// The platform's player through the sink (native-sink §4.4, §5, §6): a presentation made here
// with the platform's own encoder (H.264, fragmented MP4, each fragment named by its SHA-256),
// served from an origin on loopback, played to its end through the relay. Every object the player
// was handed is one the sink presented; the bundle verifies; a fragment changed at the origin is
// withheld from the player; and a session nobody can see ends as hidden, its player stopped.
import AVFoundation
import CryptoKit
import UniformTypeIdentifiers
import XCTest
import WaiSink

/// A short presentation in fragmented MP4 from the platform's encoder: its initialization
/// section and its media segments with their durations.
final class Fixture: NSObject, AVAssetWriterDelegate, @unchecked Sendable {
    var initSection = Data()
    var segments: [(Data, Double)] = []

    func assetWriter(_ writer: AVAssetWriter, didOutputSegmentData data: Data, segmentType: AVAssetSegmentType, segmentReport: AVAssetSegmentReport?) {
        switch segmentType {
        case .initialization: initSection = data
        case .separable: segments.append((data, segmentReport?.trackReports.first.map { $0.duration.seconds } ?? 1))
        @unknown default: break
        }
    }

    /// `seconds` of 30 frames a second, 160 by 96, a segment a second.
    static func make(seconds: Int) throws -> Fixture {
        let f = Fixture()
        let w = AVAssetWriter(contentType: UTType.mpeg4Movie)
        w.outputFileTypeProfile = .mpeg4AppleHLS
        w.preferredOutputSegmentInterval = CMTime(seconds: 1, preferredTimescale: 1)
        w.initialSegmentStartTime = .zero
        w.delegate = f
        let input = AVAssetWriterInput(mediaType: .video, outputSettings: [
            AVVideoCodecKey: AVVideoCodecType.h264, AVVideoWidthKey: 160, AVVideoHeightKey: 96,
            AVVideoCompressionPropertiesKey: [AVVideoMaxKeyFrameIntervalKey: 30, AVVideoAverageBitRateKey: 200_000],
        ])
        input.expectsMediaDataInRealTime = false
        let adaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: input, sourcePixelBufferAttributes: [
            kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32BGRA, kCVPixelBufferWidthKey as String: 160, kCVPixelBufferHeightKey as String: 96,
        ])
        w.add(input)
        guard w.startWriting() else { throw w.error ?? NSError(domain: "fixture", code: 1) }
        w.startSession(atSourceTime: .zero)
        for i in 0..<(seconds * 30) {
            while !input.isReadyForMoreMediaData { usleep(1000) }
            var pb: CVPixelBuffer?
            CVPixelBufferCreate(nil, 160, 96, kCVPixelFormatType_32BGRA, nil, &pb)
            CVPixelBufferLockBaseAddress(pb!, [])
            let base = CVPixelBufferGetBaseAddress(pb!)!.assumingMemoryBound(to: UInt8.self)
            for p in 0..<(CVPixelBufferGetBytesPerRow(pb!) * 96) { base[p] = UInt8((p + i * 7) & 0xff) }
            CVPixelBufferUnlockBaseAddress(pb!, [])
            adaptor.append(pb!, withPresentationTime: CMTime(value: CMTimeValue(i), timescale: 30))
        }
        input.markAsFinished()
        let done = DispatchSemaphore(value: 0)
        w.finishWriting { done.signal() }
        done.wait()
        guard w.status == .completed else { throw w.error ?? NSError(domain: "fixture", code: 2) }
        return f
    }

    static func name(_ d: Data) -> String { SHA256.hash(data: d).map { String(format: "%02x", $0) }.joined() + ".m4s" }

    /// The on-demand media playlist over the segments, each named by its SHA-256.
    var playlist: String {
        var s = "#EXTM3U\n#EXT-X-VERSION:7\n#EXT-X-TARGETDURATION:\(Int(segments.map(\.1).max()!.rounded(.up)))\n#EXT-X-PLAYLIST-TYPE:VOD\n#EXT-X-INDEPENDENT-SEGMENTS\n#EXT-X-MAP:URI=\"init.mp4\"\n"
        for (d, t) in segments { s += String(format: "#EXTINF:%.3f,\n", t) + Fixture.name(d) + "\n" }
        return s + "#EXT-X-ENDLIST\n"
    }
}

@MainActor
final class PlayerTests: XCTestCase {
    static let owner = String(repeating: "ab", count: 32)

    private func serve(_ f: Fixture, tamper: Int? = nil) throws -> TestOrigin {
        let o = TestOrigin()
        try o.start()
        o.put("/p/v.m3u8", Data(f.playlist.utf8), type: "application/vnd.apple.mpegurl")
        o.put("/p/init.mp4", f.initSection, type: "video/mp4")
        for (i, (d, _)) in f.segments.enumerated() {
            var b = d
            if i == tamper { b[b.count / 2] ^= 0x40 }
            o.put("/p/" + Fixture.name(d), b, type: "video/iso.segment")
        }
        return o
    }

    private func play(_ origin: TestOrigin, attention: WaiAttention, config: WaiSink.Config, timeout: TimeInterval = 30, stopAfter: TimeInterval? = nil) throws -> (WaiPlayerSession, Data, WaiSink.Ended) {
        let s = try WaiPlayerSession(url: origin.url("/p/v.m3u8"), config: config, attention: attention)
        s.player.isMuted = true
        // No layer is on screen in a test: a video output is where the player presents.
        s.prepareItem = { $0.add(AVPlayerItemVideoOutput(pixelBufferAttributes: nil)) }
        let done = expectation(description: "the session ends")
        var result: (Data, WaiSink.Ended)?
        s.onEnd = { b, e in result = (b, e); done.fulfill() }
        s.start()
        if let t = stopAfter {
            DispatchQueue.main.asyncAfter(deadline: .now() + t) { MainActor.assumeIsolated { s.stop() } }
        }
        wait(for: [done], timeout: timeout)
        guard let r = result else {
            let item = s.player.currentItem
            let errs = item?.errorLog()?.events.map { "\($0.errorStatusCode) \($0.errorDomain) \($0.errorComment ?? "")" } ?? []
            XCTFail("""
                the session did not end within \(timeout) s: item status \(item?.status.rawValue ?? -1), error \(String(describing: item?.error)), \
                time control \(s.player.timeControlStatus.rawValue), reason \(String(describing: s.player.reasonForWaitingToPlay)), \
                current \(item?.currentTime().seconds ?? -1); error log \(errs); relay \(s.relay.events.map { "\($0.status) \($0.url.suffix(24)) \($0.refused ?? "")" }); \
                origin \(origin.requests)
                """)
            throw NSError(domain: "WaiSinkTests", code: 1)
        }
        return (s, r.0, r.1)
    }

    func testThePlayerPlaysThroughTheSinkToItsEnd() throws {
        let f = try Fixture.make(seconds: 3)
        XCTAssertGreaterThanOrEqual(f.segments.count, 3)
        let o = try serve(f)
        defer { o.stop() }
        let (s, bundle, ended) = try play(o, attention: WaiFixedAttention(), config: .init(channel: "film-library", owner: Self.owner, contentAddressed: true))
        XCTAssertEqual(ended, .ended)
        print("WAI-SINK end to end: \(s.relay.events.count) requests through the relay, ended \(ended.rawValue)")
        // Every segment the player was handed was presented by the sink, held to its name.
        let segs = s.relay.events.filter { $0.url.hasSuffix(".m4s") }
        XCTAssertEqual(Set(segs.map(\.url)).count, f.segments.count)
        XCTAssertTrue(segs.allSatisfy { $0.status == 200 && $0.bound == "sha256" && $0.refused == nil })
        let out = try WaiSink.verifyBundle(bundle, owner: hexData(Self.owner), channels: ["film-library"])
        XCTAssertEqual(out["outcome"] as? String, "accept", "\(out["reason"] ?? "") at \(out["at"] ?? "")")
        guard out["outcome"] as? String == "accept" else { return }
        XCTAssertEqual(out["ended"] as? String, "ended")
        XCTAssertGreaterThan(out["presented_ms"] as? Int ?? 0, 1500, "\(out)")
        XCTAssertNotNil(out["startup_ms"] as? Int)
        print("WAI-SINK end to end: bundle \(out["outcome"] ?? ""), ended \(out["ended"] ?? ""), presented_ms \(out["presented_ms"] ?? ""), startup_ms \(out["startup_ms"] ?? "")")
        let energy = out["energy"] as? [[String: Any]] ?? []
        XCTAssertEqual(energy.map { $0["class"] as? String }, ["unmetered", "unmetered"], "the platform's decoder is outside every counter (§7)")
    }

    func testAFragmentChangedAtTheOriginIsWithheld() throws {
        let f = try Fixture.make(seconds: 3)
        let o = try serve(f, tamper: 1)
        defer { o.stop() }
        // The player asks again for a segment it was refused, and waits; the viewer stops it.
        let (s, bundle, ended) = try play(o, attention: WaiFixedAttention(), config: .init(channel: "film-library", owner: Self.owner, contentAddressed: true), stopAfter: 6)
        XCTAssertTrue(ended == .user || ended == .error, "\(ended)")
        let bad = s.relay.events.filter { $0.refused == "object_digest_mismatch" }
        XCTAssertFalse(bad.isEmpty, "the changed fragment was refused")
        XCTAssertTrue(bad.allSatisfy { $0.status == 502 }, "and answered 502, never handed to the player")
        print("WAI-SINK tampered fragment: \(bad.count) requests refused object_digest_mismatch, statuses \(Set(bad.map(\.status)).sorted())")
        let out = try WaiSink.verifyBundle(bundle, owner: hexData(Self.owner), channels: ["film-library"])
        XCTAssertEqual(out["outcome"] as? String, "accept", "\(out["reason"] ?? "") at \(out["at"] ?? "")")
    }

    func testASessionNobodyCanSeeEndsAsHidden() throws {
        let f = try Fixture.make(seconds: 6)
        let o = try serve(f)
        defer { o.stop() }
        let a = WaiFixedAttention(visibleBasisPoints: 0)
        let (s, bundle, ended) = try play(o, attention: a, config: .init(channel: "film-library", owner: Self.owner, contentAddressed: true, unseenGraceMs: 1000))
        XCTAssertEqual(ended, .hidden)
        XCTAssertNil(s.player.currentItem, "the player's item is removed, so it requests nothing more")
        let out = try WaiSink.verifyBundle(bundle, owner: hexData(Self.owner), channels: ["film-library"])
        XCTAssertEqual(out["ended"] as? String, "hidden", "\(out)")
        XCTAssertEqual(out["viewable_ms"] as? Int, 0)
        print("WAI-SINK hidden: ended \(out["ended"] ?? ""), presented_ms \(out["presented_ms"] ?? ""), viewable_ms \(out["viewable_ms"] ?? "")")
    }
}