import 'dart:typed_data';

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

import '../matrix/media.dart';
import '../state.dart';
import '../theme.dart';

/// A round avatar: the picture at [mxc] when there is one, else the first
/// letter of [name] on a colour picked from [seed] (the user or room ID), so
/// the same person always gets the same colour.
class Avatar extends ConsumerStatefulWidget {
  const Avatar({
    super.key,
    required this.name,
    required this.seed,
    this.mxc,
    this.size = 40,
  });

  final String name;
  final String seed;
  final Uri? mxc;
  final double size;

  @override
  ConsumerState<Avatar> createState() => _AvatarState();
}

class _AvatarState extends ConsumerState<Avatar> {
  Future<Uint8List?>? _bytes;

  @override
  void initState() {
    super.initState();
    _load();
  }

  @override
  void didUpdateWidget(Avatar old) {
    super.didUpdateWidget(old);
    if (old.mxc != widget.mxc || old.size != widget.size) _load();
  }

  void _load() {
    final mxc = widget.mxc;
    _bytes = mxc == null || mxc.scheme != 'mxc'
        ? null
        : Media.thumbnail(ref.read(clientProvider), mxc, widget.size.round());
  }

  static const _palette = [
    Color(0xFF00A389),
    Color(0xFF1D5FD1),
    Color(0xFF8A5300),
    Color(0xFFB42318),
    Color(0xFF6D4AC2),
    Color(0xFF00806A),
    Color(0xFFC2410C),
    Color(0xFF0E7490),
  ];

  @override
  Widget build(BuildContext context) {
    final size = widget.size;
    final hash = widget.seed.codeUnits.fold<int>(
      0,
      (h, c) => (h * 31 + c) & 0x7fffffff,
    );
    final colour = _palette[hash.abs() % _palette.length];
    final letter = _initial(widget.name);
    final fallback = Container(
      width: size,
      height: size,
      alignment: Alignment.center,
      decoration: BoxDecoration(color: colour, shape: BoxShape.circle),
      child: Text(
        letter,
        style: TextStyle(
          fontFamily: fontDisplay,
          fontWeight: FontWeight.w600,
          fontSize: size * 0.42,
          color: Colors.white,
          height: 1,
        ),
      ),
    );
    final bytes = _bytes;
    if (bytes == null) return fallback;
    return FutureBuilder<Uint8List?>(
      future: bytes,
      builder: (context, snapshot) {
        final data = snapshot.data;
        if (data == null) return fallback;
        return ClipOval(
          child: Image.memory(
            data,
            width: size,
            height: size,
            fit: BoxFit.cover,
            gaplessPlayback: true,
            errorBuilder: (_, _, _) => fallback,
          ),
        );
      },
    );
  }

  static String _initial(String name) {
    final trimmed = name.replaceFirst(RegExp(r'^[@#!+]'), '').trim();
    if (trimmed.isEmpty) return '?';
    return String.fromCharCode(trimmed.runes.first).toUpperCase();
  }
}