using System.Diagnostics;
using UnityEditor;
using UnityEngine;
using UnityEngine.Profiling;
using Ashwild.Building;
using Debug = UnityEngine.Debug;

namespace Ashwild.EditorTools
{
    /// <summary>
    /// A load test for the decision to spawn every build as a NetworkObject: places a grid of structures
    /// and reports how long it took and what it cost in memory, so the "can FishNet carry a whole base"
    /// question can be answered with numbers instead of estimates.
    ///
    /// Deliberately single-instance. Measuring a second client's join bandwidth would mean two peers, and
    /// the session is wired to FishySteamworks — that costs far more setup than the risk it covers. Join
    /// traffic is a one-shot cost of roughly a spawn packet per object anyway; what actually matters day
    /// to day is the steady state, and that is exactly what this measures. Watch the profiler's frame time
    /// after the spawn, not just the numbers logged here.
    ///
    /// Caveat when reading the elapsed time: this places everything in a single frame, which no player
    /// ever does. Treat it as a worst case for the spawn burst, not as a gameplay measurement.
    /// </summary>
    public static class BuildStressTest
    {
        #region Constants

        private const float Spacing = 4f;
        private const float GroundHeight = 0f;

        #endregion

        #region Menu

        /// <summary>
        /// Places 250 structures — a realistic co-op base.
        /// </summary>
        [MenuItem("Tools/Ashwild/Stress Test/Spawn 250 Builds")]
        public static void Spawn250() => SpawnGrid(250);

        /// <summary>
        /// Places 1000 structures — an ambitious long-save base, the level the NetworkObject decision was
        /// judged against.
        /// </summary>
        [MenuItem("Tools/Ashwild/Stress Test/Spawn 1000 Builds")]
        public static void Spawn1000() => SpawnGrid(1000);

        #endregion

        #region Internal Helpers

        /// <summary>
        /// Commits <paramref name="count"/> builds of the first usable buildable on a grid around the
        /// origin, then logs the elapsed time and the memory delta. Requires play mode with a live session,
        /// since committing goes through the registry's server RPC exactly as a real placement would.
        /// </summary>
        private static void SpawnGrid(int count)
        {
            if (!Application.isPlaying)
            {
                Debug.LogError("[BuildStressTest] Enter play mode and host a session first — builds are spawned through the server.");
                return;
            }
            if (BuildRegistry.Instance == null)
            {
                Debug.LogError("[BuildStressTest] No BuildRegistry in the session — is the scene's BuildRegistry present and the session started?");
                return;
            }

            if (!TryResolveBuildable(out ushort id, out string label)) return;

            int side = Mathf.CeilToInt(Mathf.Sqrt(count));
            long memoryBefore = Profiler.GetTotalAllocatedMemoryLong();
            Stopwatch watch = Stopwatch.StartNew();

            for (int i = 0; i < count; i++)
            {
                Vector3 position = new Vector3((i % side) * Spacing, GroundHeight, (i / side) * Spacing);
                BuildRegistry.Instance.RequestBuild(id, position, Quaternion.identity);
            }

            watch.Stop();
            long memoryDelta = Profiler.GetTotalAllocatedMemoryLong() - memoryBefore;

            Debug.Log($"[BuildStressTest] Requested {count}× '{label}' in {watch.ElapsedMilliseconds} ms " +
                      $"({memoryDelta / 1024f / 1024f:F1} MB allocated this frame). " +
                      "Spawns complete over the next frames — check the profiler's steady-state frame time now.");
        }

        /// <summary>
        /// Picks the first buildable that can actually be spawned, so the test never fails halfway on a
        /// half-authored asset. Reports clearly when the database is empty or unbuilt.
        /// </summary>
        private static bool TryResolveBuildable(out ushort id, out string label)
        {
            id = 0;
            label = string.Empty;

            BuildableDatabase database = BuildableDatabase.Instance;
            if (database == null || database.Buildables == null || database.Buildables.Length == 0)
            {
                Debug.LogError("[BuildStressTest] BuildableDatabase is empty — run Tools ▸ Ashwild ▸ Rebuild Buildable Database.");
                return false;
            }

            foreach (BuildableData buildable in database.Buildables)
            {
                if (buildable == null || buildable.BuiltPrefab == null) continue;

                id = database.GetId(buildable);
                label = buildable.name;
                return true;
            }

            Debug.LogError("[BuildStressTest] No buildable with a BuiltPrefab found.");
            return false;
        }

        #endregion
    }
}