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 userSecure: Boolean = true,
        var userChoiceApplied: Boolean = false,
    )

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

    private fun evaluate(window: Window, state: State) {
        if (state.userSecure || (!state.userChoiceApplied && state.leases > 0)) {
            window.setFlags(
                WindowManager.LayoutParams.FLAG_SECURE,
                WindowManager.LayoutParams.FLAG_SECURE,
            )
        } else {
            window.clearFlags(WindowManager.LayoutParams.FLAG_SECURE)
        }
    }

    /** Set the user's screenshot preference for this window. */
    fun setUserSecure(window: Window, secure: Boolean) {
        synchronized(states) {
            val state = states.getOrPut(window) { State() }
            state.userSecure = secure
            state.userChoiceApplied = true
            evaluate(window, state)
        }
    }

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

    /** Release one lease; re-evaluates the flag. */
    fun release(window: Window) {
        synchronized(states) {
            val state = states[window] ?: return
            if (state.leases > 0) state.leases--
            evaluate(window, state)
        }
    }
}