using System.Collections.Generic;
using System.Linq;
using System.Windows;
using System.Windows.Media;

namespace BeWo.Scheduling.SchedulingUtils
{
    public class AppointmentColorHelper
    {
        public LinearGradientBrush ResourceAndCustomerBackground { get; set; }
        public LinearGradientBrush EmployeeBackground { get; set; }

        public AppointmentColorHelper(Color employeeColor, List<Color> resourceColors, bool hasCustomers, bool isTask)
        {
            var defaultColor = isTask ? Color.FromRgb(153, 59, 59) : Color.FromRgb(192, 255, 208);

            EmployeeBackground = new LinearGradientBrush(new GradientStopCollection { new GradientStop(employeeColor, 1) }, new Point(0, 0), new Point(0, 1));

            if(resourceColors is null)
            {
                resourceColors = new List<Color>();
            }

            // Weder Ressourcen noch Klienten vorhanden
            if(!resourceColors.Any() && !hasCustomers)
            {
                ResourceAndCustomerBackground = new LinearGradientBrush(new GradientStopCollection { new GradientStop(defaultColor, 1) }, new Point(.5, 0), new Point(.5, 1));
            }

            var colorList = new List<Color>();
            var gradientStopCollection = new GradientStopCollection();

            if(hasCustomers)
            {
                colorList.Add(Color.FromRgb(59, 119, 153));
            }

            if(resourceColors.Any())
            {
                colorList.Add(Color.FromRgb(4, 180, 208));
            }

            switch(colorList.Count)
            {
                case 1:
                    if(BeWoApp.AppSettings.ShowMultipleResourceColors)
                    {
                        AddResourceColors(gradientStopCollection, resourceColors, hasCustomers);
                    }
                    else
                    {
                        var color = resourceColors.Count >= 1 ? resourceColors[0] : Color.FromRgb(4, 180, 208);

                        var gradientStop = new GradientStop(color, 1);
                        gradientStopCollection.Add(gradientStop);
                    }
                    break;
                case 2:
                    // 1. Klientenfarbe
                    gradientStopCollection.Add(new GradientStop(colorList[0], .5));

                    // 2. Ressourcenfarben
                    if(BeWoApp.AppSettings.ShowMultipleResourceColors)
                    {
                        AddResourceColors(gradientStopCollection, resourceColors, hasCustomers);
                    }
                    else
                    {
                        var color = resourceColors.Count >= 1 ? resourceColors[0] : Color.FromRgb(4, 180, 208);

                        gradientStopCollection.Add(new GradientStop(color, .5));
                    }
                    break;
                default:
                    gradientStopCollection.Add(new GradientStop(defaultColor, 1));
                    break;
            }

            ResourceAndCustomerBackground = new LinearGradientBrush(gradientStopCollection, new Point(.5, 0), new Point(.5, 1));
        }

        private static void AddResourceColors(GradientStopCollection gradientStopCollection, List<Color> resourceColors, bool hasCustomers)
        {
            var previousOffset = hasCustomers ? .5 : 0;

            var numberOfResources = resourceColors.Count;

            if(numberOfResources == 0)
            {
                return;
            }

            if(numberOfResources > 4)
            {
                numberOfResources = 4;
            }

            var iterator = hasCustomers ? previousOffset / numberOfResources : 1d / numberOfResources;

            for(var i = 0; i < numberOfResources; i++)
            {
                var currentOffset = previousOffset;
                var nextOffset = currentOffset + iterator;

                if(nextOffset > 1)
                {
                    nextOffset = 1;
                }

                previousOffset = nextOffset;

                gradientStopCollection.Add(new GradientStop(resourceColors[i], currentOffset));
                gradientStopCollection.Add(new GradientStop(resourceColors[i], nextOffset));
            }
        }
    }
}