frontend/src/lib/useCriticalAlarm.ts

"use client"

import { useCallback, useEffect, useRef, useState } from "react"

/**
 * ICU Critical Alarm System
 * 
 * Uses Web Audio API to generate realistic ICU monitor alarm sounds.
 * - Critical: Rapid triple-beep pattern (like real ICU cardiac monitors)
 * - Warning: Double-beep pattern (medium urgency)
 * 
 * No external audio files needed — pure synthesis.
 */

type AlarmLevel = 'critical' | 'warning' | null

interface UseCriticalAlarmReturn {
    /** Play the alarm for the given level */
    playAlarm: (level: AlarmLevel) => void
    /** Stop any currently playing alarm */
    stopAlarm: () => void
    /** Whether sound is muted */
    isMuted: boolean
    /** Toggle mute state */
    toggleMute: () => void
    /** Whether an alarm is currently active */
    isPlaying: boolean
}

// Persist mute state across component mounts
let globalMuted = false

export function useCriticalAlarm(): UseCriticalAlarmReturn {
    const [isMuted, setIsMuted] = useState(globalMuted)
    const [isPlaying, setIsPlaying] = useState(false)
    const audioCtxRef = useRef<AudioContext | null>(null)
    const intervalRef = useRef<ReturnType<typeof setInterval> | null>(null)
    const timeoutRefs = useRef<ReturnType<typeof setTimeout>[]>([])
    const activeNodesRef = useRef<OscillatorNode[]>([])

    // Initialize AudioContext lazily (must be after user interaction)
    const getAudioContext = useCallback(() => {
        if (!audioCtxRef.current) {
            audioCtxRef.current = new (window.AudioContext || (window as any).webkitAudioContext)()
        }
        if (audioCtxRef.current.state === 'suspended') {
            audioCtxRef.current.resume()
        }
        return audioCtxRef.current
    }, [])

    // Play a single beep tone
    const playBeep = useCallback((
        frequency: number,
        duration: number,
        volume: number = 0.3,
        type: OscillatorType = 'sine'
    ) => {
        try {
            const ctx = getAudioContext()
            const oscillator = ctx.createOscillator()
            const gainNode = ctx.createGain()

            oscillator.type = type
            oscillator.frequency.setValueAtTime(frequency, ctx.currentTime)

            // Attack-decay envelope for realistic beep
            gainNode.gain.setValueAtTime(0, ctx.currentTime)
            gainNode.gain.linearRampToValueAtTime(volume, ctx.currentTime + 0.01)
            gainNode.gain.setValueAtTime(volume, ctx.currentTime + duration - 0.05)
            gainNode.gain.linearRampToValueAtTime(0, ctx.currentTime + duration)

            oscillator.connect(gainNode)
            gainNode.connect(ctx.destination)

            oscillator.start(ctx.currentTime)
            oscillator.stop(ctx.currentTime + duration)

            activeNodesRef.current.push(oscillator)

            oscillator.onended = () => {
                activeNodesRef.current = activeNodesRef.current.filter(n => n !== oscillator)
                gainNode.disconnect()
            }
        } catch (e) {
            console.warn('Audio playback failed:', e)
        }
    }, [getAudioContext])

    // ICU Critical alarm pattern: rapid triple beep (like cardiac monitor)
    // Frequency ~1000Hz, pattern: beep-beep-beep ... pause ... repeat
    const playCriticalPattern = useCallback(() => {
        // Triple beep: 3 quick beeps
        playBeep(1000, 0.15, 0.35, 'sine')

        const t1 = setTimeout(() => playBeep(1000, 0.15, 0.35, 'sine'), 200)
        const t2 = setTimeout(() => playBeep(1000, 0.15, 0.35, 'sine'), 400)

        // Second harmonic overlay for urgency
        const t3 = setTimeout(() => playBeep(1500, 0.08, 0.15, 'square'), 450)

        timeoutRefs.current.push(t1, t2, t3)
    }, [playBeep])

    // Warning alarm pattern: double beep (medium urgency)
    const playWarningPattern = useCallback(() => {
        playBeep(800, 0.12, 0.2, 'sine')
        const t1 = setTimeout(() => playBeep(800, 0.12, 0.2, 'sine'), 250)
        timeoutRefs.current.push(t1)
    }, [playBeep])

    const stopAlarm = useCallback(() => {
        // Clear all scheduled beeps
        if (intervalRef.current) {
            clearInterval(intervalRef.current)
            intervalRef.current = null
        }

        timeoutRefs.current.forEach(t => clearTimeout(t))
        timeoutRefs.current = []

        // Stop any active oscillators
        activeNodesRef.current.forEach(osc => {
            try { osc.stop() } catch { }
        })
        activeNodesRef.current = []

        setIsPlaying(false)
    }, [])

    const playAlarm = useCallback((level: AlarmLevel) => {
        if (!level || isMuted) {
            stopAlarm()
            return
        }

        // Stop existing alarm before starting new one
        stopAlarm()

        setIsPlaying(true)

        if (level === 'critical') {
            // Play immediately
            playCriticalPattern()
            // Repeat every 1.5 seconds (ICU-style persistent alarm)
            intervalRef.current = setInterval(() => {
                if (!globalMuted) {
                    playCriticalPattern()
                }
            }, 1500)

            // Auto-stop after 10 seconds to avoid infinite alarm
            const autoStop = setTimeout(() => {
                stopAlarm()
            }, 10000)
            timeoutRefs.current.push(autoStop)
        } else if (level === 'warning') {
            // Play immediately
            playWarningPattern()
            // Repeat every 3 seconds (less urgent)
            intervalRef.current = setInterval(() => {
                if (!globalMuted) {
                    playWarningPattern()
                }
            }, 3000)

            // Auto-stop after 6 seconds
            const autoStop = setTimeout(() => {
                stopAlarm()
            }, 6000)
            timeoutRefs.current.push(autoStop)
        }
    }, [isMuted, stopAlarm, playCriticalPattern, playWarningPattern])

    const toggleMute = useCallback(() => {
        const newMuted = !isMuted
        globalMuted = newMuted
        setIsMuted(newMuted)
        if (newMuted) {
            stopAlarm()
        }
    }, [isMuted, stopAlarm])

    // Cleanup on unmount
    useEffect(() => {
        return () => {
            stopAlarm()
        }
    }, [stopAlarm])

    return {
        playAlarm,
        stopAlarm,
        isMuted,
        toggleMute,
        isPlaying,
    }
}