// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Thibault Ducray
//
// This file is part of MyPwdTool's open-source sync/encryption core — see
// LICENSE-SYNC-CRYPTO.md at the repo root and https://mypwdtool.com/open-source/.
// The rest of this application is proprietary and NOT covered by this license.

package fr.tducray.mypwdtool.sync

import fr.tducray.mypwdtool.vault.Entry
import java.util.UUID

/**
 * Port of `Sync/SyncOutbox.swift` — a trivial in-memory FIFO, deliberately not persisted (the
 * local vault DB is the source of truth). Not just "requeued next time that entry changes" —
 * SyncManager's poll loop also retries a non-empty outbox on every tick now (added 2026-09-05:
 * previously the outbox was *only* ever drained in direct response to enqueueUpsert/enqueueDelete,
 * so if the very first drain attempt's guards failed — e.g. peers not yet populated right after a
 * fresh join — the items sat stuck forever with nothing to retry them until an unrelated edit
 * happened to touch the outbox again; reproduced live importing a backup immediately after
 * joining a sync group, entries never reached the other device).
 */
class SyncOutbox {
    data class Item(val op: SyncOp, val entryId: UUID, val updatedAt: String, val entry: Entry?)

    private val lock = Object()
    private val items = mutableListOf<Item>()

    fun enqueue(item: Item) {
        synchronized(lock) { items.add(item) }
    }

    fun drain(): List<Item> = synchronized(lock) {
        val drained = items.toList()
        items.clear()
        drained
    }

    val isEmpty: Boolean get() = synchronized(lock) { items.isEmpty() }
}