"use strict";

const fs = require("fs");
const path = require("path");
const cbor = require("cbor");

function sanitizeTestName(name) {
	return name.replace(/[\/\\\s]+/g, "-");
}

function serializeValue(value) {
	return cbor.encodeOne(value, { highWaterMark: 1e8 });
}

function deserializeValue(value) {
	return cbor.decodeFirstSync(value);
}

module.exports = {
	setup: function (tape, snapshotsRoot) {
		Object.assign(tape.Test.prototype, {
			equalsSnapshot: function (value, id) {
				let testName = sanitizeTestName(this.name);
				let snapshotNumber = (this.__lastSnapshot ?? 0) + 1;

				this.__lastSnapshot = snapshotNumber;

				let fullTestName = (id != null)
					? `${testName}-${id}`
					: `${testName}-snapshot-${snapshotNumber}`

				let snapshotPath = path.resolve(snapshotsRoot, `${fullTestName}.cbor`);
				let serializedValue = serializeValue(value);

				if (process.env.UPDATE_SNAPSHOT === "ALL" || process.env.UPDATE_SNAPSHOT === fullTestName) {
					fs.mkdirSync(snapshotsRoot, { recursive: true });
					fs.writeFileSync(snapshotPath, serializedValue);
					console.warn(`[!] Snapshot for '${fullTestName}' was updated`);
				} else if (fs.existsSync(snapshotPath)) {
					// NOTE: To ensure that the replacer transforms are applied to *both* values, we *always* serialize the current value even when we're just comparing it against a known one; we then just deserialize it again below.
					// TODO: Investigate whether this can be optimized with a recursive object transform instead
					let knownValue = deserializeValue(fs.readFileSync(snapshotPath));
					let deserializedValue = deserializeValue(serializedValue);

					this.deepEquals(deserializedValue, knownValue, `Snapshot for '${fullTestName}' does not match; re-run with UPDATE_SNAPSHOT=${fullTestName} to update the snapshot and mark the current result as valid`);
				} else {
					throw new Error(`No known snapshot for '${fullTestName}'; re-run with UPDATE_SNAPSHOT=${fullTestName} to create it automatically`);
				}
			}
		});
	}
};