<?php
namespace Zadex\Frontend;

defined('ABSPATH') || exit;

/**
 * Motion effects (T160 scrolling, T161 mouse) and sticky (T162) settings -> data attributes on the element root.
 * Mirrors src/frontend/lib/motion-config.ts exactly (same keys, same order, defaults omitted), so the live page and
 * the editor canvas carry identical markup. The runtime is the `src/frontend/motion.ts` entry, enqueued by
 * Frontend only when an element rendered with these attributes (Renderer::uses_feature('motion')).
 */
final class MotionAttrs
{
    public const DEVICES = ['desktop', 'tablet', 'mobile'];
    public const EFFECTS = ['y', 'x', 'opacity', 'blur', 'rotate', 'scale'];

    private const DIRS = [
        'y'       => ['up', 'down'],
        'x'       => ['left', 'right'],
        'opacity' => ['in', 'out', 'in-out', 'out-in'],
        'blur'    => ['in', 'out', 'in-out', 'out-in'],
        'rotate'  => ['right', 'left'],
        'scale'   => ['up', 'down', 'up-down', 'down-up'],
    ];
    /** [settings suffix, default, max] of the speed / level field. */
    private const AMOUNT = [
        'y'       => ['speed', 4, 10],
        'x'       => ['speed', 4, 10],
        'opacity' => ['level', 10, 10],
        'blur'    => ['level', 7, 15],
        'rotate'  => ['speed', 1, 10],
        'scale'   => ['speed', 4, 10],
    ];
    private const RANGE = [
        'y'       => [0, 100],
        'x'       => [0, 100],
        'opacity' => [20, 80],
        'blur'    => [20, 80],
        'rotate'  => [0, 100],
        'scale'   => [0, 100],
    ];

    /** @return array<string, mixed>|null */
    public static function config(array $s): ?array
    {
        $out = [];
        if (self::on($s['_scroll_fx'] ?? false)) {
            $scroll = [];
            foreach (self::EFFECTS as $key) {
                if (!self::on($s['_fx_' . $key] ?? false)) {
                    continue;
                }
                [$suffix, $def, $max] = self::AMOUNT[$key];
                $scroll[$key] = [
                    'dir'   => self::pick($s['_fx_' . $key . '_dir'] ?? null, self::DIRS[$key]),
                    'speed' => self::num($s['_fx_' . $key . '_' . $suffix] ?? null, $def, 0, $max),
                    'start' => self::num($s['_fx_' . $key . '_start'] ?? null, self::RANGE[$key][0], 0, 100),
                    'end'   => self::num($s['_fx_' . $key . '_end'] ?? null, self::RANGE[$key][1], 0, 100),
                ];
            }
            if ($scroll) {
                $out['scroll'] = $scroll;
                $devices = self::devices($s['_fx_devices'] ?? null);
                if (count($devices) < count(self::DEVICES)) {
                    $out['devices'] = $devices;
                }
            }
        }
        if (self::on($s['_mouse_fx'] ?? false)) {
            $mouse = [];
            if (self::on($s['_mouse_track'] ?? false)) {
                $mouse['track'] = ['dir' => self::pick($s['_mouse_track_dir'] ?? null, ['opposite', 'direct']), 'speed' => self::num($s['_mouse_track_speed'] ?? null, 1, 0, 10)];
            }
            if (self::on($s['_mouse_tilt'] ?? false)) {
                $mouse['tilt'] = [
                    'dir'         => self::pick($s['_mouse_tilt_dir'] ?? null, ['direct', 'opposite']),
                    'max'         => self::num($s['_mouse_tilt_max'] ?? null, 10, 0, 45),
                    'perspective' => self::num($s['_mouse_tilt_perspective'] ?? null, 1000, 100, 5000),
                ];
                if (self::on($s['_mouse_tilt_glare'] ?? false)) {
                    $mouse['tilt']['glare'] = true;
                }
            }
            if ($mouse) {
                $out['mouse'] = $mouse;
            }
        }
        // Scroll-linked keyframes (T212), mirrors keyframesConfig() in src/frontend/lib/scroll-keyframes.ts.
        $kf = self::keyframes($s['_scroll_kf'] ?? null);
        if ($kf !== null) {
            $out['kf'] = $kf;
        }
        return $out ? $out : null;
    }

    public const KF_PROPS = ['x', 'y', 'scale', 'rotate', 'tiltX', 'tiltY', 'opacity', 'blur'];
    private const KF_RANGE = [
        'x'       => [-2000, 2000],
        'y'       => [-2000, 2000],
        'scale'   => [0, 10],
        'rotate'  => [-3600, 3600],
        'tiltX'   => [-180, 180],
        'tiltY'   => [-180, 180],
        'opacity' => [0, 1],
        'blur'    => [0, 100],
    ];
    private const KF_EASINGS = ['ease', 'ease-in', 'ease-out', 'ease-in-out'];
    public const MAX_KEYFRAMES = 20;

    /**
     * `_scroll_kf` = {enabled, anchor, start, end, devices, keyframes: [{at, x, y, scale, rotate, tiltX, tiltY,
     * opacity, blur, easing}]} -> {start, end, anchor?, devices?, frames} (null when off or < 2 keyframes).
     *
     * @return array<string, mixed>|null
     */
    public static function keyframes($value): ?array
    {
        if (!is_array($value) || array_is_list($value) && $value !== [] || !self::on($value['enabled'] ?? false)) {
            return null;
        }
        $by_at = [];
        $raw = is_array($value['keyframes'] ?? null) ? array_slice(array_values($value['keyframes']), 0, self::MAX_KEYFRAMES * 2) : [];
        foreach ($raw as $k) {
            if (!is_array($k)) {
                continue;
            }
            $at = self::knum($k['at'] ?? null, 0, 100, 1);
            if ($at === null) {
                continue;
            }
            $frame = ['at' => $at];
            foreach (self::KF_PROPS as $p) {
                [$min, $max] = self::KF_RANGE[$p];
                $n = self::knum($k[$p] ?? null, $min, $max, in_array($p, ['opacity', 'scale'], true) ? 3 : 2);
                if ($n !== null) {
                    $frame[$p] = $n;
                }
            }
            if (isset($k['easing']) && is_string($k['easing']) && in_array($k['easing'], self::KF_EASINGS, true)) {
                $frame['easing'] = $k['easing'];
            }
            $key = (string) $at;
            unset($by_at[$key]);
            $by_at[$key] = $frame;
        }
        $frames = array_values($by_at);
        usort($frames, static fn(array $a, array $b): int => $a['at'] <=> $b['at']);
        $frames = array_slice($frames, 0, self::MAX_KEYFRAMES);
        if (count($frames) < 2) {
            return null;
        }
        $out = [
            'start' => self::knum($value['start'] ?? null, 0, 100, 2) ?? 0,
            'end'   => self::knum($value['end'] ?? null, 0, 100, 2) ?? 100,
        ];
        $anchor = isset($value['anchor']) && in_array($value['anchor'], ['self', 'parent', 'page'], true) ? $value['anchor'] : 'self';
        if ($anchor !== 'self') {
            $out['anchor'] = $anchor;
        }
        if (isset($value['devices']) && is_array($value['devices'])) {
            $devices = self::devices($value['devices']);
            if (count($devices) < count(self::DEVICES)) {
                $out['devices'] = $devices;
            }
        }
        $out['frames'] = $frames;
        return $out;
    }

    /** Number rounded to `$digits` (null when not numeric); whole numbers become ints (JSON `4`, not `4.0`). */
    private static function knum($v, $min, $max, int $digits)
    {
        if (is_string($v) && trim($v) !== '' && is_numeric(trim($v))) {
            $v = (float) trim($v);
        }
        if (is_bool($v) || (!is_int($v) && !is_float($v)) || (is_float($v) && !is_finite($v))) {
            return null;
        }
        $n = round(min($max, max($min, (float) $v)), $digits);
        if ($n == 0.0) {
            return 0;
        }
        return floor($n) === $n ? (int) $n : $n;
    }

    /**
     * @param array<string, mixed> $s
     * @return array<string, string>
     */
    public static function attrs(array $s): array
    {
        $attrs = [];
        $config = self::config($s);
        if ($config !== null) {
            $attrs['data-zx-motion'] = (string) wp_json_encode($config, JSON_UNESCAPED_SLASHES);
        }
        $sticky = isset($s['_sticky']) && in_array($s['_sticky'], ['top', 'bottom'], true) ? $s['_sticky'] : '';
        if ($sticky !== '') {
            $attrs['data-zx-sticky'] = $sticky;
            if (self::on($s['_sticky_parent'] ?? false)) {
                $attrs['data-zx-sticky-parent'] = '';
            }
            $fx = self::num($s['_sticky_effects_offset'] ?? null, 0, 0, 100000);
            if ($fx > 0) {
                $attrs['data-zx-sticky-fx'] = (string) (int) round($fx);
            }
            $devices = self::devices($s['_sticky_devices'] ?? null);
            if (count($devices) < count(self::DEVICES)) {
                $attrs['data-zx-sticky-devices'] = implode(' ', $devices);
            }
        }
        return $attrs;
    }

    /** @return string[] */
    public static function devices($value): array
    {
        if (!is_array($value)) {
            return self::DEVICES;
        }
        return array_values(array_filter(self::DEVICES, static fn(string $d): bool => in_array($d, $value, true)));
    }

    private static function on($v): bool
    {
        return $v === true || $v === 1 || $v === '1' || $v === 'true';
    }

    private static function pick($v, array $list): string
    {
        return is_string($v) && in_array($v, $list, true) ? $v : $list[0];
    }

    /** Rounded to 2 decimals; whole numbers are ints so the JSON matches JavaScript's (`4`, not `4.0`). */
    private static function num($v, $def, $min, $max)
    {
        if (is_string($v) && trim($v) !== '' && is_numeric(trim($v))) {
            $v = (float) trim($v);
        }
        if (!is_int($v) && !is_float($v)) {
            return $def;
        }
        if (is_float($v) && !is_finite($v)) {
            return $def;
        }
        $n = round(min($max, max($min, (float) $v)), 2);
        return floor($n) === $n ? (int) $n : $n;
    }
}