import 'package:clide/builtin/settings_ui/src/settings_category_view.dart';
import 'package:clide/kernel/kernel.dart';
import 'package:clide/widgets/widgets.dart';
import 'package:flutter/services.dart';
import 'package:flutter/widgets.dart';

/// The schema-driven Settings panel shell (T-445, epic T-444).
///
/// A centered modal over the dimmed app (hosted by [DialogHost] via
/// `ctx.dialog.show`), built from the `modalSurface*` tokens (D-7, no
/// Material). It frames the two regions the epic fills in:
///
/// - the **category rail** on the left (interactive navigation lands in
///   T-447; the list is data-driven from the registered schemas), and
/// - the **scrolling carded panel** on the right (the schema field renderer
///   is [SettingsCategoryView], T-448).
///
/// Categories come from the kernel [SettingsRegistry]; until one registers a
/// schema the panel shows its empty state. Dismiss with the close button, Esc,
/// or a barrier tap (the last handled by [DialogHost]).
///
/// Wireframe: `docs/design/wireframes/settings/settings-screen.png`.
class SettingsModal extends StatefulWidget {
  const SettingsModal({super.key, required this.onDismiss});

  /// Closes the modal. Wired to the dialog router's `dismiss` by the
  /// opener (see `SettingsUiExtension`).
  final VoidCallback onDismiss;

  static const ns = 'builtin.settings-ui';

  // The modal is a fixed-size desktop surface (the app is a desktop host);
  // the right panel scrolls when its cards exceed the height (surface.md).
  static const double _width = 760;
  static const double _height = 560;
  static const double _railWidth = 196;

  @override
  State<SettingsModal> createState() => _SettingsModalState();
}

class _SettingsModalState extends State<SettingsModal> {
  /// Selected category id; null falls back to the first registered category.
  /// The rail sets this in T-447.
  String? _selectedId;

  /// Cross-category search query (T-450); non-empty swaps the panel to results.
  String _query = '';

  @override
  Widget build(BuildContext context) {
    final i = ClideKernel.of(context).i18n;
    final tokens = ClideTheme.of(context).surface;
    final title = i.string('modal.title', namespace: SettingsModal.ns, placeholder: 'Settings');

    return Focus(
      autofocus: true,
      onKeyEvent: (node, event) {
        if (event is KeyDownEvent && event.logicalKey == LogicalKeyboardKey.escape) {
          widget.onDismiss();
          return KeyEventResult.handled;
        }
        return KeyEventResult.ignored;
      },
      child: Semantics(
        container: true,
        label: title,
        explicitChildNodes: true,
        child: ClideSurface(
          width: SettingsModal._width,
          height: SettingsModal._height,
          color: tokens.modalSurfaceBackground,
          border: tokens.modalSurfaceBorder,
          borderRadius: BorderRadius.circular(6),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              _Header(title: title, onClose: widget.onDismiss),
              const ClideDivider(),
              Expanded(
                child: Row(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    SizedBox(
                      width: SettingsModal._railWidth,
                      child: _CategoryRail(
                        selectedId: _selectedId,
                        query: _query,
                        onSelect: (id) => setState(() => _selectedId = id),
                        onQueryChanged: (q) => setState(() => _query = q),
                      ),
                    ),
                    const ClideDivider(axis: Axis.vertical),
                    Expanded(
                      child: ColoredBox(
                        color: tokens.panelBackground,
                        child: _query.trim().isEmpty ? _SettingsPanel(selectedId: _selectedId) : SettingsSearchResults(query: _query),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// Title bar: gear glyph + "Settings" on the left, close ✕ on the right.
class _Header extends StatelessWidget {
  const _Header({required this.title, required this.onClose});

  final String title;
  final VoidCallback onClose;

  @override
  Widget build(BuildContext context) {
    final tokens = ClideTheme.of(context).surface;
    return Padding(
      padding: const EdgeInsets.fromLTRB(16, 12, 10, 12),
      child: Row(
        children: [
          ClideIcon(const GearIcon(), size: 16, color: tokens.globalForeground),
          const SizedBox(width: 8),
          Expanded(child: ClideText(title, fontSize: 15, fontWeight: FontWeight.w600)),
          _CloseButton(onTap: onClose),
        ],
      ),
    );
  }
}

class _CloseButton extends StatelessWidget {
  const _CloseButton({required this.onTap});

  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final tokens = ClideTheme.of(context).surface;
    final i = ClideKernel.of(context).i18n;
    final label = i.string('modal.close', namespace: SettingsModal.ns, placeholder: 'Close');
    final hint = i.string('modal.close.hint', namespace: SettingsModal.ns, placeholder: 'Close settings');
    return Semantics(
      button: true,
      label: label,
      hint: hint,
      onTap: onTap,
      excludeSemantics: true,
      child: ClideTappable(
        cursor: SystemMouseCursors.click,
        onTap: onTap,
        builder: (ctx, hovered, pressed) => Container(
          padding: const EdgeInsets.all(6),
          decoration: BoxDecoration(color: hovered ? tokens.listItemHoverBackground : null, borderRadius: BorderRadius.circular(4)),
          child: ClideIcon(const CloseIcon(), size: 16, color: tokens.globalForeground),
        ),
      ),
    );
  }
}

/// Left rail — a cross-category search box atop the registered categories,
/// data-driven from the [SettingsRegistry]. Selecting one swaps the panel
/// (T-447); while searching, each row shows its match count and zero-match
/// rows dim (T-450).
class _CategoryRail extends StatelessWidget {
  const _CategoryRail({required this.selectedId, required this.query, required this.onSelect, required this.onQueryChanged});

  /// The modal's chosen category id (null → the first category).
  final String? selectedId;
  final String query;
  final void Function(String id) onSelect;
  final ValueChanged<String> onQueryChanged;

  @override
  Widget build(BuildContext context) {
    final tokens = ClideTheme.of(context).surface;
    final i = ClideKernel.of(context).i18n;
    final registry = ClideKernel.of(context).settingsRegistry;
    final searching = query.trim().isNotEmpty;
    return ListenableBuilder(
      listenable: registry,
      builder: (context, _) {
        final categories = registry.categories;
        final effectiveId = selectedId ?? (categories.isEmpty ? null : categories.first.id);
        return Column(
          crossAxisAlignment: CrossAxisAlignment.stretch,
          children: [
            Padding(
              padding: const EdgeInsets.fromLTRB(10, 10, 10, 8),
              child: ClideFilterBox(
                hint: i.string('search.hint', namespace: SettingsModal.ns, placeholder: 'Search settings…'),
                onChanged: onQueryChanged,
              ),
            ),
            Padding(
              padding: const EdgeInsets.fromLTRB(14, 2, 12, 6),
              child: ClideText(
                i.string('rail.header', namespace: SettingsModal.ns, placeholder: 'Categories'),
                fontSize: clideFontCaption,
                color: tokens.sidebarSectionHeader,
                fontFamily: ClideSettings.fonts.monoOf(context),
              ),
            ),
            Expanded(
              child: SingleChildScrollView(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.stretch,
                  children: [
                    for (final c in categories)
                      _RailRow(
                        category: c,
                        selected: !searching && c.id == effectiveId,
                        matchCount: searching ? settingsMatchCount(c, query) : null,
                        onTap: () => onSelect(c.id),
                      ),
                  ],
                ),
              ),
            ),
          ],
        );
      },
    );
  }
}

/// One category row: optional glyph + title, accent left-stripe + surfaceHi
/// fill when selected (surface.md side panels). When [matchCount] is non-null
/// (searching) it shows the count and dims to muted on zero matches (T-450).
class _RailRow extends StatelessWidget {
  const _RailRow({required this.category, required this.selected, required this.matchCount, required this.onTap});

  final SettingsCategory category;
  final bool selected;
  final int? matchCount;
  final VoidCallback onTap;

  @override
  Widget build(BuildContext context) {
    final tokens = ClideTheme.of(context).surface;
    final dim = matchCount == 0;
    final fg = dim ? tokens.globalTextMuted : (selected ? tokens.globalForeground : tokens.sidebarForeground);
    return Semantics(
      button: true,
      selected: selected,
      label: category.title,
      excludeSemantics: true,
      child: ClideTappable(
        cursor: SystemMouseCursors.click,
        onTap: onTap,
        builder: (ctx, hovered, _) => Container(
          // color: null => no paint (shows the modal surface behind the rail).
          color: selected ? tokens.sidebarItemSelected : (hovered ? tokens.sidebarItemHover : null),
          child: Row(
            children: [
              // Accent left-stripe; the 2px slot is reserved either way so the
              // row never shifts. Painted only when selected — no color literal.
              SizedBox(width: 2, child: selected ? ColoredBox(color: tokens.panelActiveBorder) : null),
              Expanded(
                child: Padding(
                  padding: const EdgeInsets.fromLTRB(10, 7, 12, 7),
                  child: Row(
                    children: [
                      if (category.iconName != null) ...[ClideIcon(PhosphorIcons.byName(category.iconName!), size: 15, color: fg), const SizedBox(width: 8)],
                      Expanded(
                        child: ClideText(category.title, color: fg, maxLines: 1, overflow: TextOverflow.ellipsis),
                      ),
                      if (matchCount != null) ClideText('$matchCount', fontSize: clideFontCaption, color: tokens.globalTextMuted),
                    ],
                  ),
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

/// Right panel — renders the selected category's schema (or the first
/// registered one) via [SettingsCategoryView]; the empty state shows when no
/// category is registered. The region recedes to panelBackground (set by the
/// modal) so the panelHeader cards pop (surface.md).
class _SettingsPanel extends StatelessWidget {
  const _SettingsPanel({required this.selectedId});

  final String? selectedId;

  @override
  Widget build(BuildContext context) {
    final registry = ClideKernel.of(context).settingsRegistry;
    return ListenableBuilder(
      listenable: registry,
      builder: (context, _) {
        final categories = registry.categories;
        if (categories.isEmpty) return const _EmptyState();
        final selected = (selectedId == null ? null : registry.byId(selectedId!)) ?? categories.first;
        return SettingsCategoryView(category: selected);
      },
    );
  }
}

class _EmptyState extends StatelessWidget {
  const _EmptyState();

  @override
  Widget build(BuildContext context) {
    final tokens = ClideTheme.of(context).surface;
    final i = ClideKernel.of(context).i18n;
    return Center(
      child: Padding(
        padding: const EdgeInsets.all(24),
        child: ClideText(
          i.string('panel.empty', namespace: SettingsModal.ns, placeholder: 'No settings categories are registered yet.'),
          color: tokens.globalTextMuted,
          textAlign: TextAlign.center,
        ),
      ),
    );
  }
}