import 'package:flutter/material.dart';

/// Responsive & hinge-aware layout utilities for iPhone Duo (folded, unfolded, and Split View postures).
class DuoResponsive {
  DuoResponsive._();

  /// Viewport width threshold (in logical points) where the layout transitions
  /// from folded / narrow Split View to the unfolded inner display posture.
  static const double unfoldedBreakpoint = 600.0;

  /// Reserved center fold clearance (~40pt) for unfolded dual-pane postures
  /// since MediaQuery.displayFeatures does not natively report the iOS fold yet.
  static const double foldGap = 40.0;

  /// Maximum width for dialogs and modal bottom sheets so they do not stretch
  /// awkwardly across the 40pt center fold when unfolded.
  static const double maxModalWidth = 420.0;

  /// Standard capped width for navigation drawers on wide/unfolded screens.
  static const double maxDrawerWidth = 320.0;

  /// Width of the adaptive side navigation rail when unfolded.
  static const double sideRailWidth = 88.0;

  /// Returns true when the current window width is in the unfolded / expanded posture.
  static bool isUnfolded(BuildContext context) {
    return MediaQuery.sizeOf(context).width >= unfoldedBreakpoint;
  }

  /// Returns true when the given constraint or viewport width is in the unfolded posture.
  static bool isWideWidth(double width) {
    return width >= unfoldedBreakpoint;
  }

  /// Calculates the width of a single pane when split across the center fold gap.
  static double singlePaneWidth(double availableWidth, {double horizontalPadding = 0.0}) {
    double usable = availableWidth - (horizontalPadding * 2);
    if (!isWideWidth(availableWidth)) {
      return usable;
    }
    return ((usable - foldGap) / 2).clamp(0.0, double.infinity);
  }

  /// Returns adaptive dialog insetPadding so dialogs stay within a single pane
  /// or centered with a comfortable width instead of stretching across the hinge.
  static EdgeInsets dialogInsetPadding(BuildContext context, {double defaultHorizontal = 21.0, double defaultVertical = 24.0}) {
    Size size = MediaQuery.sizeOf(context);
    if (size.width >= unfoldedBreakpoint) {
      double horizontal = ((size.width - maxModalWidth) / 2).clamp(defaultHorizontal, size.width * 0.35);
      return EdgeInsets.symmetric(horizontal: horizontal, vertical: defaultVertical);
    }
    return EdgeInsets.symmetric(horizontal: defaultHorizontal, vertical: defaultVertical);
  }

  /// Returns BoxConstraints for modal bottom sheets so they never stretch across the fold.
  static BoxConstraints bottomSheetConstraints(BuildContext context, {double? maxHeight}) {
    Size size = MediaQuery.sizeOf(context);
    bool unfolded = size.width >= unfoldedBreakpoint;
    return BoxConstraints(
      maxWidth: unfolded ? maxModalWidth : size.width,
      maxHeight: maxHeight ?? double.infinity,
    );
  }
}

/// A two-pane row that automatically inserts [DuoResponsive.foldGap] (~40pt)
/// between [startPane] and [endPane] when in the unfolded posture, or [compactSpacing]
/// when in the folded / compact posture.
class DuoSplitRow extends StatelessWidget {
  final Widget startPane;
  final Widget endPane;
  final double compactSpacing;
  final CrossAxisAlignment crossAxisAlignment;

  const DuoSplitRow({
    Key? key,
    required this.startPane,
    required this.endPane,
    this.compactSpacing = 9.0,
    this.crossAxisAlignment = CrossAxisAlignment.start,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (BuildContext context, BoxConstraints constraints) {
        bool isWide = DuoResponsive.isWideWidth(constraints.maxWidth) || DuoResponsive.isUnfolded(context);
        double gap = isWide ? DuoResponsive.foldGap : compactSpacing;
        return Row(
          crossAxisAlignment: crossAxisAlignment,
          children: <Widget>[
            Expanded(child: startPane),
            SizedBox(width: gap),
            Expanded(child: endPane),
          ],
        );
      },
    );
  }
}

/// Constrains wide content (such as forms, cards, or lists) on unfolded screens
/// while letting it fill the width naturally when folded.
class DuoContentConstraint extends StatelessWidget {
  final Widget child;
  final double maxWidth;
  final AlignmentGeometry alignment;

  const DuoContentConstraint({
    Key? key,
    required this.child,
    this.maxWidth = 720.0,
    this.alignment = Alignment.topCenter,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (BuildContext context, BoxConstraints constraints) {
        if (constraints.maxWidth <= maxWidth) {
          return child;
        }
        return Align(
          alignment: alignment,
          child: ConstrainedBox(
            constraints: BoxConstraints(maxWidth: maxWidth),
            child: child,
          ),
        );
      },
    );
  }
}