import Foundation

@main
struct StreamResolverTests {
    static func main() async {
        testClassifierPrefersObservedDirectFile()
        testResolverSelectsUnsupportedDirectURLAndHeaders()
        testResolverRejectsHLSOnlyResponse()
        testRedactorHandlesPercentEncodedPath()
        testPlaybackTimeFormatting()
        testSubtitleCandidateParsing()
        testOpenSubtitlesV3CandidateParsing()
        testOpenSubtitlesNestedAttributesFilesParsing()
        testOpenSubtitlesManifestIDsAreNotResolvedAsSubtitles()
        testOpenSubtitlesArtworkAndAddonEndpointsAreIgnored()
        testStremioSubtitleDownloadURLParsing()
        testOpenSubtitlesV3DownloadResponseResolution()
        testOpenSubtitlesNestedDownloadResponseResolution()
        await testSubtitleResolverDownloadJSONReturningLink()
        await testSubtitleResolverRedirectToDirectSubtitle()
        await testSubtitleResolverRejectsNonSubtitleAPIResponse()
        testSubtitleCandidateDeduplicationPreservesLabels()
        testSubtitleCandidateDeduplicationUpgradesLabels()
        testSubtitleDisplayNameNormalization()
        testSubtitleDisplayNameUsesPreservedNamesForGenericVLCTracks()
        testSubtitleOptionMappingIncludesNone()
        testHTTPRangeParsing()
        testContentRangeFormatting()
        testCacheLookupAcrossChunkBoundaries()
        testCacheEvictionOutsideByteBudget()
        testProxyForwardsUpstreamHeaders()
        testProxyPassThroughFallbackStatus()
        print("StreamResolverTests passed")
    }

    private static func testClassifierPrefersObservedDirectFile() {
        let body: [String: Any] = [
            "url": "https://cdn.example.test/movie.mkv?token=secret",
            "resolverUrl": "https://addon.debridio.com/play/example"
        ]
        let candidate = StreamCandidate(messageBody: body)!
        let request = StreamClassifier.playbackRequest(from: candidate, userAgent: "DreamioTest/1")!

        assertEqual(request.playbackURL.absoluteString, "https://cdn.example.test/movie.mkv?token=secret")
        assertEqual(request.headers["Referer"], "https://web.stremio.com/")
        assertEqual(request.headers["User-Agent"], "DreamioTest/1")
    }

    private static func testHTTPRangeParsing() {
        assertEqual(HTTPRange.parse("bytes=10-20"), HTTPRange(start: 10, end: 20))
        assertEqual(HTTPRange.parse("bytes=10-"), HTTPRange(start: 10, end: nil))
        assert(HTTPRange.parse("items=10-20") == nil, "Expected non-byte range to be rejected")
        assert(HTTPRange.parse("bytes=-20") == nil, "Expected suffix ranges to be rejected for v1")
        assert(HTTPRange.parse("bytes=20-10") == nil, "Expected inverted ranges to be rejected")
        assert(HTTPRange.parse("bytes=1-2,3-4") == nil, "Expected multipart ranges to be rejected")
    }

    private static func testContentRangeFormatting() {
        assertEqual(HTTPRange.contentRange(start: 10, end: 20, totalLength: 100), "bytes 10-20/100")
        assertEqual(HTTPRange.contentRange(start: 10, end: 20, totalLength: nil), "bytes 10-20/*")
    }

    private static func testCacheLookupAcrossChunkBoundaries() {
        let store = CachedRangeStore(sessionID: "test-\(UUID().uuidString)", byteBudget: 1024)
        defer { store.removeAll() }
        store.store(data: Data("abc".utf8), start: 0)
        store.store(data: Data("def".utf8), start: 3)

        let lookup = store.lookup(range: HTTPRange(start: 0, end: 5), maximumLength: 6)

        assertEqual(String(data: lookup?.data ?? Data(), encoding: .utf8), "abcdef")
        assertEqual(lookup?.isComplete, true)
    }

    private static func testCacheEvictionOutsideByteBudget() {
        let store = CachedRangeStore(sessionID: "test-\(UUID().uuidString)", byteBudget: 6)
        defer { store.removeAll() }
        store.store(data: Data("abcdef".utf8), start: 0)
        store.store(data: Data("ghijkl".utf8), start: 6)

        let oldLookup = store.lookup(range: HTTPRange(start: 0, end: 5), maximumLength: 6)
        let newLookup = store.lookup(range: HTTPRange(start: 6, end: 11), maximumLength: 6)

        assert(oldLookup == nil, "Expected old chunk to be evicted outside the byte budget")
        assertEqual(String(data: newLookup?.data ?? Data(), encoding: .utf8), "ghijkl")
    }

    private static func testProxyForwardsUpstreamHeaders() {
        let proxy = NativeStreamCacheProxy(session: NativeStreamCacheProxy.Session(request: proxyTestRequest()))
        let upstreamRequest = proxy.upstreamRequest(for: HTTPRange(start: 12, end: 34))

        assertEqual(upstreamRequest.value(forHTTPHeaderField: "Range"), "bytes=12-34")
        assertEqual(upstreamRequest.value(forHTTPHeaderField: "Referer"), "https://resolver.example.test/")
        assertEqual(upstreamRequest.value(forHTTPHeaderField: "User-Agent"), "DreamioTest/1")
        assertEqual(upstreamRequest.value(forHTTPHeaderField: "Authorization"), "Bearer secret")
    }

    private static func testProxyPassThroughFallbackStatus() {
        assertEqual(NativeStreamCacheProxy.responseStatusForUpstreamStatus(206), 206)
        assertEqual(NativeStreamCacheProxy.responseStatusForUpstreamStatus(200), 200)
    }

    private static func proxyTestRequest() -> NativePlaybackRequest {
        NativePlaybackRequest(
            playbackURL: URL(string: "https://cdn.example.test/movie.mkv")!,
            observedURL: URL(string: "https://cdn.example.test/movie.mkv")!,
            resolverURL: URL(string: "https://resolver.example.test/play")!,
            pageURL: nil,
            userAgent: "DreamioTest/1",
            referer: "https://resolver.example.test/",
            headers: [
                "Referer": "https://resolver.example.test/",
                "User-Agent": "DreamioTest/1",
                "Authorization": "Bearer secret"
            ],
            classification: StreamClassification(
                sourceKind: .directFile,
                containerGuess: .mkv,
                reason: "test",
                shouldIntercept: true,
                sanitizedObservedURL: "https://cdn.example.test/movie.mkv",
                sanitizedResolverURL: nil
            ),
            subtitleCandidates: []
        )
    }

    private static func testResolverSelectsUnsupportedDirectURLAndHeaders() {
        let payload: [String: Any] = [
            "streams": [
                [
                    "url": "https://cdn.example.test/trailer.mp4"
                ],
                [
                    "externalUrl": "https://cdn.example.test/movie.mkv?signature=secret",
                    "behaviorHints": [
                        "proxyHeaders": [
                            "request": [
                                "Referer": "https://resolver.example.test/",
                                "User-Agent": "ResolverAgent/1"
                            ]
                        ]
                    ]
                ]
            ]
        ]

        let stream = StremioStreamResolver.bestPlayableStream(
            in: payload,
            fallbackHeaders: ["Referer": "https://web.stremio.com/"]
        )!

        assertEqual(stream.playbackURL.absoluteString, "https://cdn.example.test/movie.mkv?signature=secret")
        assertEqual(stream.headers["Referer"], "https://resolver.example.test/")
        assertEqual(stream.headers["User-Agent"], "ResolverAgent/1")
    }

    private static func testResolverRejectsHLSOnlyResponse() {
        let payload: [String: Any] = [
            "streams": [
                ["url": "https://cdn.example.test/live.m3u8"]
            ]
        ]

        let stream = StremioStreamResolver.bestPlayableStream(
            in: payload,
            fallbackHeaders: ["Referer": "https://web.stremio.com/"]
        )

        assert(stream == nil, "Expected HLS-only resolver response to stay out of native playback")
    }

    private static func testRedactorHandlesPercentEncodedPath() {
        let original = "https://cdn.example.test/video/abcdefghijklmnopqrstuvwxyz012345/%E2%9C%93.mp4?token=secret#fragment"
        let redacted = URLRedactor.redactedURLString(original)

        assertEqual(redacted, "https://cdn.example.test/video/%5Bredacted%5D/%E2%9C%93.mp4")
    }

    private static func testPlaybackTimeFormatting() {
        assertEqual(PlaybackTimeFormatter.label(for: 0), "0:00")
        assertEqual(PlaybackTimeFormatter.label(for: 65), "1:05")
        assertEqual(PlaybackTimeFormatter.label(for: 3_725), "1:02:05")
    }

    private static func testSubtitleCandidateParsing() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "lang": "eng",
                    "url": "https://opensubtitles.example.test/download/subtitle.srt?token=secret"
                ],
                [
                    "language": "Spanish",
                    "file": "https://cdn.example.test/movie.es.vtt"
                ],
                "https://cdn.example.test/ignored.txt"
            ],
            "nested": [
                "body": "metadata https://cdn.example.test/movie.fr.ass?download=1"
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 3)
        assertEqual(candidates[0].language, "eng")
        assertEqual(candidates[1].label, "Spanish")
        assertEqual(candidates[2].url.absoluteString, "https://cdn.example.test/movie.fr.ass?download=1")
    }

    private static func testOpenSubtitlesV3CandidateParsing() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "language": "English",
                    "download": "https://api.opensubtitles.com/api/v1/download/subtitle-file",
                    "nested": [
                        [
                            "file": "https://dl.opensubtitles.org/en/subtitle.vtt?download=1"
                        ]
                    ]
                ],
                [
                    "lang": "spa",
                    "url": "https://opensubtitles.example.test/download/episode.srt"
                ]
            ],
            "body": "alternate https://cdn.example.test/from-string.ass?source=opensubtitles",
            "ignored": [
                "https://cdn.example.test/poster.jpg",
                ["file": "https://cdn.example.test/video.mkv"]
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 4)
        assertEqual(candidates[0].label, "English")
        assertEqual(candidates[0].language, "English")
        assertEqual(candidates[1].url.absoluteString, "https://dl.opensubtitles.org/en/subtitle.vtt?download=1")
        assertEqual(candidates[1].label, "English")
        assertEqual(candidates[1].language, "English")
        assertEqual(candidates[2].label, "spa")
        assertEqual(candidates[2].language, "spa")
        assertEqual(candidates[3].url.absoluteString, "https://cdn.example.test/from-string.ass?source=opensubtitles")
    }

    private static func testOpenSubtitlesNestedAttributesFilesParsing() {
        let payload: [String: Any] = [
            "data": [
                [
                    "attributes": [
                        "language": "English",
                        "file_name": "episode.en.srt",
                        "files": [
                            [
                                "file_id": 12345,
                                "file_name": "nested.en.srt"
                            ],
                            [
                                "link": "https://dl.opensubtitles.org/en/download/nested.vtt?token=secret",
                                "language": "eng"
                            ]
                        ]
                    ]
                ]
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 2)
        assertEqual(candidates[0].url.absoluteString, "https://api.opensubtitles.com/api/v1/download/12345")
        assertEqual(candidates[0].label, "nested.en.srt")
        assertEqual(candidates[0].language, "English")
        assertEqual(candidates[1].url.absoluteString, "https://dl.opensubtitles.org/en/download/nested.vtt?token=secret")
        assertEqual(candidates[1].label, "eng")
        assertEqual(candidates[1].language, "eng")
    }

    private static func testOpenSubtitlesManifestIDsAreNotResolvedAsSubtitles() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "url": "https://opensubtitles-v3.strem.io/manifest.json_14",
                    "file_id": 98765,
                    "lang": "eng"
                ],
                [
                    "url": "https://opensubtitles-v3.strem.io/manifest.json_15",
                    "lang": "spa"
                ],
                "https://opensubtitles-v3.strem.io/manifest.json_16"
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 1)
        assertEqual(candidates[0].url.absoluteString, "https://api.opensubtitles.com/api/v1/download/98765")
        assertEqual(candidates[0].language, "eng")
    }

    private static func testOpenSubtitlesArtworkAndAddonEndpointsAreIgnored() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "label": "External Subtitle",
                    "url": "http://www.strem.io/images/addons/opensubtitles-logo.png"
                ],
                [
                    "label": "External Subtitle",
                    "url": "https://opensubtitles.strem.io/stremio/v1"
                ],
                [
                    "label": "English",
                    "url": "https://opensubtitles.example.test/subtitles/movie.en.srt"
                ]
            ],
            "body": "metadata https://www.strem.io/images/addons/opensubtitles-logo.png"
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 1)
        assertEqual(candidates[0].url.absoluteString, "https://opensubtitles.example.test/subtitles/movie.en.srt")
        assertEqual(candidates[0].label, "English")
    }

    private static func testStremioSubtitleDownloadURLParsing() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "label": "English",
                    "lang": "eng",
                    "url": "https://subs5.strem.io/en/download/subencoding-stremio-utf8/src-api/file/1952341941"
                ],
                [
                    "label": "Not a subtitle",
                    "url": "https://www.strem.io/images/addons/opensubtitles-logo.png"
                ]
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 1)
        assertEqual(candidates[0].url.absoluteString, "https://subs5.strem.io/en/download/subencoding-stremio-utf8/src-api/file/1952341941")
        assertEqual(candidates[0].label, "English")
        assertEqual(candidates[0].language, "eng")
        assert(SubtitleResolver.isDirectSubtitleFile(candidates[0].url), "Expected Stremio subtitle downloads to be attachable without another resolver hop")
    }

    private static func testOpenSubtitlesV3DownloadResponseResolution() {
        let payload = """
        {
          "link": "https://dl.opensubtitles.org/en/download/subtitle.srt?token=secret",
          "file_name": "episode.srt",
          "requests": 1
        }
        """.data(using: .utf8)!
        let original = SubtitleCandidate(
            url: URL(string: "https://api.opensubtitles.com/api/v1/download")!,
            label: "English",
            language: "eng"
        )

        let candidate = SubtitleResolver.bestPlayableCandidate(
            from: payload,
            responseURL: original.url,
            original: original
        )

        assertEqual(candidate?.url.absoluteString, "https://dl.opensubtitles.org/en/download/subtitle.srt?token=secret")
        assertEqual(candidate?.label, "English")
        assertEqual(candidate?.language, "eng")
    }

    private static func testOpenSubtitlesNestedDownloadResponseResolution() {
        let payload = """
        {
          "data": {
            "attributes": {
              "files": [
                {
                  "file_name": "ignored.txt",
                  "link": "https://cdn.example.test/ignored.txt"
                },
                {
                  "file_name": "episode.en.ass",
                  "download": {
                    "link": "https://dl.opensubtitles.org/en/download/episode.en.ass?token=secret"
                  }
                }
              ]
            }
          }
        }
        """.data(using: .utf8)!
        let original = SubtitleCandidate(
            url: URL(string: "https://api.opensubtitles.com/api/v1/download/987")!,
            label: "English SDH",
            language: "eng"
        )

        let candidate = SubtitleResolver.bestPlayableCandidate(
            from: payload,
            responseURL: original.url,
            original: original
        )

        assertEqual(candidate?.url.absoluteString, "https://dl.opensubtitles.org/en/download/episode.en.ass?token=secret")
        assertEqual(candidate?.label, "English SDH")
        assertEqual(candidate?.language, "eng")
    }

    private static func testSubtitleResolverDownloadJSONReturningLink() async {
        MockURLProtocol.handlers = [
            "https://api.opensubtitles.com/api/v1/download/123": (
                200,
                URL(string: "https://api.opensubtitles.com/api/v1/download/123")!,
                #"{"link":"https://dl.opensubtitles.org/en/download/movie.srt?token=secret"}"#.data(using: .utf8)!
            )
        ]
        let resolver = SubtitleResolver(session: mockSession())
        let candidate = await resolver.resolve(SubtitleCandidate(
            url: URL(string: "https://api.opensubtitles.com/api/v1/download/123")!,
            label: "English",
            language: "eng"
        ))

        assertEqual(candidate?.url.absoluteString, "https://dl.opensubtitles.org/en/download/movie.srt?token=secret")
        assertEqual(candidate?.label, "English")
        assertEqual(candidate?.language, "eng")
    }

    private static func testSubtitleResolverRedirectToDirectSubtitle() async {
        MockURLProtocol.handlers = [
            "https://api.opensubtitles.com/api/v1/download/redirect": (
                200,
                URL(string: "https://dl.opensubtitles.org/en/redirected.vtt?download=1")!,
                Data()
            )
        ]
        let resolver = SubtitleResolver(session: mockSession())
        let candidate = await resolver.resolve(SubtitleCandidate(
            url: URL(string: "https://api.opensubtitles.com/api/v1/download/redirect")!,
            label: "English",
            language: "eng"
        ))

        assertEqual(candidate?.url.absoluteString, "https://dl.opensubtitles.org/en/redirected.vtt?download=1")
    }

    private static func testSubtitleResolverRejectsNonSubtitleAPIResponse() async {
        MockURLProtocol.handlers = [
            "https://api.opensubtitles.com/api/v1/download/not-found": (
                200,
                URL(string: "https://api.opensubtitles.com/api/v1/download/not-found")!,
                #"{"message":"not found"}"#.data(using: .utf8)!
            )
        ]
        let resolver = SubtitleResolver(session: mockSession())
        let candidate = await resolver.resolve(SubtitleCandidate(
            url: URL(string: "https://api.opensubtitles.com/api/v1/download/not-found")!,
            label: "English",
            language: "eng"
        ))

        assert(candidate == nil, "Expected non-subtitle API response to be rejected")
    }

    private static func testSubtitleCandidateDeduplicationPreservesLabels() {
        let payload: [String: Any] = [
            "subtitles": [
                [
                    "label": "English SDH",
                    "lang": "eng",
                    "url": "https://opensubtitles.example.test/download/duplicate.srt"
                ],
                [
                    "label": "Duplicate",
                    "language": "English",
                    "download": "https://opensubtitles.example.test/download/duplicate.srt"
                ],
                "https://opensubtitles.example.test/download/duplicate.srt"
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 1)
        assertEqual(candidates[0].label, "English SDH")
        assertEqual(candidates[0].language, "eng")
    }

    private static func testSubtitleCandidateDeduplicationUpgradesLabels() {
        let payload: [String: Any] = [
            "subtitles": [
                "https://opensubtitles.example.test/download/duplicate.srt",
                [
                    "label": "English SDH",
                    "lang": "eng",
                    "url": "https://opensubtitles.example.test/download/duplicate.srt"
                ]
            ]
        ]

        let candidates = SubtitleCandidateParser.candidates(in: payload)

        assertEqual(candidates.count, 1)
        assertEqual(candidates[0].label, "English SDH")
        assertEqual(candidates[0].language, "eng")
    }

    private static func testSubtitleOptionMappingIncludesNone() {
        let options = SubtitleOptionMapper.options(from: [
            SubtitleTrack(id: 2, name: "English"),
            SubtitleTrack(id: 5, name: "Spanish")
        ])

        assertEqual(options.map(\.name), ["None", "English", "Spanish"])
        assertEqual(options.first?.id, -1)
    }

    private static func testSubtitleDisplayNameNormalization() {
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://opensubtitles.example.test/download/subtitle.srt")!,
                label: "Track 1",
                language: "eng"
            )),
            "English"
        )
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://opensubtitles.example.test/download/subtitle.srt")!,
                label: "Track 2",
                language: "Spanish"
            )),
            "Spanish"
        )
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://opensubtitles.example.test/download/subtitle.srt")!,
                label: "English SDH",
                language: "eng"
            )),
            "English SDH"
        )
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://cdn.example.test/subtitles/movie.es.srt")!,
                label: "External Subtitle",
                language: nil
            )),
            "movie.es"
        )
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://opensubtitles.example.test/download/subtitle.srt")!,
                label: "Track 3",
                language: "nld"
            )),
            "Dutch"
        )
        assertEqual(
            SubtitleDisplayName.displayName(for: SubtitleCandidate(
                url: URL(string: "https://opensubtitles.example.test/download/subtitle.srt")!,
                label: "Track 4",
                language: "dan"
            )),
            "Danish"
        )
    }

    private static func testSubtitleDisplayNameUsesPreservedNamesForGenericVLCTracks() {
        let options = SubtitleOptionMapper.options(from: [
            SubtitleTrack(
                id: 3,
                name: SubtitleDisplayName.name(forVLCTrackName: "Track 1", preservedName: "English")
            ),
            SubtitleTrack(
                id: 4,
                name: SubtitleDisplayName.name(forVLCTrackName: "Commentary", preservedName: "Spanish")
            )
        ])

        assertEqual(options.map(\.name), ["None", "English", "Commentary"])
    }

    private static func assertEqual<T: Equatable>(_ actual: T?, _ expected: T, file: StaticString = #file, line: UInt = #line) {
        assert(actual == expected, "Expected \(String(describing: expected)), got \(String(describing: actual))", file: file, line: line)
    }

    private static func mockSession() -> URLSession {
        let configuration = URLSessionConfiguration.ephemeral
        configuration.protocolClasses = [MockURLProtocol.self]
        return URLSession(configuration: configuration)
    }
}

private final class MockURLProtocol: URLProtocol {
    static var handlers: [String: (status: Int, url: URL, data: Data)] = [:]

    override class func canInit(with request: URLRequest) -> Bool {
        true
    }

    override class func canonicalRequest(for request: URLRequest) -> URLRequest {
        request
    }

    override func startLoading() {
        guard let url = request.url,
              let handler = Self.handlers[url.absoluteString],
              let response = HTTPURLResponse(
                url: handler.url,
                statusCode: handler.status,
                httpVersion: "HTTP/1.1",
                headerFields: nil
              )
        else {
            client?.urlProtocol(self, didFailWithError: URLError(.badURL))
            return
        }

        client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
        client?.urlProtocol(self, didLoad: handler.data)
        client?.urlProtocolDidFinishLoading(self)
    }

    override func stopLoading() {}
}