using System.Globalization;
using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using ytLive.Models;

namespace ytLive.Services;

/// <summary>
/// Renders one event's celebration animation into a BGRA8 frame for the AlertBox.
/// Six event kinds, six UNIQUE animations — each a distinct gesture, palette and
/// layout (the creator's ruling: these are the monetization shout-outs and free
/// branded product placement; a one-template recoloring loses all interest in two
/// iterations). Each card carries the bottom-right brand line so every broadcast
/// of an event is an in-video ad placement.
///
/// <paramref name="t01"/> walks 0→1 over the whole animation; each kind splits it
/// into enter / hold / exit phases with its own easing.
/// </summary>
public sealed class AlertRenderer
{
    private const double EnterEnd = 0.16;
    private const double ExitStart = 0.80;
    private const string Brand = "made with LlamaCasty!";

    private static readonly CultureInfo Invariant = CultureInfo.InvariantCulture;
    private static readonly Color White = Colors.White;
    private static readonly Color[] ConfettiPalette =
    {
        Color.FromRgb(0xf4, 0x2f, 0x5f), Color.FromRgb(0xff, 0xd1, 0x66),
        Color.FromRgb(0x38, 0xb6, 0xf8), Color.FromRgb(0xa7, 0x8b, 0xfa),
        Color.FromRgb(0x39, 0xd3, 0x53),
    };

    public VideoFrame Render(ChatMessage e, double t01, int width, int height)
    {
        return e.Kind switch
        {
            ChatEventKind.SuperChat => SuperChat(e, t01, width, height),
            ChatEventKind.SuperSticker => SuperSticker(e, t01, width, height),
            ChatEventKind.NewMember => NewMember(e, t01, width, height),
            ChatEventKind.MemberGift => MemberGift(e, t01, width, height),
            ChatEventKind.GiftReceived => GiftReceived(e, t01, width, height),
            ChatEventKind.MemberMilestone => Milestone(e, t01, width, height),
            _ => SuperChat(e, t01, width, height),
        };
    }

    private static VideoFrame SuperChat(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.03;
            var cardX = margin;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = cardX + cardW / 2;

            var enter = Clamp01(t / EnterEnd);
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var exitEase = EaseInCubic(exit);
            var cardY = Lerp(h + cardH, margin, EaseOutCubic(enter));
            cardY = Lerp(cardY, -cardH, exitEase);

            DrawCard(ctx, cardX, cardY, cardW, cardH, "#0d3b2b", "#14532d", 14);
            DrawBrand(ctx, cardX, cardY, cardW, cardH);

            var shownAmount = e.SuperChatDisplayString
                ?? (e.SuperChatCurrency is { Length: > 0 } cur ? $"{cur}{e.SuperChatAmount:0.00}" : $"${e.SuperChatAmount:0.00}");
            var fontSize = cardH * 0.24;
            DrawCentered(ctx, shownAmount, cardCX, cardY + cardH * 0.24, fontSize, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW);

            DrawCentered(ctx, e.AuthorName, cardCX, cardY + cardH * 0.56, cardH * 0.13, FontWeights.SemiBold, White, cardW);
            DrawCentered(ctx, e.Message, cardCX, cardY + cardH * 0.74, cardH * 0.10, FontWeights.Normal, Color.FromRgb(0xdd, 0xff, 0xf0), cardW * 0.92);

            if (t >= EnterEnd && t <= ExitStart)
            {
                var sweep = (t - EnterEnd) / (ExitStart - EnterEnd);
                var shineX = cardX + (sweep * 2 - 0.5) * cardW;
                ctx.DrawRectangle(
                    new LinearGradientBrush(
                        Colors.Transparent,
                        Color.FromArgb(0x30, 0xff, 0xff, 0xff),
                        new Point(0, 0),
                        new Point(1, 0)),
                    null,
                    new Rect(shineX - cardW * 0.25, cardY, cardW * 0.5, cardH));
            }
        }
        return CreateFrame(visual, w, h, dpi);
    }

    private static VideoFrame SuperSticker(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.04;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = w / 2.0;

            var enter = Clamp01(t / EnterEnd);
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var scale = EaseOutBack(enter) * (0.85 + 0.15 * (1 - exit));
            if (t > EnterEnd && t <= ExitStart)
                scale = 1.0 + 0.02 * Math.Sin(t * 26.0);
            var alpha = 1.0 - exit;

            ctx.PushOpacity(alpha);

            var slick = new RotateTransform(-6, w / 2.0, h / 2.0);
            ctx.PushTransform(slick);
            ctx.PushTransform(new ScaleTransform(scale, scale, w / 2.0, h / 2.0));

            DrawCard(ctx, margin, margin, cardW, cardH, "#4a044e", "#7e22ce", 20);
            DrawBrand(ctx, margin, margin, cardW, cardH);

            var desc = string.IsNullOrWhiteSpace(e.SuperStickerDescription) ? "SUPER STICKER" : e.SuperStickerDescription.ToUpperInvariant();
            DrawCentered(ctx, desc, cardCX, h / 2.0 - cardH * 0.12, cardH * 0.17, FontWeights.Bold, White, cardW * 0.9);

            DrawCentered(ctx, e.AuthorName, cardCX, h / 2.0 + cardH * 0.16, cardH * 0.12, FontWeights.SemiBold, Color.FromRgb(0xff, 0xb3, 0xd9), cardW * 0.9);
            var tier = e.SuperChatDisplayString ?? (e.SuperChatCurrency is { Length: > 0 } cur ? $"{cur}{e.SuperChatAmount:0.00}" : null);
            if (!string.IsNullOrWhiteSpace(tier))
                DrawCentered(ctx, tier, cardCX, h / 2.0 + cardH * 0.32, cardH * 0.10, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);

            ctx.Pop();
            ctx.Pop();
            ctx.Pop();
        }
        return CreateFrame(visual, w, h, dpi);
    }

    private static VideoFrame NewMember(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.035;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = w / 2.0;

            var enter = Clamp01(t / EnterEnd);
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var cardY = Lerp(-cardH, margin, EaseOutCubic(enter));
            cardY = Lerp(cardY, h, EaseInCubic(exit));

            DrawCard(ctx, margin, cardY, cardW, cardH, "#2e1065", "#5b21b6", 16);
            DrawBrand(ctx, margin, cardY, cardW, cardH);

            if (t <= ExitStart)
            {
                var bandP = EaseOutCubic(Clamp01(t / 0.22));
                ctx.DrawRectangle(
                    new LinearGradientBrush(Color.FromArgb(0, 0xff, 0xff, 0xff), Colors.Transparent, new Point(0, 0), new Point(0, 1)),
                    null,
                    new Rect(margin, cardY + cardH * 0.30, cardW * bandP, cardH * 0.18));
            }

            DrawCentered(ctx, e.AuthorName, cardCX, cardY + cardH * 0.36, cardH * 0.22, FontWeights.Bold, White, cardW * 0.9);
            DrawCentered(ctx, "JOINED THE MEMBERSHIP", cardCX, cardY + cardH * 0.62, cardH * 0.11, FontWeights.SemiBold, Color.FromRgb(0xf5, 0xd0, 0xfe), cardW * 0.9);

            var level = string.IsNullOrWhiteSpace(e.MembershipLevel) ? "MEMBER" : e.MembershipLevel.ToUpperInvariant();
            DrawCentered(ctx, level, cardCX, cardY + cardH * 0.80, cardH * 0.10, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);
        }
        return CreateFrame(visual, w, h, dpi);
    }

    private static VideoFrame MemberGift(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.035;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = w / 2.0;

            var enter = Clamp01(t / EnterEnd);
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var cardX = Lerp(-cardW, margin, EaseOutCubic(enter));
            cardX = Lerp(cardX, -cardW, EaseInCubic(exit));

            DrawCard(ctx, cardX, margin, cardW, cardH, "#422006", "#a16207", 16);
            DrawBrand(ctx, cardX, margin, cardW, cardH);

            var count = Math.Max(1, e.GiftNewMembersCount);
            var spread = 1.0 - exit;
            var hero = count > 1 ? $"×{count}" : "MEMBERSHIP";
            DrawCentered(ctx, hero, cardCX, margin + cardH * 0.24, cardH * 0.26, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.8);
            DrawCentered(ctx, $"{e.AuthorName} is gifting", cardCX, margin + cardH * 0.52, cardH * 0.11, FontWeights.SemiBold, White, cardW * 0.9);

            var chipCount = Math.Min(count, 6);
            for (var i = 0; i < chipCount; i++)
            {
                var slot = (chipCount - 1) * 0.5;
                var gap = cardH * 0.13 * EaseOutCubic(Clamp01(t / 0.30)) * spread;
                var chipX = cardCX + (i - slot) * gap;
                var chipY = margin + cardH * 0.70 + Math.Sin((i + t * 6) * 2.4) * cardH * 0.015;
                ctx.DrawRoundedRectangle(
                    new SolidColorBrush(Color.FromRgb(0xff, 0xf3, 0xc4)),
                    null,
                    new Rect(chipX - cardH * 0.05, chipY, cardH * 0.10, cardH * 0.10),
                    cardH * 0.03, cardH * 0.03);
            }
        }
        return CreateFrame(visual, w, h, dpi);
    }

    private static VideoFrame GiftReceived(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.04;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = w / 2.0;

            var enter = Clamp01(t / (EnterEnd * 1.4));
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var scale = 0.5 + 0.5 * EaseOutBack(enter);
            var alpha = Math.Min(1.0, enter * 1.6) * (1 - exit);

            ctx.PushOpacity(alpha);
            ctx.PushTransform(new ScaleTransform(scale, scale, w / 2.0, h / 2.0));

            DrawCard(ctx, margin, margin, cardW, cardH, "#14532d", "#4c1d95", 18);
            DrawBrand(ctx, margin, margin, cardW, cardH);

            // Confetti falling inside the card during the hold (deterministic seed).
            if (t >= EnterEnd && t <= ExitStart)
            {
                var hold = (t - EnterEnd) / (ExitStart - EnterEnd);
                for (var i = 0; i < 14; i++)
                {
                    var seed = i * 37 + 11;
                    var dotX = margin + cardW * (((seed * 53) % 97) / 97.0);
                    var dotY = margin + cardH * (((seed + hold * 0.85) % 1.0));
                    var size = cardH * 0.02 + (i % 3) * cardH * 0.006;
                    ctx.DrawRectangle(
                        new SolidColorBrush(ConfettiPalette[i % ConfettiPalette.Length]),
                        null,
                        new Rect(dotX, dotY, size, size));
                }
            }

            DrawCentered(ctx, "GIFTED MEMBERSHIP", cardCX, margin + cardH * 0.22, cardH * 0.12, FontWeights.Bold, Color.FromRgb(0xff, 0xd1, 0x66), cardW * 0.9);
            var giver = string.IsNullOrWhiteSpace(e.GifterName) ? e.AuthorName : e.GifterName;
            DrawCentered(ctx, giver, cardCX, margin + cardH * 0.42, cardH * 0.20, FontWeights.Bold, White, cardW * 0.9);
            DrawCentered(ctx, "gave you a membership — celebrate!", cardCX, margin + cardH * 0.68, cardH * 0.11, FontWeights.Normal, Color.FromRgb(0xdb, 0xff, 0xf0), cardW * 0.9);

            ctx.Pop();
            ctx.Pop();
        }
        return CreateFrame(visual, w, h, dpi);
    }

    private static VideoFrame Milestone(ChatMessage e, double t, int w, int h)
    {
        var dpi = 96.0;
        var visual = new DrawingVisual();
        using (var ctx = visual.RenderOpen())
        {
            var margin = Math.Max(w, h) * 0.04;
            var cardW = w - margin * 2;
            var cardH = h - margin * 2;
            var cardCX = w / 2.0;

            var enter = Clamp01(t / EnterEnd);
            var exit = Clamp01((t - ExitStart) / (1 - ExitStart));
            var cardY = Lerp(h + cardH, margin, EaseOutCubic(enter));
            cardY = Lerp(cardY, -cardH, EaseInCubic(exit));

            DrawCard(ctx, margin, cardY, cardW, cardH, "#431407", "#c2410c", 14);
            DrawBrand(ctx, margin, cardY, cardW, cardH);

            var hero = e.MilestoneMonths > 0 ? $"{e.MilestoneMonths}" : "MILESTONE";
            DrawCentered(ctx, hero, cardCX, cardY + cardH * 0.26, cardH * 0.30, FontWeights.Bold, Color.FromRgb(0xff, 0xdd, 0x66), cardW * 0.8);

            var sub = e.MilestoneMonths > 0 ? "MONTHS STRONG" : "SUPPORTING THE STREAM";
            DrawCentered(ctx, sub, cardCX, cardY + cardH * 0.52, cardH * 0.11, FontWeights.SemiBold, White, cardW * 0.9);
            DrawCentered(ctx, "— " + e.AuthorName + " —", cardCX, cardY + cardH * 0.70, cardH * 0.10, FontWeights.Normal, Color.FromRgb(0xff, 0xe8, 0xd0), cardW * 0.9);

            // Tenure bar: grows through the first half, retracts on exit.
            var barP = Clamp01((t - 0.10) / 0.55) * (1 - exit);
            var barW = cardW * 0.6 * barP;
            ctx.DrawRoundedRectangle(
                new SolidColorBrush(Color.FromRgb(0xff, 0xd1, 0x66)),
                null,
                new Rect(cardCX - barW / 2, cardY + cardH * 0.84, barW, cardH * 0.045),
                4, 4);
        }
        return CreateFrame(visual, w, h, dpi);
    }

    // ─── Shared drawing ───

    private static void DrawCard(DrawingContext ctx, double x, double y, double w, double h, string fromHex, string toHex, double radius)
    {
        var brush = new LinearGradientBrush(ParseColor(fromHex), ParseColor(toHex), new Point(0, 0), new Point(1, 1));
        ctx.DrawRoundedRectangle(brush, new Pen(new SolidColorBrush(Color.FromArgb(0x66, 0xff, 0xff, 0xff)), Math.Max(1, radius * 0.06)), new Rect(x, y, w, h), radius, radius);
    }

    private static void DrawBrand(DrawingContext ctx, double x, double y, double w, double h)
    {
        var formatted = new FormattedText(
            Brand, Invariant, FlowDirection.LeftToRight,
            new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.Normal, FontStretches.Normal),
            Math.Max(9, h * 0.055),
            new SolidColorBrush(Color.FromArgb(0x88, 0xff, 0xff, 0xff)),
            96.0);
        ctx.DrawText(formatted, new Point(x + w - formatted.Width - h * 0.08, y + h - formatted.Height - h * 0.05));
    }

    private static void DrawCentered(DrawingContext ctx, string text, double cx, double cy, double size, FontWeight weight, Color color, double maxWidth)
    {
        var formatted = new FormattedText(
            text, Invariant, FlowDirection.LeftToRight,
            new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, weight, FontStretches.Normal),
            size,
            new SolidColorBrush(color),
            96.0);
        formatted.MaxTextWidth = maxWidth;
        formatted.MaxLineCount = 1;
        formatted.Trimming = TextTrimming.CharacterEllipsis;
        ctx.DrawText(formatted, new Point(cx - formatted.Width / 2, cy - formatted.Height / 2));
    }

    private static Color ParseColor(string hex)
    {
        hex = hex.Trim().TrimStart('#');
        if (hex.Length == 6)
        {
            var r = byte.Parse(hex.AsSpan(0, 2), NumberStyles.HexNumber);
            var g = byte.Parse(hex.AsSpan(2, 2), NumberStyles.HexNumber);
            var b = byte.Parse(hex.AsSpan(4, 2), NumberStyles.HexNumber);
            return Color.FromRgb(r, g, b);
        }
        if (hex.Length == 8)
        {
            var a = byte.Parse(hex.AsSpan(0, 2), NumberStyles.HexNumber);
            var r = byte.Parse(hex.AsSpan(2, 2), NumberStyles.HexNumber);
            var g = byte.Parse(hex.AsSpan(4, 2), NumberStyles.HexNumber);
            var b = byte.Parse(hex.AsSpan(6, 2), NumberStyles.HexNumber);
            return Color.FromArgb(a, r, g, b);
        }
        return Colors.White;
    }

    private static VideoFrame CreateFrame(DrawingVisual visual, int width, int height, double dpi)
    {
        var rtb = new RenderTargetBitmap(width, height, dpi, dpi, PixelFormats.Pbgra32);
        rtb.Render(visual);

        var stride = width * 4;
        var pixels = new byte[stride * height];
        rtb.CopyPixels(pixels, stride, 0);

        for (var i = 0; i < pixels.Length; i += 4)
        {
            (pixels[i], pixels[i + 2]) = (pixels[i + 2], pixels[i]);
        }

        return new VideoFrame(width, height, pixels);
    }

    private static double Clamp01(double v) => Math.Clamp(v, 0.0, 1.0);

    private static double Lerp(double a, double b, double p) => a + (b - a) * p;

    private static double EaseInCubic(double p) => p * p * p;

    private static double EaseOutCubic(double p) => 1 - Math.Pow(1 - p, 3);

    private static double EaseOutBack(double p)
    {
        const double c1 = 1.70158;
        const double c3 = c1 + 1;
        return 1 + c3 * Math.Pow(p - 1, 3) + c1 * Math.Pow(p - 1, 2);
    }
}