Zazama / node-id3

import { FrameBuilder } from "../FrameBuilder"

import { FrameReader } from "../FrameReader"

import { Popularimeter } from "../types/TagFrames"

export const POPM = {

    create: (data: Popularimeter): Buffer => {

        if(data.email == undefined) {

            throw new RangeError("An email is expected")

        }

        // TODO: starting version 0.3 for both rating and counter do not

        // implicitely trunc and use Number.isInteger() instead to validate

        const rating = Math.trunc(data.rating)

        if( isNaN(rating) || rating < 0 || rating > 255) {

            throw new RangeError(

                `Provided rating ${data.rating} is not in the valid range 0-255`

            )

        }

        // TODO: According to specs, the counter can be omitted

        // TODO: According to specs if the value is bigger than a 32 bits

        // a byte can be added and so on... (very unlikely to happen in

        // real life as it means more than 4GB listenings!)

        const counter = Math.trunc(data.counter)

        if (isNaN(counter) || counter < 0) {

            throw new RangeError(

                `Provided counter ${data.counter} is not a positive integer`

            )

        }

        return new FrameBuilder("POPM")

            .appendTerminatedText(data.email)

            .appendNumber(rating, {size: 1})

            .appendNumber(counter, {size: 4})

            .getBufferWithPartialHeader()

    },

    read: (buffer: Buffer): Popularimeter => {

        const reader = new FrameReader(buffer)

        return {

            email: reader.consumeTerminatedText(),

            rating: reader.consumeNumber({size: 1}),

            counter: reader.consumeNumber({size: 4})

        }

    }

}