == t)
					failed(e);
			});
		} else {
			message("Loading…");
			Api.async(Api::folders, folders -> {
				if (tab != FOLDERS)
					return;
				List<TileAdapter.Tile> tiles = new ArrayList<>();
				for (Api.Folder f : folders)
					tiles.add(new TileAdapter.Tile(f.avatarUrl, f.name, R.drawable.ic_folder, -1,
							() -> FolderActivity.open(this, f)));
				setContent(Ui.grid(this, tiles, 160, 160, 5));
			}, e -> {
				if (tab == t)
					failed(e);
			});
		}
	}

	@Override
	protected void onResume() {
		super.onResume();
		resumed = true;
		if (!ready) {
			if (!connecting && !App.locked)
				connect(); // also retries after an error, e.g. back from Settings
			return;
		}
		handler.removeCallbacks(rotate);
		handler.postDelayed(rotate, Prefs.backgroundSeconds() * 1000L);
		if (tab == LIKED)
			show(LIKED); // unliked posts drop out
		else if (homeRows != null)
			homeRows.refreshHearts(homeList);
	}

	@Override
	protected void onPause() {
		super.onPause();
		resumed = false;
		handler.removeCallbacks(rotate);
	}

	/** Back from Liked or Folders returns to Home; from Home it leaves the app. */
	@Override
	@SuppressWarnings("deprecation") // no predictive back on this TV; onBackPressed still fires
	public void onBackPressed() {
		if (ready && tab != HOME)
			show(HOME);
		else
			super.onBackPressed();
	}

	@Override
	protected void onDestroy() {
		handler.removeCallbacks(rotate);
		super.onDestroy();
	}

	private void rotateBackground() {
		if (backgrounds.isEmpty())
			return;
		Post p = backgrounds.get(ThreadLocalRandom.current().nextInt(backgrounds.size()));
		// Never pass the old drawable as a Glide placeholder: Glide may recycle its bitmap.
		ImageView back = layers[1 - front], top = layers[front];
		back.animate().cancel();
		back.setAlpha(0f);
		back.bringToFront();
		Glide.with(back).load(p.media.get(0).thumbnailUrl).listener(new RequestListener<Drawable>() {
			@Override
			public boolean onLoadFailed(GlideException e, Object model, Target<Drawable> target, boolean first) {
				return false;
			}

			@Override
			public boolean onResourceReady(Drawable d, Object model, Target<Drawable> target, DataSource source,
					boolean first) {
				front = 1 - front; // only now, so a failed load leaves the old layer on top
				back.animate().alpha(1f).setDuration(1500).withEndAction(() -> {
					if (!isDestroyed())
						Glide.with(top).clear(top);
				}).start();
				return false;
			}
		}).into(back);
		if (resumed)
			handler.postDelayed(rotate, Prefs.backgroundSeconds() * 1000L);
	}

	private void message(String s) {
		setContent(centered(s));
	}

	private TextView centered(String s) {
		TextView t = Ui.text(this, s, 18);
		t.setGravity(Gravity.CENTER);
		return t;
	}

	private void setContent(View v) {
		content.removeAllViews();
		content.addView(v, FILL);
	}
}