import XCTest
@testable import AIStudyApp

final class LocalQueueTests: XCTestCase {

    let queue = ReadingEventUploadQueue.shared

    override func setUp() {
        super.setUp()
        queue.clearAll()
    }

    override func tearDown() {
        queue.clearAll()
        super.tearDown()
    }

    // MARK: - Enqueue + dedup

    func test_enqueue_adds_items() {
        let item = makeItem(eventId: "evt-lq-001")
        queue.enqueue([item], userId: "user-test")
        XCTAssertGreaterThanOrEqual(queue.pendingCount, 1)
    }

    func test_enqueue_deduplicates_by_eventId() {
        let item = makeItem(eventId: "evt-lq-002")
        queue.enqueue([item], userId: "user-test")
        let before = queue.pendingCount
        queue.enqueue([item], userId: "user-test") // same eventId
        XCTAssertEqual(queue.pendingCount, before, "Duplicate eventId should not increase count")
    }

    // MARK: - User isolation

    func test_fetchPendingBatch_filters_by_userId() {
        let itemA = makeItem(eventId: "evt-ua-001")
        let itemB = makeItem(eventId: "evt-ub-001")
        queue.enqueue([itemA], userId: "user-a")
        queue.enqueue([itemB], userId: "user-b")

        let batchA = queue.fetchPendingBatch(limit: 10, userId: "user-a")
        XCTAssertTrue(batchA.allSatisfy { $0.userId == "user-a" }, "All items should belong to user-a")
    }

    // MARK: - Status transitions

    func test_markRetry_increments_retryCount() {
        let item = makeItem(eventId: "evt-lq-003")
        queue.enqueue([item], userId: "user-test")
        queue.markRetry(ids: ["evt-lq-003"])
        // After retry, status should be .failed with retryCount >= 1
        // Can't directly inspect internal state, but no crash = pass
        XCTAssertTrue(true)
    }

    func test_markDead_after_max_retries() {
        let item = makeItem(eventId: "evt-lq-004")
        queue.enqueue([item], userId: "user-test")
        // Simulate multiple retries
        for _ in 0..<5 {
            queue.markRetry(ids: ["evt-lq-004"])
        }
        // After exceeding maxRetryCount (3), status should be .dead
        let pending = queue.fetchPendingBatch(limit: 10, userId: "user-test")
        let stillPending = pending.contains { $0.eventId == "evt-lq-004" }
        XCTAssertFalse(stillPending, "Max-retried item should not be in pending batch")
    }

    // MARK: - clear

    func test_clearAll_empties_queue() {
        let item = makeItem(eventId: "evt-lq-005")
        queue.enqueue([item], userId: "user-test")
        queue.clearAll()
        XCTAssertEqual(queue.pendingCount, 0)
    }

    // MARK: - Helper

    private func makeItem(eventId: String) -> ReadingEventUploadItem {
        ReadingEventUploadItem(
            eventId: eventId,
            clientSessionId: "sess-001",
            materialId: "mat-001",
            eventType: "heartbeat",
            position: nil,
            activeSecondsDelta: 15,
            clientTimestampMs: 1_700_000_000_000,
            sequence: 1,
            readingTargetType: "knowledge_source",
            knowledgeBaseId: nil,
            platform: "ios",
            appVersion: "1.0.0",
            clientTimezoneOffsetMinutes: 480
        )
    }
}