import XCTest
@testable import HaptikaSignal

final class PPGCoherencePolicyTests: XCTestCase {
  func testSessionDurationLimitsRemainPurposeSpecific() {
    XCTAssertEqual(PPGCoherencePolicy.maximumDurationSeconds(isCoherence: false), 120)
    XCTAssertEqual(PPGCoherencePolicy.maximumDurationSeconds(isCoherence: true), 300)
    XCTAssertEqual(PPGCoherencePolicy.coherenceBufferDurationSeconds, 75)
  }

  func testLiveTrackerPublishesEveryNewBeatOnlyOnce() {
    var tracker = PPGLiveBeatTracker()
    let first = tracker.ingest([
      interval(end: 1, duration: 800), interval(end: 1.8, duration: 800),
    ])
    XCTAssertEqual(first.map(\.sequence), [1, 2])
    let overlapping = tracker.ingest([
      interval(end: 1.82, duration: 800), interval(end: 2.6, duration: 780),
    ])
    XCTAssertEqual(overlapping.map(\.sequence), [3])
    XCTAssertEqual(overlapping.first?.timestampSeconds, 2.6)
  }

  func testTrackerDoesNotMoveBackwardAndResetsCleanly() {
    var tracker = PPGLiveBeatTracker()
    _ = tracker.ingest([interval(end: 10, duration: 700)])
    XCTAssertTrue(tracker.ingest([interval(end: 9.9, duration: 700)]).isEmpty)
    tracker.reset()
    XCTAssertEqual(tracker.ingest([interval(end: 1, duration: 700)]).first?.sequence, 1)
  }

  func testTrackerRejectsInvalidAndRejectedIntervals() {
    var tracker = PPGLiveBeatTracker()
    let rejected = PulseInterval(
      sourceIndex: 0, startSeconds: 0, endSeconds: 1,
      durationMilliseconds: 800, rejectionReason: .localOutlier, qualityScore: 1
    )
    XCTAssertTrue(tracker.ingest([
      rejected, interval(end: .nan, duration: 800), interval(end: 2, duration: 2_500),
    ]).isEmpty)
  }

  private func interval(end: Double, duration: Double) -> PulseInterval {
    PulseInterval(
      sourceIndex: 0,
      startSeconds: end - duration / 1_000,
      endSeconds: end,
      durationMilliseconds: duration,
      qualityScore: 0.9
    )
  }
}