package com.craigvg.lichun_android.ui.navigation

import androidx.compose.animation.ExperimentalSharedTransitionApi
import androidx.compose.animation.SharedTransitionScope
import androidx.compose.runtime.Composable
import androidx.compose.runtime.compositionLocalOf
import androidx.compose.ui.Modifier
import androidx.navigation3.ui.LocalNavAnimatedContentScope

/**
 * Plumbing for Navigation 3 shared-element transitions.
 *
 * [SharedTransitionLayout][androidx.compose.animation.SharedTransitionLayout] in
 * [MainNavigation] exposes a [SharedTransitionScope]; that scope is published here so any
 * descendant composable (a list card on the source screen, an avatar on the destination
 * screen) can opt into a shared-element transition without threading the scope through every
 * call site.
 *
 * The per-destination [androidx.compose.animation.AnimatedVisibilityScope] is read from
 * Nav3's [LocalNavAnimatedContentScope].
 *
 * All helpers degrade gracefully: when either scope is absent (e.g. a screen rendered in an
 * `@Preview`, inside a modal, or outside the [NavDisplay][androidx.navigation3.ui.NavDisplay]),
 * the modifier is a no-op so the same composables stay reusable everywhere.
 */
val LocalSharedTransitionScope = compositionLocalOf<SharedTransitionScope?> { null }

/** Stable shared-element key for a character avatar shared into [PersonDetailKey]. */
fun personAvatarSharedKey(personId: String): String = "person-avatar-$personId"

/** Stable shared-element key for a dating profile card shared into [RelationshipDetailKey]. */
fun datingProfileSharedKey(personId: String): String = "dating-profile-$personId"

/** Stable shared-element key for an activity icon shared into [ActivityDetailKey]. */
fun activityIconSharedKey(activityId: String): String = "activity-icon-$activityId"

/**
 * Tags this composable as one half of a shared-element transition identified by [key].
 *
 * Matching keys on the source and destination composables produce the seamless
 * grow/shrink animation as the user navigates between them. Safe to call when no
 * shared-transition scope is in scope — it simply returns [this] unchanged.
 */
@OptIn(ExperimentalSharedTransitionApi::class)
@Composable
fun Modifier.sharedElementKey(key: String): Modifier {
    val sharedScope = LocalSharedTransitionScope.current ?: return this
    val animatedScope = LocalNavAnimatedContentScope.current
    with(sharedScope) {
        return this@sharedElementKey.sharedElement(
            sharedContentState = rememberSharedContentState(key),
            animatedVisibilityScope = animatedScope
        )
    }
}