package com.example.aiapp

import androidx.compose.foundation.lazy.LazyItemScope
import androidx.compose.foundation.lazy.LazyListScope
import androidx.compose.foundation.lazy.items
import androidx.compose.runtime.Composable

/**
 * Keyed [items], with anything repeating a key already used left out.
 *
 * A lazy list throws when two of its items claim the same key, and the throw happens during measure
 * on the main thread -- so it is not an error the screen can show, it closes the app. That is a
 * disproportionate answer to a list with a repeat in it, and it lands on the reader rather than on
 * whoever produced the repeat: on 2026-08-31 the import list crashed on a Claude Code session id
 * recorded under two project directories, which is an ordinary state of a machine.
 *
 * Every list in this app keyed on an id keyed it on an id *the server chose*, so all of them shared
 * the hazard and none could rule it out locally. Hence one function they all go through.
 *
 * Dropping the repeat is right here because the key is the whole identity: two rows with one id are
 * two rows every action would treat as the same thing. Where the duplicate means something, the fix
 * belongs at the source, and this is only what stops a data problem from being a crash. It is
 * counted so the render report says it happened rather than leaving a silently shorter list.
 *
 * The transcript's own list is deliberately not on this: its keys are made here rather than
 * received, and it is the one list where an extra pass over the items is measurable.
 */
inline fun <T> LazyListScope.uniqueItems(
    items: List<T>,
    crossinline key: (T) -> Any,
    noinline contentType: (T) -> Any? = { null },
    crossinline itemContent: @Composable LazyItemScope.(T) -> Unit,
) {
    val seen = HashSet<Any>(items.size)
    val unique = items.filter { seen.add(key(it)) }
    if (unique.size != items.size) {
        DebugStats.count("list items dropped for a repeated key")
    }
    items(unique, key = { key(it) }, contentType = contentType) { itemContent(it) }
}