using UnityEngine;
using Ashwild.Audio;

namespace Ashwild.Player
{
    /// <summary>
    /// Plays the local player's footstep and landing sounds, picking the clip set from the
    /// surface underfoot. A footstep fires every "stride" meters of horizontal travel, the stride
    /// being chosen by gait — so the step rate scales with speed (sprinting sounds faster than
    /// walking) and stays in sync with movement. The surface is sampled lazily and cached.
    /// </summary>
    [DisallowMultipleComponent]
    public class PlayerAudio : MonoBehaviour
    {
        #region Serialized Fields

        [Header("Stride (meters of travel between footsteps — smaller = faster cadence)")]
        [SerializeField, Tooltip("Step rate is speed / stride, so smaller strides give a faster footstep cadence. Tune per gait.")]
        private float walkStride = 2.75f;
        [SerializeField] private float sprintStride = 2.8f;
        [SerializeField] private float crouchStride = 1.5f;

        [Header("Audio")]
        [SerializeField] private AudioSource audioSource;

        [Header("Surface profiles")]
        [SerializeField] private SurfaceSoundProfile defaultProfile;
        [SerializeField] private SurfaceSoundProfile[] surfaceProfiles;
        [SerializeField, Tooltip("Resample dominant terrain layer only after the player moves this many meters since the last sample.")]
        private float surfaceResampleDistance = 0.5f;

        [Header("Landing sound")]
        [SerializeField, Tooltip("Minimum drop in meters required before the landing sound fires. Avoids spam on stairs and terrain bumps where the capsule briefly leaves the ground.")]
        private float minLandingSoundDrop = 0.5f;

        #endregion

        #region State

        private Vector2 moveInput;
        private bool isGrounded = true;
        private bool isSprinting;
        private bool isCrouching;
        private PhysicsMaterial groundMaterial;

        private float distanceTravelled;
        private bool wasMoving;
        private Vector3 lastPosition;
        private int lastClipIndex = -1;

        private SurfaceSoundProfile cachedSurface;
        private Vector3 lastSampledPosition;
        private bool surfaceCacheValid;

        #endregion

        #region Unity Lifecycle

        /// <summary>
        /// Seeds the position trackers so the first frame doesn't report a huge delta.
        /// </summary>
        private void Start()
        {
            lastPosition = transform.position;
            lastSampledPosition = lastPosition;
        }

        /// <summary>
        /// Subscribes to the movement and ground events that drive footstep playback.
        /// </summary>
        private void OnEnable()
        {
            PlayerEvents.MoveInput += OnMoveInput;
            PlayerEvents.SprintChanged += OnSprintChanged;
            PlayerEvents.CrouchChanged += OnCrouchChanged;
            PlayerEvents.GroundedChanged += OnGroundedChanged;
            PlayerEvents.GroundMaterialChanged += OnGroundMaterialChanged;
        }

        /// <summary>
        /// Unsubscribes — must mirror OnEnable exactly.
        /// </summary>
        private void OnDisable()
        {
            PlayerEvents.MoveInput -= OnMoveInput;
            PlayerEvents.SprintChanged -= OnSprintChanged;
            PlayerEvents.CrouchChanged -= OnCrouchChanged;
            PlayerEvents.GroundedChanged -= OnGroundedChanged;
            PlayerEvents.GroundMaterialChanged -= OnGroundMaterialChanged;
        }

        /// <summary>
        /// Accumulates horizontal distance travelled and fires a footstep every time it crosses the
        /// current stride. Driving steps off real distance (not a timer) is what keeps them in sync:
        /// the faster the player moves, the sooner the stride is covered, so sprinting produces a
        /// faster cadence on its own.
        ///
        /// The very first step when movement begins is played immediately rather than after a full
        /// stride, otherwise there is an audible 0.5s+ gap before the first footstep when you start
        /// walking. The leftover distance is carried into the next step (subtracted, not zeroed) so
        /// the per-frame overshoot doesn't randomly stretch steps at high speed; the second check
        /// clamps a single huge delta (e.g. a teleport) so it can't fire a burst of steps.
        ///
        /// While airborne the accumulator is frozen (not reset) and lastPosition keeps tracking, so
        /// a one-frame ground-check flicker on bumps or stairs no longer wipes the accumulated
        /// distance — that wipe was causing random silent gaps mid-walk. It only resets when the
        /// player is genuinely stationary.
        /// </summary>
        private void Update()
        {
            if (PlayerEvents.IsDead) return;
            if (!isGrounded)
            {
                lastPosition = transform.position;
                return;
            }

            Vector3 current = transform.position;
            Vector3 delta = current - lastPosition;
            delta.y = 0f;
            float moved = delta.magnitude;
            lastPosition = current;

            if (moveInput.sqrMagnitude < 0.01f)
            {
                distanceTravelled = 0f;
                wasMoving = false;
                return;
            }

            if (!wasMoving)
            {
                wasMoving = true;
                distanceTravelled = 0f;
                PlayFootstep();
                return;
            }

            distanceTravelled += moved;

            float stride = GetCurrentStride();
            if (distanceTravelled >= stride)
            {
                PlayFootstep();
                distanceTravelled -= stride;
                if (distanceTravelled >= stride) distanceTravelled = 0f;
            }
        }

        #endregion

        #region Bus Handlers

        /// <summary>
        /// Caches the raw move input; a near-zero magnitude stops footstep accumulation.
        /// </summary>
        private void OnMoveInput(Vector2 v) => moveInput = v;

        /// <summary>
        /// Tracks sprint state to select the sprint stride and clip volume.
        /// </summary>
        private void OnSprintChanged(bool b) => isSprinting = b;

        /// <summary>
        /// Tracks crouch state to select the crouch stride and clip volume.
        /// </summary>
        private void OnCrouchChanged(bool b) => isCrouching = b;

        /// <summary>
        /// Updates grounded state and plays a landing sound on touchdown when the drop is large
        /// enough. The step accumulator is deliberately left untouched here: Update already freezes
        /// it while airborne, and wiping it on every un-ground turned brief ground-check flickers
        /// (stairs, terrain bumps) into random silent gaps in the footstep cadence.
        /// </summary>
        private void OnGroundedChanged(bool grounded, float dropDistance)
        {
            bool wasGrounded = isGrounded;
            isGrounded = grounded;
            if (grounded && !wasGrounded && dropDistance >= minLandingSoundDrop) PlayLandingSound();
        }

        /// <summary>
        /// Records the new ground physics material and invalidates the surface cache so the next
        /// footstep resolves the matching profile.
        /// </summary>
        private void OnGroundMaterialChanged(PhysicsMaterial mat)
        {
            groundMaterial = mat;
            surfaceCacheValid = false;
        }

        #endregion

        #region Step Cadence

        /// <summary>
        /// Returns the meters of travel between footsteps for the current gait. Crouch takes
        /// priority over sprint (you can't sprint while crouched), and walking is the default.
        /// </summary>
        private float GetCurrentStride()
        {
            if (isCrouching) return crouchStride;
            if (isSprinting) return sprintStride;
            return walkStride;
        }

        #endregion

        #region Surface Detection

        /// <summary>
        /// Returns the surface profile underfoot, resampling only after the player has moved past
        /// the resample distance or the ground material changed — GetAlphamaps is too costly to
        /// run every frame, so the result is cached between samples.
        /// </summary>
        private SurfaceSoundProfile GetCurrentSurface()
        {
            if (surfaceProfiles == null || surfaceProfiles.Length == 0) return defaultProfile;

            if (!surfaceCacheValid || (transform.position - lastSampledPosition).sqrMagnitude >= surfaceResampleDistance * surfaceResampleDistance)
            {
                cachedSurface = ResolveSurface();
                lastSampledPosition = transform.position;
                surfaceCacheValid = true;
            }
            return cachedSurface ?? defaultProfile;
        }

        /// <summary>
        /// Resolves the surface profile, preferring the dominant terrain layer and falling back to
        /// the ground physics material, then to the default profile.
        /// </summary>
        private SurfaceSoundProfile ResolveSurface()
        {
            SurfaceSoundProfile terrain = ResolveTerrainSurface();
            if (terrain != null) return terrain;

            if (groundMaterial != null)
            {
                for (int i = 0; i < surfaceProfiles.Length; i++)
                    if (surfaceProfiles[i] != null && surfaceProfiles[i].physicsMaterial == groundMaterial)
                        return surfaceProfiles[i];
            }
            return defaultProfile;
        }

        /// <summary>
        /// Samples the active terrain's alphamap at the player position, finds the dominant layer,
        /// and returns the profile mapped to that layer. Returns null when there's no terrain or no
        /// profile matches, letting the caller fall back to physics material / default.
        /// </summary>
        private SurfaceSoundProfile ResolveTerrainSurface()
        {
            Terrain terrain = Terrain.activeTerrain;
            if (terrain == null) return null;

            TerrainData td = terrain.terrainData;
            if (td == null || td.terrainLayers == null || td.terrainLayers.Length == 0) return null;

            Vector3 terrainPos = terrain.transform.position;
            Vector3 playerPos = transform.position;

            float nx = Mathf.Clamp01((playerPos.x - terrainPos.x) / td.size.x);
            float nz = Mathf.Clamp01((playerPos.z - terrainPos.z) / td.size.z);

            int mapX = Mathf.RoundToInt(nx * (td.alphamapWidth - 1));
            int mapZ = Mathf.RoundToInt(nz * (td.alphamapHeight - 1));
            float[,,] alpha = td.GetAlphamaps(mapX, mapZ, 1, 1);

            int dominantIndex = 0;
            float maxWeight = 0f;
            int layers = alpha.GetLength(2);
            for (int i = 0; i < layers; i++)
            {
                float w = alpha[0, 0, i];
                if (w > maxWeight) { maxWeight = w; dominantIndex = i; }
            }

            if (dominantIndex >= td.terrainLayers.Length) return null;

            TerrainLayer dominant = td.terrainLayers[dominantIndex];
            for (int i = 0; i < surfaceProfiles.Length; i++)
                if (surfaceProfiles[i] != null && surfaceProfiles[i].terrainLayer == dominant)
                    return surfaceProfiles[i];

            return null;
        }

        #endregion

        #region Playback

        /// <summary>
        /// Plays one footstep from the current surface at the gait-appropriate volume and a random
        /// pitch, then raises the footstep and surface bus events for other listeners (UI, etc.).
        /// Stops the source first so a previous step that is still ringing out (some clips are
        /// longer than the stride interval) is cut instead of overlapping into a muddy double-step.
        /// </summary>
        private void PlayFootstep()
        {
            SurfaceSoundProfile profile = GetCurrentSurface();
            if (profile == null || profile.footstepClips == null || profile.footstepClips.Length == 0) return;

            float volume = isCrouching ? profile.crouchVolume
                         : isSprinting ? profile.sprintVolume
                         : profile.walkVolume;
            float pitch = Random.Range(profile.pitchMin, profile.pitchMax);
            AudioClip clip = PickRandomClip(profile.footstepClips, ref lastClipIndex);

            if (audioSource == null) return;
            audioSource.Stop();
            audioSource.pitch = pitch;
            audioSource.PlayOneShot(clip, volume);

            PlayerEvents.RaiseFootstepTriggered(profile, volume);
            PlayerEvents.RaiseSurfaceChanged(profile);
        }

        /// <summary>
        /// Plays the landing sound for the current surface at neutral pitch.
        /// </summary>
        private void PlayLandingSound()
        {
            SurfaceSoundProfile profile = GetCurrentSurface();
            if (profile == null || profile.landingClips == null || profile.landingClips.Length == 0) return;

            int idx = -1;
            AudioClip clip = PickRandomClip(profile.landingClips, ref idx);
            if (audioSource == null) return;
            audioSource.pitch = 1f;
            audioSource.PlayOneShot(clip, profile.landingVolume);
        }

        /// <summary>
        /// Returns a random clip from the set, never repeating the previous index so two identical
        /// steps don't play back to back. Updates lastIndex with the chosen clip.
        /// </summary>
        private AudioClip PickRandomClip(AudioClip[] clips, ref int lastIndex)
        {
            if (clips.Length == 1) return clips[0];
            int index;
            do { index = Random.Range(0, clips.Length); } while (index == lastIndex);
            lastIndex = index;
            return clips[index];
        }

        #endregion
    }
}