/**
 * TODO: bigint, large decimals. For right now, only use numbers that fit in
 * JavaScript number.
 */
export const Types = {
    BERT_START: 131,
    SMALL_ATOM: 119,
    ATOM: 100,
    BINARY: 109,
    SMALL_INTEGER: 97,
    INTEGER: 98,
    SMALL_BIG: 110,
    LARGE_BIG: 111,
    FLOAT: 99,
    STRING: 107,
    LIST: 108,
    SMALL_TUPLE: 104,
    LARGE_TUPLE: 105, // TODO: Implement.
    MAP: 116,
    NIL: 106,
    NEW_FLOAT: 70,
    ZERO: 0,
};
export const Lang = {
    ELIXIR: 0,
    ERLANG: 1,
};
/**
 * WIP WIP WIP
 *
 * @param key
 * @param value
 * @returns
 */
const reviver = (key, value) => {
    if (typeof value === "object" && value.type === "atom") {
        return Atom.toAtom(value.value);
    }
    else if (typeof value === "object" && value.type === "tuple") {
        return new Tuple(value.values);
    }
    else
        return value;
};
const log = (msg) => process.stderr.write(`${msg}\r\n`);
/**
 * Return a subarray of the supplied buffer, minus len bytes from the front.
 *
 * @param buffer
 * @param len Number of bytes to chop off front
 * @returns Subarray of buffer
 */
const chopl = (buffer, len = 1) => buffer.subarray(len);
export class Atom {
    value;
    constructor(value) {
        this.value = value;
    }
    static atoms = {};
    static toAtom = (value) => {
        return Atom.atoms[value] || (Atom.atoms[value] = new Atom(value));
    };
}
/**
 * WIP WIP WIP
 */
export class Tuple {
    values;
    constructor(values) {
        // Yes right now this is only one level deep.
        this.values = [...values];
    }
}
export class Bert {
    allBinariesAsString;
    mapKeyAsAtom;
    decodeUndefinedValues;
    convention;
    outputBuffer;
    constructor(allBinariesAsString = false, mapKeyAsAtom = true, decodeUndefinedValues = true, convention = Lang.ELIXIR) {
        this.allBinariesAsString = allBinariesAsString;
        this.mapKeyAsAtom = mapKeyAsAtom;
        this.decodeUndefinedValues = decodeUndefinedValues;
        this.convention = convention;
        this.outputBuffer = Buffer.alloc(10000000);
        this.outputBuffer[0] = Types.BERT_START;
    }
    toAtom = toAtom;
    toTuple = toTuple;
    #encode = (obj, buffer) => this[`encode_${typeof obj}`](obj, buffer);
    encode = (obj, copy = true) => {
        const tailBuffer = this.#encode(obj, this.outputBuffer.subarray(1));
        log(`tailbuffer length: ${tailBuffer.length}`);
        if (tailBuffer.length === 0) {
            throw new Error("Bert encode a too big term, encoding buffer overflow");
        }
        else if (copy) {
            const ret = Buffer.alloc(tailBuffer.length + 1);
            this.outputBuffer.copy(ret, 0, 0, ret.length + 1);
            return ret;
        }
        else {
            return this.outputBuffer.subarray(0, tailBuffer.length + 1);
        }
    };
    #decode = (buffer) => {
        const t = buffer[0];
        buffer = chopl(buffer);
        switch (t) {
            case Types.SMALL_ATOM:
                return this.decode_atom(buffer, 1);
            case Types.ATOM:
                return this.decode_atom(buffer, 2);
            case Types.BINARY:
                return this.decode_binary(buffer);
            case Types.SMALL_INTEGER:
                return this.decode_integer(buffer, 1, true);
            case Types.INTEGER:
                return this.decode_integer(buffer, 4);
            case Types.SMALL_BIG:
                return this.decode_big(buffer, 1);
            case Types.LARGE_BIG:
                return this.decode_big(buffer, 4);
            case Types.FLOAT:
                return this.decode_float(buffer);
            case Types.NEW_FLOAT:
                return this.decode_new_float(buffer);
            case Types.STRING:
                return this.decode_string(buffer);
            case Types.LIST:
                return this.decode_list(buffer);
            case Types.SMALL_TUPLE:
                return this.decode_tuple(buffer, 1);
            // case Types.LARGE_TUPLE:
            //    return this.decode_large_tuple(buffer, 4)
            case Types.NIL:
                return this.decode_nil(buffer);
            case Types.MAP:
                return this.decode_map(buffer);
            default:
                throw new Error(`Unexpected BERT type: ${t}`);
        }
    };
    decode = (buffer) => {
        if (buffer[0] !== Types.BERT_START) {
            throw new Error("Invalid BERT start magic");
        }
        const obj = this.#decode(chopl(buffer));
        if (obj.rest.length !== 0) {
            throw new Error(`Invalid BERT, remainder was: ${obj.rest.length}`);
        }
        return obj.value;
    };
    encode_string = (obj, buffer) => {
        if (this.convention === Lang.ELIXIR) {
            return this.encode_binary(Buffer.from(obj), buffer);
        }
        else {
            buffer[0] = Types.STRING;
            buffer.writeUInt16BE(Buffer.byteLength(obj, "utf-8"), 1);
            const len = buffer.write(obj, 3);
            return buffer.subarray(0, 3 + len);
        }
    };
    encode_boolean = (obj, buffer) => {
        if (obj) {
            return this.#encode(this.toAtom("true"), buffer);
        }
        else {
            return this.#encode(this.toAtom("false"), buffer);
        }
    };
    encode_number = (obj, buffer) => {
        const isInteger = obj % 1 === 0;
        // Handle floats...
        if (!isInteger) {
            return this.encode_float(obj, buffer);
        }
        // Small int...
        if (isInteger && obj >= 0 && obj < 256) {
            buffer[0] = Types.SMALL_INTEGER;
            buffer.writeUInt8(obj, 1);
            return buffer.subarray(0, 2);
        }
        // 4 byte int...
        if (isInteger && obj >= -134217728 && obj <= 134217727) {
            buffer[0] = Types.INTEGER;
            buffer.writeInt32BE(obj, 1);
            return buffer.subarray(0, 5);
        }
        // Bignum...
        const numBuffer = Buffer.alloc(buffer.length);
        if (obj < 0) {
            obj *= -1;
            numBuffer[0] = 1;
        }
        else {
            numBuffer[0] = 0;
        }
        let offset = 1;
        while (obj !== 0) {
            numBuffer[offset] = obj % 256;
            obj = Math.floor(obj / 256);
            offset++;
        }
        if (offset < 256) {
            buffer[0] = Types.SMALL_BIG;
            buffer.writeUInt8(offset - 1, 1);
            numBuffer.copy(buffer, 2, 0, offset);
            return buffer.subarray(0, 2 + offset);
        }
        else {
            buffer[0] = Types.LARGE_BIG;
            buffer.writeUInt32BE(offset - 1, 1);
            numBuffer.copy(buffer, 5, 0, offset);
            return buffer.subarray(0, 5 + offset);
        }
    };
    encode_float = (obj, buffer) => {
        // float...
        buffer[0] = Types.NEW_FLOAT;
        buffer.writeDoubleBE(obj, 1);
        return buffer.subarray(0, 9);
    };
    encode_object = (obj, buffer) => {
        // Check if it's an atom, binary, or tuple...
        if (obj === null) {
            const undefinedAtom = this.convention === Lang.ELIXIR ? "nil" : "undefined";
            return this.#encode(this.toAtom(undefinedAtom), buffer);
        }
        if (Buffer.isBuffer(obj)) {
            return this.encode_binary(obj, buffer);
        }
        if (Array.isArray(obj)) {
            return this.encode_array(obj, buffer);
        }
        if (obj.type === "Atom") {
            return this.encode_atom(obj, buffer);
        }
        if (obj.type === "Tuple") {
            return this.encode_tuple(obj, buffer);
        }
        // Treat the object as an associative array...
        return this.encode_map(obj, buffer);
    };
    encode_atom = (obj, buffer) => {
        buffer[0] = Types.ATOM;
        buffer.writeUInt16BE(obj.value.length, 1);
        const len = buffer.write(obj.value, 3);
        return buffer.subarray(0, 3 + len);
    };
    encode_binary = (obj, buffer) => {
        buffer[0] = Types.BINARY;
        buffer.writeUInt32BE(obj.length, 1);
        const len = obj.copy(buffer, 5);
        return buffer.subarray(0, 5 + len);
    };
    encode_undefined = (_obj, buffer) => {
        return this.#encode(null, buffer);
    };
    encode_tuple = (obj, buffer) => {
        if (obj.length < 256) {
            buffer[0] = Types.SMALL_TUPLE;
            buffer.writeUInt8(obj.length, 1);
            buffer = buffer.subarray(0, 2);
        }
        else {
            buffer[0] = Types.LARGE_TUPLE;
            buffer.writeUInt32BE(obj.length, 1);
            buffer = buffer.subarray(0, 5);
        }
        for (let i = 0; i < obj.length; ++i) {
            buffer = this.#encode(obj[i], buffer);
        }
        return buffer;
    };
    encode_array = (obj, buffer) => {
        if (obj.length === 0) {
            buffer[0] = Types.NIL;
            return buffer.subarray(0, 1);
        }
        buffer[0] = Types.LIST;
        buffer.writeUInt32BE(obj.length, 1);
        buffer = buffer.subarray(0, 5);
        for (let i = 0; i < obj.length; ++i) {
            buffer = this.#encode(obj[i], buffer);
        }
        buffer[0] = Types.NIL;
        return buffer.subarray(0, 1);
    };
    encode_map = (obj, buffer) => {
        const keys = Object.keys(obj);
        buffer[0] = Types.MAP;
        buffer.writeUInt32BE(keys.length, 1);
        buffer = buffer.subarray(0, 5);
        for (let i = 0; i < keys.length; ++i) {
            const key = this.mapKeyAsAtom ? this.toAtom(keys[i]) : keys[i];
            buffer = this.#encode(key, buffer);
            buffer = this.#encode(obj[keys[i]], buffer);
        }
        return buffer;
    };
    decode_atom = (buffer, count) => {
        const size = this.bytesToInt(buffer, count, true);
        buffer = chopl(buffer, count);
        let value = buffer.toString("utf8", 0, size);
        if (value === "true") {
            value = true;
        }
        else if (value === "false") {
            value = false;
        }
        else if (this.decodeUndefinedValues &&
            this.convention === Lang.ELIXIR &&
            value === "nil") {
            value = null;
        }
        else if (this.decodeUndefinedValues &&
            this.convention === Lang.ERLANG &&
            value === "undefined") {
            value = null;
        }
        else {
            value = this.toAtom(value);
        }
        return {
            value,
            rest: chopl(buffer, size),
        };
    };
    decode_binary = (buffer) => {
        const size = this.bytesToInt(buffer, 4, true);
        buffer = chopl(buffer, 4);
        const bin = Buffer.alloc(size);
        buffer.copy(bin, 0, 0, size);
        return {
            value: this.convention === Lang.ELIXIR && this.allBinariesAsString
                ? bin.toString("utf-8")
                : bin,
            rest: chopl(buffer, size),
        };
    };
    decode_integer = (buffer, count, unsigned = false) => {
        return {
            value: this.bytesToInt(buffer, count, unsigned),
            rest: chopl(buffer, count),
        };
    };
    decode_big = (buffer, count) => {
        const size = this.bytesToInt(buffer, count, true);
        buffer = chopl(buffer, count);
        let num = 0;
        const isNegative = buffer[0] === 1;
        buffer = chopl(buffer);
        for (let i = size - 1; i >= 0; --i) {
            const n = buffer[i];
            if (num === 0) {
                num = n;
            }
            else {
                num = num * 256 + n;
            }
        }
        if (isNegative) {
            num = num * -1;
        }
        return {
            value: num,
            rest: chopl(buffer, size),
        };
    };
    decode_float = (buffer) => {
        const size = 31;
        return {
            value: parseFloat(buffer.toString("utf8", 0, size)),
            rest: chopl(buffer, size),
        };
    };
    decode_new_float = (buffer) => {
        return {
            value: buffer.readDoubleBE(0),
            rest: chopl(buffer, 8),
        };
    };
    decode_string = (buffer) => {
        const sizeLen = this.convention === Lang.ELIXIR ? 4 : 2;
        const size = this.bytesToInt(buffer, sizeLen, true);
        buffer = chopl(buffer, sizeLen);
        return {
            value: buffer.toString("utf8", 0, size),
            rest: chopl(buffer, size),
        };
    };
    decode_list = (buffer) => {
        const arr = [];
        const size = this.bytesToInt(buffer, 4, true);
        buffer = chopl(buffer, 4);
        for (let i = 0; i < size; ++i) {
            const el = this.#decode(buffer);
            arr.push(el.value);
            buffer = el.rest;
        }
        const lastChar = buffer[0];
        if (lastChar !== Types.NIL) {
            throw new Error("List does not end with NIL");
        }
        buffer = chopl(buffer);
        return {
            value: arr,
            rest: buffer,
        };
    };
    decode_map = (buffer) => {
        const map = {};
        const size = this.bytesToInt(buffer, 4, true);
        buffer = chopl(buffer, 4);
        for (let i = 0; i < size; ++i) {
            let el = this.#decode(buffer);
            const key = el.value;
            el = this.#decode(el.rest);
            const value = el.value;
            map[key] = value;
            buffer = el.rest;
        }
        return {
            value: map,
            rest: buffer,
        };
    };
    decode_tuple = (buffer, count) => {
        const arr = [];
        const size = this.bytesToInt(buffer, count, true);
        buffer = chopl(buffer, count);
        for (let i = 0; i < size; ++i) {
            const el = this.#decode(buffer);
            arr.push(el.value);
            buffer = el.rest;
        }
        return {
            value: this.toTuple(arr),
            rest: buffer,
        };
    };
    decode_nil = (buffer) => {
        // nil is an empty list
        return {
            value: [],
            rest: buffer,
        };
    };
    bytesToInt = (buffer, length, unsigned) => {
        switch (length) {
            case 1:
                return unsigned ? buffer.readUInt8(0) : buffer.readInt8(0);
            case 2:
                return unsigned ? buffer.readUInt16BE(0) : buffer.readInt16BE(0);
            case 4:
                return unsigned ? buffer.readUInt32BE(0) : buffer.readInt32BE(0);
        }
    };
}
/**
 * Convert object to atom.
 *
 */
export const toAtom = (str) => ({
    type: "Atom",
    value: str,
    toString: () => str,
});
/**
 * Convert array of items to tuple.
 *
 */
export const toTuple = (arr) => ({
    ...arr,
    type: "Tuple",
    length: arr.length,
    value: arr,
    toString: () => "{" +
        arr
            .filter((i) => i !== "")
            .map((i) => i.toString())
            .join(", ") +
        "}",
});