import {ed25519} from "@noble/curves/ed25519";
import BufferReader from "./buffer_reader.js";
import BufferWriter from "./buffer_writer.js";

class Advert {

    static ADV_TYPE_NONE = 0;
    static ADV_TYPE_CHAT = 1;
    static ADV_TYPE_REPEATER = 2;
    static ADV_TYPE_ROOM = 3;

    static ADV_LATLON_MASK = 0x10;
    static ADV_BATTERY_MASK = 0x20;
    static ADV_TEMPERATURE_MASK = 0x40;
    static ADV_NAME_MASK = 0x80;

    constructor(publicKey, timestamp, signature, appData) {
        this.publicKey = publicKey;
        this.timestamp = timestamp;
        this.signature = signature;
        this.appData = appData;
        this.parsed = this.parseAppData();
    }

    static fromBytes(bytes) {

        // read bytes
        const bufferReader = new BufferReader(bytes);
        const publicKey = bufferReader.readBytes(32);
        const timestamp = bufferReader.readUInt32LE();
        const signature = bufferReader.readBytes(64);
        const appData = bufferReader.readRemainingBytes();

        return new Advert(publicKey, timestamp, signature, appData);

    }

    getFlags() {
        return this.appData[0];
    }

    getTypeString() {
        const flags = this.getFlags();
        if(flags & Advert.ADV_TYPE_NONE) return "ADV_TYPE_NONE";
        if(flags & Advert.ADV_TYPE_CHAT) return "ADV_TYPE_CHAT";
        if(flags & Advert.ADV_TYPE_REPEATER) return "ADV_TYPE_REPEATER";
        if(flags & Advert.ADV_TYPE_ROOM) return "ADV_TYPE_ROOM";
        return null;
    }

    isVerified() {

        // build signed data
        const bufferWriter = new BufferWriter();
        bufferWriter.writeBytes(this.publicKey);
        bufferWriter.writeUInt32LE(this.timestamp);
        bufferWriter.writeBytes(this.appData);

        // verify signature
        return ed25519.verify(this.signature, bufferWriter.toBytes(), this.publicKey);

    }

    parseAppData() {

        // read app data
        const bufferReader = new BufferReader(this.appData);
        const flags = bufferReader.readByte();

        // parse lat lon
        var lat = null;
        var lon = null;
        if(flags & Advert.ADV_LATLON_MASK){
            lat = bufferReader.readInt32LE();
            lon = bufferReader.readInt32LE();
        }

        // parse name (remainder of app data)
        var name = null;
        if(flags & Advert.ADV_NAME_MASK){
            name = bufferReader.readString();
        }

        return {
            type: this.getTypeString(),
            lat: lat,
            lon: lon,
            name: name,
        };

    }

}

export default Advert;