feat(android): discover last repurchase batch safely (#367)

2026-10-08 17:49:02 +08:00
parent e450ac2898
commit 87192f75d4
2 changed files with 344 additions and 0 deletions
@@ -0,0 +1,153 @@
+package cn.ilapage.goauto.agent.service
+
+import cn.ilapage.goauto.agent.network.HistoryPage
+import cn.ilapage.goauto.agent.network.PurchaseHistoryItem
+import java.text.ParsePosition
+import java.text.SimpleDateFormat
+import java.util.Collections
+import java.util.Locale
+import java.util.TimeZone
+
+data class RepurchaseHistoryQuery(val page: Int, val pageSize: Int = 50, val days: Int = 30, val status: String? = null, val taskNo: String? = null)
+
+enum class RepurchaseBatchFailure { PAGE_FAILED, INVALID_PAGE, INVALID_TIMESTAMP, INVALID_ORDER, INCOMPLETE_BATCH, LIST_CHANGED, PAGE_LIMIT }
+
+class RepurchaseBatchException(val reason: RepurchaseBatchFailure) : IllegalStateException(reason.name)
+
+class RepurchaseBatch internal constructor(items: List<PurchaseHistoryItem>) {
+    val items: List<PurchaseHistoryItem> = immutable(items)
+    val candidates: List<PurchaseHistoryItem> = immutable(items.filter { it.status == "failed" && it.retryable })
+    val failures: List<PurchaseHistoryItem> = immutable(items.filter { it.status == "failed" })
+    val skips: List<PurchaseHistoryItem> = immutable(failures.filterNot { it.retryable })
+    val headTaskId = items.firstOrNull()?.taskId
+    val newestCreatedAt = items.firstOrNull()?.createdAt
+    val oldestCreatedAt = items.lastOrNull()?.createdAt
+
+    private fun immutable(items: List<PurchaseHistoryItem>): List<PurchaseHistoryItem> =
+        Collections.unmodifiableList(ArrayList(items))
+}
+
+/** Read-only discovery. The callback must use the current device's authenticated history endpoint.
+ *
+ * Offset overlap is tolerated; a changed head is rejected. This is not a snapshot guarantee for
+ * arbitrary concurrent deletion, reassignment or timestamp edits on the server.
+ */
+class RepurchaseBatchDiscovery(
+    private val fetchPage: (RepurchaseHistoryQuery) -> HistoryPage<PurchaseHistoryItem>,
+    private val nowMillis: () -> Long = System::currentTimeMillis,
+    private val maxPages: Int = 200,
+) {
+    init { require(maxPages > 0) }
+
+    fun discover(): RepurchaseBatch {
+        val startedAt = nowMillis()
+        val seen = linkedMapOf<Long, Entry>()
+        val batch = mutableListOf<PurchaseHistoryItem>()
+        var head: Long? = null
+        var previous: Entry? = null
+        var originalTotal: Long? = null
+        var foundBoundary = false
+        var reachedEnd = false
+        for (pageNumber in 1..maxPages) {
+            val page = readPage(pageNumber)
+            if (originalTotal == null) originalTotal = page.total
+            else if (page.total != originalTotal) refuse(RepurchaseBatchFailure.LIST_CHANGED)
+            val entries = parseOrdered(page.items)
+            if (pageNumber == 1) head = entries.firstOrNull()?.item?.taskId
+            for (entry in entries) {
+                val duplicate = seen[entry.item.taskId]
+                if (duplicate != null) {
+                    if (duplicate.time != entry.time) refuse(RepurchaseBatchFailure.INVALID_ORDER)
+                    continue
+                }
+                val prior = previous
+                if (prior != null) {
+                    if (ENTRY_ORDER.compare(prior, entry) > 0) refuse(RepurchaseBatchFailure.INVALID_ORDER)
+                    if (prior.time.moreThanSixtySecondsAfter(entry.time)) {
+                        foundBoundary = true
+                        break
+                    }
+                }
+                seen[entry.item.taskId] = entry
+                batch += entry.item
+                previous = entry
+            }
+            if (foundBoundary) break
+            if (pageNumber.toLong() * PAGE_SIZE >= page.total) {
+                // Offset overlap without enough unique rows cannot establish a complete tail.
+                if (seen.size.toLong() != page.total) refuse(RepurchaseBatchFailure.INCOMPLETE_BATCH)
+                reachedEnd = true
+                break
+            }
+        }
+        if (!foundBoundary && !reachedEnd) refuse(RepurchaseBatchFailure.PAGE_LIMIT)
+
+        val finalPage = readPage(1)
+        val finalHead = parseOrdered(finalPage.items).firstOrNull()?.item?.taskId
+        if (finalHead != head || finalPage.total != originalTotal) refuse(RepurchaseBatchFailure.LIST_CHANGED)
+        if (reachedEnd && previous != null) {
+            // The API applies a rolling 30-day range, not a midnight-based date filter.
+            // Use the later clock reading because the floor can advance during pagination.
+            val floorMillis = maxOf(startedAt, nowMillis()) - DAYS * 24L * 60 * 60 * 1000
+            val floorSeconds = floorMillis / 1000 - if (floorMillis < 0 && floorMillis % 1000 != 0L) 1 else 0
+            val floor = Timestamp(floorSeconds, ((floorMillis - floorSeconds * 1000) * 1_000_000).toInt())
+            if (!previous.time.moreThanSixtySecondsAfter(floor)) refuse(RepurchaseBatchFailure.INCOMPLETE_BATCH)
+        }
+        return RepurchaseBatch(batch)
+    }
+
+    private fun readPage(pageNumber: Int): HistoryPage<PurchaseHistoryItem> {
+        val page = try {
+            fetchPage(RepurchaseHistoryQuery(page = pageNumber))
+        } catch (_: Exception) {
+            // Do not expose a network exception that might contain credentials or response data.
+            refuse(RepurchaseBatchFailure.PAGE_FAILED)
+        }
+        val offset = (pageNumber - 1L) * PAGE_SIZE
+        if (page.page != pageNumber || page.pageSize != PAGE_SIZE || page.total < 0 ||
+            page.items.size.toLong() != (page.total - offset).coerceIn(0, PAGE_SIZE.toLong()) ||
+            page.items.any { it.taskId <= 0 } || page.items.map { it.taskId }.distinct().size != page.items.size
+        ) refuse(RepurchaseBatchFailure.INVALID_PAGE)
+        return page
+    }
+
+    private fun parseOrdered(items: List<PurchaseHistoryItem>): List<Entry> {
+        val entries = items.map { Entry(it, parseTime(it.createdAt)) }
+        val ordered = entries.sortedWith(ENTRY_ORDER)
+        if (entries != ordered) refuse(RepurchaseBatchFailure.INVALID_ORDER)
+        return ordered
+    }
+
+    private fun parseTime(raw: String): Timestamp {
+        val match = TIMESTAMP.matchEntire(raw) ?: refuse(RepurchaseBatchFailure.INVALID_TIMESTAMP)
+        val zone = match.groupValues[3].let { if (it == "Z") "+0000" else it.replace(":", "") }
+        val normalized = match.groupValues[1] + zone
+        val position = ParsePosition(0)
+        val parsed = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ssZ", Locale.ROOT).apply {
+            isLenient = false
+            timeZone = TimeZone.getTimeZone("UTC")
+        }.parse(normalized, position)
+        if (parsed == null || position.index != normalized.length) refuse(RepurchaseBatchFailure.INVALID_TIMESTAMP)
+        return Timestamp(parsed.time / 1000, match.groupValues[2].padEnd(9, '0').toInt())
+    }
+
+    private data class Entry(val item: PurchaseHistoryItem, val time: Timestamp)
+
+    private data class Timestamp(val seconds: Long, val nanos: Int) : Comparable<Timestamp> {
+        override fun compareTo(other: Timestamp): Int =
+            seconds.compareTo(other.seconds).takeIf { it != 0 } ?: nanos.compareTo(other.nanos)
+
+        fun moreThanSixtySecondsAfter(older: Timestamp): Boolean {
+            val secondsApart = seconds - older.seconds
+            return secondsApart > 60 || (secondsApart == 60L && nanos > older.nanos)
+        }
+    }
+
+    companion object {
+        private const val PAGE_SIZE = 50
+        private const val DAYS = 30
+        private val TIMESTAMP = Regex("(\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2})(?:\\.(\\d{1,9}))?(Z|[+-]\\d{2}:\\d{2})")
+        private val ENTRY_ORDER = compareByDescending<Entry> { it.time }.thenByDescending { it.item.taskId }
+        private fun refuse(reason: RepurchaseBatchFailure): Nothing = throw RepurchaseBatchException(reason)
+    }
+}
@@ -0,0 +1,191 @@
+package cn.ilapage.goauto.agent.service
+
+import cn.ilapage.goauto.agent.network.HistoryPage
+import cn.ilapage.goauto.agent.network.PurchaseHistoryItem
+import org.junit.Assert.*
+import org.junit.Test
+import java.text.SimpleDateFormat
+import java.util.Date
+import java.util.Locale
+import java.util.TimeZone
+
+class RepurchaseBatchTest {
+    private val now = 1_791_446_400_000L
+    private fun at(secondsAgo: Long) = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'", Locale.ROOT).apply {
+        timeZone = TimeZone.getTimeZone("UTC")
+    }.format(Date(now - secondsAgo * 1000))
+
+    private fun item(id: Long, secondsAgo: Long = 0, status: String = "failed", retryable: Boolean = true) = PurchaseHistoryItem(
+        id, status, "synthetic", "synthetic", "synthetic", "", "", "", "", 1, null, "CNY", null, null,
+        null, null, retryable, if (retryable) null else "不可重试", at(secondsAgo),
+    )
+
+    private fun discover(items: List<PurchaseHistoryItem>): RepurchaseBatch = RepurchaseBatchDiscovery({ q ->
+        HistoryPage(items.drop((q.page - 1) * 50).take(50), items.size.toLong(), q.page, 50)
+    }, { now }).discover()
+
+    private fun refused(reason: RepurchaseBatchFailure, block: () -> Unit) {
+        try { block(); fail("Expected $reason") } catch (e: RepurchaseBatchException) { assertEquals(reason, e.reason) }
+    }
+
+    @Test fun sixtySecondsJoinsTransitivelyButSixtyOneStartsOlderBatch() {
+        val batch = discover(listOf(item(5), item(4, 60), item(3, 120), item(2, 181), item(1, 182)))
+        assertEquals(listOf(5L, 4L, 3L), batch.items.map { it.taskId })
+        assertEquals(at(0), batch.newestCreatedAt)
+        assertEquals(at(120), batch.oldestCreatedAt)
+        assertEquals(5L, batch.headTaskId)
+    }
+
+    @Test fun equalInstantsUseDescendingIdsAndRespectTimezones() {
+        val batch = discover(listOf(item(3).copy(createdAt = "2026-10-08T08:00:00.123456789+08:00"),
+            item(2).copy(createdAt = "2026-10-08T00:00:00.123456789Z"),
+            item(1).copy(createdAt = "2026-10-07T20:00:00.123456789-04:00")))
+        assertEquals(listOf(3L, 2L, 1L), batch.items.map { it.taskId })
+    }
+
+    @Test fun subMillisecondGapAboveSixtySecondsIsBoundary() {
+        val batch = discover(listOf(item(2).copy(createdAt = "2026-10-08T00:01:00.000000001Z"),
+            item(1).copy(createdAt = "2026-10-08T00:00:00Z")))
+        assertEquals(listOf(2L), batch.items.map { it.taskId })
+    }
+
+    @Test fun readsFullStateHistoryAcrossFiftyItemBoundaryAndRechecksHead() {
+        val requests = mutableListOf<RepurchaseHistoryQuery>()
+        val data = (70L downTo 1).map { item(it, 70 - it, if (it % 2 == 0L) "failed" else "order_created") }
+        val result = RepurchaseBatchDiscovery({ q ->
+            requests += q
+            HistoryPage(data.drop((q.page - 1) * 50).take(50), 70, q.page, 50)
+        }, { now }).discover()
+        assertEquals(70, result.items.size)
+        assertEquals(35, result.candidates.size)
+        assertEquals(listOf(1, 2, 1), requests.map { it.page })
+        assertTrue(requests.all { it.days == 30 && it.pageSize == 50 && it.status == null && it.taskNo == null })
+    }
+
+    @Test fun overlappingPagesDeduplicateTaskIdsBeforeBoundary() {
+        val data = (60L downTo 1).map { item(it, if (it >= 10) 60 - it else 300) }
+        val result = RepurchaseBatchDiscovery({ q ->
+            val page = if (q.page == 1) data.take(50) else data.drop(49)
+            HistoryPage(page, 61, q.page, 50)
+        }, { now }).discover()
+        assertEquals(51, result.items.size)
+        assertEquals(51, result.items.map { it.taskId }.distinct().size)
+    }
+
+    @Test fun headChangeRefusesEvenWhenBoundaryAlreadyFound() {
+        var calls = 0
+        refused(RepurchaseBatchFailure.LIST_CHANGED) {
+            RepurchaseBatchDiscovery({ q ->
+                calls++
+                HistoryPage(if (calls == 1) listOf(item(2), item(1, 100)) else listOf(item(3), item(2), item(1, 100)),
+                    if (calls == 1) 2 else 3, q.page, 50)
+            }, { now }).discover()
+        }
+    }
+
+    @Test fun invalidDatesAndMissingZonesAreRefused() {
+        listOf("", "2026-02-30T00:00:00Z", "2026-10-08T00:00:00", "2026-10-08T00:00:00+25:00", "2026-10-08T00:00:00Zjunk").forEach {
+            refused(RepurchaseBatchFailure.INVALID_TIMESTAMP) { discover(listOf(item(1).copy(createdAt = it))) }
+        }
+    }
+
+    @Test fun invertedChronologicalOrIdOrderingIsRefused() {
+        refused(RepurchaseBatchFailure.INVALID_ORDER) { discover(listOf(item(2, 20), item(1))) }
+        refused(RepurchaseBatchFailure.INVALID_ORDER) { discover(listOf(item(1), item(2))) }
+    }
+
+    @Test fun nearThirtyDayCutoffCannotProveBatchComplete() {
+        val days30 = 30L * 24 * 60 * 60
+        listOf(days30, days30 - 60, days30 + 1).forEach { age ->
+            refused(RepurchaseBatchFailure.INCOMPLETE_BATCH) { discover(listOf(item(1, age))) }
+        }
+        assertEquals(1, discover(listOf(item(1, days30 - 61))).items.size)
+    }
+
+    @Test fun latestSuccessfulBatchDoesNotFallBackToOlderFailures() {
+        val result = discover(listOf(item(2, status = "order_created"), item(1, 61)))
+        assertEquals(1, result.items.size)
+        assertTrue(result.failures.isEmpty())
+        assertTrue(result.candidates.isEmpty())
+    }
+
+    @Test fun onlyFailedRetryableAreCandidatesAndSecondRoundUsesRemainingFailures() {
+        val items = (10L downTo 1).map { item(it, status = if (it <= 4) "failed" else "order_created") }
+        val first = discover(items)
+        assertEquals(listOf(4L, 3L, 2L, 1L), first.candidates.map { it.taskId })
+        val second = discover(items.map { if (it.taskId in 3L..4L) it.copy(status = "order_created") else it })
+        assertEquals(listOf(2L, 1L), second.candidates.map { it.taskId })
+        val blocked = discover(listOf(item(2, retryable = false), item(1, status = "pending")))
+        assertEquals(1, blocked.failures.size)
+        assertEquals("不可重试", blocked.skips.single().retryDisabledReason)
+        assertTrue(blocked.candidates.isEmpty())
+    }
+
+    @Test fun pageFailureCannotReturnPartOfBatch() {
+        refused(RepurchaseBatchFailure.PAGE_FAILED) {
+            RepurchaseBatchDiscovery({ q ->
+                if (q.page == 2) error("synthetic network failure")
+                HistoryPage((60L downTo 11).map { item(it, 60 - it) }, 60, q.page, 50)
+            }, { now }).discover()
+        }
+    }
+
+    @Test fun shortPageWithUnseenTotalAndWrongMetadataAreRefused() {
+        listOf(HistoryPage(listOf(item(1)), 2, 1, 50), HistoryPage(listOf(item(1)), 1, 2, 50),
+            HistoryPage(listOf(item(1)), 1, 1, 20), HistoryPage(emptyList(), -1, 1, 50)).forEach { page ->
+            refused(RepurchaseBatchFailure.INVALID_PAGE) { RepurchaseBatchDiscovery({ page }, { now }).discover() }
+        }
+    }
+
+    @Test fun maximumPagesCannotReturnTruncatedBatch() {
+        refused(RepurchaseBatchFailure.PAGE_LIMIT) {
+            RepurchaseBatchDiscovery({ q -> HistoryPage((60L downTo 11).map { item(it, 60 - it) }, 60, q.page, 50) },
+                { now }, maxPages = 1).discover()
+        }
+    }
+
+    @Test fun crossPageOrderInversionAndChangedDuplicateTimestampAreRefused() {
+        listOf(item(1, 1), item(11, 99)).forEach { next ->
+            refused(RepurchaseBatchFailure.INVALID_ORDER) {
+                RepurchaseBatchDiscovery({ q ->
+                    HistoryPage(if (q.page == 1) (60L downTo 11).map { item(it, 60 - it) } else listOf(next),
+                        51, q.page, 50)
+                }, { now }).discover()
+            }
+        }
+    }
+
+    @Test fun duplicatesCannotMakeAnIncompleteTailLookComplete() {
+        refused(RepurchaseBatchFailure.INCOMPLETE_BATCH) {
+            RepurchaseBatchDiscovery({ q ->
+                HistoryPage(if (q.page == 1) (60L downTo 11).map { item(it, 60 - it) } else listOf(item(11, 49)),
+                    51, q.page, 50)
+            }, { now }).discover()
+        }
+    }
+
+    @Test fun failedHeadRecheckRefusesTheAlreadyFoundBatch() {
+        var calls = 0
+        refused(RepurchaseBatchFailure.PAGE_FAILED) {
+            RepurchaseBatchDiscovery({ q ->
+                if (++calls > 1) error("synthetic network failure")
+                HistoryPage(listOf(item(1)), 1, q.page, 50)
+            }, { now }).discover()
+        }
+    }
+
+    @Test fun emptyHistoryIsRecheckedAndReturnedEmpty() {
+        var calls = 0
+        val batch = RepurchaseBatchDiscovery({ q -> calls++; HistoryPage(emptyList(), 0, q.page, 50) }, { now }).discover()
+        assertTrue(batch.items.isEmpty())
+        assertNull(batch.headTaskId)
+        assertEquals(2, calls)
+    }
+
+    @Test fun immutableSnapshotDoesNotExposeMutableLists() {
+        val batch = discover(listOf(item(1)))
+        listOf(batch.items, batch.candidates, batch.failures).forEach { items ->
+            try { (items as MutableList).clear(); fail("Mutable snapshot") } catch (_: UnsupportedOperationException) { }
+        }
+    }
+}