// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.

#nullable disable

using System;
using osuTK;
using osuTK.Graphics;
using osu.Framework.Graphics;
using System.Collections.Generic;
using System.Linq;
using Newtonsoft.Json;

namespace osu.Game.Storyboards
{
    public delegate CommandTimeline<T> CommandTimelineSelector<T>(CommandTimelineGroup commandTimelineGroup);

    public class CommandTimelineGroup
    {
        public CommandTimeline<float> X = new CommandTimeline<float>();
        public CommandTimeline<float> Y = new CommandTimeline<float>();
        public CommandTimeline<float> Scale = new CommandTimeline<float>();
        public CommandTimeline<Vector2> VectorScale = new CommandTimeline<Vector2>();
        public CommandTimeline<float> Rotation = new CommandTimeline<float>();
        public CommandTimeline<Color4> Colour = new CommandTimeline<Color4>();
        public CommandTimeline<float> Alpha = new CommandTimeline<float>();
        public CommandTimeline<BlendingParameters> BlendingParameters = new CommandTimeline<BlendingParameters>();
        public CommandTimeline<bool> FlipH = new CommandTimeline<bool>();
        public CommandTimeline<bool> FlipV = new CommandTimeline<bool>();

        private readonly ICommandTimeline[] timelines;

        public CommandTimelineGroup()
        {
            timelines = new ICommandTimeline[]
            {
                X,
                Y,
                Scale,
                VectorScale,
                Rotation,
                Colour,
                Alpha,
                BlendingParameters,
                FlipH,
                FlipV
            };
        }

        /// <summary>
        /// Returns the earliest visible time. Will be null unless this group's first <see cref="Alpha"/> command has a start value of zero.
        /// </summary>
        public double? EarliestDisplayedTime
        {
            get
            {
                var first = Alpha.Commands.FirstOrDefault();

                return first?.StartValue == 0 ? first.StartTime : (double?)null;
            }
        }

        [JsonIgnore]
        public double CommandsStartTime
        {
            get
            {
                // if the first alpha command starts at zero it should be given priority over anything else.
                // this is due to it creating a state where the target is not present before that time, causing any other events to not be visible.
                double? earliestDisplay = EarliestDisplayedTime;
                if (earliestDisplay != null)
                    return earliestDisplay.Value;

                double min = double.MaxValue;

                for (int i = 0; i < timelines.Length; i++)
                    min = Math.Min(min, timelines[i].StartTime);

                return min;
            }
        }

        [JsonIgnore]
        public double CommandsEndTime
        {
            get
            {
                double max = double.MinValue;

                for (int i = 0; i < timelines.Length; i++)
                    max = Math.Max(max, timelines[i].EndTime);

                return max;
            }
        }

        [JsonIgnore]
        public double CommandsDuration => CommandsEndTime - CommandsStartTime;

        [JsonIgnore]
        public virtual double StartTime => CommandsStartTime;

        [JsonIgnore]
        public virtual double EndTime => CommandsEndTime;

        [JsonIgnore]
        public double Duration => EndTime - StartTime;

        [JsonIgnore]
        public bool HasCommands
        {
            get
            {
                for (int i = 0; i < timelines.Length; i++)
                {
                    if (timelines[i].HasCommands)
                        return true;
                }

                return false;
            }
        }

        public virtual IEnumerable<CommandTimeline<T>.TypedCommand> GetCommands<T>(CommandTimelineSelector<T> timelineSelector, double offset = 0)
        {
            if (offset != 0)
            {
                return timelineSelector(this).Commands.Select(command =>
                    new CommandTimeline<T>.TypedCommand
                    {
                        Easing = command.Easing,
                        StartTime = offset + command.StartTime,
                        EndTime = offset + command.EndTime,
                        StartValue = command.StartValue,
                        EndValue = command.EndValue,
                    });
            }

            return timelineSelector(this).Commands;
        }
    }
}