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() {
        #expect(ExerciseMotionLibrary.resources(for: "Bench Press") == nil)
        #expect(FigureAnimation(exerciseName: "Bench Press") == 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)

        let handR = try #require(geo.limbs[.armR]?.last)
        #expect(abs(handR.x - 111) < 1e-3)
        #expect(abs(handR.y - 154) < 1e-3)
        let handL = try #require(geo.limbs[.armL]?.last)
        #expect(abs(handL.x - 105) < 1e-3)
        #expect(abs(handL.y - 152) < 1e-3)

        #expect(abs(geo.headCenter.x - 86.195568) < 1e-4)
        #expect(abs(geo.headCenter.y - 95.140457) < 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 above.
        #expect(geo.shade[.armR] == .far)
        #expect(geo.shade[.armL] == .near)
        #expect(abs(resolved.shoulderR.flexion - 73.289190) < 1e-4)
        #expect(abs(resolved.elbowR.flexion - 17.443758) < 1e-4)
        #expect(geo.order == ["arm_r", "leg_r", "spine", "arm_l", "leg_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 plantedHand = try #require(geo.limbs[.armR]?.last)
        #expect(abs(plantedHand.x - 111) < 1e-3)
        #expect(abs(plantedHand.y - 154) < 1e-3)

        let releasedHand = try #require(geo.limbs[.armL]?.last)
        #expect(hypot(releasedHand.x - 105, releasedHand.y - 152) > 1)
    }

    /// Prop-free bodyweight motions slowly orbit the camera while looping; motions with
    /// equipment (view-locked scene shapes) or a hide list keep their authored view.
    @Test func orbitAppliesOnlyToPropFreeMotions() throws {
        let birdDog = try #require(FigureAnimation(exerciseName: "Bird Dog"))
        #expect(birdDog.orbits)
        // Same loop phase seconds apart: the orbit yaw differs, so the projected head
        // moves even though the pose is identical.
        let duration = birdDog.timeline.duration
        let head0 = birdDog.geometry(at: 0).headCenter
        let head1 = birdDog.geometry(at: duration * 2).headCenter
        #expect(hypot(head0.x - head1.x, head0.y - head1.y) > 1)

        let legPress = try #require(FigureAnimation(exerciseName: "Leg Press"))
        #expect(!legPress.orbits)
        let fixed0 = legPress.geometry(at: 0).headCenter
        let fixed1 = legPress.geometry(at: legPress.timeline.duration * 2).headCenter
        #expect(abs(fixed0.x - fixed1.x) < 1e-9 && abs(fixed0.y - fixed1.y) < 1e-9)
    }

    /// 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 (Bird Dog) two orbit-camera views.
    @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))
        #expect(fixtures.exercises.count == 22)

        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")

            for orbit in exercise.orbit ?? [] {
                expectMatch(MotionSolver.frameGeometry(norms[0], prof: profile, cam: orbit.yaw).1,
                            orbit.sample, "\(exercise.name) orbit \(orbit.yaw)")
            }
        }
    }
}

/// 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 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]]

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

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")
}