import Testing
@testable import MusicShared

struct HLSManifestGeneratorTests {
    // Generates a manifest for a 16-second track with 6s segments.
    // Expects 3 segments: 6s, 6s, 4s (remainder).
    @Test func generatesCorrectManifestForTypicalTrack() {
        let manifest = HLSManifestGenerator.manifest(
            trackId: 42,
            duration: 16.0,
            segmentDuration: 6.0
        )

        #expect(manifest.contains("#EXTM3U"))
        #expect(manifest.contains("#EXT-X-VERSION:3"))
        #expect(manifest.contains("#EXT-X-TARGETDURATION:6"))
        #expect(manifest.contains("#EXT-X-MEDIA-SEQUENCE:0"))
        #expect(manifest.contains("#EXTINF:6.000,"))
        #expect(manifest.contains("#EXTINF:4.000,"))
        #expect(manifest.contains("segments/0.mp3"))
        #expect(manifest.contains("segments/1.mp3"))
        #expect(manifest.contains("segments/2.mp3"))
        #expect(!manifest.contains("segments/3.mp3"))
        #expect(manifest.contains("#EXT-X-ENDLIST"))
    }

    // A track whose duration is an exact multiple of the segment duration.
    // Expects no short final segment.
    @Test func exactMultipleOfSegmentDuration() {
        let manifest = HLSManifestGenerator.manifest(
            trackId: 1,
            duration: 12.0,
            segmentDuration: 6.0
        )

        let segmentCount = manifest.components(separatedBy: "#EXTINF:6.000,").count - 1
        #expect(segmentCount == 2)
        #expect(!manifest.contains("segments/2.mp3"))
    }

    // A very short track (shorter than one segment).
    // Expects a single segment with the track's full duration.
    @Test func veryShortTrack() {
        let manifest = HLSManifestGenerator.manifest(
            trackId: 7,
            duration: 2.5,
            segmentDuration: 6.0
        )

        #expect(manifest.contains("#EXTINF:2.500,"))
        #expect(manifest.contains("segments/0.mp3"))
        #expect(!manifest.contains("segments/1.mp3"))
    }

    // Segment count helper returns the correct number of segments.
    @Test func segmentCountCalculation() {
        #expect(HLSManifestGenerator.segmentCount(duration: 16.0, segmentDuration: 6.0) == 3)
        #expect(HLSManifestGenerator.segmentCount(duration: 12.0, segmentDuration: 6.0) == 2)
        #expect(HLSManifestGenerator.segmentCount(duration: 2.5, segmentDuration: 6.0) == 1)
        #expect(HLSManifestGenerator.segmentCount(duration: 6.0, segmentDuration: 6.0) == 1)
    }

    // Time range for a given segment index returns correct start and duration.
    @Test func segmentTimeRange() {
        // Track: 16s, segment: 6s → segments at 0-6, 6-12, 12-16
        let range0 = HLSManifestGenerator.segmentTimeRange(
            index: 0, trackDuration: 16.0, segmentDuration: 6.0
        )
        #expect(range0.start == 0.0)
        #expect(range0.duration == 6.0)

        let range2 = HLSManifestGenerator.segmentTimeRange(
            index: 2, trackDuration: 16.0, segmentDuration: 6.0
        )
        #expect(range2.start == 12.0)
        #expect(range2.duration == 4.0)
    }
}