package emu.grasscutter.utils;

import java.io.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.StandardCopyOption;
import java.time.*;
import java.time.temporal.TemporalAdjusters;
import java.util.*;
import java.util.concurrent.ThreadLocalRandom;

import emu.grasscutter.Grasscutter;
import emu.grasscutter.data.DataLoader;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufUtil;
import io.netty.buffer.Unpooled;
import it.unimi.dsi.fastutil.ints.IntArrayList;
import it.unimi.dsi.fastutil.ints.IntList;

import org.slf4j.Logger;

import javax.annotation.Nullable;

import static emu.grasscutter.utils.Language.translate;

@SuppressWarnings({"UnusedReturnValue", "BooleanMethodIsAlwaysInverted"})
public final class Utils {
	public static final Random random = new Random();

	public static int randomRange(int min, int max) {
		return random.nextInt(max - min + 1) + min;
	}

	public static float randomFloatRange(float min, float max) {
		return random.nextFloat() * (max - min) + min;
	}

	public static double getDist(Position pos1, Position pos2) {
		double xs = pos1.getX() - pos2.getX();
		xs = xs * xs;

		double ys = pos1.getY() - pos2.getY();
		ys = ys * ys;

		double zs = pos1.getZ() - pos2.getZ();
		zs = zs * zs;

		return Math.sqrt(xs + zs + ys);
	}

	public static int getCurrentSeconds() {
		return (int) (System.currentTimeMillis() / 1000.0);
	}

	public static String lowerCaseFirstChar(String s) {
		StringBuilder sb = new StringBuilder(s);
		sb.setCharAt(0, Character.toLowerCase(sb.charAt(0)));
		return sb.toString();
	}

	public static String toString(InputStream inputStream) throws IOException {
		BufferedInputStream bis = new BufferedInputStream(inputStream);
		ByteArrayOutputStream buf = new ByteArrayOutputStream();
		for (int result = bis.read(); result != -1; result = bis.read()) {
			buf.write((byte) result);
		}
		return buf.toString();
	}

	public static void logByteArray(byte[] array) {
		ByteBuf b = Unpooled.wrappedBuffer(array);
		Grasscutter.getLogger().info("\n" + ByteBufUtil.prettyHexDump(b));
		b.release();
	}

	private static final char[] HEX_ARRAY = "0123456789abcdef".toCharArray();
	public static String bytesToHex(byte[] bytes) {
		if (bytes == null) return "";
		char[] hexChars = new char[bytes.length * 2];
		for (int j = 0; j < bytes.length; j++) {
			int v = bytes[j] & 0xFF;
			hexChars[j * 2] = HEX_ARRAY[v >>> 4];
			hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
		}
		return new String(hexChars);
	}

	public static String bytesToHex(ByteBuf buf) {
		return bytesToHex(byteBufToArray(buf));
	}

	public static byte[] byteBufToArray(ByteBuf buf) {
		byte[] bytes = new byte[buf.capacity()];
		buf.getBytes(0, bytes);
		return bytes;
	}

	public static int abilityHash(String str) {
		int v7 = 0;
		int v8 = 0;
		while (v8 < str.length()) {
			v7 = str.charAt(v8++) + 131 * v7;
		}
		return v7;
	}

	/**
	 * Creates a string with the path to a file.
	 * @param path The path to the file.
	 * @return A path using the operating system's file separator.
	 */
	public static String toFilePath(String path) {
		return path.replace("/", File.separator);
	}

	/**
	 * Checks if a file exists on the file system.
	 * @param path The path to the file.
	 * @return True if the file exists, false otherwise.
	 */
	public static boolean fileExists(String path) {
		return new File(path).exists();
	}

	/**
	 * Creates a folder on the file system.
	 * @param path The path to the folder.
	 * @return True if the folder was created, false otherwise.
	 */
	public static boolean createFolder(String path) {
		return new File(path).mkdirs();
	}

	/**
	 * Copies a file from the archive's resources to the file system.
	 * @param resource The path to the resource.
	 * @param destination The path to copy the resource to.
	 * @return True if the file was copied, false otherwise.
	 */
	public static boolean copyFromResources(String resource, String destination) {
		try (InputStream stream = Grasscutter.class.getResourceAsStream(resource)) {
			if(stream == null) {
				Grasscutter.getLogger().warn("Could not find resource: " + resource);
				return false;
			}

			Files.copy(stream, new File(destination).toPath(), StandardCopyOption.REPLACE_EXISTING);
			return true;
		} catch (Exception exception) {
			Grasscutter.getLogger().warn("Unable to copy resource " + resource + " to " + destination, exception);
			return false;
		}
	}

	/**
	 * Logs an object to the console.
	 * @param object The object to log.
	 */
	public static void logObject(Object object) {
		String asJson = Grasscutter.getGsonFactory().toJson(object);
		Grasscutter.getLogger().info(asJson);
	}

	/**
	 * Checks for required files and folders before startup.
	 */
	public static void startupCheck() {
		ConfigContainer config = Grasscutter.getConfig();
		Logger logger = Grasscutter.getLogger();
		boolean exit = false;

		String resourcesFolder = config.folderStructure.resources;
		String dataFolder = config.folderStructure.data;

		// Check for resources folder.
		if(!fileExists(resourcesFolder)) {
			logger.info(translate("messages.status.create_resources"));
			logger.info(translate("messages.status.resources_error"));
			createFolder(resourcesFolder); exit = true;
		}

		// Check for BinOutput + ExcelBinOutput.
		if(!fileExists(resourcesFolder + "BinOutput") ||
				!fileExists(resourcesFolder + "ExcelBinOutput")) {
			logger.info(translate("messages.status.resources_error"));
			exit = true;
		}

		// Check for game data.
		if(!fileExists(dataFolder))
			createFolder(dataFolder);

		// Make sure the data folder is populated, if there are any missing files copy them from resources
		DataLoader.CheckAllFiles();

		if(exit) System.exit(1);
	}

	/**
	 * Gets the timestamp of the next hour.
	 * @return The timestamp in UNIX seconds.
	 */
	public static int getNextTimestampOfThisHour(int hour, String timeZone, int param) {
		ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of(timeZone));
		for (int i = 0; i < param; i ++){
			if (zonedDateTime.getHour() < hour) {
				zonedDateTime = zonedDateTime.withHour(hour).withMinute(0).withSecond(0);
			} else {
				zonedDateTime = zonedDateTime.plusDays(1).withHour(hour).withMinute(0).withSecond(0);
			}
		}
		return (int) zonedDateTime.toInstant().atZone(ZoneOffset.UTC).toEpochSecond();
	}

	/**
	 * Gets the timestamp of the next hour in a week.
	 * @return The timestamp in UNIX seconds.
	 */
	public static int getNextTimestampOfThisHourInNextWeek(int hour, String timeZone, int param) {
		ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of(timeZone));
		for (int i = 0; i < param; i++) {
			if (zonedDateTime.getDayOfWeek() == DayOfWeek.MONDAY && zonedDateTime.getHour() < hour) {
				zonedDateTime = ZonedDateTime.now(ZoneId.of(timeZone)).withHour(hour).withMinute(0).withSecond(0);
			} else {
				zonedDateTime = zonedDateTime.with(TemporalAdjusters.next(DayOfWeek.MONDAY)).withHour(hour).withMinute(0).withSecond(0);
			}
		}
		return (int) zonedDateTime.toInstant().atZone(ZoneOffset.UTC).toEpochSecond();
	}

	/**
	 * Gets the timestamp of the next hour in a month.
	 * @return The timestamp in UNIX seconds.
	 */
	public static int getNextTimestampOfThisHourInNextMonth(int hour, String timeZone, int param) {
		ZonedDateTime zonedDateTime = ZonedDateTime.now(ZoneId.of(timeZone));
		for (int i = 0; i < param; i++) {
			if (zonedDateTime.getDayOfMonth() == 1 && zonedDateTime.getHour() < hour) {
				zonedDateTime = ZonedDateTime.now(ZoneId.of(timeZone)).withHour(hour).withMinute(0).withSecond(0);
			} else {
				zonedDateTime = zonedDateTime.with(TemporalAdjusters.firstDayOfNextMonth()).withHour(hour).withMinute(0).withSecond(0);
			}
		}
		return (int) zonedDateTime.toInstant().atZone(ZoneOffset.UTC).toEpochSecond();
	}

	/**
	 * Retrieves a string from an input stream.
	 * @param stream The input stream.
	 * @return The string.
	 */
	public static String readFromInputStream(@Nullable InputStream stream) {
		if(stream == null) return "empty";

		StringBuilder stringBuilder = new StringBuilder();
		try (BufferedReader reader = new BufferedReader(new InputStreamReader(stream, StandardCharsets.UTF_8))) {
			String line; while ((line = reader.readLine()) != null) {
				stringBuilder.append(line);
			} stream.close();
		} catch (IOException e) {
			Grasscutter.getLogger().warn("Failed to read from input stream.");
		} catch (NullPointerException ignored) {
			return "empty";
		} return stringBuilder.toString();
	}

	/**
	 * Performs a linear interpolation using a table of fixed points to create an effective piecewise f(x) = y function.
	 * @param x The x value.
	 * @param xyArray Array of points in [[x0,y0], ... [xN, yN]] format
	 * @return f(x) = y
	 */
	public static int lerp(int x, int[][] xyArray) {
		try {
			if (x <= xyArray[0][0]){  // Clamp to first point
				return xyArray[0][1];
			} else if (x >= xyArray[xyArray.length-1][0]) {  // Clamp to last point
				return xyArray[xyArray.length-1][1];
			}
			// At this point we're guaranteed to have two lerp points, and pity be somewhere between them.
			for (int i=0; i < xyArray.length-1; i++) {
				if (x == xyArray[i+1][0]) {
					return xyArray[i+1][1];
				}
				if (x < xyArray[i+1][0]) {
					// We are between [i] and [i+1], interpolation time!
					// Using floats would be slightly cleaner but we can just as easily use ints if we're careful with order of operations.
					int position = x - xyArray[i][0];
					int fullDist = xyArray[i+1][0] - xyArray[i][0];
					int prevValue = xyArray[i][1];
					int fullDelta = xyArray[i+1][1] - prevValue;
					return prevValue + ( (position * fullDelta) / fullDist );
				}
			}
		} catch (IndexOutOfBoundsException e) {
			Grasscutter.getLogger().error("Malformed lerp point array. Must be of form [[x0, y0], ..., [xN, yN]].");
		}
		return 0;
	}

	/**
	 * Checks if an int is in an int[]
	 * @param key int to look for
	 * @param array int[] to look in
	 * @return key in array
	 */
	public static boolean intInArray(int key, int[] array) {
		for (int i : array) {
			if (i == key) {
				return true;
			}
		}
		return false;
	}

	/**
	 * Return a copy of minuend without any elements found in subtrahend.
	 * @param minuend The array we want elements from
	 * @param subtrahend The array whose elements we don't want
	 * @return The array with only the elements we want, in the order that minuend had them
	 */
	public static int[] setSubtract(int[] minuend, int[] subtrahend) {
		IntList temp = new IntArrayList();
		for (int i : minuend) {
			if (!intInArray(i, subtrahend)) {
				temp.add(i);
			}
		}
		return temp.toIntArray();
	}

	/**
	 * Gets the language code from a given locale.
	 * @param locale A locale.
	 * @return A string in the format of 'XX-XX'.
	 */
	public static String getLanguageCode(Locale locale) {
		return String.format("%s-%s", locale.getLanguage(), locale.getCountry());
	}

	/**
	 * Base64 encodes a given byte array.
	 * @param toEncode An array of bytes.
	 * @return A base64 encoded string.
	 */
	public static String base64Encode(byte[] toEncode) {
		return Base64.getEncoder().encodeToString(toEncode);
	}

	/**
	 * Base64 decodes a given string.
	 * @param toDecode A base64 encoded string.
	 * @return An array of bytes.
	 */
	public static byte[] base64Decode(String toDecode) {
		return Base64.getDecoder().decode(toDecode);
	}

	/**
	 * Safely JSON decodes a given string.
	 * @param jsonData The JSON-encoded data.
	 * @return JSON decoded data, or null if an exception occurred.
	 */
	public static <T> T jsonDecode(String jsonData, Class<T> classType) {
		try {
			return Grasscutter.getGsonFactory().fromJson(jsonData, classType);
		} catch (Exception ignored) {
			return null;
		}
	}

	/***
	 * Draws a random element from the given list, following the given probability distribution, if given.
	 * @param list The list from which to draw the element.
	 * @param probabilities The probability distribution. This is given as a list of probabilities of the same length it `list`.
	 * @return A randomly drawn element from the given list.
	 */
	public static <T> T drawRandomListElement(List<T> list, List<Integer> probabilities) {
		// If we don't have a probability distribution, or the size of the distribution does not match
		// the size of the list, we assume uniform distribution.
		if (probabilities == null || probabilities.size() <= 1 || probabilities.size() != list.size()) {
			int index = ThreadLocalRandom.current().nextInt(0, list.size());
			return list.get(index);
		}

		// Otherwise, we roll with the given distribution.
		int totalProbabilityMass = probabilities.stream().reduce(Integer::sum).get();
		int roll = ThreadLocalRandom.current().nextInt(1, totalProbabilityMass + 1);

		int currentTotalChance = 0;
		for (int i = 0; i < list.size(); i++) {
			currentTotalChance += probabilities.get(i);

			if (roll <= currentTotalChance) {
				return list.get(i);
			}
		}

		// Should never happen.
		return list.get(0);
	}

	/***
	 * Draws a random element from the given list, following a uniform probability distribution.
	 * @param list The list from which to draw the element.
	 * @return A randomly drawn element from the given list.
	 */
	public static <T> T drawRandomListElement(List<T> list) {
		return drawRandomListElement(list, null);
	}
}
