/**
 * The code box class
 */
class CodeBox {
    constructor(codeBoxID, initialStackID, outputID) {
        /**
         * Possible vectors the pointer can move in
         * @type {Object}
         */
        this.directions = {
            NORTH:  [ 0, -1],
            EAST:   [ 1,  0],
            SOUTH:  [ 0,  1],
            WEST:   [-1,  0],
        };
        /**
         * The current vector of the pointer
         * @type {int[]}
         */
        this.curr_direction = this.directions.EAST;
        /**
         * The Set of instructions to execute
         * 
         * Either a 1 or 2-dimensional array
         * @type {Array|Array[]}
         */
        this.box = [];
        /**
         * The farthest right the box goes
         * @type {int}
         */
        this.maxBoxWidth = 0;
        /**
         * The bottom of the box
         * 
         * @type {int}
         */
        this.maxBoxHeight = 0;
        /**
         * The coordinates of the currently executing instruction inside the code box
         * @type {Object}
         */
        this.pointer = {
            X: 0,
            Y: 0,
        };
        /**
         * Was the instruction last moving in the left direction
         * 
         * Used by the {@link Fisherman}
         * @type {boolean}
         */
        this.dirWasLeft = false;
        /**
         * Are we currently under the influence of the {@link Fisherman}
         * @type {boolean}
         */
        this.onTheHook = false;
        /**
         * Are we currently processing code box instructions as a string
         *
         * 0 when false, otherwise it holds the char code for string delimiter, either
         * 34 or 39
         *
         * @type {int}
         */
        this.stringMode = 0;
        /**
         * The stack for the code box to work with
         *
         * @TODO Implement multiple stacks
         *
         * @type {Stack}
         */
        this.stack = new Stack();

        this.codeBoxDOM = document.getElementById(codeBoxID);
        if(!this.codeBoxDOM) {
            throw new Error(`Failed to find textarea with ID: ${codeBoxID}`);
        }

        this.outputDOM = document.getElementById(outputID);
        if(!this.outputDOM) {
            throw new Error(`Failed to find textarea with ID: ${outputID}`);
        }

        this.initialStackDOM = document.getElementById(initialStackID);
        if(!this.initialStackDOM) {
            throw new Error(`Failed to find input with ID: ${initialStackID}`);
        }
    }

    /**
     * Parse the initial code box
     * 
     * Transforms the textual code box into usable matrix
     */
    ParseCodeBox() {
        // Reset some field for a clean run
        this.box = [];
        this.pointer = {X: 0, Y: 0};
        this.curr_direction = this.directions.EAST;
        this.outputDOM.value = "";

        const cbRaw = this.codeBoxDOM.value;
        const rows = cbRaw.split("\n").filter((r) => r.length);

        let maxRowLength = 0;
        for(const row of rows) {
            const rowSplit = row.split("");

            // Store this for later processing
            while(rowSplit.length > maxRowLength) {
                maxRowLength = rowSplit.length
            }

            this.box.push(rowSplit);
        }

        this.EqualizeBoxWidth(maxRowLength);

        this.maxBoxWidth = maxRowLength - 1;
        this.maxBoxHeight = this.box.length - 1;
        
        let fin = null;

        try {
            while(!fin) {
                fin = this.Swim();
            }
        }
        catch(e) {
            console.error(e);
        }
    }

    /**
     * Make all the rows in the code box the same length
     *
     * All rows not long enough will have NOPs added until they're uniform in size.
     *
     * @param {int} [rowLength] The longest row in the code box
     */
    EqualizeBoxWidth(rowLength = null) {
        if(!rowLength) {
            for(const row of this.box) {
                if(row.length > rowLength) {
                    rowLength = row.length;
                }
            }
        }

        for(const row of this.box) {
            while(row.length < rowLength) {
                row.push(" ");
            }
        }
    }

    /**
     * Print the value to the display 
     *
     * @TODO Set up an actual display
     * @param {*} value 
     */
    Output(value) {
        this.outputDOM.value += value;
    }

    Execute(instruction) {
        let output = null;
        try{
            switch(instruction) {
                // NOP
                case " ":
                    break;
                // Numbers
                case "1":
                case "2":
                case "3":
                case "4":
                case "5":
                case "6":
                case "7":
                case "8":
                case "9":
                case "0":
                case "a":
                case "b":
                case "c":
                case "d":
                case "e":
                case "f":
                    this.stack.Push(parseInt(instruction, 16));
                    break;
                // Operators
                case "+": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.Push(y + x);
                    break;
                }
                case "-": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.Push(y - x);
                    break;
                }
                case "*": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.Push(y * x);
                    break;
                }
                case ",": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.Push(y / x);
                    break;
                }
                case "%": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.Push(y % x);
                    break;
                }
                case "(": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.push(y < x ? 1 : 0);
                    break;
                }
                case ")": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.push(y > x ? 1 : 0);
                    break;
                }
                case "=": {
                    const x = this.stack.Pop();
                    const y = this.stack.Pop();
                    this.stack.push(y == x ? 1 : 0);
                    break;
                }
                // Movement
                case "^":
                    this.MoveUp();
                    break;
                case ">":
                    this.MoveRight();
                    break;
                case "v":
                    this.MoveDown();
                    break;
                case "<":
                    this.MoveLeft();
                    break;
                // Mirrors
                case "/":
                    this.ReflectForward();
                    break;
                case "\\":
                    this.ReflectBack();
                    break;
                case "_":
                    this.VerticalMirror();
                    break;
                case "|":
                    this.HorizontalMirror();
                    break;
                case "#":
                    this.OmniMirror();
                    break;
                // Stack manipulation
                case ":":
                    this.stack.Duplicate();
                    break;
                case "~":
                    this.stack.Remove();
                    break;
                case "$":
                    this.stack.SwapTwo();
                    break;
                case "@":
                    this.stack.SwapThree();
                    break;
                case "{":
                    this.stack.ShiftLeft();
                    break;
                case "}":
                    this.stack.ShiftRight();
                    break;
                case "r":
                    this.stack.Reverse();
                    break;
                case "l":
                    this.stack.PushLength();
                    break;
                // case "[":
                //     break;
                // case "]":
                //     break;
                // case "I":
                //     this.curr_stack++;
                //     break;
                // case "D":
                //     this.curr_stack--;
                //     break;
                // Output
                case "n": 
                    output = this.stack.Pop();
                    break;
                case "o":
                    output = String.fromCharCode(this.stack.Pop());
                    break;
                // End execution
                case ";":
                    output = true;
                    break;
                default:
                    throw new Error();
            }
        }
        catch(e) {
            console.error(`Something smells fishy!\nInstruction: ${instruction}\nStack: ${JSON.stringify(this.stack.stack)}`);
        }

        return output;
    }

    Swim() {
        const instruction = this.box[this.pointer.Y][this.pointer.X];

        if(this.stringMode != 0 && instruction != this.stringMode) {
            this.stack.Push(dec(instruction));
        }
        else {
            const exeResult = this.Execute(instruction);
            if(exeResult === true) {
                return true;
            }
            else if(exeResult != null) {
                this.Output(exeResult);
            }
        }

        this.Move();
    }

    Move() {
        let newX = this.pointer.X + this.curr_direction[0];
        let newY = this.pointer.Y + this.curr_direction[1];

        // Keep the X coord in the boxes bounds
        if(newX < 0) {
            newX = this.maxBoxWidth;
        }
        else if(newX > this.maxBoxWidth) {
            newX = 0;
        }
        // Keep the Y coord in the boxes bounds
        if(newY < 0) {
            newY = this.maxBoxHeight;
        }
        else if(newY > this.maxBoxHeight) {
            newY = 0;
        }

        this.SetPointer(newX, newY);
    }

    /**
     * Implement C and .
     */
    SetPointer(x, y) {
        this.pointer = {X: x, Y: y};
    }

    /**
     * Implement ^
     * 
     * Changes the swim direction upward
     */
    MoveUp() {
        this.curr_direction = this.directions.NORTH;
    }
    /**
     * Implement >
     * 
     * Changes the swim direction rightward
     */
    MoveRight() {
        this.curr_direction = this.directions.EAST;
        this.dirWasLeft = false;
    }
    /**
     * Implement v
     * 
     * Changes the swim direction downward
     */
    MoveDown() {
        this.curr_direction = this.directions.SOUTH;
    }
    /**
     * Implement <
     * 
     * Changes the swim direction leftward
     */
    MoveLeft() {
        this.curr_direction = this.directions.WEST;
        this.dirWasLeft = true;
    }

    /**
     * Implement /
     * 
     * Reflects the swim direction depending on its starting value
     */
    ReflectForward() {
        if (this.curr_direction == this.directions.NORTH) {
            this.MoveRight();
        }
        else if (this.curr_direction == this.directions.EAST) {
            this.MoveUp();
        }
        else if (this.curr_direction == this.directions.SOUTH) {
            this.MoveLeft();
        }
        else {
            this.MoveDown();
        }
    }
    /**
     * Implement \
     * 
     * Reflects the swim direction depending on its starting value
     */
    ReflectBack() {
        if (this.curr_direction == this.directions.NORTH) {
            this.MoveLeft();
        }
        else if (this.curr_direction == this.directions.EAST) {
            this.MoveDown();
        }
        else if (this.curr_direction == this.directions.SOUTH) {
            this.MoveRight();
        }
        else {
            this.MoveUp();
        }
    }

    /**
     * Implement |
     * 
     * Swaps the horizontal swim direction to its opposite
     */
    HorizontalMirror() {
        if (this.curr_direction == this.directions.EAST) {
            this.MoveLeft();
        }
        else {
            this.MoveRight();
        }
    }
    /**
     * Implement _
     * 
     * Swaps the horizontal swim direction to its opposite
     */
    VerticalMirror() {
        if (this.curr_direction == this.directions.NORTH) {
            this.MoveDown();
        }
        else {
            this.MoveUp();
        }
    }
    /**
     * Implement #
     * 
     * A combination of the vertical and the horizontal mirror
     */
    OmniMirror() {
        if (this.curr_direction[0]) {
            this.VerticalMirror();
        }
        else {
            this.HorizontalMirror();
        }
    }

    /**
     * Implement x
     * 
     * Pseudo-randomly switches the swim direction
     */
    ShuffleDirection() {
        this.curr_direction = Object.values(this.directions)[Math.floor(Math.random() * 4)];
    }

    /**
     * Implement `
     * 
     * Changes the swim direction based on the previous direction
     * @see https://esolangs.org/wiki/Starfish#Fisherman
     */
    Fisherman() {
        if (this.curr_direction[0]) {
            if (this.dirWasLeft) {
                this.MoveLeft();
            }
            else {
                this.MoveRight();
            }
        }
        else {
            if (this.onTheHook) {
                this.onTheHook = false;
                this.MoveUp();
            }
            else {
                this.onTheHook = true;    
                this.MoveDown();
            }
        }
    }
}
/**
 * The stack class
 */
class Stack {
    constructor() {
        /**
         * The stack
         * @type {int[]}
         */
        this.stack = [];
        /**
         * A single value saved off the stack
         * @type {int}
         */
        this.register = null;
    }

    /**
     * Wrapper function for Array.prototype.push
     * @param {*} newValue 
     */
    Push(newValue) {
        this.stack.push(newValue);
    }
    /**
     * Wrapper function for Array.prototype.pop
     * @returns {*}
     */
    Pop() {
        const value = this.stack.pop();
        if(value == undefined){ throw new Error(); }

        return value;
    }

    /**
     * Implement }
     * 
     * Shifts the entire stack leftward by one value
     */
    ShiftLeft() {
        const temp = this.stack.shift();
        this.stack.push(temp);
    }
    /**
     * Implement {
     * 
     * Shifts the entire stack rightward by one value
     */
    ShiftRight() {
        const temp = this.stack.pop();
        this.stack.unshift(temp);
    }
    /**
     * Implement $
     * 
     * Swaps the top two values of the stack
     */
    SwapTwo() {
        if(this.stack.length < 2) { throw new Error(); }
        const popped = this.stack.splice(this.stack.length - 2, 2);
        this.stack.push(...popped.reverse());
    }
    /**
     * Implement @
     * 
     * Swaps the top three values of the stack
     */
    SwapThree() {
        if(this.stack.length < 3) { throw new Error(); }
        // Get the top three values
        const popped = this.stack.splice(this.stack.length - 3, 3);
        // Shift the elements to the right
        popped.unshift(popped.pop());
        this.stack.push(...popped);
    }

    /**
     * Implement :
     * 
     * Duplicates the element on the top of the stack
     */
    Duplicate() {
        this.stack.push(this.stack[this.stack.length-1]);
    }
    /**
     * Implements ~
     * 
     * Removes the element on the top of the stack 
     */
    Remove() {
        this.stack.pop();
    }

    /**
     * Implement r
     * 
     * Reverses the entire stack
     */
    Reverse() {
        this.stack.reverse();
    }

    /**
     * Implement l
     * 
     * Pushes the length of the stack onto the top of the stack
     */
    PushLength() {
        this.stack.push(this.stack.length);
    }
}

/**
 * Get the char code of any character
 *
 * Can actually take any length of a value, but only returns the
 * char code of the first character.
 *
 * @param {*} value Any character
 * @returns {int} The value's char code
 */
function dec(value) {
    return value.toString().charCodeAt(0);
}