package bjc.dicelang.ast;

import java.util.Deque;
import java.util.InputMismatchException;
import java.util.function.Function;
import java.util.function.Predicate;

import bjc.utils.funcdata.FunctionalList;
import bjc.utils.funcdata.FunctionalMap;
import bjc.utils.funcdata.IList;
import bjc.utils.funcdata.IMap;
import bjc.utils.funcdata.ITree;
import bjc.utils.funcdata.Tree;
import bjc.utils.funcutils.StringUtils;
import bjc.utils.parserutils.TreeConstructor;

import bjc.dicelang.IDiceExpression;
import bjc.dicelang.ast.nodes.DiceLiteralNode;
import bjc.dicelang.ast.nodes.DiceLiteralType;
import bjc.dicelang.ast.nodes.IDiceASTNode;
import bjc.dicelang.ast.nodes.ILiteralDiceNode;
import bjc.dicelang.ast.nodes.IntegerLiteralNode;
import bjc.dicelang.ast.nodes.OperatorDiceNode;
import bjc.dicelang.ast.nodes.VariableDiceNode;

/**
 * Parse a string expression into AST form. Doesn't do anything else
 * 
 * @author ben
 *
 */
public class DiceASTParser {
	private static IDiceASTNode convertLeafNode(String leafNode) {
		DiceLiteralType literalType = ILiteralDiceNode
				.getLiteralType(leafNode);

		if (literalType != null) {
			switch (literalType) {
				case DICE:
					return new DiceLiteralNode(
							IDiceExpression.toExpression(leafNode));
				case INTEGER:
					return new IntegerLiteralNode(
							Integer.parseInt(leafNode));
				default:
					throw new InputMismatchException(
							"Cannot convert string '" + leafNode
									+ "' into a literal.");
			}
		}

		if (leafNode.matches("[+-]?\\d*\\.\\d+")) {
			throw new InputMismatchException(
					"Floating point literals are not supported");
		}

		return new VariableDiceNode(leafNode);
	}

	private static IDiceASTNode convertOperatorNode(String operatorNode) {
		try {
			return OperatorDiceNode.fromString(operatorNode);
		} catch (IllegalArgumentException iaex) {
			InputMismatchException imex = new InputMismatchException(
					"Attempted to parse invalid operator " + operatorNode);

			imex.initCause(iaex);

			throw imex;
		}
	}

	/**
	 * Create an AST from a list of tokens
	 * 
	 * @param tokens
	 *            The list of tokens to convert
	 * @return An AST built from the tokens
	 */
	public static ITree<IDiceASTNode> createFromString(
			IList<String> tokens) {
		Predicate<String> specialPicker = (operator) -> {
			if (StringUtils.containsOnly(operator, "\\[")) {
				return true;
			} else if (StringUtils.containsOnly(operator, "\\]")) {
				return true;
			}

			return false;
		};

		IMap<String, Function<Deque<ITree<String>>, ITree<String>>> operators = new FunctionalMap<>();

		operators.put("[", (queuedTrees) -> {
			Tree<String> openArray = new Tree<>("[");

			return openArray;
		});

		operators.put("]", (queuedTrees) -> {
			return parseCloseArray(queuedTrees);
		});

		ITree<String> rawTokens = TreeConstructor.constructTree(tokens,
				(token) -> {
					return isOperatorNode(token);
				}, specialPicker, operators::get);

		ITree<IDiceASTNode> tokenizedTree = rawTokens.rebuildTree(
				DiceASTParser::convertLeafNode,
				DiceASTParser::convertOperatorNode);

		return tokenizedTree;
	}

	private static boolean isOperatorNode(String token) {
		if (StringUtils.containsOnly(token, "\\[")) {
			return true;
		} else if (StringUtils.containsOnly(token, "\\]")) {
			return true;
		}

		if (token.equals("[]")) {
			// This is a synthetic operator, constructed by [ and ]
			return true;
		}

		try {
			OperatorDiceNode.fromString(token);
			return true;
		} catch (@SuppressWarnings("unused") IllegalArgumentException iaex) {
			// We don't care about details
			return false;
		}
	}

	private static ITree<String> parseCloseArray(
			Deque<ITree<String>> queuedTrees) {
		IList<ITree<String>> children = new FunctionalList<>();

		while (shouldContinuePopping(queuedTrees)) {
			children.add(queuedTrees.pop());
		}

		queuedTrees.pop();

		children.reverse();

		ITree<String> arrayTree = new Tree<>("[]", children);

		return arrayTree;
	}

	private static boolean shouldContinuePopping(
			Deque<ITree<String>> queuedTrees) {
		String peekToken = queuedTrees.peek().getHead();

		return !peekToken.equals("[");
	}
}