<?php
/** Deterministic SVG geometry. GPL-2.0-or-later. */
defined( 'ABSPATH' ) || exit;

function sflo_number( $value, $fallback, $min, $max ) {
    if ( ! is_numeric( $value ) || ! is_finite( (float) $value ) ) {
        return $fallback;
    }
    return (int) max( $min, min( $max, floor( (float) $value + 0.5 ) ) );
}

function sflo_color( $value, $fallback ) {
    if ( ! is_string( $value ) ) { return $fallback; }
    if ( preg_match( '/^#[0-9a-f]{3}$/i', $value ) ) {
        $value = '#' . $value[1] . $value[1] . $value[2] . $value[2] . $value[3] . $value[3];
    }
    return preg_match( '/^#[0-9a-f]{6}$/i', $value ) ? strtolower( $value ) : $fallback;
}

function sflo_normalize( $input ) {
    $c = is_array( $input ) ? $input : array();
    return array(
        'family' => isset( $c['family'] ) && in_array( $c['family'], array( 'triangles', 'steps', 'diagonal', 'curves', 'waves' ), true ) ? $c['family'] : 'triangles',
        'seed' => sflo_number( $c['seed'] ?? null, 21873, 1, 2147483646 ),
        'count' => sflo_number( $c['count'] ?? null, 7, 2, 16 ),
        'amplitude' => sflo_number( $c['amplitude'] ?? null, 32, 0, 60 ),
        'layers' => sflo_number( $c['layers'] ?? null, 1, 1, 3 ),
        'upper' => sflo_color( $c['upper'] ?? null, '#f0f4f8' ),
        'lower' => sflo_color( $c['lower'] ?? null, '#263b53' ),
        'desktop' => sflo_number( $c['desktop'] ?? null, 112, 16, 300 ),
        'tablet' => sflo_number( $c['tablet'] ?? null, 84, 16, 220 ),
        'mobile' => sflo_number( $c['mobile'] ?? null, 56, 12, 160 ),
        'flip' => ( $c['flip'] ?? null ) === true,
        'motion' => ( $c['motion'] ?? null ) === true,
    );
}

function sflo_fmt( $value ) {
    $result = rtrim( rtrim( number_format( $value, 3, '.', '' ), '0' ), '.' );
    return $result === '-0' ? '0' : $result;
}

function sflo_geometry( $input ) {
    $c = sflo_normalize( $input );
    $state = $c['seed'];
    $rand = static function () use ( &$state ) {
        $state = ( $state * 16807 ) % 2147483647;
        return ( $state - 1 ) / 2147483646;
    };
    $a = $c['amplitude']; $n = $c['count']; $points = array(); $d = '';
    $phase = $rand() * M_PI * 2;
    if ( $c['family'] === 'triangles' ) {
        $points[] = array( 0, 62 );
        for ( $i = 0; $i < $n; $i++ ) {
            $points[] = array( ( $i + 0.25 + $rand() * 0.5 ) * 1200 / $n, 62 - $a * ( 0.25 + $rand() * 0.65 ) );
            $points[] = array( ( $i + 1 ) * 1200 / $n, 62 + $a * $rand() * 0.2 );
        }
    } elseif ( $c['family'] === 'steps' ) {
        $d = 'M0 ' . sflo_fmt( 55 + ( $rand() - 0.5 ) * $a );
        for ( $i = 1; $i <= $n; $i++ ) {
            $d .= 'H' . sflo_fmt( $i * 1200 / $n );
            if ( $i < $n ) { $d .= 'V' . sflo_fmt( 55 + ( $rand() - 0.5 ) * $a ); }
        }
    } elseif ( $c['family'] === 'diagonal' ) {
        $direction = $rand() > 0.5 ? 1 : -1;
        for ( $i = 0; $i <= $n; $i++ ) {
            $points[] = array( $i * 1200 / $n, 55 + $direction * ( $i / $n - 0.5 ) * $a + ( $rand() - 0.5 ) * $a * 0.3 );
        }
    } else {
        $segments = $c['family'] === 'waves' ? $n * 2 : $n;
        for ( $i = 0; $i <= $segments; $i++ ) {
            $y = $c['family'] === 'waves' ? 55 + sin( $i / $segments * M_PI * $n + $phase ) * $a * 0.38 : 55 + ( $rand() - 0.5 ) * $a;
            $points[] = array( $i * 1200 / $segments, $y );
        }
        $d = 'M' . sflo_fmt( $points[0][0] ) . ' ' . sflo_fmt( $points[0][1] );
        $length = count( $points );
        for ( $i = 0; $i < $length - 1; $i++ ) {
            $p0 = $points[ max( 0, $i - 1 ) ]; $p1 = $points[$i];
            $p2 = $points[$i + 1]; $p3 = $points[ min( $length - 1, $i + 2 ) ];
            $d .= 'C' . sflo_fmt( $p1[0] + ( $p2[0] - $p0[0] ) / 6 ) . ' ' . sflo_fmt( $p1[1] + ( $p2[1] - $p0[1] ) / 6 )
                . ' ' . sflo_fmt( $p2[0] - ( $p3[0] - $p1[0] ) / 6 ) . ' ' . sflo_fmt( $p2[1] - ( $p3[1] - $p1[1] ) / 6 )
                . ' ' . sflo_fmt( $p2[0] ) . ' ' . sflo_fmt( $p2[1] );
        }
    }
    if ( $d === '' ) {
        foreach ( $points as $i => $p ) { $d .= ( $i ? 'L' : 'M' ) . sflo_fmt( $p[0] ) . ' ' . sflo_fmt( $p[1] ); }
    }
    $d .= 'L1200 140L0 140Z';
    $paths = array();
    for ( $i = 0; $i < $c['layers']; $i++ ) {
        $paths[] = array( 'd' => $d, 'offset' => -( $c['layers'] - 1 - $i ) * 7, 'opacity' => $i === $c['layers'] - 1 ? 1 : 0.22 + $i * 0.25 );
    }
    return array( 'config' => $c, 'paths' => $paths, 'hidden' => $c['upper'] === $c['lower'] );
}

function sflo_svg( $input ) {
    $g = sflo_geometry( $input ); $c = $g['config'];
    if ( $g['hidden'] ) { return ''; }
    $svg = '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1200 100" width="1200" height="100" preserveAspectRatio="none" aria-hidden="true" focusable="false" style="display:block;width:100%;height:100%;overflow:hidden">';
    $svg .= '<rect width="1200" height="100" fill="' . esc_attr( $c['upper'] ) . '"/><g' . ( $c['flip'] ? ' transform="translate(1200 0) scale(-1 1)"' : '' ) . '><g class="' . ( $c['motion'] ? 'sflo-motion' : 'sflo-still' ) . '">';
    foreach ( $g['paths'] as $p ) {
        $svg .= '<path d="' . esc_attr( $p['d'] ) . '" fill="' . esc_attr( $c['lower'] ) . '" opacity="' . esc_attr( sflo_fmt( $p['opacity'] ) ) . '" transform="translate(0 ' . (int) $p['offset'] . ')"/>';
    }
    return $svg . '</g></g></svg>';
}