From 3df0b6ba76ffab1e1c73140c583d07c30fac38a4 Mon Sep 17 00:00:00 2001
From: Narek Hovhannisyan <narhovhannisian@gmail.com>
Date: Thu, 9 Jan 2025 14:53:32 +0400
Subject: [PATCH] feat(builtins): implement GCD calculation and resampling
 resolution logic for time sync

---
 src/if-run/builtins/time-sync/index.ts | 54 +++++++++++++++++++++++++-
 1 file changed, 53 insertions(+), 1 deletion(-)

diff --git a/src/if-run/builtins/time-sync/index.ts b/src/if-run/builtins/time-sync/index.ts
index 0c1ecfb2..763c0d3c 100644
--- a/src/if-run/builtins/time-sync/index.ts
+++ b/src/if-run/builtins/time-sync/index.ts
@@ -483,6 +483,57 @@ export const TimeSync = PluginFactory<TimeNormalizerConfig>({
       }, [] as PluginParams[]);
 
     /** Implementation */
+    /**
+     * Calculates the greatest common divisor (GCD) of two numbers using the Euclidean algorithm.
+     */
+    const greatestCommonDivisor = (a: number, b: number): number => {
+      while (b !== 0) {
+        [a, b] = [b, a % b];
+      }
+
+      return a;
+    };
+
+    /**
+     * Calculates the greatest common divisor (GCD) of an array of numbers.
+     */
+    const calculateGCD = (numbers: number[]) =>
+      numbers.reduce((acc, val) => greatestCommonDivisor(acc, val));
+
+    /**
+     * Returns an array of unique values from the given array.
+     */
+    const getUniqueValues = (arr: number[]) => Array.from(new Set(arr));
+
+    /**
+     * Finds the most efficient resampling resolution based on the given inputs and user-defined interval.
+     *
+     * This function calculates the greatest common divisor (GCD) of the combined unique values from:
+     * - A: All unique values of (timestamp + duration) for each input.
+     * - B: All unique values of (next timestamp - current timestamp + duration) for each input.
+     */
+    const findResamplingResolution = (
+      inputs: PluginParams[],
+      userInterval: number
+    ): number => {
+      const A: number[] = [];
+      const B: number[] = [];
+
+      for (let i = 0; i < inputs.length - 1; i++) {
+        const currentTimestamp = parseDate(inputs[i].timestamp).toMillis();
+        const nextTimestamp = parseDate(inputs[i + 1].timestamp).toMillis();
+
+        A.push(currentTimestamp + inputs[i].duration);
+        B.push(nextTimestamp - currentTimestamp + inputs[i].duration);
+      }
+
+      const uniqueA = getUniqueValues(A);
+      const uniqueB = getUniqueValues(B);
+      const combined = [...uniqueA, ...uniqueB, userInterval];
+
+      return calculateGCD(combined);
+    };
+
     const timeParams = {
       startTime: DateTime.fromISO(config['start-time'] as string),
       endTime: DateTime.fromISO(config['end-time'] as string),
@@ -490,8 +541,9 @@ export const TimeSync = PluginFactory<TimeNormalizerConfig>({
       allowPadding: config['allow-padding'],
       upsamplingResolution: config['upsampling-resolution']
         ? config['upsampling-resolution']
-        : 1,
+        : findResamplingResolution(inputs, config.interval),
     };
+
     validateIntervalForResample(
       timeParams.interval,
       timeParams.upsamplingResolution,