using System.Globalization;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;

namespace OmniNotify;

public sealed class PopupCoordinator
{
    private readonly Dictionary<string, Queue<(Channel Channel, IncomingMessage Message)>> _queues = [];
    private readonly Dictionary<string, List<PopupWindow>> _visible = [];

    public void Show(Channel channel, IncomingMessage message)
    {
        var key = Key(channel.Profile);
        if (channel.Profile.OverflowMode == OverflowMode.Split)
        {
            var parts = SplitBody(message.Body, message.Title, channel.Profile).ToList();
            if (parts.Count > 1)
            {
                var splitChannel = CloneForSplit(channel);
                foreach (var part in parts)
                {
                    Enqueue(splitChannel, new IncomingMessage { Channel = message.Channel, Title = message.Title, Body = part }, key, true);
                }
                return;
            }
        }

        Enqueue(channel, message, key, false);
    }

    public void ShowSystem(string title, string body)
    {
        var channel = new Channel
        {
            Name = "system",
            Profile = NotificationProfile.CreateDefault()
        };
        channel.Profile.BackgroundColor = "#7F1D1D";
        channel.Profile.BorderColor = "#FCA5A5";
        Show(channel, new IncomingMessage { Channel = "system", Title = title, Body = body });
    }

    private void Enqueue(Channel channel, IncomingMessage message, string key, bool forceQueue)
    {
        if (!_visible.TryGetValue(key, out var windows))
        {
            windows = [];
            _visible[key] = windows;
        }

        if (forceQueue)
        {
            if (windows.Count == 0)
            {
                ShowNow(channel, message, key, 0);
                return;
            }

            if (!_queues.ContainsKey(key))
            {
                _queues[key] = new Queue<(Channel, IncomingMessage)>();
            }

            _queues[key].Enqueue((channel, message));
            return;
        }

        switch (channel.Profile.StackMode)
        {
            case StackMode.Replace:
                foreach (var popup in windows.ToList())
                {
                    popup.CloseImmediately();
                }
                windows.Clear();
                ShowNow(channel, message, key, 0);
                break;
            case StackMode.Push:
                ShowNow(channel, message, key, windows.Count);
                Relayout(key);
                break;
            default:
                if (windows.Count == 0)
                {
                    ShowNow(channel, message, key, 0);
                }
                else
                {
                    if (!_queues.ContainsKey(key))
                    {
                        _queues[key] = new Queue<(Channel, IncomingMessage)>();
                    }
                    _queues[key].Enqueue((channel, message));
                }
                break;
        }
    }

    private void ShowNow(Channel channel, IncomingMessage message, string key, int offsetIndex)
    {
        var popup = new PopupWindow(channel.Profile, message, offsetIndex);
        _visible[key].Add(popup);
        popup.Closed += (_, _) =>
        {
            if (_visible.TryGetValue(key, out var windows))
            {
                windows.Remove(popup);
            }

            if (channel.Profile.StackMode == StackMode.Queue && _queues.TryGetValue(key, out var queue) && queue.Count > 0)
            {
                var next = queue.Dequeue();
                ShowNow(next.Channel, next.Message, key, 0);
            }
            else
            {
                Relayout(key);
            }
        };
        popup.Show();
    }

    private void Relayout(string key)
    {
        if (!_visible.TryGetValue(key, out var windows))
        {
            return;
        }

        for (var i = 0; i < windows.Count; i++)
        {
            windows[i].MoveToSlot(i);
        }
    }

    private static string Key(NotificationProfile profile) => $"{profile.ScreenIndex}:{profile.Anchor}";

    private static IEnumerable<string> SplitBody(string body, string title, NotificationProfile profile)
    {
        var contentWidth = PopupWindow.GetBodyContentWidth(profile);
        var titleHeight = MeasureTextHeight(
            title,
            profile,
            contentWidth,
            profile.TitleFontSize,
            null,
            FontWeights.SemiBold);
        var bodyViewportHeight = PopupWindow.GetBodyViewportHeight(profile, titleHeight);
        var textElements = TextElements(body.Replace("\r\n", "\n")).ToList();

        for (var start = 0; start < textElements.Count;)
        {
            var remaining = textElements.Count - start;
            var low = 1;
            var high = remaining;
            var best = 1;

            while (low <= high)
            {
                var middle = low + (high - low) / 2;
                var candidate = string.Concat(textElements.Skip(start).Take(middle));
                if (FitsBodyViewport(candidate, profile, contentWidth, bodyViewportHeight))
                {
                    best = middle;
                    low = middle + 1;
                }
                else
                {
                    high = middle - 1;
                }
            }

            var page = string.Concat(textElements.Skip(start).Take(best)).Trim('\r', '\n');
            if (!string.IsNullOrEmpty(page))
            {
                yield return page;
            }

            start += best;
            while (start < textElements.Count && IsLineBreak(textElements[start]))
            {
                start++;
            }
        }
    }

    private static bool FitsBodyViewport(string text, NotificationProfile profile, double width, double bodyViewportHeight)
    {
        var measuredHeight = MeasureTextHeight(
            text,
            profile,
            width,
            profile.BodyFontSize,
            PopupWindow.GetBodyLineHeight(profile),
            FontWeights.Normal);
        return measuredHeight <= Math.Floor(bodyViewportHeight);
    }

    private static double MeasureTextHeight(
        string text,
        NotificationProfile profile,
        double width,
        double fontSize,
        double? lineHeight,
        FontWeight fontWeight)
    {
        var textBlock = new TextBlock
        {
            Text = text,
            TextWrapping = TextWrapping.Wrap,
            FontFamily = new System.Windows.Media.FontFamily(profile.FontFamily),
            FontSize = fontSize,
            FontWeight = fontWeight
        };

        if (lineHeight is not null)
        {
            textBlock.LineStackingStrategy = LineStackingStrategy.BlockLineHeight;
            textBlock.LineHeight = lineHeight.Value;
        }

        textBlock.Measure(new System.Windows.Size(width, double.PositiveInfinity));
        return Math.Ceiling(textBlock.DesiredSize.Height + 2);
    }

    private static IEnumerable<string> TextElements(string text)
    {
        var enumerator = StringInfo.GetTextElementEnumerator(text);
        while (enumerator.MoveNext())
        {
            yield return enumerator.GetTextElement();
        }
    }

    private static bool IsLineBreak(string textElement)
    {
        return textElement is "\r" or "\n" or "\r\n";
    }

    private static Channel CloneForSplit(Channel channel)
    {
        var profile = channel.Profile;
        return new Channel
        {
            Id = channel.Id,
            Name = channel.Name,
            Profile = new NotificationProfile
            {
                ScreenIndex = profile.ScreenIndex,
                Anchor = profile.Anchor,
                MarginX = profile.MarginX,
                MarginY = profile.MarginY,
                Width = profile.Width,
                MaxHeight = profile.MaxHeight,
                Padding = profile.Padding,
                FontFamily = profile.FontFamily,
                TitleFontSize = profile.TitleFontSize,
                BodyFontSize = profile.BodyFontSize,
                TextColor = profile.TextColor,
                BackgroundColor = profile.BackgroundColor,
                BackgroundOpacity = profile.BackgroundOpacity,
                BorderColor = profile.BorderColor,
                BorderOpacity = profile.BorderOpacity,
                OverallOpacity = profile.OverallOpacity,
                LifetimeSeconds = Math.Max(0.5, profile.SplitIntervalSeconds),
                EnterAnimation = profile.EnterAnimation,
                ExitAnimation = profile.ExitAnimation,
                StackMode = StackMode.Queue,
                OverflowMode = OverflowMode.Split,
                SplitIntervalSeconds = profile.SplitIntervalSeconds,
                VerticalScrollHoldSeconds = profile.VerticalScrollHoldSeconds,
                VerticalScrollSpeed = profile.VerticalScrollSpeed
            }
        };
    }
}