import Foundation
import Testing
@testable import Workouts

/// Locks the Swift motion solver to the Exercise Library's anatomical 3D reference
/// (`Exercise Library/kinematics.py` + `render.py`): the bundled rig resources must
/// decode, and the FK / IK / frame-geometry / tween math must reproduce the projected
/// geometry the Python computes — captured in `Fixtures/figure-fixtures.json`. The two
/// renderers are meant to stay in lockstep.
struct ExerciseMotionTests {

    @Test func bundledBirdDogResourcesDecode() throws {
        let resources = try #require(ExerciseMotionLibrary.resources(for: "Bird Dog"))
        #expect(resources.motion.name == "Bird Dog")
        // Bird Dog alternates sides, so all four limbs are in the working set and the
        // loop is four key frames (support both hands, lift one arm/leg pair, and back).
        #expect(resources.motion.frames.count == 4)
        #expect(resources.motion.working == ["arm_l", "leg_r", "arm_r", "leg_l"])
        #expect(resources.profile.upperArm == 30)
        #expect(MotionTimeline(motion: resources.motion, profile: resources.profile) != nil)
    }

    @Test func exerciseWithoutBundledMotionLoadsNothing() {
        // Cardio equipment is a permanent library exclusion (see COVERAGE.md).
        #expect(ExerciseMotionLibrary.resources(for: "Treadmill") == nil)
        #expect(FigureAnimation(exerciseName: "Treadmill") == nil)
    }

    /// Resolving Bird Dog's first key frame must reproduce the reference IK: both
    /// pinned hands land exactly on their canvas targets, the head projects to the
    /// reference point, and the far right arm's solved anatomical angles match.
    @Test func birdDogFrameZeroMatchesReference() throws {
        let resources = try #require(ExerciseMotionLibrary.resources(for: "Bird Dog"))
        let cam = resources.motion.camera?.yaw ?? 0
        let frame = MotionSolver.normalize(resources.motion.frames[0])
        let (resolved, geo) = MotionSolver.frameGeometry(frame, prof: resources.profile, cam: cam)

        // Pins solve in the flat authored view, then the posed body tilts through the
        // default camera pitch — so drawn hands straddle the floor plane around their
        // authored canvas targets (x exact, y shifted by each hand's depth).
        let handR = try #require(geo.limbs[.armR]?.last)
        #expect(abs(handR.x - 111) < 1e-2)
        #expect(abs(handR.y - 151.391) < 1e-2)
        let handL = try #require(geo.limbs[.armL]?.last)
        #expect(abs(handL.x - 105) < 1e-2)
        #expect(abs(handL.y - 153.211) < 1e-2)

        #expect(abs(geo.headCenter.x - 86.195568) < 1e-4)
        #expect(abs(geo.headCenter.y - 95.305438) < 1e-4)

        // The right arm is the far member here, so its angles solve against the
        // offset target; the drawn hand still lands on the authored pin (flat view).
        #expect(geo.shade[.armR] == .far)
        #expect(geo.shade[.armL] == .near)
        #expect(abs(resolved.shoulderR.flexion - 73.384213) < 1e-4)
        #expect(abs(resolved.elbowR.flexion - 17.076663) < 1e-4)
        // Depth-sorted under the elevated camera (arm attach points are the widest).
        #expect(geo.order == ["arm_r", "leg_r", "leg_l", "spine", "arm_l", "head"])
    }

    /// Mid-tween of resolved frames 1→2: a hand pinned in BOTH frames stays planted
    /// exactly; a pin present in only one frame releases and swings off its target.
    @Test func tweenKeepsSharedPinsAndReleasesOthers() throws {
        let resources = try #require(ExerciseMotionLibrary.resources(for: "Bird Dog"))
        let cam = resources.motion.camera?.yaw ?? 0
        let r0 = MotionSolver.frameGeometry(MotionSolver.normalize(resources.motion.frames[0]), prof: resources.profile, cam: cam).0
        let r1 = MotionSolver.frameGeometry(MotionSolver.normalize(resources.motion.frames[1]), prof: resources.profile, cam: cam).0
        let mid = MotionSolver.lerpFrames(r0, r1, MotionSolver.ease(0.5))

        #expect(mid.pins["hand_r"] != nil)
        #expect(mid.pins["hand_l"] == nil)

        let (_, geo) = MotionSolver.frameGeometry(mid, prof: resources.profile, cam: cam)
        let (_, geo0) = MotionSolver.frameGeometry(r0, prof: resources.profile, cam: cam)
        let plantedHand = try #require(geo.limbs[.armR]?.last)
        let plantedHand0 = try #require(geo0.limbs[.armR]?.last)
        #expect(hypot(plantedHand.x - plantedHand0.x, plantedHand.y - plantedHand0.y) < 1e-3)

        let releasedHand = try #require(geo.limbs[.armL]?.last)
        let releasedHand0 = try #require(geo0.limbs[.armL]?.last)
        #expect(hypot(releasedHand.x - releasedHand0.x, releasedHand.y - releasedHand0.y) > 1)
    }

    /// Every motion slowly orbits the camera while looping — bodyweight moves and
    /// machines alike, since the equipment layer rotates with the figure.
    @Test func everyMotionOrbits() throws {
        // Same loop phase seconds apart: the orbit yaw differs, so the projected head
        // moves even though the pose is identical.
        let birdDog = try #require(FigureAnimation(exerciseName: "Bird Dog"))
        let head0 = birdDog.geometry(at: 0).headCenter
        let head1 = birdDog.geometry(at: birdDog.timeline.duration * 2).headCenter
        #expect(hypot(head0.x - head1.x, head0.y - head1.y) > 1)

        // A machine orbits too, and its equipment turns with the figure: the seat
        // slab's projected points move between the same two loop phases.
        let legPress = try #require(FigureAnimation(exerciseName: "Leg Press"))
        let geo0 = legPress.geometry(at: 0)
        let geo1 = legPress.geometry(at: legPress.timeline.duration * 2)
        #expect(hypot(geo0.headCenter.x - geo1.headCenter.x,
                      geo0.headCenter.y - geo1.headCenter.y) > 1)
        guard case .poly(let seat0, _, _) = geo0.propsBackground.first,
              case .poly(let seat1, _, _) = geo1.propsBackground.first,
              let s0 = seat0.first, let s1 = seat1.first else {
            Issue.record("expected the Leg Press backrest slab as the first background prop")
            return
        }
        #expect(hypot(s0.x - s1.x, s0.y - s1.y) > 1)
    }

    /// Every exported motion in the bundle decodes and builds a playable timeline.
    @Test func allBundledMotionsBuildTimelines() throws {
        let urls = Bundle.main.urls(forResourcesWithExtension: "json", subdirectory: nil) ?? []
        let motionURLs = urls.filter { $0.lastPathComponent.hasSuffix(".motion.json") }
        #expect(!motionURLs.isEmpty)
        for url in motionURLs {
            let name = url.lastPathComponent.replacingOccurrences(of: ".motion.json", with: "")
            let resources = try #require(ExerciseMotionLibrary.resources(for: name))
            let timeline = try #require(MotionTimeline(motion: resources.motion, profile: resources.profile))
            #expect(timeline.duration > 0)
        }
    }

    /// The projected-geometry ground truth: for every exercise and key frame, the draw
    /// order and near/far shading must match exactly and every point land within 0.5 px
    /// of the reference, plus the mid-tween sample and orbit-camera views taken through
    /// the presentation path — resolve at the authored camera, clear the pins, rotate
    /// the posed body — with the equipment layer resolved into rotated primitives.
    @Test func figureFixturesMatchReference() throws {
        let bundle = Bundle(for: FigureFixtureMarker.self)
        let url = try #require(
            bundle.url(forResource: "figure-fixtures", withExtension: "json"),
            "figure-fixtures.json must be bundled as a WorkoutsTests resource (see project.yml)")
        let fixtures = try JSONDecoder().decode(FigureFixtures.self, from: Data(contentsOf: url))
        // One fixture entry per bundled motion: the loop below proves fixtures ⊆ bundle,
        // and matching counts close the other direction (a bundled motion the reference
        // pipeline never snapshotted would otherwise slip through unverified).
        #expect(fixtures.exercises.count == ExerciseMotionLibrary.exerciseNames.count)

        for exercise in fixtures.exercises {
            let resources = try #require(ExerciseMotionLibrary.resources(for: exercise.name),
                                         "no bundled motion for \(exercise.name)")
            let cam = resources.motion.camera?.yaw ?? 0
            let profile = resources.profile
            let norms = resources.motion.frames.map { MotionSolver.normalize($0) }

            var resolved: [NormalizedFrame] = []
            for (index, frame) in norms.enumerated() {
                let (resolvedFrame, geo) = MotionSolver.frameGeometry(frame, prof: profile, cam: cam)
                resolved.append(resolvedFrame)
                if index < exercise.frames.count {
                    expectMatch(geo, exercise.frames[index], "\(exercise.name) frame \(index)")
                }
            }

            let mid = MotionSolver.lerpFrames(resolved[0], resolved[1], MotionSolver.ease(exercise.tween.t))
            expectMatch(MotionSolver.frameGeometry(mid, prof: profile, cam: cam).1,
                        exercise.tween.sample, "\(exercise.name) tween")

            guard let orbits = exercise.orbit, !orbits.isEmpty else { continue }
            let (posedFrame, authored) = MotionSolver.frameGeometry(norms[0], prof: profile, cam: cam)
            var posed = posedFrame
            posed.pins = [:]
            for orbit in orbits {
                let geo = MotionSolver.frameGeometry(posed, prof: profile, cam: orbit.yaw).1
                expectMatch(geo, orbit.sample, "\(exercise.name) orbit \(orbit.yaw)")
                guard let propFixture = orbit.sample.props else { continue }
                let rotation = MotionSolver.propRotation(pitch: fixtures.pitch, yawOffset: orbit.yaw - cam)
                let (bg, fg) = MotionSolver.resolveProps(
                    resources.motion.props ?? [], geo: geo, authored: authored,
                    anchor: norms[0].rootPos, rotation: rotation, pitch: fixtures.pitch)
                expectPrims(bg, propFixture.bg, "\(exercise.name) orbit \(orbit.yaw) bg")
                expectPrims(fg, propFixture.fg, "\(exercise.name) orbit \(orbit.yaw) fg")
            }
        }
    }
}

/// Marker for locating the test bundle that carries `figure-fixtures.json`.
private final class FigureFixtureMarker {}

// MARK: - Fixture decoding + comparison

private struct FigureFixtures: Decodable {
    let profile: String
    let pitch: Double
    let exercises: [FixtureExercise]
}

private struct FixtureExercise: Decodable {
    let name: String
    let camera: Double
    let frames: [FixtureSample]
    let tween: FixtureTween
    let orbit: [FixtureOrbit]?
}

private struct FixtureTween: Decodable { let t: Double; let sample: FixtureSample }
private struct FixtureOrbit: Decodable { let yaw: Double; let sample: FixtureSample }

private struct FixtureSample: Decodable {
    let order: [String]
    let shade: [String: String]
    let spine: [[Double]]
    let head: [Double]
    let nose: [[Double]]?
    let armR: [[Double]]
    let armL: [[Double]]
    let legR: [[Double]]
    let legL: [[Double]]
    let props: FixtureProps?

    enum CodingKeys: String, CodingKey {
        case order, shade, spine, head, nose, props
        case armR = "arm_r", armL = "arm_l", legR = "leg_r", legL = "leg_l"
    }
}

private struct FixtureProps: Decodable {
    let bg: [FixturePrim]
    let fg: [FixturePrim]
}

/// One reference prop primitive: a line/poly (`pts`) or a circle (`c` + `r`).
private struct FixturePrim: Decodable {
    let kind: String
    let pts: [[Double]]?
    let c: [Double]?
    let r: Double?
    let w: Double?
    let fill: Bool?
    let color: String
}

private func expectClose(_ point: CGPoint, _ expected: [Double], _ label: String) {
    #expect(abs(Double(point.x) - expected[0]) < 0.5 && abs(Double(point.y) - expected[1]) < 0.5,
            "\(label): got (\(point.x), \(point.y)) expected \(expected)")
}

private func expectChain(_ points: [CGPoint]?, _ expected: [[Double]], _ label: String) {
    guard let points, points.count == expected.count else {
        Issue.record("\(label): chain length mismatch")
        return
    }
    for (index, (point, target)) in zip(points, expected).enumerated() {
        expectClose(point, target, "\(label)[\(index)]")
    }
}

private func expectMatch(_ geo: FigureGeometry, _ fixture: FixtureSample, _ label: String) {
    #expect(geo.order == fixture.order, "\(label) order")
    let shade = Dictionary(uniqueKeysWithValues: geo.shade.map { ($0.key.rawValue, $0.value == .near ? "near" : "far") })
    #expect(shade == fixture.shade, "\(label) shade")

    expectChain([geo.spineStart, geo.spineControl, geo.spineEnd], fixture.spine, "\(label).spine")
    expectClose(geo.headCenter, fixture.head, "\(label).head")

    if let nose = fixture.nose {
        #expect(geo.noseStart != nil && geo.noseEnd != nil, "\(label): expected a nose tick")
        if let start = geo.noseStart, let end = geo.noseEnd {
            expectClose(start, nose[0], "\(label).nose.start")
            expectClose(end, nose[1], "\(label).nose.end")
        }
    } else {
        #expect(geo.noseStart == nil, "\(label): expected no nose tick")
    }

    expectChain(geo.limbs[.armR], fixture.armR, "\(label).arm_r")
    expectChain(geo.limbs[.armL], fixture.armL, "\(label).arm_l")
    expectChain(geo.limbs[.legR], fixture.legR, "\(label).leg_r")
    expectChain(geo.limbs[.legL], fixture.legL, "\(label).leg_l")
}

/// One resolved equipment layer against its reference: same primitive kinds and inks
/// in the same order, every point within 0.5 px, radii and widths matching.
private func expectPrims(_ prims: [PropPrimitive], _ fixtures: [FixturePrim], _ label: String) {
    guard prims.count == fixtures.count else {
        Issue.record("\(label): \(prims.count) primitives, expected \(fixtures.count)")
        return
    }
    for (index, (prim, fixture)) in zip(prims, fixtures).enumerated() {
        let tag = "\(label)[\(index)]"
        switch prim {
        case .line(let points, let width, let ink):
            #expect(fixture.kind == "line", "\(tag) kind")
            expectChain(points, fixture.pts ?? [], tag)
            #expect(width == (fixture.w ?? 4), "\(tag) width")
            expectInk(ink, fixture.color, tag)
        case .poly(let points, let width, let ink):
            #expect(fixture.kind == "poly", "\(tag) kind")
            expectChain(points, fixture.pts ?? [], tag)
            #expect(width == (fixture.w ?? 4), "\(tag) width")
            expectInk(ink, fixture.color, tag)
        case .circle(let center, let radius, _, let fill, let ink):
            #expect(fixture.kind == "circle", "\(tag) kind")
            expectClose(center, fixture.c ?? [], tag)
            #expect(radius == fixture.r, "\(tag) radius")
            #expect(fill == (fixture.fill ?? false), "\(tag) fill")
            expectInk(ink, fixture.color, tag)
        }
    }
}

private func expectInk(_ ink: PropInk, _ expected: String, _ label: String) {
    #expect((ink == .prop ? "prop" : "equipment") == expected, "\(label) ink")
}