med-det-samme/app/src/main/java/no/naiv/meddetsamme/alarm/DoseAlarmReceiver.kt

package no.naiv.meddetsamme.alarm

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
import no.naiv.meddetsamme.data.DoseLog
import no.naiv.meddetsamme.data.DoseStatus
import no.naiv.meddetsamme.data.MedDatabase
import no.naiv.meddetsamme.notify.Notifications

/**
 * Fires for both alarm kinds:
 * - occurrence alarm (EXTRA_DOSE_TIME_ID + EXTRA_SCHEDULED_AT): creates the
 *   PENDING log, notifies, starts escalation, and re-arms the next occurrence.
 * - escalation alarm (EXTRA_LOG_ID): re-nags an unresolved log until the cap.
 *
 * Both paths are idempotent: a duplicate delivery finds existing state and
 * does nothing harmful — important because AlarmManager redelivery and boot
 * re-arming can overlap.
 */
class DoseAlarmReceiver : BroadcastReceiver() {

    companion object {
        const val EXTRA_DOSE_TIME_ID = "doseTimeId"
        const val EXTRA_SCHEDULED_AT = "scheduledAt"
        const val EXTRA_LOG_ID = "logId"
    }

    override fun onReceive(context: Context, intent: Intent) {
        val pending = goAsync() // keep the process alive for the DB round-trip
        CoroutineScope(Dispatchers.IO).launch {
            try {
                val logId = intent.getLongExtra(EXTRA_LOG_ID, -1)
                if (logId >= 0) {
                    escalate(context, logId)
                } else {
                    fireOccurrence(
                        context,
                        intent.getLongExtra(EXTRA_DOSE_TIME_ID, -1),
                        intent.getLongExtra(EXTRA_SCHEDULED_AT, -1),
                    )
                }
            } finally {
                pending.finish()
            }
        }
    }

    private suspend fun fireOccurrence(context: Context, doseTimeId: Long, scheduledAt: Long) {
        if (doseTimeId < 0 || scheduledAt < 0) return
        val db = MedDatabase.get(context)
        val scheduler = AlarmScheduler(context)

        // ALWAYS arm the next occurrence first — even if this one turns out to be
        // stale, the chain must never break.
        scheduler.armDoseTime(doseTimeId)

        val doseTime = db.doseTimeDao().getById(doseTimeId) ?: return
        val med = db.medicationDao().getById(doseTime.medId) ?: return
        if (!med.med.active) return

        val existing = db.doseLogDao().getForOccurrence(doseTimeId, scheduledAt)
        val log = when {
            existing == null -> {
                val id = db.doseLogDao().insert(
                    DoseLog(
                        medId = med.med.id,
                        doseTimeId = doseTimeId,
                        scheduledAtMillis = scheduledAt,
                        amount = doseTime.amount,
                    ),
                )
                db.doseLogDao().getById(id)!!
            }
            // Already resolved (e.g. taken early from the UI) — no notification.
            existing.status == DoseStatus.TAKEN || existing.status == DoseStatus.SKIPPED -> return
            else -> existing
        }

        Notifications.post(
            context,
            Notifications.doseNotificationId(log.id),
            Notifications.buildDoseNotification(context, med, log),
        )
        if (log.nagCount < AlarmScheduler.NAG_CAP) scheduler.armEscalation(log.id)
    }

    private suspend fun escalate(context: Context, logId: Long) {
        val db = MedDatabase.get(context)
        val log = db.doseLogDao().getById(logId) ?: return
        // Only unresolved doses nag. TAKEN/SKIPPED here means the cancel raced us.
        if (log.status != DoseStatus.PENDING && log.status != DoseStatus.SNOOZED) return
        if (log.nagCount >= AlarmScheduler.NAG_CAP) return
        // A future dose can't be overdue — drop stray escalations (defense in
        // depth against any path that arms one too early).
        if (log.scheduledAtMillis > System.currentTimeMillis()) return

        val med = db.medicationDao().getById(log.medId) ?: return
        val nagged = log.copy(nagCount = log.nagCount + 1)
        db.doseLogDao().setNagCount(logId, nagged.nagCount)

        Notifications.post(
            context,
            Notifications.doseNotificationId(logId),
            Notifications.buildDoseNotification(context, med, nagged),
        )
        if (nagged.nagCount < AlarmScheduler.NAG_CAP) AlarmScheduler(context).armEscalation(logId)
    }
}