package net.minecraft.util.parsing.packrat;

import java.util.ArrayList;
import java.util.List;
import net.minecraft.util.Util;

public interface ErrorCollector<S> {
	void store(int cursor, SuggestionSupplier<S> suggestions, Object reason);

	default void store(final int cursor, final Object reason) {
		this.store(cursor, SuggestionSupplier.empty(), reason);
	}

	void finish(int finalCursor);

	public static class LongestOnly<S> implements ErrorCollector<S> {
		private ErrorCollector.LongestOnly.MutableErrorEntry<S>[] entries = new ErrorCollector.LongestOnly.MutableErrorEntry[16];
		private int nextErrorEntry;
		private int lastCursor = -1;

		private void discardErrorsFromShorterParse(final int cursor) {
			if (cursor > this.lastCursor) {
				this.lastCursor = cursor;
				this.nextErrorEntry = 0;
			}
		}

		@Override
		public void finish(final int finalCursor) {
			this.discardErrorsFromShorterParse(finalCursor);
		}

		@Override
		public void store(final int cursor, final SuggestionSupplier<S> suggestions, final Object reason) {
			this.discardErrorsFromShorterParse(cursor);
			if (cursor == this.lastCursor) {
				this.addErrorEntry(suggestions, reason);
			}
		}

		private void addErrorEntry(final SuggestionSupplier<S> suggestions, final Object reason) {
			int currentSize = this.entries.length;
			if (this.nextErrorEntry >= currentSize) {
				int newSize = Util.growByHalf(currentSize, this.nextErrorEntry + 1);
				ErrorCollector.LongestOnly.MutableErrorEntry<S>[] newEntries = new ErrorCollector.LongestOnly.MutableErrorEntry[newSize];
				System.arraycopy(this.entries, 0, newEntries, 0, currentSize);
				this.entries = newEntries;
			}

			int entryIndex = this.nextErrorEntry++;
			ErrorCollector.LongestOnly.MutableErrorEntry<S> entry = this.entries[entryIndex];
			if (entry == null) {
				entry = new ErrorCollector.LongestOnly.MutableErrorEntry<>();
				this.entries[entryIndex] = entry;
			}

			entry.suggestions = suggestions;
			entry.reason = reason;
		}

		public List<ErrorEntry<S>> entries() {
			int errorCount = this.nextErrorEntry;
			if (errorCount == 0) {
				return List.of();
			} else {
				List<ErrorEntry<S>> result = new ArrayList(errorCount);

				for (int i = 0; i < errorCount; i++) {
					ErrorCollector.LongestOnly.MutableErrorEntry<S> entry = this.entries[i];
					result.add(new ErrorEntry<>(this.lastCursor, entry.suggestions, entry.reason));
				}

				return result;
			}
		}

		public int cursor() {
			return this.lastCursor;
		}

		private static class MutableErrorEntry<S> {
			private SuggestionSupplier<S> suggestions = SuggestionSupplier.empty();
			private Object reason = "empty";
		}
	}

	public static class Nop<S> implements ErrorCollector<S> {
		@Override
		public void store(final int cursor, final SuggestionSupplier<S> suggestions, final Object reason) {
		}

		@Override
		public void finish(final int finalCursor) {
		}
	}
}