package net.minecraft.commands.functions;

import it.unimi.dsi.fastutil.ints.IntArrayList;
import it.unimi.dsi.fastutil.ints.IntList;
import java.util.ArrayList;
import java.util.List;
import net.minecraft.commands.ExecutionCommandSource;
import net.minecraft.commands.execution.UnboundEntryAction;
import net.minecraft.resources.Identifier;
import org.jspecify.annotations.Nullable;

class FunctionBuilder<T extends ExecutionCommandSource<T>> {
	private @Nullable List<UnboundEntryAction<T>> plainEntries = new ArrayList<>();
	private @Nullable List<MacroFunction.Entry<T>> macroEntries;
	private final List<String> macroArguments = new ArrayList<>();

	public void addCommand(final UnboundEntryAction<T> command) {
		if (this.macroEntries != null) {
			this.macroEntries.add(new MacroFunction.PlainTextEntry<>(command));
		} else {
			this.plainEntries.add(command);
		}
	}

	private int getArgumentIndex(final String id) {
		int index = this.macroArguments.indexOf(id);
		if (index == -1) {
			index = this.macroArguments.size();
			this.macroArguments.add(id);
		}

		return index;
	}

	private IntList convertToIndices(final List<String> ids) {
		IntArrayList result = new IntArrayList(ids.size());

		for (String id : ids) {
			result.add(this.getArgumentIndex(id));
		}

		return result;
	}

	public void addMacro(final String command, final int line, final T compilationContext) {
		StringTemplate parseResults;
		try {
			parseResults = StringTemplate.fromString(command);
		} catch (Exception e) {
			throw new IllegalArgumentException("Can't parse function line " + line + ": '" + command + "'", e);
		}

		if (this.plainEntries != null) {
			this.macroEntries = new ArrayList<>(this.plainEntries.size() + 1);

			for (UnboundEntryAction<T> plainEntry : this.plainEntries) {
				this.macroEntries.add(new MacroFunction.PlainTextEntry<>(plainEntry));
			}

			this.plainEntries = null;
		}

		this.macroEntries.add(new MacroFunction.MacroEntry<>(parseResults, this.convertToIndices(parseResults.variables()), compilationContext));
	}

	public CommandFunction<T> build(final Identifier id) {
		return this.macroEntries != null ? new MacroFunction<>(id, this.macroEntries, this.macroArguments) : new PlainTextFunction<>(id, this.plainEntries);
	}
}