package net.minecraft.util;

import java.util.Optional;
import net.minecraft.ChatFormatting;
import net.minecraft.network.chat.FormattedText;
import net.minecraft.network.chat.Style;

public class StringDecomposer {
	private static final char REPLACEMENT_CHAR = '�';
	private static final Optional<Object> STOP_ITERATION = Optional.of(Unit.INSTANCE);

	private static boolean feedChar(final Style style, final FormattedCharSink output, final int pos, final char ch) {
		return Character.isSurrogate(ch) ? output.accept(pos, style, 65533) : output.accept(pos, style, ch);
	}

	public static boolean iterate(final String string, final Style style, final FormattedCharSink output) {
		int size = string.length();

		for (int i = 0; i < size; i++) {
			char ch = string.charAt(i);
			if (Character.isHighSurrogate(ch)) {
				if (i + 1 >= size) {
					if (!output.accept(i, style, 65533)) {
						return false;
					}
					break;
				}

				char low = string.charAt(i + 1);
				if (Character.isLowSurrogate(low)) {
					if (!output.accept(i, style, Character.toCodePoint(ch, low))) {
						return false;
					}

					i++;
				} else if (!output.accept(i, style, 65533)) {
					return false;
				}
			} else if (!feedChar(style, output, i, ch)) {
				return false;
			}
		}

		return true;
	}

	public static boolean iterateBackwards(final String string, final Style style, final FormattedCharSink output) {
		int size = string.length();

		for (int i = size - 1; i >= 0; i--) {
			char ch = string.charAt(i);
			if (Character.isLowSurrogate(ch)) {
				if (i - 1 < 0) {
					if (!output.accept(0, style, 65533)) {
						return false;
					}
					break;
				}

				char high = string.charAt(i - 1);
				if (Character.isHighSurrogate(high)) {
					if (!output.accept(--i, style, Character.toCodePoint(high, ch))) {
						return false;
					}
				} else if (!output.accept(i, style, 65533)) {
					return false;
				}
			} else if (!feedChar(style, output, i, ch)) {
				return false;
			}
		}

		return true;
	}

	public static boolean iterateFormatted(final String string, final Style style, final FormattedCharSink output) {
		return iterateFormatted(string, 0, style, output);
	}

	public static boolean iterateFormatted(final String string, final int offset, final Style style, final FormattedCharSink output) {
		return iterateFormatted(string, offset, style, style, output);
	}

	public static boolean iterateFormatted(final String string, final int offset, final Style currentStyle, final Style resetStyle, final FormattedCharSink output) {
		int size = string.length();
		Style style = currentStyle;

		for (int i = offset; i < size; i++) {
			char ch = string.charAt(i);
			if (ch == 167) {
				if (i + 1 >= size) {
					break;
				}

				char code = string.charAt(i + 1);
				ChatFormatting formatting = ChatFormatting.getByCode(code);
				if (formatting != null) {
					style = formatting == ChatFormatting.RESET ? resetStyle : style.applyLegacyFormat(formatting);
				}

				i++;
			} else if (Character.isHighSurrogate(ch)) {
				if (i + 1 >= size) {
					if (!output.accept(i, style, 65533)) {
						return false;
					}
					break;
				}

				char low = string.charAt(i + 1);
				if (Character.isLowSurrogate(low)) {
					if (!output.accept(i, style, Character.toCodePoint(ch, low))) {
						return false;
					}

					i++;
				} else if (!output.accept(i, style, 65533)) {
					return false;
				}
			} else if (!feedChar(style, output, i, ch)) {
				return false;
			}
		}

		return true;
	}

	public static boolean iterateFormatted(final FormattedText component, final Style rootStyle, final FormattedCharSink output) {
		return component.visit((style, contents) -> iterateFormatted(contents, 0, style, output) ? Optional.empty() : STOP_ITERATION, rootStyle).isEmpty();
	}

	public static String filterBrokenSurrogates(final String input) {
		StringBuilder builder = new StringBuilder();
		iterate(input, Style.EMPTY, (position, style, codepoint) -> {
			builder.appendCodePoint(codepoint);
			return true;
		});
		return builder.toString();
	}

	public static String getPlainText(final FormattedText input) {
		StringBuilder builder = new StringBuilder();
		iterateFormatted(input, Style.EMPTY, (position, style, codepoint) -> {
			builder.appendCodePoint(codepoint);
			return true;
		});
		return builder.toString();
	}
}