import XCTest
@testable import AIStudyApp

final class ReadingEventUploadItemTests: XCTestCase {

    // MARK: - Codable roundtrip

    func test_codable_roundtrip_without_position() throws {
        let item = ReadingEventUploadItem(
            eventId: "evt-001",
            clientSessionId: "sess-001",
            materialId: "mat-001",
            eventType: "material_opened",
            position: nil,
            activeSecondsDelta: 0,
            clientTimestampMs: 1_718_150_400_000,
            sequence: 1,
            readingTargetType: "knowledge_source",
            knowledgeBaseId: "kb-001",
            platform: "ios",
            appVersion: "1.0.0",
            clientTimezoneOffsetMinutes: 480
        )
        let data = try JSONEncoder().encode(item)
        let decoded = try JSONDecoder().decode(ReadingEventUploadItem.self, from: data)

        XCTAssertEqual(decoded.eventId, "evt-001")
        XCTAssertEqual(decoded.materialId, "mat-001")
        XCTAssertEqual(decoded.eventType, "material_opened")
        XCTAssertEqual(decoded.readingTargetType, "knowledge_source")
        XCTAssertEqual(decoded.knowledgeBaseId, "kb-001")
        XCTAssertEqual(decoded.platform, "ios")
        XCTAssertEqual(decoded.appVersion, "1.0.0")
        XCTAssertEqual(decoded.clientTimezoneOffsetMinutes, 480)
    }

    func test_codable_roundtrip_nil_knowledge_base_id() throws {
        let item = ReadingEventUploadItem(
            eventId: "evt-002",
            clientSessionId: "sess-002",
            materialId: "mat-002",
            eventType: "heartbeat",
            position: nil,
            activeSecondsDelta: 30,
            clientTimestampMs: 1_718_150_500_000,
            sequence: 2,
            readingTargetType: "temporary_file",
            knowledgeBaseId: nil,
            platform: "ios",
            appVersion: "1.0.0",
            clientTimezoneOffsetMinutes: 480
        )
        let data = try JSONEncoder().encode(item)
        let decoded = try JSONDecoder().decode(ReadingEventUploadItem.self, from: data)

        XCTAssertNil(decoded.knowledgeBaseId)
    }

    func test_json_uses_camel_case_keys() throws {
        let item = ReadingEventUploadItem(
            eventId: "evt-003",
            clientSessionId: "sess-003",
            materialId: "mat-003",
            eventType: "position_changed",
            position: nil,
            activeSecondsDelta: 15,
            clientTimestampMs: 1_718_150_600_000,
            sequence: 3,
            readingTargetType: "knowledge_source",
            knowledgeBaseId: nil,
            platform: "ios",
            appVersion: "1.0.0",
            clientTimezoneOffsetMinutes: 480
        )
        let data = try JSONEncoder().encode(item)
        let json = try JSONSerialization.jsonObject(with: data) as! [String: Any]

        XCTAssertNotNil(json["eventId"])
        XCTAssertNotNil(json["clientSessionId"])
        XCTAssertNotNil(json["materialId"])
        XCTAssertNotNil(json["eventType"])
        XCTAssertNotNil(json["clientTimestampMs"])
        XCTAssertNotNil(json["readingTargetType"])
        XCTAssertNotNil(json["clientTimezoneOffsetMinutes"])
        XCTAssertNil(json["event_id"]) // snake_case should not appear
    }

    // MARK: - Batch request/response

    func test_batch_request_encodes_events_array() throws {
        let events = [
            ReadingEventUploadItem(
                eventId: "evt-001",
                clientSessionId: "sess-001",
                materialId: "mat-001",
                eventType: "material_opened",
                position: nil,
                activeSecondsDelta: 0,
                clientTimestampMs: 1_718_150_400_000,
                sequence: 1,
                readingTargetType: "knowledge_source",
                knowledgeBaseId: nil,
                platform: "ios",
                appVersion: "1.0.0",
                clientTimezoneOffsetMinutes: 480
            )
        ]
        let batch = ReadingEventBatchRequest(events: events)
        let data = try JSONEncoder().encode(batch)
        let json = try JSONSerialization.jsonObject(with: data) as! [String: Any]

        let eventsArray = json["events"] as! [[String: Any]]
        XCTAssertEqual(eventsArray.count, 1)
        XCTAssertEqual(eventsArray[0]["eventId"] as? String, "evt-001")
    }

    func test_batch_response_decodes() throws {
        let json = """
        {
            "processed": 3,
            "duplicate": 1,
            "failed": 0,
            "warnings": [
                {"eventId": "evt-dup", "code": "DUPLICATE_EVENT", "message": "already processed"}
            ]
        }
        """.data(using: .utf8)!

        let resp = try JSONDecoder().decode(ReadingEventBatchResponse.self, from: json)
        XCTAssertEqual(resp.processed, 3)
        XCTAssertEqual(resp.duplicate, 1)
        XCTAssertEqual(resp.failed, 0)
        XCTAssertEqual(resp.warnings?.count, 1)
        XCTAssertEqual(resp.warnings?.first?.code, "DUPLICATE_EVENT")
    }
}