package pw.binom

import kotlinx.coroutines.flow.toList
import kotlinx.coroutines.test.runTest
import pw.binom.agentik.content.Content
import pw.binom.agentik.cursor.Cursor
import pw.binom.db.ksqlite.SQLiteConnection
import kotlin.test.Test
import kotlin.test.assertEquals
import kotlin.test.assertFailsWith
import kotlin.test.assertNull
import kotlin.test.assertTrue
import kotlin.time.Instant

private const val EPOCH = 1_700_000_000_000L

/**
 * Полный набор тестов [MessageStore] на in-memory SQLite: все ветки push, проекция,
 * курсорная фильтрация, слияние двух таблиц, пагинация, каскадное удаление, откат транзакции,
 * границы журнала и round-trip содержимого.
 */
class MessageStoreTest {

    private var counter = 0UL

    private val t0 = Instant.fromEpochMilliseconds(EPOCH)

    private fun nextCursor() = Cursor(createdAt = EPOCH, offset = ++counter)

    private fun cursorAt(offset: ULong) = Cursor(createdAt = EPOCH, offset = offset)

    private suspend fun withStore(block: suspend (MessageStore) -> Unit) {
        val conn = SQLiteConnection.memory("message-store-${kotlin.random.Random.nextLong()}")
        val store = MessageStore(connection = conn, ownsConnection = false)
        try {
            block(store)
        } finally {
            store.close()
            conn.close()
        }
    }

    // ---- пустое хранилище -------------------------------------------------------------------

    @Test
    fun emptyStoreHasNoStateAndEmptyStreams() = runTest {
        withStore { store ->
            assertNull(store.minCursor)
            assertNull(store.maxCursor)
            assertTrue(store.getState(nextCursor()).toList().isEmpty())
            assertTrue(store.get(nextCursor()).getOrException().toList().isEmpty())
        }
    }

    @Test
    fun clearOnEmptyStoreIsNoop() = runTest {
        withStore { store ->
            store.clear()
            assertNull(store.minCursor)
            assertNull(store.maxCursor)
            assertTrue(store.getState(nextCursor()).toList().isEmpty())
        }
    }

    // ---- курсоры ---------------------------------------------------------------------------

    @Test
    fun minAndMaxCursorTrackPushes() = runTest {
        withStore { store ->
            assertNull(store.minCursor)
            assertNull(store.maxCursor)

            store.push(MessageEvent.CreateConversation("c", "T"), cursorAt(3u))
            assertEquals(cursorAt(3u), store.minCursor)
            assertEquals(cursorAt(3u), store.maxCursor)

            store.push(MessageEvent.RenameConversation("c", "T2"), cursorAt(7u))
            assertEquals(cursorAt(3u), store.minCursor)
            assertEquals(cursorAt(7u), store.maxCursor)
        }
    }

    @Test
    fun pushRejectsNonIncreasingCursorAndRollsBackProjection() = runTest {
        withStore { store ->
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("a"))), cursorAt(5u))

            assertFailsWith<IllegalArgumentException> {
                store.push(
                    MessageEvent.AddUserMessage("m2", t0, "c", listOf(Content.Text("b"))),
                    cursorAt(5u),
                )
            }
            assertFailsWith<IllegalArgumentException> {
                store.push(
                    MessageEvent.AddUserMessage("m3", t0, "c", listOf(Content.Text("c"))),
                    cursorAt(4u),
                )
            }

            // Проекция откатилась: только первое сообщение, курсор на месте.
            assertEquals(
                listOf<MessageRecord>(MessageRecord.UserMessage("m1", t0, listOf(Content.Text("a")), "c")),
                store.getState(cursorAt(5u)).toList(),
            )
            assertEquals(cursorAt(5u), store.maxCursor)
        }
    }

    @Test
    fun clearResetsCursorSoLowerCursorAccepted() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), cursorAt(9u))
            store.clear()

            assertNull(store.minCursor)
            assertNull(store.maxCursor)

            store.push(MessageEvent.CreateConversation("c", "T"), cursorAt(1u))
            assertEquals(cursorAt(1u), store.minCursor)
            assertEquals(cursorAt(1u), store.maxCursor)
        }
    }

    // ---- беседа: create / rename / delete --------------------------------------------------

    @Test
    fun conversationLifecycleUpdatesCursorOnChange() = runTest {
        withStore { store ->
            val created = nextCursor()
            store.push(MessageEvent.CreateConversation("c1", "First"), created)
            assertEquals(
                listOf<MessageRecord>(MessageRecord.Conversation("c1", "First")),
                store.getState(created).toList(),
            )

            val renamed = nextCursor()
            store.push(MessageEvent.RenameConversation("c1", "Renamed"), renamed)
            assertEquals(
                listOf<MessageRecord>(MessageRecord.Conversation("c1", "Renamed")),
                store.getState(renamed).toList(),
            )
            // Изменённая позже строка выпадает из состояния на более раннем курсоре.
            assertTrue(store.getState(created).toList().isEmpty())

            val deleted = nextCursor()
            store.push(MessageEvent.DeleteConversation("c1"), deleted)
            assertTrue(store.getState(deleted).toList().isEmpty())
        }
    }

    @Test
    fun deletingConversationRemovesItsMessages() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("a", "A"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "a", listOf(Content.Text("1"))), nextCursor())
            store.push(MessageEvent.CreateConversation("b", "B"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m2", t0, "b", listOf(Content.Text("2"))), nextCursor())
            store.push(MessageEvent.DeleteConversation("a"), nextCursor())

            // Сообщения удалённой беседы не остаются сиротами в состоянии.
            assertEquals(
                listOf<MessageRecord>(
                    MessageRecord.Conversation("b", "B"),
                    MessageRecord.UserMessage("m2", t0, listOf(Content.Text("2")), "b"),
                ),
                store.getState(store.maxCursor!!).toList(),
            )
        }
    }

    @Test
    fun deletingConversationKeepsJournalEvents() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("a", "A"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "a", listOf(Content.Text("1"))), nextCursor())
            store.push(MessageEvent.DeleteConversation("a"), nextCursor())

            // Журнал append-only: удаление проекции не трогает историю событий.
            val events = store.get(cursorAt(1u)).getOrException().toList()
            assertEquals(3, events.size)
            assertTrue(events.last().data is MessageEvent.DeleteConversation)
        }
    }

    @Test
    fun deletingUnknownConversationIsNoop() = runTest {
        withStore { store ->
            store.push(MessageEvent.DeleteConversation("nope"), nextCursor())
            assertTrue(store.getState(store.maxCursor!!).toList().isEmpty())
        }
    }

    // ---- сообщения: все типы + содержимое --------------------------------------------------

    @Test
    fun allMessageTypesInCursorOrder() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("hi"))), nextCursor())
            store.push(MessageEvent.AddAssistantMessage("m2", t0, "c", listOf(Content.Text("yo"))), nextCursor())
            store.push(MessageEvent.AddToolCall("m3", t0, "c", "search", "{}"), nextCursor())
            store.push(MessageEvent.AddToolResponse("m4", t0, "c", "m3", "ok"), nextCursor())
            store.push(MessageEvent.AddToolFail("m5", t0, "c", "m3", "err"), nextCursor())

            assertEquals(
                listOf<MessageRecord>(
                    MessageRecord.Conversation("c", "T"),
                    MessageRecord.UserMessage("m1", t0, listOf(Content.Text("hi")), "c"),
                    MessageRecord.AssistantMessage("m2", t0, "c", listOf(Content.Text("yo"))),
                    MessageRecord.ToolCall("m3", t0, "c", "search", "{}"),
                    MessageRecord.ToolResponse("m4", t0, "c", "m3", "ok"),
                    MessageRecord.ToolFail("m5", t0, "c", "m3", "err"),
                ),
                store.getState(store.maxCursor!!).toList(),
            )
        }
    }

    @Test
    fun imageContentRoundTrips() = runTest {
        withStore { store ->
            val image = Content.Image(byteArrayOf(1, 2, 3, -1, 0, 7), "image/png")
            store.push(
                MessageEvent.AddUserMessage("m", t0, "c", listOf(Content.Text("see"), image)),
                nextCursor(),
            )

            assertEquals(
                listOf<MessageRecord>(
                    MessageRecord.UserMessage("m", t0, listOf(Content.Text("see"), image), "c"),
                ),
                store.getState(store.maxCursor!!).toList(),
            )
        }
    }

    @Test
    fun duplicateMessageIdIsReplacedAtLaterCursor() = runTest {
        withStore { store ->
            store.push(MessageEvent.AddUserMessage("m", t0, "c", listOf(Content.Text("v1"))), nextCursor())
            store.push(MessageEvent.AddUserMessage("m", t0, "c", listOf(Content.Text("v2"))), nextCursor())

            assertEquals(
                listOf<MessageRecord>(MessageRecord.UserMessage("m", t0, listOf(Content.Text("v2")), "c")),
                store.getState(store.maxCursor!!).toList(),
            )
        }
    }

    // ---- состояние: фильтр по курсору и слияние --------------------------------------------

    @Test
    fun stateIsFilteredByCursor() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("1"))), nextCursor())
            store.push(MessageEvent.AddUserMessage("m2", t0, "c", listOf(Content.Text("2"))), nextCursor())

            assertEquals(3, store.getState(cursorAt(3u)).toList().size)
            assertEquals(2, store.getState(cursorAt(2u)).toList().size)
            assertTrue(store.getState(cursorAt(0u)).toList().isEmpty())
        }
    }

    @Test
    fun stateCursorAboveMaxReturnsEverything() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("x"))), nextCursor())

            assertEquals(2, store.getState(cursorAt(999u)).toList().size)

            // Курсор из другой (более старой) эпохи не видит строк текущей.
            assertTrue(store.getState(Cursor(EPOCH - 1, 999u)).toList().isEmpty())
        }
    }

    @Test
    fun interleavedTablesMergeInCursorOrder() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("a", "A"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "a", listOf(Content.Text("x"))), nextCursor())
            store.push(MessageEvent.CreateConversation("b", "B"), nextCursor())
            store.push(MessageEvent.AddAssistantMessage("m2", t0, "b", listOf(Content.Text("y"))), nextCursor())

            assertEquals(
                listOf<MessageRecord>(
                    MessageRecord.Conversation("a", "A"),
                    MessageRecord.UserMessage("m1", t0, listOf(Content.Text("x")), "a"),
                    MessageRecord.Conversation("b", "B"),
                    MessageRecord.AssistantMessage("m2", t0, "b", listOf(Content.Text("y"))),
                ),
                store.getState(store.maxCursor!!).toList(),
            )
        }
    }

    // ---- пагинация -------------------------------------------------------------------------

    @Test
    fun getStatePaginatesAcrossPageBoundary() = runTest {
        withStore { store ->
            repeat(100) { i ->
                store.push(MessageEvent.CreateConversation("c$i", "T$i"), nextCursor())
            }
            assertEquals(100, store.getState(store.maxCursor!!).toList().size)

            store.push(MessageEvent.CreateConversation("c100", "T100"), nextCursor())
            assertEquals(101, store.getState(store.maxCursor!!).toList().size)
        }
    }

    @Test
    fun interleavedTablesMergeAcrossPages() = runTest {
        withStore { store ->
            repeat(120) { i ->
                store.push(MessageEvent.CreateConversation("c$i", "T$i"), nextCursor())
                store.push(MessageEvent.AddUserMessage("m$i", t0, "c$i", listOf(Content.Text("$i"))), nextCursor())
            }

            val records = store.getState(store.maxCursor!!).toList()
            assertEquals(240, records.size)
            for (i in 0 until 120) {
                assertEquals(
                    MessageRecord.Conversation("c$i", "T$i"),
                    records[i * 2],
                )
                assertEquals(
                    MessageRecord.UserMessage("m$i", t0, listOf(Content.Text("$i")), "c$i"),
                    records[i * 2 + 1],
                )
            }
        }
    }

    // ---- журнал: get / expired -------------------------------------------------------------

    @Test
    fun journalKeepsEventsInOrder() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), cursorAt(1u))
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("hi"))), cursorAt(2u))

            val events = store.get(cursorAt(1u)).getOrException().toList()

            assertEquals(listOf(1uL, 2uL), events.map { it.seq.offset })
            assertTrue(events[0].data is MessageEvent.CreateConversation)
            assertTrue(events[1].data is MessageEvent.AddUserMessage)
        }
    }

    @Test
    fun journalGetIsInclusiveAtMinAndExpiredBelow() = runTest {
        withStore { store ->
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("hi"))), cursorAt(5u))

            val atMin = store.get(cursorAt(5u)).getOrException().toList()
            assertEquals(1, atMin.size)
            assertEquals(5uL, atMin[0].seq.offset)

            assertTrue(store.get(cursorAt(1u)).isExpired)
        }
    }

    // ---- clear -----------------------------------------------------------------------------

    @Test
    fun clearRemovesStateAndJournal() = runTest {
        withStore { store ->
            store.push(MessageEvent.CreateConversation("c", "T"), nextCursor())
            store.push(MessageEvent.AddUserMessage("m1", t0, "c", listOf(Content.Text("hi"))), nextCursor())

            store.clear()

            assertNull(store.minCursor)
            assertNull(store.maxCursor)
            assertTrue(store.getState(nextCursor()).toList().isEmpty())
            assertTrue(store.get(nextCursor()).getOrException().toList().isEmpty())
        }
    }
}