import 'package:flutter/material.dart';

/// Visual theme token set for the AR-Autopilot display app.
///
/// Every widget reads design tokens from [AutopilotTheme] via
/// [AutopilotThemeProvider]. No widget hard-codes colors.
///
/// ## Design invariants (apply to ALL themes)
/// 1. **DISENGAGE** is always the highest-contrast element on screen.
///    If the palette makes red ambiguous, it changes to amber (wine theme).
/// 2. **Action buttons** (DODGE, ±1°, ±10°) must be legible at rest —
///    operators work with gloves in rain; hover/tap is not reliable.
/// 3. **Compass heading text** uses [textMain] with [accentGlowColor] glow.
/// 4. **Set-point** always uses [setLight] (amber/gold) — cognitively stable
///    across palettes; represents "operator intent".
/// 5. **North mark** is always a warm color ([northColor]) — nautical convention.
/// 6. **Touch targets**: 48×48 px nominal, 60×60 px for critical controls.
/// 7. **No glow in light mode**: [accentGlowRadius] == 0.0 for `light` theme.
class AutopilotTheme {
  const AutopilotTheme({
    required this.id,
    required this.displayName,
    // Backgrounds
    required this.background,
    required this.backgroundMid,
    required this.backgroundDeep,
    required this.backgroundDeepest,
    this.backgroundGradient,
    // Panels
    required this.panelBackground,
    required this.panelBorder,
    // Text
    required this.textMain,
    required this.textMuted,
    required this.textSoft,
    required this.textDisabled,
    // Accent — heading arc, active mode indicator, rudder indicator
    required this.accentLight,
    required this.accentMid,
    required this.accentDark,
    required this.accentGlowRadius,
    required this.accentGlowColor,
    // Set-point / desired heading
    required this.setLight,
    required this.setDark,
    required this.setGlow,
    // Semantic states
    required this.okColor,
    required this.warnColor,
    required this.northColor,
    // DISENGAGE — always high contrast, always unambiguous
    required this.disengageBackground,
    required this.disengageText,
    required this.disengageBorder,
    required this.disengageGlow,
    // Action buttons (DODGE, ±1°, ±10°)
    required this.actionButtonBackground,
    required this.actionButtonBorder,
    required this.actionButtonText,
    required this.actionButtonGlow,
  });

  final String id;
  final String displayName;

  // ── Backgrounds ────────────────────────────────────────────────────────────
  /// Dominant background color. Used as solid fill (light) or radial
  /// gradient center (dark themes). See [backgroundDecoration].
  final Color background;
  final Color backgroundMid;
  final Color backgroundDeep;
  final Color backgroundDeepest;

  /// Radial gradient for dark themes; `null` for the light theme
  /// (which uses a solid [background]).
  final Gradient? backgroundGradient;

  // ── Panels ──────────────────────────────────────────────────────────────────
  final Gradient panelBackground;
  final Color panelBorder;

  // ── Text ────────────────────────────────────────────────────────────────────
  final Color textMain;
  final Color textMuted;
  final Color textSoft;
  final Color textDisabled;

  // ── Accent ──────────────────────────────────────────────────────────────────
  final Color accentLight;
  final Color accentMid;
  final Color accentDark;

  /// Blur radius for accent glow effect. Zero in light mode (no glow).
  final double accentGlowRadius;
  final Color accentGlowColor;

  // ── Set-point ───────────────────────────────────────────────────────────────
  final Color setLight;
  final Color setDark;
  final Color setGlow;

  // ── Semantic states ─────────────────────────────────────────────────────────
  /// GPS OK, NMEA sentence valid, SOG within range.
  final Color okColor;

  /// Heading error, cross-track error warning.
  final Color warnColor;

  /// North mark on the compass rose. Always a warm color (never blue).
  final Color northColor;

  // ── DISENGAGE ───────────────────────────────────────────────────────────────
  final Gradient disengageBackground;
  final Color disengageText;
  final Color disengageBorder;
  final Color disengageGlow;

  // ── Action buttons (DODGE, ±1°, ±10°) ──────────────────────────────────────
  final Gradient actionButtonBackground;
  final Color actionButtonBorder;
  final Color actionButtonText;
  final Color actionButtonGlow;

  // ── Computed helpers ────────────────────────────────────────────────────────

  /// [BoxDecoration] for the full-screen background container.
  BoxDecoration get backgroundDecoration => backgroundGradient != null
      ? BoxDecoration(gradient: backgroundGradient)
      : BoxDecoration(color: background);

  /// [BoxShadow] list for accented glow (empty in light mode).
  List<BoxShadow> glowShadow(Color color, double radius) => radius > 0
      ? [BoxShadow(color: color, blurRadius: radius, spreadRadius: 1)]
      : const [];
}