import 'dart:math' as math;

import 'package:cached_network_image/cached_network_image.dart';
import 'package:flutter/material.dart';

import '../../app/theme.dart';
import '../../core/models.dart';

/// Dark fade behind text on photos so it stays readable on any image.
class PhotoScrim extends StatelessWidget {
  const PhotoScrim({super.key, this.begin = Alignment.topCenter, this.end = Alignment.bottomCenter, this.stops});

  final Alignment begin;
  final Alignment end;
  final List<double>? stops;

  @override
  Widget build(BuildContext context) => DecoratedBox(
        decoration: BoxDecoration(
          gradient: LinearGradient(
            begin: begin,
            end: end,
            stops: stops ?? const [0.3, 1],
            colors: [NkColors.ground.withValues(alpha: 0), NkColors.ground.withValues(alpha: 0.9)],
          ),
        ),
      );
}

/// Cover for a song: remote cover, bundled photo, or the generated occasion cover.
class TrackArtwork extends StatelessWidget {
  const TrackArtwork({
    super.key,
    required this.coverUrl,
    required this.coverAsset,
    required this.occasion,
    this.title,
    this.size = 56,
    this.radius = 10,
  });

  TrackArtwork.track(Track t, {Key? key, double size = 56, double radius = 10, bool showTitle = false})
      : this(
          key: key,
          coverUrl: t.coverUrl,
          coverAsset: t.coverAsset,
          occasion: t.occasion,
          title: showTitle ? t.titleLatin : null,
          size: size,
          radius: radius,
        );

  final String? coverUrl;
  final String? coverAsset;
  final Occasion occasion;
  final String? title;
  final double size;
  final double radius;

  @override
  Widget build(BuildContext context) {
    final Widget child;
    if (coverUrl != null) {
      child = CachedNetworkImage(
        imageUrl: coverUrl!,
        fit: BoxFit.cover,
        placeholder: (_, _) => OccasionCover(occasion: occasion, size: size),
        errorWidget: (_, _, _) => OccasionCover(occasion: occasion, size: size),
      );
    } else if (coverAsset != null) {
      child = Image.asset(coverAsset!, fit: BoxFit.cover, cacheWidth: (size * 3).round());
    } else {
      child = OccasionCover(occasion: occasion, size: size, title: title);
    }
    return ClipRRect(
      borderRadius: BorderRadius.circular(radius),
      child: SizedBox.square(dimension: size, child: child),
    );
  }
}

/// Generated cover: occasion colour, label and the white-cloth border stripe.
class OccasionCover extends StatelessWidget {
  const OccasionCover({super.key, required this.occasion, required this.size, this.title, this.label});

  final Occasion occasion;
  final double size;
  final String? title;

  /// Top line; defaults to the occasion's name.
  final String? label;

  @override
  Widget build(BuildContext context) {
    final band = math.max(4.0, size * 0.06);
    final showText = size >= 96;
    return Container(
      color: occasion.color,
      child: Stack(
        fit: StackFit.expand,
        children: [
          if (showText)
            Padding(
              padding: EdgeInsets.fromLTRB(size * 0.08, size * 0.08, size * 0.08, band * 2.5),
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  Text(
                    (label ?? occasion.label).toUpperCase(),
                    style: TextStyle(
                      fontSize: size * 0.07,
                      letterSpacing: 1.6,
                      fontWeight: FontWeight.w800,
                      color: NkColors.cream.withValues(alpha: 0.85),
                    ),
                  ),
                  if (title != null)
                    Text(
                      title!,
                      maxLines: 3,
                      overflow: TextOverflow.ellipsis,
                      style: Theme.of(context).textTheme.titleLarge?.copyWith(fontSize: size * 0.11),
                    ),
                ],
              ),
            )
          else
            Center(child: Icon(occasion.icon, color: NkColors.cream.withValues(alpha: 0.7), size: size * 0.4)),
          Positioned(left: 0, right: 0, bottom: 0, height: band, child: const ColoredBox(color: NkColors.cream)),
          Positioned(
            left: 0,
            right: 0,
            bottom: band * 0.3,
            height: band * 0.3,
            child: const ColoredBox(color: NkColors.ground),
          ),
        ],
      ),
    );
  }
}

/// Singer photo, or initials in a dashed ring until a permitted photo exists.
/// Album cover photo, or a generated cover in the occasion style with a colour that stays
/// the same per album.
class AlbumCover extends StatelessWidget {
  const AlbumCover({super.key, required this.album, required this.size});

  final Album album;
  final double size;

  @override
  Widget build(BuildContext context) {
    final palette = Occasion.values;
    final hash = album.title.codeUnits.fold<int>(7, (h, c) => (h * 31 + c) & 0x7fffffff);
    final generated = OccasionCover(occasion: palette[hash % palette.length], size: size, label: 'Album', title: album.title);
    if (album.coverUrl == null) return generated;
    return CachedNetworkImage(
      imageUrl: album.coverUrl!,
      fit: BoxFit.cover,
      memCacheWidth: (size * 3).round(),
      placeholder: (_, _) => generated,
      errorWidget: (_, _, _) => generated,
    );
  }
}

class SingerAvatar extends StatelessWidget {
  const SingerAvatar({super.key, required this.artist, this.size = 76});

  final Artist artist;
  final double size;

  @override
  Widget build(BuildContext context) {
    if (artist.photoUrl != null) {
      return ClipOval(
        child: CachedNetworkImage(imageUrl: artist.photoUrl!, width: size, height: size, fit: BoxFit.cover),
      );
    }
    return CustomPaint(
      painter: _DashedRingPainter(),
      child: Container(
        width: size,
        height: size,
        alignment: Alignment.center,
        decoration: const BoxDecoration(color: NkColors.emblemGreen, shape: BoxShape.circle),
        child: Text(
          artist.initials,
          style: Theme.of(context).textTheme.titleLarge?.copyWith(fontSize: size * 0.3),
        ),
      ),
    );
  }
}

class _DashedRingPainter extends CustomPainter {
  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = NkColors.teaLeaf
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2;
    final rect = Offset.zero & size;
    const dashes = 24;
    const sweep = 2 * math.pi / dashes;
    for (var i = 0; i < dashes; i++) {
      canvas.drawArc(rect.deflate(1), i * sweep, sweep * 0.6, false, paint);
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}