import { VOICE_SILENCE_GATE_ACTIVE_RATIO_MAX, VOICE_SILENCE_GATE_ACTIVE_SAMPLE_MIN_ABS, VOICE_SILENCE_GATE_MIN_CLIP_MS, VOICE_SILENCE_GATE_PEAK_MAX, VOICE_SILENCE_GATE_RMS_MAX } from "./voiceSessionManager.constants.ts";

type MonoPcmSignalAnalysis = { sampleCount: number; rms: number; peak: number; activeSampleRatio: number; };

type PcmSilenceGateEvaluation = MonoPcmSignalAnalysis & { clipDurationMs: number; drop: boolean; };

type PcmBufferLike = Buffer | Uint8Array | ArrayBuffer | ArrayLike | null | undefined;

function getPcmByteLength(pcmBuffer: PcmBufferLike) { if (!pcmBuffer) return 0; if (Buffer.isBuffer(pcmBuffer) || pcmBuffer instanceof Uint8Array) { return pcmBuffer.length; } if (pcmBuffer instanceof ArrayBuffer) { return pcmBuffer.byteLength; } return Math.max(0, Number(pcmBuffer.length) || 0); }

function toPcmBuffer(pcmBuffer: PcmBufferLike) { if (Buffer.isBuffer(pcmBuffer)) return pcmBuffer; if (pcmBuffer instanceof Uint8Array) return Buffer.from(pcmBuffer); if (pcmBuffer instanceof ArrayBuffer) return Buffer.from(new Uint8Array(pcmBuffer)); return Buffer.from(pcmBuffer || []); }

export function estimatePcm16MonoDurationMs(pcmByteLength: number, sampleRateHz = 24000) { const normalizedBytes = Math.max(0, Number(pcmByteLength) || 0); const normalizedRate = Math.max(1, Number(sampleRateHz) || 24000); return Math.round((normalizedBytes / (2 * normalizedRate)) * 1000); }

export function estimateDiscordPcmPlaybackDurationMs(pcmByteLength: number) { const normalizedBytes = Math.max(0, Number(pcmByteLength) || 0); const bytesPerSecond = 48_000 * 2 * 2; return Math.round((normalizedBytes / bytesPerSecond) * 1000); }

export function analyzeMonoPcmSignal(pcmBuffer: PcmBufferLike): MonoPcmSignalAnalysis { const buffer = toPcmBuffer(pcmBuffer); const evenByteLength = Math.max(0, buffer.length - (buffer.length % 2)); if (evenByteLength <= 0) { return { sampleCount: 0, rms: 0, peak: 0, activeSampleRatio: 0 }; }

let sumSquares = 0; let peakAbs = 0; let activeSamples = 0; const sampleCount = evenByteLength / 2; for (let offset = 0; offset < evenByteLength; offset += 2) { const sample = buffer.readInt16LE(offset); const absSample = Math.abs(sample); sumSquares += sample * sample; if (absSample > peakAbs) { peakAbs = absSample; } if (absSample >= VOICE_SILENCE_GATE_ACTIVE_SAMPLE_MIN_ABS) { activeSamples += 1; } }

const rmsAbs = Math.sqrt(sumSquares / sampleCount); return { sampleCount, rms: rmsAbs / 32768, peak: peakAbs / 32768, activeSampleRatio: activeSamples / sampleCount }; }

export function evaluatePcmSilenceGate({ pcmBuffer, sampleRateHz = 24000 }: { pcmBuffer: PcmBufferLike; sampleRateHz?: number; }): PcmSilenceGateEvaluation { const clipDurationMs = estimatePcm16MonoDurationMs(getPcmByteLength(pcmBuffer), sampleRateHz); const signal = analyzeMonoPcmSignal(pcmBuffer); const eligibleForGate = clipDurationMs >= VOICE_SILENCE_GATE_MIN_CLIP_MS; const nearSilentSignal = signal.rms <= VOICE_SILENCE_GATE_RMS_MAX && signal.peak <= VOICE_SILENCE_GATE_PEAK_MAX && signal.activeSampleRatio <= VOICE_SILENCE_GATE_ACTIVE_RATIO_MAX;

return { clipDurationMs, ...signal, drop: Boolean(eligibleForGate && nearSilentSignal) }; }