//
// Copyright 2026 Element Creations Ltd.
//
// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
// Please see LICENSE files in the repository root for full details.
//

import Combine
@testable import ElementX
import Testing

@MainActor
struct SearchScreenViewModelTests {
    let viewModel: SearchScreenViewModelProtocol
    let searchService: SearchServiceProxyMock
    let userIndicatorController: UserIndicatorControllerMock
    let userSettings: UserSettings
    /// The rooms known to the client, empty until the room list loads.
    let staticRoomListSubject = CurrentValueSubject<[RoomSummary], Never>([])
    /// Fires with the query each time the (async, debounced) message search runs.
    let setQuerySubject = PassthroughSubject<String, Never>()
    /// Fires each time an indicator is submitted.
    let submitIndicatorSubject = PassthroughSubject<Void, Never>()
    /// Fires each time a search backfill is started, with whether it used the foreground strategy.
    let startSearchBackfillSubject = PassthroughSubject<Bool, Never>()
    
    var context: SearchScreenViewModelType.Context {
        viewModel.context
    }
    
    init() {
        searchService = SearchServiceProxyMock()
        searchService.underlyingResultsPublisher = CurrentValueSubject<[SearchServiceResult], Never>([]).asCurrentValuePublisher()
        searchService.underlyingPaginationStatePublisher = CurrentValueSubject(.idle(endReached: true)).asCurrentValuePublisher()
        searchService.setQueryClosure = { [setQuerySubject] query in
            setQuerySubject.send(query)
            return .success(())
        }
        
        userIndicatorController = UserIndicatorControllerMock()
        userIndicatorController.submitIndicatorDelayClosure = { [submitIndicatorSubject] _, _ in
            submitIndicatorSubject.send(())
        }
        
        let clientProxy = ClientProxyMock(.init())
        clientProxy.searchService = searchService
        clientProxy.startSearchBackfillStrategyClosure = { [startSearchBackfillSubject] strategy in
            startSearchBackfillSubject.send(strategy == .foreground)
        }
        let staticRoomSummaryProvider = RoomSummaryProviderMock()
        staticRoomSummaryProvider.roomListPublisher = staticRoomListSubject.asCurrentValuePublisher()
        clientProxy.staticRoomSummaryProvider = staticRoomSummaryProvider
        clientProxy.roomSummaryForIdentifierClosure = { [staticRoomListSubject] identifier in
            staticRoomListSubject.value.first { $0.id == identifier }
        }
        
        userSettings = UserSettings.mock()
        
        viewModel = SearchScreenViewModel(roomSummaryProvider: RoomSummaryProviderMock(.init(state: .loaded(.mockRooms))),
                                          userSession: UserSessionMock(.init(clientProxy: clientProxy, userSettings: userSettings)),
                                          userIndicatorController: userIndicatorController)
    }
    
    @Test
    func searching() async throws {
        let deferred = deferFulfillment(context.observe(\.viewState.rooms)) { $0.count == 1 }
        context.searchQuery = "Second"
        try await deferred.fulfill()
        
        // The rooms tab must not trigger the slow message search.
        #expect(!searchService.setQueryCalled)
    }
    
    @Test
    func messageSearch() async throws {
        let deferred = deferFulfillment(setQuerySubject) { $0 == "Foundation" }
        context.searchMode = .messages
        context.searchQuery = "Foundation"
        try await deferred.fulfill()
        
        #expect(searchService.setQueryReceivedQuery == "Foundation")
    }
    
    @Test
    func openingMessagesTabStartsSearchBackfill() async throws {
        let deferred = deferFulfillment(startSearchBackfillSubject) { $0 }
        context.searchMode = .messages
        try await deferred.fulfill()
    }
    
    @Test
    func messageSearchFailureShowsErrorIndicator() async throws {
        searchService.setQueryClosure = { _ in .failure(.sdkError(SearchScreenViewModelTestsError.failed)) }
        
        let deferred = deferFulfillment(submitIndicatorSubject) { _ in true }
        context.searchMode = .messages
        context.searchQuery = "Foundation"
        try await deferred.fulfill()
        
        #expect(userIndicatorController.submitIndicatorDelayCalled)
    }
    
    @Test
    func roomSelection() async throws {
        let deferred = deferFulfillment(viewModel.actionsPublisher) { action in
            switch action {
            case .presentRoom(let roomID, _):
                roomID == "2"
            case .cancel:
                false
            }
        }
        
        context.send(viewAction: .selectRoom(roomID: "2"))
        
        try await deferred.fulfill()
    }
    
    @Test
    func selectionRecordsBreadcrumbs() {
        // Typing alone doesn't record the query, only submitting it does.
        context.searchQuery = "Second"
        context.send(viewAction: .selectRoom(roomID: "2"))
        
        #expect(userSettings.account.searchBreadcrumbs == [.room(roomID: "2")])
        
        context.send(viewAction: .submitQuery)
        
        #expect(userSettings.account.searchBreadcrumbs == [.query("Second"), .room(roomID: "2")])
        
        // Selecting the same room again from the empty state only bumps it back to the top.
        context.searchQuery = ""
        context.send(viewAction: .selectRoom(roomID: "2"))
        
        #expect(userSettings.account.searchBreadcrumbs == [.room(roomID: "2"), .query("Second")])
        
        // Submitting an empty query records nothing.
        context.send(viewAction: .submitQuery)
        
        #expect(userSettings.account.searchBreadcrumbs == [.room(roomID: "2"), .query("Second")])
    }
    
    @Test
    func removingBreadcrumbs() {
        userSettings.account.searchBreadcrumbs = [.query("Second"), .room(roomID: "2")]
        
        context.send(viewAction: .removeBreadcrumb(.query("Second")))
        
        #expect(userSettings.account.searchBreadcrumbs == [.room(roomID: "2")])
        
        context.send(viewAction: .removeBreadcrumb(.room(SearchScreenRoom(.mock(id: "2", name: "Second")))))
        
        #expect(userSettings.account.searchBreadcrumbs.isEmpty)
    }
    
    @Test
    func clearingBreadcrumbs() {
        userSettings.account.searchBreadcrumbs = [.query("Second"), .room(roomID: "2")]
        
        context.send(viewAction: .clearBreadcrumbs)
        
        #expect(userSettings.account.searchBreadcrumbs.isEmpty)
    }
    
    @Test
    func breadcrumbsAreDisplayed() async throws {
        staticRoomListSubject.send([.mock(id: "2", name: "Second")])
        
        let deferred = deferFulfillment(context.observe(\.viewState.breadcrumbs)) { $0.count == 2 }
        userSettings.account.searchBreadcrumbs = [.query("Second"), .room(roomID: "2")]
        try await deferred.fulfill()
        
        #expect(context.viewState.breadcrumbs.map(\.id) == ["query-Second", "room-2"])
    }
    
    @Test
    func breadcrumbsOfRoomsThatAreNotJoinedAreHidden() async throws {
        staticRoomListSubject.send([.mock(id: "2", name: "Second"), .mock(id: "left", name: "Left", isJoined: false)])
        
        let deferred = deferFulfillment(context.observe(\.viewState.breadcrumbs)) { !$0.isEmpty }
        userSettings.account.searchBreadcrumbs = [.room(roomID: "left"), .room(roomID: "2")]
        try await deferred.fulfill()
        
        #expect(context.viewState.breadcrumbs.map(\.id) == ["room-2"])
    }
    
    /// The room list is empty when the app launches, so the rooms need resolving again once it has loaded.
    @Test
    func roomBreadcrumbsAreDisplayedAfterTheRoomListLoads() async throws {
        var deferred = deferFulfillment(context.observe(\.viewState.breadcrumbs)) { $0.count == 1 }
        userSettings.account.searchBreadcrumbs = [.query("Second"), .room(roomID: "2")]
        try await deferred.fulfill()
        
        #expect(context.viewState.breadcrumbs.map(\.id) == ["query-Second"])
        
        deferred = deferFulfillment(context.observe(\.viewState.breadcrumbs)) { $0.count == 2 }
        staticRoomListSubject.send([.mock(id: "2", name: "Second")])
        try await deferred.fulfill()
        
        #expect(context.viewState.breadcrumbs.map(\.id) == ["query-Second", "room-2"])
    }
    
    @Test
    func cancel() async throws {
        let deferred = deferFulfillment(viewModel.actionsPublisher) { action in
            switch action {
            case .cancel:
                true
            default:
                false
            }
        }
        
        context.send(viewAction: .cancel)
        
        try await deferred.fulfill()
    }
}

private enum SearchScreenViewModelTestsError: Error {
    case failed
}