package com.peachpasswords.vault

import androidx.annotation.VisibleForTesting
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch
import javax.inject.Inject
import javax.inject.Singleton

/**
 * Idle auto-lock timer. The vault locks [VaultSettings.autoLockMinutes] after the
 * last user interaction; a null (or non-positive) setting means "never". [poke]
 * restarts the countdown, so only the final interaction before the idle window
 * elapses triggers the lock. Reads the live setting from [VaultRepository] each
 * time so a settings change takes effect on the next interaction without rewiring.
 */
@Singleton
class VaultLockTimer @Inject constructor(
    private val vault: VaultRepository,
) {
    // Test seam: replaced with a TestScope so the countdown can be driven on
    // virtual time. Defaults to a process-lifetime background scope in production.
    @VisibleForTesting
    internal var scope: CoroutineScope = CoroutineScope(Dispatchers.Default + SupervisorJob())

    private var timerJob: Job? = null

    /** Reset the idle countdown. No-op (and cancels) when auto-lock is off or locked. */
    fun poke() {
        val minutes = vault.settings.value.autoLockMinutes
        if (minutes == null || minutes <= 0 || !vault.isUnlocked.value) {
            cancel()
            return
        }
        timerJob?.cancel()
        timerJob = scope.launch {
            delay(minutes * 60_000L)
            vault.lock()
        }
    }

    /** Begin the idle countdown after an unlock. */
    fun start() = poke()

    /** Stop the countdown (manual lock, background lock). */
    fun cancel() {
        timerJob?.cancel()
        timerJob = null
    }
}