package com.peachpasswords.ui.components

import android.view.Window
import android.view.WindowManager
import java.util.WeakHashMap

/**
 * The only owner of [WindowManager.LayoutParams.FLAG_SECURE] transitions.
 *
 * Release activities install a permanent policy and therefore no later
 * composable can accidentally clear the activity-wide protection. Debug-only
 * secret screens take reference-counted leases so nested effects cannot clear
 * the flag while another secret screen is still composed. Window instances are
 * weakly keyed because their lifecycle owns the actual resources.
 */
internal object SecureWindowPolicy {
    private data class State(
        var leases: Int = 0,
        var releaseOwned: Boolean = false,
    )

    private val states = WeakHashMap<Window, State>()

    /** Install a release-wide owner that is never cleared for this window. */
    fun installRelease(window: Window) {
        synchronized(states) {
            val state = states.getOrPut(window) { State() }
            state.releaseOwned = true
            window.setFlags(
                WindowManager.LayoutParams.FLAG_SECURE,
                WindowManager.LayoutParams.FLAG_SECURE,
            )
        }
    }

    /** Acquire one debug/composable lease for a window. */
    fun acquire(window: Window) {
        synchronized(states) {
            val state = states.getOrPut(window) { State() }
            state.leases++
            window.setFlags(
                WindowManager.LayoutParams.FLAG_SECURE,
                WindowManager.LayoutParams.FLAG_SECURE,
            )
        }
    }

    /** Release one lease; release-owned windows remain protected forever. */
    fun release(window: Window) {
        synchronized(states) {
            val state = states[window] ?: return
            if (state.leases > 0) state.leases--
            if (state.leases == 0 && !state.releaseOwned) {
                window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
                states.remove(window)
            }
        }
    }
}