using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.Rendering;

namespace Luneraria.EditorTools
{
    /// <summary>
    /// Renders every pipeline asset in a neutral preview scene (URP, one sun, 3/4 front view) to
    /// docs/port/screenshots/u2a/. Buildings show their intact state; the tower also its ruin;
    /// rigged figures their bind pose and the hit frame of attack_a.
    /// Unity -batchmode -projectPath . -executeMethod Luneraria.EditorTools.LuneAssetPreview.RenderAll
    /// </summary>
    public static class LuneAssetPreview
    {
        const int Width = 1600;
        const int Height = 1000;

        public static void RenderAll()
        {
            int code = 0;
            try
            {
                string folder = Path.Combine(Path.GetDirectoryName(Application.dataPath), "docs/port/screenshots/u2a");
                Directory.CreateDirectory(folder);
                EditorSceneManager.NewScene(NewSceneSetup.EmptyScene, NewSceneMode.Single);
                var sun = new GameObject("Sun").AddComponent<Light>();
                sun.type = LightType.Directional;
                sun.intensity = 1.6f;
                sun.color = new Color(1f, .89f, .74f);
                sun.shadows = LightShadows.Soft;
                sun.transform.rotation = Quaternion.Euler(48f, 150f, 0f);
                RenderSettings.ambientMode = AmbientMode.Trilight;
                RenderSettings.ambientSkyColor = new Color(.55f, .6f, .68f);
                RenderSettings.ambientEquatorColor = new Color(.42f, .42f, .44f);
                RenderSettings.ambientGroundColor = new Color(.2f, .19f, .18f);
                var ground = GameObject.CreatePrimitive(PrimitiveType.Plane);
                ground.transform.localScale = new Vector3(20f, 1f, 20f);
                var camera = new GameObject("PreviewCamera").AddComponent<Camera>();
                camera.clearFlags = CameraClearFlags.SolidColor;
                camera.backgroundColor = new Color(.16f, .18f, .21f);
                camera.fieldOfView = 30f;
                foreach (string model in ExportReport.AllModels("Assets/Luneraria/Art").OrderBy(p => p, StringComparer.Ordinal))
                {
                    ExportReport report = ExportReport.ForModel(model);
                    var prefab = AssetDatabase.LoadAssetAtPath<GameObject>(model);
                    foreach (var shot in Shots(report))
                    {
                        var instance = (GameObject)PrefabUtility.InstantiatePrefab(prefab);
                        shot.Value(instance);
                        Render(camera, instance, Path.Combine(folder, report.Id + shot.Key + ".png"));
                        UnityEngine.Object.DestroyImmediate(instance);
                    }
                }
            }
            catch (Exception error)
            {
                Debug.LogError("LUNE_PREVIEW failed: " + error);
                code = 1;
            }
            EditorApplication.Exit(code);
        }

        static IEnumerable<KeyValuePair<string, Action<GameObject>>> Shots(ExportReport report)
        {
            string group = (string)report.Data["group"];
            if (group == "Buildings")
            {
                yield return Shot("", go => Show(go, n => !n.StartsWith("Upper_Damaged") && !n.StartsWith("Debris") && !n.StartsWith("Ruin")));
                if (report.Id == "grenzwacht")
                    yield return Shot("-ruin", go => Show(go, n => n.StartsWith("Ruin")));
            }
            else if (group == "Environment")
            {
                yield return Shot("", Row);
            }
            else if (report.Skinned)
            {
                yield return Shot("", go => Sample(go, "idle", 0f));
                yield return Shot("-attack_a", go => Sample(go, "attack_a", .9f));
            }
            else
            {
                yield return Shot("", go => { });
            }
        }

        static KeyValuePair<string, Action<GameObject>> Shot(string suffix, Action<GameObject> prepare)
        {
            return new KeyValuePair<string, Action<GameObject>>(suffix, prepare);
        }

        static void Show(GameObject root, Func<string, bool> visible)
        {
            foreach (Renderer renderer in root.GetComponentsInChildren<Renderer>(true))
                renderer.enabled = visible(renderer.gameObject.name);
        }

        /// <summary>The prop library keeps every prop at the origin; the preview sets them out in a grid.</summary>
        static void Row(GameObject root)
        {
            const int columns = 5;
            const float cell = 7.5f;
            int index = 0;
            foreach (Transform child in root.transform.Cast<Transform>().OrderBy(t => t.name, StringComparer.Ordinal).ToList())
            {
                var renderer = child.GetComponent<Renderer>();
                if (renderer == null)
                    continue;
                Vector3 center = renderer.bounds.center;
                var slot = new Vector3((index % columns) * cell, 0f, -(index / columns) * cell);
                child.position += slot - new Vector3(center.x, 0f, center.z);
                index++;
            }
        }

        static void Sample(GameObject root, string clipName, float seconds)
        {
            string path = AssetDatabase.GetAssetPath(PrefabUtility.GetCorrespondingObjectFromSource(root));
            AnimationClip clip = AssetDatabase.LoadAllAssetsAtPath(path).OfType<AnimationClip>().FirstOrDefault(c => c.name == clipName);
            if (clip != null)
                clip.SampleAnimation(root, seconds);
        }

        static void Render(Camera camera, GameObject root, string file)
        {
            var renderers = root.GetComponentsInChildren<Renderer>().Where(r => r.enabled).ToList();
            Bounds bounds = renderers[0].bounds;
            foreach (Renderer renderer in renderers)
                bounds.Encapsulate(renderer.bounds);
            // 3/4 front view: the models face +Z, the camera stands in front, to the right, above.
            Vector3 direction = new Vector3(.62f, .42f, 1f).normalized;
            float radius = bounds.extents.magnitude;
            float distance = radius / Mathf.Sin(camera.fieldOfView * .5f * Mathf.Deg2Rad) * .92f;
            camera.aspect = (float)Width / Height;
            camera.transform.position = bounds.center + direction * distance;
            camera.transform.LookAt(bounds.center);
            camera.nearClipPlane = Mathf.Max(.01f, distance - radius * 2f);
            camera.farClipPlane = distance + radius * 4f;
            var target = new RenderTexture(Width, Height, 24, RenderTextureFormat.ARGB32) { antiAliasing = 8 };
            camera.targetTexture = target;
            camera.Render();
            RenderTexture.active = target;
            var image = new Texture2D(Width, Height, TextureFormat.RGB24, false);
            image.ReadPixels(new Rect(0, 0, Width, Height), 0, 0);
            image.Apply();
            File.WriteAllBytes(file, image.EncodeToPNG());
            RenderTexture.active = null;
            camera.targetTexture = null;
            UnityEngine.Object.DestroyImmediate(target);
            UnityEngine.Object.DestroyImmediate(image);
            Debug.Log("LUNE_PREVIEW wrote " + file);
        }
    }
}