import { Readable } from "readable-stream";

import { CompressedJSON, Value } from "quicktype-core";

import { Parser } from "stream-json";

const methodMap: { [name: string]: string } = {

startObject: "pushObjectContext",

endObject: "finishObject",

startArray: "pushArrayContext",

endArray: "finishArray",

startNumber: "handleStartNumber",

numberChunk: "handleNumberChunk",

endNumber: "handleEndNumber",

keyValue: "setPropertyKey",

stringValue: "commitString",

nullValue: "commitNull",

trueValue: "handleTrueValue",

falseValue: "handleFalseValue"

};

export class CompressedJSONFromStream extends CompressedJSON<Readable> {

async parse(readStream: Readable): Promise<Value> {

const combo = new Parser({ packKeys: true, packStrings: true });

combo.on("data", (item: { name: string; value: string | undefined }) => {

if (typeof methodMap[item.name] === "string") {

(this as any)[methodMap[item.name]](item.value);

}

});

const promise = new Promise<Value>((resolve, reject) => {

combo.on("end", () => {

resolve(this.finish());

});

combo.on("error", (err: any) => {

reject(err);

});

});

readStream.setEncoding("utf8");

readStream.pipe(combo);

readStream.resume();

return promise;

}

protected handleStartNumber = (): void => {

this.pushContext();

this.context.currentNumberIsDouble = false;

};

protected handleNumberChunk = (s: string): void => {

const ctx = this.context;

if (!ctx.currentNumberIsDouble && /[\.e]/i.test(s)) {

ctx.currentNumberIsDouble = true;

}

};

protected handleEndNumber(): void {

const isDouble = this.context.currentNumberIsDouble;

this.popContext();

this.commitNumber(isDouble);

}

protected handleTrueValue(): void {

this.commitBoolean(true);

}

protected handleFalseValue(): void {

this.commitBoolean(false);

}

}