From 14df5b3845649258e43c8733717eda864b4d88d2 Mon Sep 17 00:00:00 2001
From: Chigozirim Igweamaka <cgzirim@gmail.com>
Date: Wed, 16 Jul 2025 05:08:05 +0100
Subject: [PATCH] feat: enhance generateFingerprint function to handle stereo
 input audio

---
 server/wasm/wasm_main.go | 63 +++++++++++++++++++++++++++++++++-------
 1 file changed, 52 insertions(+), 11 deletions(-)

diff --git a/server/wasm/wasm_main.go b/server/wasm/wasm_main.go
index 2afb489..030da71 100644
--- a/server/wasm/wasm_main.go
+++ b/server/wasm/wasm_main.go
@@ -4,16 +4,17 @@
 package main
 
 import (
+	"song-recognition/models"
 	"song-recognition/shazam"
 	"song-recognition/utils"
 	"syscall/js"
 )
 
 func generateFingerprint(this js.Value, args []js.Value) interface{} {
-	if len(args) < 2 {
+	if len(args) < 3 {
 		return js.ValueOf(map[string]interface{}{
 			"error": 1,
-			"data":  "Expected audio array and sample rate",
+			"data":  "Expected audio array, sample rate, and number of channels",
 		})
 	}
 
@@ -24,6 +25,14 @@ func generateFingerprint(this js.Value, args []js.Value) interface{} {
 		})
 	}
 
+	channels := args[2].Int()
+	if args[2].Type() != js.TypeNumber || (channels != 1 && channels != 2) {
+		return js.ValueOf(map[string]interface{}{
+			"error": 2,
+			"data":  "Invalid number of channels; expected 1 or 2",
+		})
+	}
+
 	inputArray := args[0]
 	sampleRate := args[1].Int()
 
@@ -32,16 +41,48 @@ func generateFingerprint(this js.Value, args []js.Value) interface{} {
 		audioData[i] = inputArray.Index(i).Float()
 	}
 
-	spectrogram, err := shazam.Spectrogram(audioData, sampleRate)
-	if err != nil {
-		return js.ValueOf(map[string]interface{}{
-			"error": 3,
-			"data":  "Error generating spectrogram: " + err.Error(),
-		})
-	}
+	fingerprint := make(map[uint32]models.Couple)
+	var leftChannel, rightChannel []float64
 
-	peaks := shazam.ExtractPeaks(spectrogram, float64(len(audioData)/sampleRate))
-	fingerprint := shazam.Fingerprint(peaks, utils.GenerateUniqueID())
+	if channels == 1 {
+		leftChannel = audioData
+		spectrogram, err := shazam.Spectrogram(audioData, sampleRate)
+		if err != nil {
+			return js.ValueOf(map[string]interface{}{
+				"error": 3,
+				"data":  "Error generating spectrogram: " + err.Error(),
+			})
+		}
+		peaks := shazam.ExtractPeaks(spectrogram, float64(len(audioData))/float64(sampleRate))
+		fingerprint = shazam.Fingerprint(peaks, utils.GenerateUniqueID())
+	} else {
+		for i := 0; i < len(audioData); i += 2 {
+			leftChannel = append(leftChannel, audioData[i])
+			rightChannel = append(rightChannel, audioData[i+1])
+		}
+
+		// LEFT
+		spectrogram, err := shazam.Spectrogram(leftChannel, sampleRate)
+		if err != nil {
+			return js.ValueOf(map[string]interface{}{
+				"error": 3,
+				"data":  "Error generating spectrogram: " + err.Error(),
+			})
+		}
+		peaks := shazam.ExtractPeaks(spectrogram, float64(len(leftChannel))/float64(sampleRate))
+		utils.ExtendMap(fingerprint, shazam.Fingerprint(peaks, utils.GenerateUniqueID()))
+
+		// RIGHT
+		spectrogram, err = shazam.Spectrogram(rightChannel, sampleRate)
+		if err != nil {
+			return js.ValueOf(map[string]interface{}{
+				"error": 3,
+				"data":  "Error generating spectrogram: " + err.Error(),
+			})
+		}
+		peaks = shazam.ExtractPeaks(spectrogram, float64(len(rightChannel))/float64(sampleRate))
+		utils.ExtendMap(fingerprint, shazam.Fingerprint(peaks, utils.GenerateUniqueID()))
+	}
 
 	fingerprintArray := []interface{}{}
 	for address, couple := range fingerprint {