<?php

namespace App\Support;

use App\Rules\ScalarSetting;

/**
 * Structural schema for the user settings document.
 *
 * The settings blob is stored as JSON, so validation is the only thing
 * standing between the client and whatever ends up being read back as
 * `preset.id` or a shader uniform. Keys are whitelisted, values are bounded
 * and required to be scalar, so no nested structure can be smuggled in.
 */
final class SettingsSchema
{
    /**
     * Current schema version, stored alongside the settings so a later
     * migration can tell old documents from new ones.
     */
    public const VERSION = 1;

    /**
     * Maximum number of stored presets per user.
     */
    public const MAX_PRESETS = 50;

    /**
     * Maximum length of any string value inside the settings document.
     */
    public const MAX_STRING_LENGTH = 4096;

    /**
     * Top-level settings keys the API accepts. Anything else is rejected
     * rather than quietly persisted.
     *
     * @return array<int, string>
     */
    public static function allowedKeys(): array
    {
        return [
            'version',
            'theme',
            'floatingLines',
            'appearance',
            'accentColor',
            'language',
            'emotionGradientStart',
            'emotionGradientEnd',
            'timelineZoom',
            'timelineScrollLeft',
            'showFps',
            'presets',
            'activePresetId',
        ];
    }

    /**
     * Keys allowed inside `floatingLines`, mirroring FLOATING_LINES_DEFAULTS
     * in the Quasar settings store.
     *
     * @return array<int, string>
     */
    public static function allowedFloatingLineKeys(): array
    {
        return [
            // Lines
            'speed', 'lineCount', 'spread', 'fanSpread', 'lineSharpness',
            'lineThickness', 'waveFrequency', 'bezierCurvature', 'circleRadius',
            'glowSize', 'glowStrength', 'lineBrightness',
            // Background
            'bgCenter', 'bgEdge', 'gradientStops', 'backgroundImage',
            // Horizon
            'horizonMode', 'horizonOpacity', 'horizonBlend',
            // Labels
            'labelSize', 'labelColor', 'labelOpacity', 'labelConnectorLength',
            // Dot border
            'dotBorderWidth', 'dotBorderColor',
            // Mode
            'lineMode', 'staticLineColor', 'staticLineShadowStrength',
        ];
    }

    /**
     * Validation rules for the settings document.
     *
     * @return array<string, array<int, mixed>>
     */
    public static function rules(): array
    {
        return [
            'settings' => ['required', 'array'],
            'settings.version' => ['nullable', 'integer', 'min:1', 'max:'.self::VERSION],
            ...self::snapshotRules('settings.'),
            'settings.timelineScrollLeft' => ['nullable', 'numeric', 'min:0'],

            'settings.presets' => ['nullable', 'array', 'max:'.self::MAX_PRESETS],
            'settings.presets.*' => ['array'],
            'settings.presets.*.id' => ['required', 'string', 'max:100'],
            'settings.presets.*.name' => ['required', 'string', 'max:100'],
            'settings.presets.*.updatedAt' => ['nullable', 'numeric'],
            'settings.presets.*.settings' => ['required', 'array'],
            ...self::snapshotRules('settings.presets.*.settings.'),

            'settings.activePresetId' => ['nullable', 'string', 'max:100'],
        ];
    }

    /**
     * Rules for the fields a preset snapshot shares with the top-level
     * settings. Every field needs an explicit rule: Laravel's `validated()`
     * only returns keys that have one, so a field left out here would be
     * silently dropped when a preset is saved.
     *
     * @return array<string, array<int, mixed>>
     */
    private static function snapshotRules(string $prefix): array
    {
        return [
            $prefix.'theme' => ['nullable', 'string', 'max:50'],
            $prefix.'appearance' => ['nullable', 'string', 'max:50'],
            $prefix.'accentColor' => ['nullable', 'string', 'max:50'],
            $prefix.'language' => ['nullable', 'string', 'max:10'],
            $prefix.'emotionGradientStart' => ['nullable', 'string', 'max:20'],
            $prefix.'emotionGradientEnd' => ['nullable', 'string', 'max:20'],
            $prefix.'timelineZoom' => ['nullable', 'numeric', 'min:0.1', 'max:10'],
            $prefix.'showFps' => ['nullable', 'boolean'],
            $prefix.'floatingLines' => ['nullable', 'array'],
            $prefix.'floatingLines.*' => ['nullable', new ScalarSetting(self::MAX_STRING_LENGTH)],
        ];
    }
}