import 'package:flutter/material.dart';
import 'package:material_symbols_icons/symbols.dart';

import '../i18n/strings.g.dart';
import 'seed_glyph.dart';
import 'theme.dart';

/// One onboarding page: a large emblem (a bundled seed glyph or a Material
/// symbol), a title and a short body. Illustrations use the app's own icon set
/// rather than photos — no image licensing, and it keeps the bundle light.
class _Slide {
  const _Slide({
    this.glyph,
    this.icon,
    required this.title,
    required this.body,
  });

  /// A `seedks` glyph char (see [SeedGlyphs]); mutually exclusive with [icon].
  final String? glyph;

  /// A Material symbol, used where no seed glyph fits (privacy, sprout).
  final IconData? icon;
  final String title;
  final String body;
}

/// The first-run intro carousel (also reachable later from the drawer): a few
/// swipeable cards explaining what Tanemaki is, how privacy works, how sharing
/// works and the Plantare. [onDone] fires when the user skips or finishes, and
/// is where the caller marks the intro as seen and leaves the screen.
class IntroScreen extends StatefulWidget {
  const IntroScreen({required this.onDone, super.key});

  final VoidCallback onDone;

  @override
  State<IntroScreen> createState() => _IntroScreenState();
}

class _IntroScreenState extends State<IntroScreen> {
  final _controller = PageController();
  int _page = 0;

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  List<_Slide> _slides(Translations t) => [
    _Slide(
      glyph: SeedGlyphs.scattered,
      title: t.intro.slides.welcome.title,
      body: t.intro.slides.welcome.body,
    ),
    _Slide(
      glyph: SeedGlyphs.jars,
      title: t.intro.slides.inventory.title,
      body: t.intro.slides.inventory.body,
    ),
    _Slide(
      icon: Icons.lock_outline,
      title: t.intro.slides.privacy.title,
      body: t.intro.slides.privacy.body,
    ),
    _Slide(
      glyph: SeedGlyphs.share,
      title: t.intro.slides.share.title,
      body: t.intro.slides.share.body,
    ),
    _Slide(
      icon: Symbols.potted_plant,
      title: t.intro.slides.plantare.title,
      body: t.intro.slides.plantare.body,
    ),
  ];

  void _next(int count) {
    if (_page >= count - 1) {
      widget.onDone();
      return;
    }
    _controller.nextPage(
      duration: const Duration(milliseconds: 280),
      curve: Curves.easeInOut,
    );
  }

  @override
  Widget build(BuildContext context) {
    final t = context.t;
    final slides = _slides(t);
    final isLast = _page == slides.length - 1;
    return Scaffold(
      backgroundColor: seedCanvas,
      body: SafeArea(
        child: Column(
          children: [
            Align(
              alignment: AlignmentDirectional.centerEnd,
              child: TextButton(
                onPressed: widget.onDone,
                child: Text(t.intro.skip),
              ),
            ),
            Expanded(
              child: PageView.builder(
                controller: _controller,
                onPageChanged: (i) => setState(() => _page = i),
                itemCount: slides.length,
                itemBuilder: (context, i) => _SlideView(slide: slides[i]),
              ),
            ),
            _Dots(count: slides.length, active: _page),
            Padding(
              padding: const EdgeInsets.fromLTRB(24, 20, 24, 24),
              child: SizedBox(
                width: double.infinity,
                child: FilledButton(
                  onPressed: () => _next(slides.length),
                  child: Text(isLast ? t.intro.start : t.intro.next),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// The centred emblem + title + body for a single [slide].
class _SlideView extends StatelessWidget {
  const _SlideView({required this.slide});

  final _Slide slide;

  @override
  Widget build(BuildContext context) {
    // Centre when there's room, scroll when the viewport is short (small phones
    // in landscape, split-screen) so the card never overflows.
    return LayoutBuilder(
      builder: (context, constraints) => SingleChildScrollView(
        child: ConstrainedBox(
          constraints: BoxConstraints(minHeight: constraints.maxHeight),
          child: Center(
            child: ConstrainedBox(
              constraints: const BoxConstraints(maxWidth: 420),
              child: Padding(
                padding: const EdgeInsets.symmetric(
                  horizontal: 32,
                  vertical: 16,
                ),
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: [
                    Container(
                      width: 160,
                      height: 160,
                      decoration: const BoxDecoration(
                        color: seedPrimaryContainer,
                        shape: BoxShape.circle,
                      ),
                      alignment: Alignment.center,
                      child: slide.glyph != null
                          ? SeedGlyph(slide.glyph!, size: 76, color: seedGreen)
                          : Icon(slide.icon, size: 72, color: seedGreen),
                    ),
                    const SizedBox(height: 36),
                    Text(
                      slide.title,
                      textAlign: TextAlign.center,
                      style: const TextStyle(
                        color: seedTitle,
                        fontSize: 24,
                        fontWeight: FontWeight.w600,
                        height: 1.2,
                      ),
                    ),
                    const SizedBox(height: 14),
                    Text(
                      slide.body,
                      textAlign: TextAlign.center,
                      style: const TextStyle(
                        color: seedOnSurfaceVariant,
                        fontSize: 16,
                        height: 1.45,
                      ),
                    ),
                  ],
                ),
              ),
            ),
          ),
        ),
      ),
    );
  }
}

/// The page-position dots: the active one is a wider green pill.
class _Dots extends StatelessWidget {
  const _Dots({required this.count, required this.active});

  final int count;
  final int active;

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,
      children: [
        for (var i = 0; i < count; i++)
          AnimatedContainer(
            duration: const Duration(milliseconds: 220),
            margin: const EdgeInsets.symmetric(horizontal: 4),
            width: i == active ? 22 : 8,
            height: 8,
            decoration: BoxDecoration(
              color: i == active ? seedGreen : seedOutline,
              borderRadius: BorderRadius.circular(4),
            ),
          ),
      ],
    );
  }
}