package bjc.dicelang;

import bjc.utils.funcdata.FunctionalList;
import bjc.utils.funcdata.FunctionalMap;
import bjc.utils.funcdata.IList;
import bjc.utils.funcdata.IMap;

import java.util.Deque;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Set;

import static bjc.dicelang.Errors.ErrorKey.*;
import static bjc.dicelang.Token.Type.*;

public class Shunter {
	// The binary operators and their
	// priorities
	IMap<Token.Type, Integer> ops;

	/*
	 * Operators that are right-associative
	 */
	Set<Token.Type> rightAssoc;

	/*
	 * Operators that aren't associative
	 */
	Set<Token.Type> notAssoc;

	// Unary operators that can only be
	// applied to non-operator tokens and yield operator tokens
	Set<Token.Type> unaryAdjectives;

	// Unary operators that can only be
	// applied to operator tokens and yield operator tokens
	Set<Token.Type> unaryAdverbs;

	// Unary operators that can only be
	// applied to operator tokens and yield data tokens
	Set<Token.Type> unaryGerunds;

	public final int	MATH_PREC	= 30;
	public final int	DICE_PREC	= 20;
	public final int	STR_PREC	= 10;
	public final int	EXPR_PREC	= 0;

	public Shunter() {
		ops = new FunctionalMap<>();

		rightAssoc = new HashSet<>();
		notAssoc = new HashSet<>();

		unaryAdjectives = new HashSet<>();
		unaryAdverbs = new HashSet<>();
		unaryGerunds = new HashSet<>();

		unaryAdverbs.add(COERCE);

		ops.put(ADD, 0 + MATH_PREC);
		ops.put(SUBTRACT, 0 + MATH_PREC);

		ops.put(MULTIPLY, 1 + MATH_PREC);
		ops.put(IDIVIDE, 1 + MATH_PREC);
		ops.put(DIVIDE, 1 + MATH_PREC);

		ops.put(DICEGROUP, 0 + DICE_PREC);

		ops.put(DICECONCAT, 1 + DICE_PREC);

		ops.put(DICELIST, 2 + DICE_PREC);

		ops.put(STRCAT, 0 + STR_PREC);

		ops.put(STRREP, 1 + STR_PREC);

		ops.put(LET, 0 + EXPR_PREC);
		ops.put(BIND, 1 + EXPR_PREC);
	}

	public boolean shuntTokens(IList<Token> tks, IList<Token> returned) {
		Deque<Token> opStack = new LinkedList<>();
		Deque<Token> unaryOps = new LinkedList<>();

		Deque<Token> currReturned = new LinkedList<>();

		Deque<Token> feed = new LinkedList<>();

		for(Token tk : tks.toIterable()) {
			boolean succ;

			while(feed.size() != 0) {
				succ = shuntToken(feed.poll(), opStack, unaryOps, currReturned, feed);

				if(!succ) return false;
			}

			succ = shuntToken(tk, opStack, unaryOps, currReturned, feed);

			if(!succ) return false;
		}

		// Flush leftover operators
		while(!opStack.isEmpty()) {
			currReturned.addLast(opStack.pop());
		}

		for(Token tk : currReturned) {
			returned.add(tk);
		}

		return true;
	}

	private boolean shuntToken(Token tk, Deque<Token> opStack, Deque<Token> unaryStack, Deque<Token> currReturned,
			Deque<Token> feed) {
		if(unaryStack.size() != 0) {
			if(isUnary(tk)) {
				unaryStack.add(tk);
				return true;
			}

			Token unaryOp = unaryStack.pop();

			Token.Type unaryType = unaryOp.type;

			if(unaryAdjectives.contains(unaryType)) {
				if(isOp(tk)) {
					Errors.inst.printError(EK_SHUNT_NOTADV, unaryOp.toString(), tk.toString());
					return false;
				}

				Token newTok = new Token(TAGOPR);

				if(tk.type == TAGOP) {
					newTok.tokenValues = tk.tokenValues;
				} else {
					newTok.tokenValues = new FunctionalList<>(tk);
				}

				newTok.tokenValues.add(unaryOp);
				opStack.push(newTok);

				return true;
			} else if(unaryAdverbs.contains(unaryType)) {
				if(!isOp(tk)) {
					Errors.inst.printError(EK_SHUNT_NOTADJ, unaryOp.toString(), tk.toString());
					return false;
				}

				Token newTok = new Token(TAGOPR);

				if(tk.type == TAGOP) {
					newTok.tokenValues = tk.tokenValues;
				} else {
					newTok.tokenValues = new FunctionalList<>(tk);
				}

				newTok.tokenValues.add(unaryOp);
				opStack.push(newTok);

				return true;
			}
		}

		if(isUnary(tk)) {
			unaryStack.add(tk);
			return true;
		} else if(isOp(tk)) {
			while(!opStack.isEmpty() && isHigherPrec(tk, opStack.peek())) {
				Token newOp = opStack.pop();

				if(tk.type == newOp.type && notAssoc.contains(tk.type)) {
					Errors.inst.printError(EK_SHUNT_NOTASSOC, tk.type.toString());
				}

				currReturned.addLast(newOp);
			}

			opStack.push(tk);
		} else if(tk.type == OPAREN || tk.type == OBRACE) {
			opStack.push(tk);

			if(tk.type == OBRACE) {
				currReturned.addLast(tk);
			}
		} else if(tk.type == CPAREN || tk.type == CBRACE) {
			Token matching = null;

			switch(tk.type) {
			case CPAREN:
				matching = new Token(OPAREN, tk.intValue);
				break;
			case CBRACE:
				matching = new Token(OBRACE, tk.intValue);
				break;
			default:
				break;
			}

			if(!opStack.contains(matching)) {
				Errors.inst.printError(EK_SHUNT_NOGROUP, tk.toString(), matching.toString());
				return false;
			}

			while(!opStack.peek().equals(matching)) {
				currReturned.addLast(opStack.pop());
			}

			if(tk.type == CBRACE) {
				currReturned.addLast(tk);
			}

			opStack.pop();
		} else if(tk.type == GROUPSEP) {
			IList<Token> group = new FunctionalList<>();

			while(currReturned.size() != 0 && !currReturned.peek().isGrouper()) {
				group.add(currReturned.pop());
			}

			while(opStack.size() != 0 && !opStack.peek().isGrouper()) {
				group.add(opStack.pop());
			}

			if(currReturned.size() == 0) {
				Errors.inst.printError(EK_SHUNT_INVSEP);
				return false;
			}

			currReturned.addLast(new Token(TOKGROUP, group));
		} else {
			currReturned.addLast(tk);
		}

		return true;
	}

	private boolean isHigherPrec(Token lft, Token rght) {
		Token.Type left = lft.type;
		Token.Type right = rght.type;

		boolean exists = ops.containsKey(right);

		if(rght.type == TAGOPR) {
			exists = true;
		}

		// If it doesn't, the left is higher precedence.
		if(!exists) return false;

		int rightPrecedence;
		int leftPrecedence;

		if(rght.type == TAGOPR) {
			rightPrecedence = (int) rght.intValue;
		} else {
			rightPrecedence = ops.get(right);
		}

		if(lft.type == TAGOPR) {
			leftPrecedence = (int) lft.intValue;
		} else {
			leftPrecedence = ops.get(left);
		}

		if(rightAssoc.contains(left))
			return rightPrecedence > leftPrecedence;
		else
			return rightPrecedence >= leftPrecedence;
	}

	private boolean isOp(Token tk) {
		Token.Type ty = tk.type;

		if(ops.containsKey(ty)) return true;
		if(unaryAdjectives.contains(ty)) return true;
		if(unaryAdverbs.contains(ty)) return true;
		if(unaryGerunds.contains(ty)) return true;
		if(ty == TAGOPR) return true;

		return false;
	}

	private boolean isUnary(Token tk) {
		Token.Type ty = tk.type;

		if(unaryAdjectives.contains(ty)) return true;
		if(unaryAdverbs.contains(ty)) return true;
		if(unaryGerunds.contains(ty)) return true;

		return false;
	}
}