using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Interop;
using System.Windows.Media;
using Wox.Infrastructure.Logger;
using Wox.Infrastructure.UserSettings;

namespace Wox.Core.Resource
{
    public class Theme : Resource
    {
        private static List<string> themeDirectories = new List<string>();
        public Settings Settings { get; set; }

        public Theme()
        {
            DirectoryName = "Themes";
            themeDirectories.Add(DirectoryPath);
            MakesureThemeDirectoriesExist();
        }

        private static void MakesureThemeDirectoriesExist()
        {
            foreach (string pluginDirectory in themeDirectories)
            {
                if (!Directory.Exists(pluginDirectory))
                {
                    try
                    {
                        Directory.CreateDirectory(pluginDirectory);
                    }
                    catch (Exception e)
                    {
                        Log.Exception(e);
                    }
                }
            }
        }

        public void ChangeTheme(string themeName)
        {
            string themePath = GetThemePath(themeName);
            if (string.IsNullOrEmpty(themePath))
            {
                themePath = GetThemePath("Dark");
                if (string.IsNullOrEmpty(themePath))
                {
                    throw new Exception("Change theme failed");
                }
            }

            Settings.Theme = themeName;
            ResourceMerger.UpdateResource(this);

            // Exception of FindResource can't be cathed if global exception handle is set
            var isBlur = Application.Current.TryFindResource("ThemeBlurEnabled");
            if (isBlur is bool && Environment.OSVersion.Version >= new Version(6, 2))
            {
                SetBlurForWindow(Application.Current.MainWindow, (bool)isBlur);
            }
        }

        public override ResourceDictionary GetResourceDictionary()
        {
            var dict = new ResourceDictionary
            {
                Source = new Uri(GetThemePath(Settings.Theme), UriKind.Absolute)
            };

            Style queryBoxStyle = dict["QueryBoxStyle"] as Style;
            if (queryBoxStyle != null)
            {
                queryBoxStyle.Setters.Add(new Setter(TextBox.FontFamilyProperty, new FontFamily(Settings.QueryBoxFont)));
                queryBoxStyle.Setters.Add(new Setter(TextBox.FontStyleProperty, FontHelper.GetFontStyleFromInvariantStringOrNormal(Settings.QueryBoxFontStyle)));
                queryBoxStyle.Setters.Add(new Setter(TextBox.FontWeightProperty, FontHelper.GetFontWeightFromInvariantStringOrNormal(Settings.QueryBoxFontWeight)));
                queryBoxStyle.Setters.Add(new Setter(TextBox.FontStretchProperty, FontHelper.GetFontStretchFromInvariantStringOrNormal(Settings.QueryBoxFontStretch)));
            }

            Style resultItemStyle = dict["ItemTitleStyle"] as Style;
            Style resultSubItemStyle = dict["ItemSubTitleStyle"] as Style;
            Style resultItemSelectedStyle = dict["ItemTitleSelectedStyle"] as Style;
            Style resultSubItemSelectedStyle = dict["ItemSubTitleSelectedStyle"] as Style;
            if (resultItemStyle != null && resultSubItemStyle != null && resultSubItemSelectedStyle != null && resultItemSelectedStyle != null)
            {
                Setter fontFamily = new Setter(TextBlock.FontFamilyProperty, new FontFamily(Settings.ResultFont));
                Setter fontStyle = new Setter(TextBlock.FontStyleProperty, FontHelper.GetFontStyleFromInvariantStringOrNormal(Settings.ResultFontStyle));
                Setter fontWeight = new Setter(TextBlock.FontWeightProperty, FontHelper.GetFontWeightFromInvariantStringOrNormal(Settings.ResultFontWeight));
                Setter fontStretch = new Setter(TextBlock.FontStretchProperty, FontHelper.GetFontStretchFromInvariantStringOrNormal(Settings.ResultFontStretch));

                Setter[] setters = { fontFamily, fontStyle, fontWeight, fontStretch };
                Array.ForEach(new[] { resultItemStyle, resultSubItemStyle, resultItemSelectedStyle, resultSubItemSelectedStyle }, o => Array.ForEach(setters, p => o.Setters.Add(p)));
            }
            return dict;
        }

        public List<string> LoadAvailableThemes()
        {
            List<string> themes = new List<string>();
            foreach (var themeDirectory in themeDirectories)
            {
                themes.AddRange(
                    Directory.GetFiles(themeDirectory)
                        .Where(filePath => filePath.EndsWith(".xaml") && !filePath.EndsWith("Base.xaml"))
                        .ToList());
            }
            return themes.OrderBy(o => o).ToList();
        }

        private string GetThemePath(string themeName)
        {
            foreach (string themeDirectory in themeDirectories)
            {
                string path = Path.Combine(themeDirectory, themeName + ".xaml");
                if (File.Exists(path))
                {
                    return path;
                }
            }

            return string.Empty;
        }

        #region Blur Handling
        /*
        Found on https://github.com/riverar/sample-win10-aeroglass
        */
        private enum AccentState
        {
            ACCENT_DISABLED = 0,
            ACCENT_ENABLE_GRADIENT = 1,
            ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
            ACCENT_ENABLE_BLURBEHIND = 3,
            ACCENT_INVALID_STATE = 4
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct AccentPolicy
        {
            public AccentState AccentState;
            public int AccentFlags;
            public int GradientColor;
            public int AnimationId;
        }

        [StructLayout(LayoutKind.Sequential)]
        private struct WindowCompositionAttributeData
        {
            public WindowCompositionAttribute Attribute;
            public IntPtr Data;
            public int SizeOfData;
        }

        private enum WindowCompositionAttribute
        {
            WCA_ACCENT_POLICY = 19
        }
        [DllImport("user32.dll")]
        private static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);

        /// <summary>
        /// Sets the blur for a window via SetWindowCompositionAttribute
        /// </summary>
        /// <param name="wind">window to blur</param>
        /// <param name="isBlur">true/false - on or off correspondingly</param>
        private void SetBlurForWindow(Window wind, bool isBlur)
        {
            if (isBlur)
            {
                SetWindowAccent(wind, AccentState.ACCENT_ENABLE_BLURBEHIND);
            }
        }

        private void SetWindowAccent(Window wind, AccentState themeAccentMode)
        {
            var windowHelper = new WindowInteropHelper(wind);
            var accent = new AccentPolicy { AccentState = themeAccentMode };
            var accentStructSize = Marshal.SizeOf(accent);

            var accentPtr = Marshal.AllocHGlobal(accentStructSize);
            Marshal.StructureToPtr(accent, accentPtr, false);

            var data = new WindowCompositionAttributeData
            {
                Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY,
                SizeOfData = accentStructSize,
                Data = accentPtr
            };

            SetWindowCompositionAttribute(windowHelper.Handle, ref data);

            Marshal.FreeHGlobal(accentPtr);
        }
        #endregion
    }
}