using System.Linq;
using System.Text;
using UnityEditor;
using UnityEditor.SceneManagement;
using UnityEngine;
using UnityEngine.SceneManagement;

/// <summary>
/// Nests the authored A-scheme battlefield under the live battle prefab.
/// Gameplay actors stay on PrototypeArena; the primitive ground is turned off.
/// </summary>
public static class AttachGreenfield
{
    const string Arena = "Assets/Bundles/Scenes/Prototype/PrototypeArena.prefab";
    const string Battlefield = "Assets/Bundles/Scenes/Prototype/Battlefield/Battlefield_Greenfield.prefab";

    public static string Build()
    {
        if (EditorApplication.isPlaying) throw new System.Exception("Attach the battlefield in Edit Mode.");
        var battlefield = AssetDatabase.LoadAssetAtPath<GameObject>(Battlefield);
        if (battlefield == null) throw new System.Exception("Missing " + Battlefield);
        var root = PrefabUtility.LoadPrefabContents(Arena);
        try
        {
            var previous = root.transform.Find("Greenfield");
            if (previous != null) Object.DestroyImmediate(previous.gameObject);
            var instance = (GameObject)PrefabUtility.InstantiatePrefab(battlefield, root.transform);
            instance.name = "Greenfield";
            instance.transform.SetSiblingIndex(0);
            foreach (var transform in instance.GetComponentsInChildren<Transform>(true)) transform.gameObject.layer = 30;
            foreach (Transform child in root.transform)
            {
                if (child == instance.transform) continue;
                if (child.name == "Ground" || child.name == "Lane" || child.name == "LeftBorder" || child.name == "RightBorder" || child.name == "BattleLight")
                    child.gameObject.SetActive(false);
            }
            PrefabUtility.SaveAsPrefabAsset(root, Arena);
        }
        finally { PrefabUtility.UnloadPrefabContents(root); }
        AssetDatabase.SaveAssets();
        return Verify();
    }

    public static string Verify()
    {
        var prefab = AssetDatabase.LoadAssetAtPath<GameObject>(Arena);
        if (prefab == null) throw new System.Exception("Missing arena prefab.");
        var scene = EditorSceneManager.NewPreviewScene();
        var instance = (GameObject)PrefabUtility.InstantiatePrefab(prefab, scene);
        try
        {
            var report = new StringBuilder();
            var greenfield = instance.transform.Find("Greenfield");
            if (greenfield == null || !greenfield.gameObject.activeSelf) throw new System.Exception("Greenfield is missing.");
            Require(greenfield, "Ground/GroundMesh");
            Require(greenfield, "Routes/Lane0");
            Require(greenfield, "Routes/Lane1");
            Require(greenfield, "Routes/Lane2");
            Require(greenfield, "Lighting/Sun");
            if (greenfield.Find("Decorations/bridge") != null || greenfield.Find("Decorations/bridgeLeft") != null || greenfield.Find("Decorations/bridgeRight") != null)
                throw new System.Exception("Bridge is still placed in the battle arena.");
            var badLayer = greenfield.GetComponentsInChildren<Renderer>(true).FirstOrDefault(r => r.gameObject.layer != 30);
            if (badLayer != null) throw new System.Exception("Greenfield renderer not on layer 30: " + badLayer.name);
            foreach (string name in new[] { "Heroes", "Enemies", "Projectiles", "DeploymentMarkers", "SkillEffects", "BattleCamera", "DefenceLine" })
            {
                var node = instance.transform.Find(name);
                if (node == null || !node.gameObject.activeSelf) throw new System.Exception(name + " must stay active.");
            }
            foreach (Transform child in instance.transform)
            {
                if (child.name == "Ground" || child.name == "Lane" || child.name == "LeftBorder" || child.name == "RightBorder" || child.name == "BattleLight")
                {
                    if (child.gameObject.activeSelf) throw new System.Exception(child.name + " primitive is still active.");
                }
            }
            var mesh = greenfield.Find("Ground/GroundMesh").GetComponentInChildren<MeshRenderer>();
            if (mesh == null || mesh.sharedMaterial == null || mesh.sharedMaterial.shader.name != "Test/XPbr")
                throw new System.Exception("Greenfield ground shader is not Test/XPbr.");
            report.Append("PASS nested Greenfield; primitives hidden; gameplay nodes kept.");
            return report.ToString();
        }
        finally
        {
            Object.DestroyImmediate(instance);
            EditorSceneManager.ClosePreviewScene(scene);
        }
    }

    static void Require(Transform root, string path)
    {
        var node = root.Find(path);
        if (node == null) throw new System.Exception("Missing " + path);
    }

    public static string FramePrefabStage()
    {
        var stage = PrefabStageUtility.OpenPrefab(Arena);
        var view = SceneView.lastActiveSceneView;
        if (view == null) throw new System.Exception("No Scene View.");
        view.LookAt(new Vector3(0, 0, 3.5f), Quaternion.Euler(38, -35, 0), 22f);
        view.orthographic = false;
        view.Repaint();
        return stage.assetPath;
    }

    public static string ClosePrefabStage()
    {
        StageUtility.GoToMainStage();
        return "Closed prefab stage";
    }
}