All files mqtt-plus-codec.ts

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/*
**  MQTT+ -- MQTT Communication Patterns
**  Copyright (c) 2018-2026 Dr. Ralf S. Engelschall <rse@engelschall.com>
**
**  Permission is hereby granted, free of charge, to any person obtaining
**  a copy of this software and associated documentation files (the
**  "Software"), to deal in the Software without restriction, including
**  without limitation the rights to use, copy, modify, merge, publish,
**  distribute, sublicense, and/or sell copies of the Software, and to
**  permit persons to whom the Software is furnished to do so, subject to
**  the following conditions:
**
**  The above copyright notice and this permission notice shall be included
**  in all copies or substantial portions of the Software.
**
**  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
**  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
**  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
**  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
**  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
**  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
**  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
 
/*  external requirements  */
import { Buffer }                         from "node:buffer"
import * as CBOR                          from "cbor2"
 
/*  internal requirements  */
import type { APISchema }                 from "./mqtt-plus-api"
import { type APIOptions, OptionsTrait }  from "./mqtt-plus-options"
 
/*  JSON encode/decode with Uint8Array support  */
export class JSONX {
    private static uint8ArrayToBase64 (arr: Uint8Array): string {
        return Buffer.from(arr.buffer, arr.byteOffset, arr.byteLength).toString("base64")
    }
    private static base64ToUint8Array (base64: string): Uint8Array {
        return new Uint8Array(Buffer.from(base64, "base64"))
    }
    static stringify (obj: unknown): string {
        return JSON.stringify(obj, (_, value) =>
            value instanceof Uint8Array
                ? { __Uint8Array: this.uint8ArrayToBase64(value) }
                : value
        )
    }
    static parse (json: string): unknown {
        return JSON.parse(json, (_, value) =>
            typeof value?.__Uint8Array === "string"
                ? this.base64ToUint8Array(value.__Uint8Array)
                : value
        )
    }
}
 
/*  the encoder/decoder abstraction  */
class Codec {
    private types = new CBOR.TypeEncoderMap()
    private tags: CBOR.TagDecoderMap = new Map<CBOR.TagNumber, CBOR.TagDecoder>()
    constructor (
        private format: "cbor" | "json"
    ) {
        /*  support direct encoding/decoding of Buffer  */
        const TAG_BUFFER = 64000
        this.types.registerEncoder(Buffer, (buffer: Buffer) => {
            return [ TAG_BUFFER, new Uint8Array(buffer.buffer, buffer.byteOffset, buffer.byteLength) ]
        })
        this.tags.set(TAG_BUFFER, (tag: CBOR.ITag) => {
            return Buffer.from(tag.contents as Uint8Array)
        })
    }
    encode (data: unknown): Uint8Array | string {
        let result: Uint8Array | string
        if (this.format === "cbor") {
            try { result = CBOR.encode(data, { types: this.types }) }
            catch (err: unknown) { throw new Error("failed to encode CBOR format", { cause: err }) }
        }
        else if (this.format === "json") {
            try { result = JSONX.stringify(data) }
            catch (err: unknown) { throw new Error("failed to encode JSON format", { cause: err }) }
        }
        else
            throw new Error(`invalid format "${this.format}"`)
        return result
    }
    decode (data: Uint8Array | string): unknown {
        let result: unknown
        if (this.format === "cbor") {
            if (!(data instanceof Uint8Array))
                throw new Error("failed to decode CBOR format (data type is not Uint8Array)")
            if (data.byteLength === 0)
                throw new Error("failed to decode CBOR format (data is empty)")
            try { result = CBOR.decode(data, { tags: this.tags }) }
            catch (err: unknown) { throw new Error("failed to decode CBOR format", { cause: err }) }
        }
        else if (this.format === "json") {
            if (typeof data !== "string")
                throw new Error("failed to decode JSON format (data type is not string)")
            if (data.length === 0)
                throw new Error("failed to decode JSON format (data is empty)")
            try { result = JSONX.parse(data) }
            catch (err: unknown) { throw new Error("failed to decode JSON format", { cause: err }) }
        }
        else
            throw new Error(`invalid format "${this.format}"`)
        return result
    }
}
 
/*  Codec trait  */
export class CodecTrait<T extends APISchema = APISchema> extends OptionsTrait<T> {
    protected codec: Codec
 
    /*  construct API class  */
    constructor (
        options: Partial<APIOptions> = {}
    ) {
        super(options)
 
        /*  establish a codec  */
        this.codec = new Codec(this.options.codec)
    }
}