//
// Copyright 2022 New Vector Ltd
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

@testable import ElementX
import XCTest

@MainActor
class RoomScreenViewModelTests: XCTestCase {
    func testMessageGrouping() {
        // Given 3 messages from Bob.
        let items = [
            TextRoomTimelineItem(text: "Message 1",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 2",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 3",
                                 sender: "bob")
        ]
        
        // When showing them in a timeline.
        let timelineController = MockRoomTimelineController()
        timelineController.timelineItems = items
        let viewModel = RoomScreenViewModel(timelineController: timelineController,
                                            mediaProvider: MockMediaProvider(),
                                            roomName: nil)
        
        // Then the messages should be grouped together.
        XCTAssertEqual(viewModel.state.items[0].timelineGroupStyle, .first, "Nothing should prevent the first message from being grouped.")
        XCTAssertEqual(viewModel.state.items[1].timelineGroupStyle, .middle, "Nothing should prevent the middle message from being grouped.")
        XCTAssertEqual(viewModel.state.items[2].timelineGroupStyle, .last, "Nothing should prevent the last message from being grouped.")
    }
    
    func testMessageGroupingMultipleSenders() {
        // Given some interleaved messages from Bob and Alice.
        let items = [
            TextRoomTimelineItem(text: "Message 1",
                                 sender: "alice"),
            TextRoomTimelineItem(text: "Message 2",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 3",
                                 sender: "alice"),
            TextRoomTimelineItem(text: "Message 4",
                                 sender: "alice"),
            TextRoomTimelineItem(text: "Message 5",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 6",
                                 sender: "bob")
        ]
        
        // When showing them in a timeline.
        let timelineController = MockRoomTimelineController()
        timelineController.timelineItems = items
        let viewModel = RoomScreenViewModel(timelineController: timelineController,
                                            mediaProvider: MockMediaProvider(),
                                            roomName: nil)
        
        // Then the messages should be grouped by sender.
        XCTAssertEqual(viewModel.state.items[0].timelineGroupStyle, .single, "A message should not be grouped when the sender changes.")
        XCTAssertEqual(viewModel.state.items[1].timelineGroupStyle, .single, "A message should not be grouped when the sender changes.")
        XCTAssertEqual(viewModel.state.items[2].timelineGroupStyle, .first, "A group should start with a new sender if there are more messages from that sender.")
        XCTAssertEqual(viewModel.state.items[3].timelineGroupStyle, .last, "A group should be ended when the sender changes in the next message.")
        XCTAssertEqual(viewModel.state.items[4].timelineGroupStyle, .first, "A group should start with a new sender if there are more messages from that sender.")
        XCTAssertEqual(viewModel.state.items[5].timelineGroupStyle, .last, "A group should be ended when the sender changes in the next message.")
    }
    
    func testMessageGroupingWithLeadingReactions() {
        // Given 3 messages from Bob where the first message has a reaction.
        let items = [
            TextRoomTimelineItem(text: "Message 1",
                                 sender: "bob",
                                 addReactions: true),
            TextRoomTimelineItem(text: "Message 2",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 3",
                                 sender: "bob")
        ]
        
        // When showing them in a timeline.
        let timelineController = MockRoomTimelineController()
        timelineController.timelineItems = items
        let viewModel = RoomScreenViewModel(timelineController: timelineController,
                                            mediaProvider: MockMediaProvider(),
                                            roomName: nil)
        
        // Then the first message should not be grouped but the other two should.
        XCTAssertEqual(viewModel.state.items[0].timelineGroupStyle, .single, "When the first message has reactions it should not be grouped.")
        XCTAssertEqual(viewModel.state.items[1].timelineGroupStyle, .first, "A new group should be made when the preceding message has reactions.")
        XCTAssertEqual(viewModel.state.items[2].timelineGroupStyle, .last, "Nothing should prevent the last message from being grouped.")
    }
    
    func testMessageGroupingWithInnerReactions() {
        // Given 3 messages from Bob where the middle message has a reaction.
        let items = [
            TextRoomTimelineItem(text: "Message 1",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 2",
                                 sender: "bob",
                                 addReactions: true),
            TextRoomTimelineItem(text: "Message 3",
                                 sender: "bob")
        ]
        
        // When showing them in a timeline.
        let timelineController = MockRoomTimelineController()
        timelineController.timelineItems = items
        let viewModel = RoomScreenViewModel(timelineController: timelineController,
                                            mediaProvider: MockMediaProvider(),
                                            roomName: nil)
        
        // Then the first and second messages should be grouped and the last one should not.
        XCTAssertEqual(viewModel.state.items[0].timelineGroupStyle, .first, "Nothing should prevent the first message from being grouped.")
        XCTAssertEqual(viewModel.state.items[1].timelineGroupStyle, .last, "When the message has reactions, the group should end here.")
        XCTAssertEqual(viewModel.state.items[2].timelineGroupStyle, .single, "The last message should not be grouped when the preceding message has reactions.")
    }
    
    func testMessageGroupingWithTrailingReactions() {
        // Given 3 messages from Bob where the last message has a reaction.
        let items = [
            TextRoomTimelineItem(text: "Message 1",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 2",
                                 sender: "bob"),
            TextRoomTimelineItem(text: "Message 3",
                                 sender: "bob",
                                 addReactions: true)
        ]
        
        // When showing them in a timeline.
        let timelineController = MockRoomTimelineController()
        timelineController.timelineItems = items
        let viewModel = RoomScreenViewModel(timelineController: timelineController,
                                            mediaProvider: MockMediaProvider(),
                                            roomName: nil)
        
        // Then the messages should be grouped together.
        XCTAssertEqual(viewModel.state.items[0].timelineGroupStyle, .first, "Nothing should prevent the first message from being grouped.")
        XCTAssertEqual(viewModel.state.items[1].timelineGroupStyle, .middle, "Nothing should prevent the second message from being grouped.")
        XCTAssertEqual(viewModel.state.items[2].timelineGroupStyle, .last, "Reactions on the last message should not prevent it from being grouped.")
    }
}

private extension TextRoomTimelineItem {
    init(text: String, sender: String, addReactions: Bool = false) {
        self.init(id: UUID().uuidString,
                  timestamp: "10:47 am",
                  isOutgoing: sender == "bob",
                  isEditable: sender == "bob",
                  sender: .init(id: "@\(sender):server.com", displayName: sender),
                  content: .init(body: text),
                  properties: RoomTimelineItemProperties(reactions: addReactions ? [
                      AggregatedReaction(key: "🦄", count: 1, isHighlighted: false)
                  ] : []))
    }
}