package me.hammerle.snuviscript.code;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Stack;
import me.hammerle.snuviscript.inputprovider.InputProvider;
import me.hammerle.snuviscript.inputprovider.ConstantBoolean;
import me.hammerle.snuviscript.inputprovider.ConstantDouble;
import me.hammerle.snuviscript.inputprovider.ConstantNull;
import me.hammerle.snuviscript.inputprovider.ConstantString;
import me.hammerle.snuviscript.exceptions.PreScriptException;
import me.hammerle.snuviscript.tokenizer.Token;
import me.hammerle.snuviscript.tokenizer.TokenType;
import static me.hammerle.snuviscript.tokenizer.TokenType.*;
import me.hammerle.snuviscript.inputprovider.LocalVariable;
import me.hammerle.snuviscript.inputprovider.Variable;
import me.hammerle.snuviscript.instructions.Array;
import me.hammerle.snuviscript.instructions.Break;
import me.hammerle.snuviscript.instructions.Constant;
import me.hammerle.snuviscript.instructions.Continue;
import me.hammerle.snuviscript.instructions.Else;
import me.hammerle.snuviscript.instructions.ElseIf;
import me.hammerle.snuviscript.instructions.EndIf;
import me.hammerle.snuviscript.instructions.For;
import me.hammerle.snuviscript.instructions.Function;
import me.hammerle.snuviscript.instructions.Goto;
import me.hammerle.snuviscript.instructions.If;
import me.hammerle.snuviscript.instructions.IfGoto;
import me.hammerle.snuviscript.instructions.Instruction;
import me.hammerle.snuviscript.instructions.Return;
import me.hammerle.snuviscript.instructions.UserFunction;
import me.hammerle.snuviscript.instructions.While;

public class Compiler {
    private int index = 0;
    private Token[] tokens = null;
    private final ArrayList<Instruction> instr = new ArrayList<>();

    private HashMap<String, Integer> labels = null;
    private HashMap<String, HashMap<String, Integer>> localLabels = null;
    private HashMap<String, Variable> vars = null;
    private final HashMap<String, LocalVariable> localVars = new HashMap<>();
    private HashMap<String, Integer> functions = null;

    private final Stack<Break> breakStack = new Stack<>();
    private final Stack<Continue> continueStack = new Stack<>();

    private String inFunction = null;
    private boolean lineExpression = false;

    private void addConstant(int line, InputProvider ip) {
        instr.add(new Constant(line, ip));
    }

    private void addFunction(int line, int args, String name) {
        instr.add(new Function(line, args, FunctionRegistry.getFunction(name)));
    }

    private void addGoto(int line, int jump) {
        Goto g = new Goto(line, 0);
        g.setJump(jump);
        instr.add(g);
    }

    private boolean match(boolean notEOF, TokenType... types) {
        for(TokenType type : types) {
            if(check(type, notEOF)) {
                advance();
                return true;
            }
        }
        return false;
    }

    private boolean check(TokenType type, boolean notEOF) {
        if(isAtEnd()) {
            if(notEOF) {
                throw new PreScriptException(
                        String.format("expected %s got %s", type, peek().getType()),
                        peek().getLine());
            }
            return false;
        }
        return peek().getType() == type;
    }

    private Token advance() {
        if(!isAtEnd()) {
            index++;
        }
        return previous();
    }

    private boolean isAtEnd() {
        return peek().getType() == EOF;
    }

    private Token peek() {
        return tokens[index];
    }

    private Token previous() {
        return tokens[index - 1];
    }

    private Token consume(TokenType type) {
        if(check(type, false)) {
            return advance();
        }
        throw new PreScriptException(String.format("expected %s got %s", type, peek().getType()),
                peek().getLine());
    }

    private void noReturnForLastFunction() {
        if(!instr.isEmpty()) {
            instr.get(instr.size() - 1).setNoReturn();
        }
    }

    public Instruction[] compile(Token[] tokens, HashMap<String, Integer> labels,
            HashMap<String, Variable> vars, HashMap<String, Integer> functions,
            HashMap<String, HashMap<String, Integer>> localLabels) {
        this.tokens = tokens;
        index = 0;
        instr.clear();
        this.labels = labels;
        this.localLabels = localLabels;
        this.vars = vars;
        this.functions = functions;
        localVars.clear();
        inFunction = null;

        while(!isAtEnd()) {
            line();
        }

        this.tokens = null;
        this.labels = null;
        this.vars = null;
        this.functions = null;
        localVars.clear();

        Instruction[] code = instr.toArray(new Instruction[instr.size()]);
        instr.clear();
        return code;
    }

    private void line() {
        int oldIndex = index;
        Token t = advance();
        switch(t.getType()) {
            case LABEL:
                handleLabel();
                break;
            case IF:
                handleIf();
                break;
            case SEMICOLON:
                break;
            case FOR:
                handleFor();
                break;
            case BREAK:
                Break b = new Break(previous().getLine());
                breakStack.add(b);
                instr.add(b);
                consume(SEMICOLON);
                break;
            case CONTINUE:
                Continue c = new Continue(previous().getLine());
                continueStack.add(c);
                instr.add(c);
                consume(SEMICOLON);
                break;
            case FUNCTION:
                handleUserFunction();
                break;
            case RETURN:
                handleReturn();
                break;
            case WHILE:
                handleWhile();
                break;
            default:
                index = oldIndex;
                lineExpression = false;
                expression();
                if(!lineExpression) {
                    throw new PreScriptException("missing statement", t.getLine());
                }
                consume(SEMICOLON);
        }
        noReturnForLastFunction();
    }

    private void handleLabel() {
        String name = previous().getData().toString();
        name = name.substring(1); // cut off @ at start
        if(inFunction != null) {
            HashMap<String, Integer> llabel = localLabels.get(inFunction);
            if(llabel == null) {
                llabel = new HashMap<>();
                localLabels.put(inFunction, llabel);
            }
            llabel.put(name, instr.size() - 1);
        } else {
            labels.put(name, instr.size() - 1);
        }
    }

    private void handleIf() {
        Token t = previous();
        consume(OPEN_BRACKET);
        expression();
        If i = new If(t.getLine());
        instr.add(i);
        consume(CLOSE_BRACKET);
        consume(OPEN_CURVED_BRACKET);
        while(!match(true, CLOSE_CURVED_BRACKET)) {
            line();
        }
        i.setJump(instr.size() - 1);
        handleElseIf();
        instr.add(new EndIf(instr.get(instr.size() - 1).getLine()));
    }

    private void handleElseIf() {
        while(match(false, ELSEIF)) {
            Token t = previous();
            consume(OPEN_BRACKET);
            expression();
            ElseIf e = new ElseIf(t.getLine());
            instr.add(e);
            consume(CLOSE_BRACKET);
            consume(OPEN_CURVED_BRACKET);
            while(!match(true, CLOSE_CURVED_BRACKET)) {
                line();
            }
            e.setJump(instr.size() - 1);
        }
        handleElse();
    }

    private void handleElse() {
        if(match(false, ELSE)) {
            Else e = new Else(previous().getLine());
            instr.add(e);
            consume(OPEN_CURVED_BRACKET);
            while(!match(true, CLOSE_CURVED_BRACKET)) {
                line();
            }
            e.setJump(instr.size() - 1);
        }
    }

    private void handleFor() {
        Token t = previous();
        consume(OPEN_BRACKET);
        if(!match(false, SEMICOLON)) {
            expression();
            consume(SEMICOLON);
            noReturnForLastFunction();
        }

        int forConditionStart = instr.size() - 1;
        if(!match(false, SEMICOLON)) {
            expression();
            consume(SEMICOLON);
        } else {
            int line = instr.isEmpty() ? 1 : instr.get(instr.size() - 1).getLine();
            addConstant(line, ConstantBoolean.TRUE);
        }
        int realGotoLine = instr.get(instr.size() - 1).getLine();
        Goto forGoto = new Goto(realGotoLine, 0);
        instr.add(forGoto);

        int forLoopFunctionStart = instr.size() - 1;
        if(!match(false, CLOSE_BRACKET)) {
            expression();
            consume(CLOSE_BRACKET);
            noReturnForLastFunction();
        }
        Goto conditionGoto = new Goto(instr.get(instr.size() - 1).getLine(), 0);
        conditionGoto.setJump(forConditionStart);
        instr.add(conditionGoto);

        int forStart = instr.size() - 1;
        forGoto.setJump(forStart);
        For f = new For(t.getLine());
        instr.add(f);
        consume(OPEN_CURVED_BRACKET);
        while(!match(true, CLOSE_CURVED_BRACKET)) {
            line();
        }
        Goto loopFunctionGoto = new Goto(instr.get(instr.size() - 1).getLine(), 0);
        loopFunctionGoto.setJump(forLoopFunctionStart);
        instr.add(loopFunctionGoto);
        int forEnd = instr.size() - 1;
        f.setJump(forEnd);

        setBreakContinueJumps(forLoopFunctionStart, forEnd);
    }

    private void setBreakContinueJumps(int start, int end) {
        while(!continueStack.empty()) {
            continueStack.pop().setJump(start);
        }
        while(!breakStack.empty()) {
            breakStack.pop().setJump(end);
        }
    }

    private void handleUserFunction() {
        consume(LITERAL);
        Token t = previous();
        consume(OPEN_BRACKET);
        ArrayList<String> list = new ArrayList<>();
        if(!match(false, CLOSE_BRACKET)) {
            while(true) {
                consume(LITERAL);
                list.add(previous().getData().toString());
                if(match(false, CLOSE_BRACKET)) {
                    break;
                }
                consume(COMMA);
            }
        }
        String name = t.getData().toString().toLowerCase();
        UserFunction uf =
                new UserFunction(t.getLine(), name, list.toArray(new String[list.size()]));
        functions.put(name, instr.size());
        instr.add(uf);
        consume(OPEN_CURVED_BRACKET);
        inFunction = name;
        while(!match(true, CLOSE_CURVED_BRACKET)) {
            line();
        }
        inFunction = null;
        instr.add(new Return(instr.get(instr.size() - 1).getLine(), 0));
        uf.setJump(instr.size() - 1);
    }

    private void handleReturn() {
        Token t = previous();
        int args = 0;
        if(!match(false, SEMICOLON)) {
            args = 1;
            expression();
            consume(SEMICOLON);
        }
        instr.add(new Return(t.getLine(), args));
    }

    private void handleWhile() {
        int whileStart = instr.size() - 1;
        Token t = previous();
        consume(OPEN_BRACKET);
        expression();
        While w = new While(t.getLine());
        instr.add(w);
        consume(CLOSE_BRACKET);
        consume(OPEN_CURVED_BRACKET);
        while(!match(true, CLOSE_CURVED_BRACKET)) {
            line();
        }
        addGoto(instr.get(instr.size() - 1).getLine(), whileStart);
        int whileEnd = instr.size() - 1;
        w.setJump(whileEnd);
        setBreakContinueJumps(whileStart, whileEnd);
    }

    private void expression() {
        if(isAtEnd()) {
            throw new PreScriptException(
                    String.format("expected expression got %s", peek().getType()),
                    peek().getLine());
        }
        assignment();
    }

    private void assignment() {
        logicalOr();
        if(match(false, SET, ADD_SET, SUB_SET, MUL_SET, DIV_SET, MOD_SET, LEFT_SHIFT_SET,
                RIGHT_SHIFT_SET, BIT_AND_SET, BIT_XOR_SET, BIT_OR_SET)) {
            Token t = previous();
            assignment();
            addFunction(t.getLine(), 2, t.getType().getName());
            lineExpression = true;
        }
    }

    private void logicalOr() {
        logicalAnd();
        while(match(false, OR)) {
            Token t = previous();
            IfGoto ifGoto = new IfGoto(t.getLine(), true);
            instr.add(ifGoto);
            logicalAnd();
            ifGoto.setJump(instr.size());
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void logicalAnd() {
        equality();
        while(match(false, AND)) {
            Token t = previous();
            IfGoto ifGoto = new IfGoto(t.getLine(), false);
            instr.add(ifGoto);
            equality();
            ifGoto.setJump(instr.size());
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void equality() {
        comparison();
        while(match(false, EQUAL, NOT_EQUAL)) {
            Token t = previous();
            comparison();
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void comparison() {
        addition();
        while(match(false, GREATER, GREATER_EQUAL, LESS, LESS_EQUAL)) {
            Token t = previous();
            addition();
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void addition() {
        multiplication();
        while(match(false, SUB, ADD)) {
            Token t = previous();
            multiplication();
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void multiplication() {
        unary();
        while(match(false, DIV, MUL, MOD)) {
            Token t = previous();
            unary();
            addFunction(t.getLine(), 2, t.getType().getName());
        }
    }

    private void unary() {
        if(match(false, INVERT, BIT_INVERT, SUB, INC, DEC)) {
            Token t = previous();
            unary();
            addFunction(t.getLine(), 1, t.getType().getName());
            if(t.getType() == INC || t.getType() == DEC) {
                lineExpression = true;
            }
            return;
        }
        postUnary();
    }

    private void postUnary() {
        primary();
        while(match(false, INC, DEC)) {
            Token t = previous();
            addFunction(t.getLine(), 1, "p" + t.getType().getName());
            lineExpression = true;
        }
    }

    private void primary() {
        Token t = advance();
        switch(t.getType()) {
            case FALSE:
                addConstant(t.getLine(), ConstantBoolean.FALSE);
                return;
            case TRUE:
                addConstant(t.getLine(), ConstantBoolean.TRUE);
                return;
            case NULL:
                addConstant(t.getLine(), ConstantNull.NULL);
                return;
            case STRING:
                addConstant(t.getLine(), new ConstantString(t.getData().toString()));
                return;
            case LABEL:
                addConstant(t.getLine(), new ConstantString(t.getData().toString().substring(1)));
                return;
            case NUMBER:
                addConstant(t.getLine(), new ConstantDouble((Double) t.getData()));
                return;
            case OPEN_BRACKET:
                expression();
                consume(CLOSE_BRACKET);
                return;
            case LITERAL:
                if(match(false, OPEN_SQUARE_BRACKET)) {
                    handleArray(t);
                } else if(match(false, OPEN_BRACKET)) {
                    handleFunction(t);
                } else {
                    addConstant(t.getLine(), getVariable(t.getData().toString()));
                }
                return;
            default:
        }
        throw new PreScriptException(String.format("unexpected token %s", t.getType()),
                t.getLine());
    }

    public void handleFunction(Token t) {
        int args = 0;
        if(peek().getType() != CLOSE_BRACKET) {
            while(true) {
                args++;
                expression();
                if(match(false, CLOSE_BRACKET)) {
                    break;
                }
                consume(COMMA);
            }
        } else {
            consume(CLOSE_BRACKET);
        }
        addFunction(t.getLine(), args, t.getData().toString());
        lineExpression = true;
    }

    public void handleArray(Token t) {
        if(peek().getType() == CLOSE_SQUARE_BRACKET) {
            throw new PreScriptException("empty array access", peek().getLine());
        }
        int args = 0;
        while(true) {
            args++;
            expression();
            if(match(false, CLOSE_SQUARE_BRACKET)) {
                break;
            }
            consume(COMMA);
        }
        instr.add(new Array(t.getLine(), args, getVariable(t.getData().toString())));
    }

    private Variable getVariable(String name) {
        boolean global = name.startsWith("$");
        if(inFunction != null && !global) {
            LocalVariable v = localVars.get(name);
            if(v != null) {
                return v;
            }
            v = new LocalVariable(name);
            localVars.put(name, v);
            return v;
        }

        if(global) {
            name = name.substring(1);
        }

        Variable v = vars.get(name);
        if(v != null) {
            return v;
        }
        v = new Variable(name);
        vars.put(name, v);
        return v;
    }
}