using System;
using System.Diagnostics.CodeAnalysis;
using JetBrains.Annotations;
using UnityEditor;
using UnityEngine;

[UsedImplicitly]
[SuppressMessage("ReSharper", "CheckNamespace")]
public class LowPolyShaderGUI : ShaderGUI
{
    // Sky
    private MaterialProperty _topColor;
    private MaterialProperty _middleColor;
    private MaterialProperty _bottomColor;
    private MaterialProperty _topExponent;
    private MaterialProperty _bottomExponent;
    // Stars
    private MaterialProperty _starsTint;
    private MaterialProperty _starsExtinction;
    private MaterialProperty _starsTwinklingSpeed;
    private MaterialProperty _starsTex;
    // Sun
    private MaterialProperty _sunSize;
    private MaterialProperty _sunHalo;
    private MaterialProperty _sunTint;
    private MaterialProperty _sunTex;
    // Moon
    private MaterialProperty _moonSize;
    private MaterialProperty _moonHalo;
    private MaterialProperty _moonTint;
    private MaterialProperty _moonTex;
    // Clouds
    private MaterialProperty _cloudsTint;
    private MaterialProperty _cloudsRotation;
    private MaterialProperty _cloudsHeight;
    private MaterialProperty _cloudsTex;
    // General
    private MaterialProperty _exposure;

    //---------------------------------------------------------------------
    // Public
    //---------------------------------------------------------------------

    public override void OnGUI(MaterialEditor materialEditor, MaterialProperty[] properties)
    {
        FindProperties(properties);
        ShaderPropertiesGUI(materialEditor);
    }

    //---------------------------------------------------------------------
    // Helpers
    //---------------------------------------------------------------------

    private void FindProperties(MaterialProperty[] properties)
    {
        // Sky
        _topColor = FindProperty("_TopColor", properties);
        _middleColor = FindProperty("_MiddleColor", properties);
        _bottomColor = FindProperty("_BottomColor", properties);
        _topExponent = FindProperty("_TopExponent", properties);
        _bottomExponent = FindProperty("_BottomExponent", properties);
        // Stars
        _starsTint = FindProperty("_StarsTint", properties);
        _starsExtinction = FindProperty("_StarsExtinction", properties);
        _starsTwinklingSpeed = FindProperty("_StarsTwinklingSpeed", properties);
        _starsTex = FindProperty("_StarsTex", properties);
        // Sun
        _sunSize = FindProperty("_SunSize", properties);
        _sunHalo = FindProperty("_SunHalo", properties);
        _sunTint = FindProperty("_SunTint", properties);
        _sunTex = FindProperty("_SunTex", properties);
        // Moon
        _moonSize = FindProperty("_MoonSize", properties);
        _moonHalo = FindProperty("_MoonHalo", properties);
        _moonTint = FindProperty("_MoonTint", properties);
        _moonTex = FindProperty("_MoonTex", properties);
        // Clouds
        _cloudsTint = FindProperty("_CloudsTint", properties);
        _cloudsRotation = FindProperty("_CloudsRotation", properties);
        _cloudsHeight = FindProperty("_CloudsHeight", properties);
        _cloudsTex = FindProperty("_CloudsTex", properties);
        // General
        _exposure = FindProperty("_Exposure", properties);
    }

    private void ShaderPropertiesGUI(MaterialEditor materialEditor)
    {
        materialEditor.SetDefaultGUIWidths();
        var targetMat = materialEditor.target as Material;

        // Sky
        EditorGUILayout.BeginVertical("Box");
        EditorGUILayout.LabelField("Sky", EditorStyles.boldLabel);
        EditorGUILayout.EndVertical();

        materialEditor.ShaderProperty(_topColor, "Color Top");
        materialEditor.ShaderProperty(_middleColor, "Color Middle");
        materialEditor.ShaderProperty(_bottomColor, "Color Bottom");
        EditorGUILayout.Space();
        materialEditor.ShaderProperty(_topExponent, "Exponent Top");
        materialEditor.ShaderProperty(_bottomExponent, "Exponent Bottom");
        EditorGUILayout.Space();

        // Stars
        EditorGUILayout.BeginHorizontal("Box");
        EditorGUILayout.LabelField("Stars", EditorStyles.boldLabel);
        GUILayout.FlexibleSpace();
        var starsOn = KeywordCheckbox(targetMat, "STARS_OFF");
        EditorGUILayout.EndHorizontal();

        if (starsOn)
        {
            materialEditor.ShaderProperty(_starsTint, "Stars Tint");
            materialEditor.ShaderProperty(_starsExtinction, "Stars Extinction");
            materialEditor.ShaderProperty(_starsTwinklingSpeed, "Stars Twinkling Speed");
            materialEditor.ShaderProperty(_starsTex, "Stars Cubemap");
        }

        // Sun
        EditorGUILayout.BeginHorizontal("Box");
        EditorGUILayout.LabelField("Sun", EditorStyles.boldLabel);
        GUILayout.FlexibleSpace();
        var sunOn = KeywordCheckbox(targetMat, "SUN_OFF");
        EditorGUILayout.EndHorizontal();

        if (sunOn)
        {
            materialEditor.ShaderProperty(_sunSize, "Sun Size");
            materialEditor.ShaderProperty(_sunHalo, "Sun Halo");
            materialEditor.ShaderProperty(_sunTint, "Sun Tint");
            materialEditor.ShaderProperty(_sunTex, "Sun Texture");
        }

        // Moon
        EditorGUILayout.BeginHorizontal("Box");
        EditorGUILayout.LabelField("Moon", EditorStyles.boldLabel);
        GUILayout.FlexibleSpace();
        var moonOn = KeywordCheckbox(targetMat, "MOON_OFF");
        EditorGUILayout.EndHorizontal();

        if (moonOn)
        {
            materialEditor.ShaderProperty(_moonSize, "Moon Size");
            materialEditor.ShaderProperty(_moonHalo, "Moon Halo");
            materialEditor.ShaderProperty(_moonTint, "Moon Tint");
            materialEditor.ShaderProperty(_moonTex, "Moon Texture");
        }

        // Clouds
        EditorGUILayout.BeginHorizontal("Box");
        EditorGUILayout.LabelField("Clouds", EditorStyles.boldLabel);
        GUILayout.FlexibleSpace();
        var cloudsOn = KeywordCheckbox(targetMat, "CLOUDS_OFF");
        EditorGUILayout.EndHorizontal();

        if (cloudsOn)
        {
            materialEditor.ShaderProperty(_cloudsTint, "Clouds Tint");
            materialEditor.ShaderProperty(_cloudsRotation, "Clouds Rotation");
            materialEditor.ShaderProperty(_cloudsHeight, "Clouds Height");
            materialEditor.ShaderProperty(_cloudsTex, "Clouds Cubemap");
        }

        // General
        EditorGUILayout.BeginVertical("Box");
        EditorGUILayout.LabelField("General", EditorStyles.boldLabel);
        EditorGUILayout.EndVertical();

        materialEditor.ShaderProperty(_exposure, "Exposure");
    }

    [SuppressMessage("ReSharper", "InvertIf")]
    private static bool KeywordCheckbox(Material material, string keyword)
    {
        var keywordValue = Array.IndexOf(material.shaderKeywords, keyword) != -1;
        EditorGUI.BeginChangeCheck();
        EditorGUILayout.Space(-75f);
        var checkboxValue = EditorGUILayout.Toggle(!keywordValue);
        if (EditorGUI.EndChangeCheck()) 
        {
            if (checkboxValue)
                material.DisableKeyword(keyword);
            else
                material.EnableKeyword(keyword);            
        }

        return checkboxValue;
    }
}