<?php
/**
 * Reads a Figma document tree — REST `GET /v1/files/:key` output, or the same
 * shape emitted by the Style Bridge plugin — and yields both halves of an import:
 * the design tokens, and the frames that become YOOtheme layouts.
 *
 * Tokens are inferred from usage here, because a document tree carries fills and
 * text runs rather than named variables. When a file does have variables, the
 * plugin sends them separately and those win.
 */

namespace Fyoo\FigmaBridge;

class Figma
{
    private array $document;
    private array $textNodes = [];
    private array $fillCounts = [];
    private array $radii = [];
    private array $shadows = [];
    private ?array $pageFrame = null;

    public function __construct(array $document)
    {
        // Accept a whole REST response, a plugin payload, or a bare node.
        $this->document = $document['document'] ?? $document;

        if (isset($this->document['document'])) {
            $this->document = $this->document['document'];
        }

        if (!isset($this->document['children']) && !isset($this->document['type'])) {
            throw new \InvalidArgumentException('Not a Figma document: no node tree found.');
        }

        $this->document['name'] = $document['name'] ?? $this->document['name'] ?? 'Figma Import';
        $this->walk($this->document, 0);
    }

    public static function fromJson(string $json): self
    {
        $data = json_decode($json, true);

        if (!is_array($data)) {
            throw new \InvalidArgumentException('Figma payload is not valid JSON.');
        }

        return new self($data);
    }

    /** Fetches a file over the REST API with a personal access token. */
    public static function fetch(string $fileKeyOrUrl, string $token): self
    {
        if (preg_match('~figma\.com/(?:file|design|proto)/([A-Za-z0-9]+)~', $fileKeyOrUrl, $m)) {
            $fileKeyOrUrl = $m[1];
        }

        if (!preg_match('~^[A-Za-z0-9]{10,}$~', $fileKeyOrUrl)) {
            throw new \InvalidArgumentException('Not a Figma file key or URL.');
        }

        $context = stream_context_create(['http' => [
            'method'        => 'GET',
            'header'        => "X-Figma-Token: $token\r\n",
            'timeout'       => 90,
            'ignore_errors' => true,
        ]]);

        $body = @file_get_contents("https://api.figma.com/v1/files/$fileKeyOrUrl", false, $context);

        if ($body === false) {
            throw new \RuntimeException('Could not reach the Figma API.');
        }

        $data = json_decode($body, true);

        if (!is_array($data)) {
            throw new \RuntimeException('Figma API returned an unreadable response.');
        }

        if (isset($data['err']) && $data['err']) {
            throw new \RuntimeException('Figma API: ' . $data['err']);
        }

        return new self($data);
    }

    public function name(): string
    {
        return (string) ($this->document['name'] ?? 'Figma Import');
    }

    private function walk(array $node, int $depth): void
    {
        $type = $node['type'] ?? '';

        if ($type === 'TEXT' && isset($node['style']['fontSize'])) {
            $this->textNodes[] = $node;
        }

        // Weighted by area: a colour covering a hero counts for more than one chip.
        foreach ($this->solidFills($node) as $color) {
            $this->fillCounts[$color] = ($this->fillCounts[$color] ?? 0) + $this->area($node);
        }

        if (!empty($node['cornerRadius']) && is_numeric($node['cornerRadius'])) {
            $radius = (int) $node['cornerRadius'];
            $this->radii[$radius] = ($this->radii[$radius] ?? 0) + 1;
        }

        foreach ($node['effects'] ?? [] as $effect) {
            if (($effect['type'] ?? '') === 'DROP_SHADOW' && ($effect['visible'] ?? true)) {
                $shadow = self::shadow($effect);
                $this->shadows[$shadow] = ($this->shadows[$shadow] ?? 0) + 1;
            }
        }

        if ($depth <= 2 && $type === 'FRAME' && ($node['absoluteBoundingBox']['width'] ?? 0) >= 600) {
            if ($this->pageFrame === null || $this->area($node) > $this->area($this->pageFrame)) {
                $this->pageFrame = $node;
            }
        }

        foreach ($node['children'] ?? [] as $child) {
            $this->walk($child, $depth + 1);
        }
    }

    private function area(array $node): int
    {
        $box = $node['absoluteBoundingBox'] ?? null;

        return $box ? max(1, (int) (($box['width'] ?? 1) * ($box['height'] ?? 1) / 1000)) : 1;
    }

    /** @return string[] hex colours of a node's visible solid fills */
    private function solidFills(array $node): array
    {
        $colors = [];

        foreach ($node['fills'] ?? [] as $fill) {
            if (($fill['type'] ?? '') === 'SOLID' && ($fill['visible'] ?? true)) {
                $colors[] = self::hex($fill['color'], $fill['opacity'] ?? 1);
            }
        }

        if (!$colors && isset($node['backgroundColor'])) {
            $colors[] = self::hex($node['backgroundColor']);
        }

        return $colors;
    }

    public static function hex(array $color, float $opacity = 1.0): string
    {
        $channel = fn(float $value): string => str_pad(dechex((int) round(max(0, min(1, $value)) * 255)), 2, '0', STR_PAD_LEFT);
        $hex = '#' . $channel($color['r'] ?? 0) . $channel($color['g'] ?? 0) . $channel($color['b'] ?? 0);
        $alpha = ($color['a'] ?? 1) * $opacity;

        return strtoupper($alpha >= 0.999 ? $hex : $hex . $channel($alpha));
    }

    private static function shadow(array $effect): string
    {
        return sprintf(
            '%dpx %dpx %dpx %dpx %s',
            (int) ($effect['offset']['x'] ?? 0),
            (int) ($effect['offset']['y'] ?? 0),
            (int) ($effect['radius'] ?? 0),
            (int) ($effect['spread'] ?? 0),
            self::hex($effect['color'] ?? [])
        );
    }

    public static function luminance(string $hex): float
    {
        $hex = substr(ltrim($hex, '#'), 0, 6);

        if (strlen($hex) < 6) {
            return 0.5;
        }

        [$r, $g, $b] = array_map('hexdec', str_split($hex, 2));

        return (0.2126 * $r + 0.7152 * $g + 0.0722 * $b) / 255;
    }

    public function tokens(): Tokens
    {
        arsort($this->fillCounts);
        $surface = $this->pageFrame ? ($this->solidFills($this->pageFrame)[0] ?? null) : null;
        $color   = [];

        if ($surface !== null) {
            $color['surface'] = $surface;
        }

        $accents = [];
        $lights  = [];

        foreach (array_keys($this->fillCounts) as $hex) {
            if ($hex === $surface || strlen($hex) > 7) {
                continue;
            }

            $luminance = self::luminance($hex);

            if ($luminance > 0.06 && $luminance < 0.80) {
                $accents[] = $hex;
            } elseif ($luminance >= 0.80) {
                $lights[] = $hex;
            }
        }

        if (isset($accents[0])) {
            $color['brand-primary'] = $accents[0];
            $color['on-primary'] = self::luminance($accents[0]) > 0.55 ? '#000000' : '#FFFFFF';
        }

        if (isset($accents[1])) {
            $color['brand-secondary'] = $accents[1];
        }

        $muted = array_values(array_filter($lights, fn($c) => !in_array($c, ['#FFF', '#FFFFFF'], true)));

        if (isset($muted[0])) {
            $color['surface-muted'] = $muted[0];
        }

        $textColors = [];

        foreach ($this->textNodes as $node) {
            foreach ($this->solidFills($node) as $hex) {
                $bucket = (float) $node['style']['fontSize'] <= 20 ? 'text' : 'heading';
                $textColors[$bucket][$hex] = ($textColors[$bucket][$hex] ?? 0) + 1;
            }
        }

        foreach (['text', 'heading'] as $bucket) {
            if (!empty($textColors[$bucket])) {
                arsort($textColors[$bucket]);
                $color[$bucket] = (string) array_key_first($textColors[$bucket]);
            }
        }

        $typography = $this->typography();

        arsort($this->radii);
        $radius = $this->radii ? ['card' => array_key_first($this->radii) . 'px'] : [];

        $shadowList = array_keys($this->shadows);
        usort($shadowList, fn($a, $b) => strlen($a) <=> strlen($b));
        $shadow = [];

        foreach (['shadow-md', 'shadow-lg', 'shadow-xl'] as $index => $key) {
            if (isset($shadowList[$index])) {
                $shadow[$key] = $shadowList[$index];
            }
        }

        $spacing = [];

        if ($this->pageFrame) {
            if ($width = (int) ($this->pageFrame['absoluteBoundingBox']['width'] ?? 0)) {
                $spacing['container'] = min($width, 1600) . 'px';
            }

            if ($padding = (int) ($this->pageFrame['paddingTop'] ?? 0)) {
                $spacing['section'] = $padding . 'px';
            }
        }

        return new Tokens(Tokens::validate([
            'name'        => $this->name(),
            'source'      => 'figma',
            'version'     => '0.1',
            'generatedAt' => gmdate('c'),
            'tokens'      => [
                'color'      => $color,
                'typography' => $typography,
                'spacing'    => $spacing,
                'radius'     => $radius,
                'shadow'     => $shadow,
            ],
            'components' => $this->components(),
            'assets'     => [],
        ]));
    }

    /** The most-used text run is the body copy; every larger size is a heading step. */
    private function typography(): array
    {
        $styles = [];

        foreach ($this->textNodes as $node) {
            $style = $node['style'];
            $size  = (int) round((float) $style['fontSize']);
            $key   = $size . '/' . ($style['fontWeight'] ?? 400);

            if (!isset($styles[$key])) {
                $lineHeight = isset($style['lineHeightPercentFontSize'])
                    ? round($style['lineHeightPercentFontSize'] / 100, 3)
                    : (isset($style['lineHeightPx']) ? round($style['lineHeightPx'] / max(1, $size), 3) : 1.5);

                $styles[$key] = [
                    'size'  => $size,
                    'count' => 0,
                    'style' => array_filter([
                        'fontFamily'    => $style['fontFamily'] ?? null,
                        'fontSize'      => $size . 'px',
                        'fontWeight'    => isset($style['fontWeight']) ? (string) (int) $style['fontWeight'] : null,
                        'lineHeight'    => (string) $lineHeight,
                        'letterSpacing' => isset($style['letterSpacing']) && abs((float) $style['letterSpacing']) > 0.01
                            ? round((float) $style['letterSpacing'] / max(1, $size), 3) . 'em'
                            : null,
                    ]),
                ];
            }

            $styles[$key]['count']++;
        }

        if (!$styles) {
            return [];
        }

        uasort($styles, fn($a, $b) => $b['count'] <=> $a['count']);
        $body = reset($styles);
        $typography = ['body' => $body['style']];

        $headings = array_values(array_filter($styles, fn($s) => $s['size'] > $body['size']));
        usort($headings, fn($a, $b) => $b['size'] <=> $a['size']);
        $names = ['heading-xl', 'heading-lg', 'heading-md', 'heading-sm', 'heading-xs', 'heading-2xs'];

        foreach (array_slice($headings, 0, 6) as $index => $heading) {
            $typography[$names[$index]] = $heading['style'];
        }

        return $typography;
    }

    /** Component and instance names, so the mapper can bind them to YOOtheme elements. */
    private function components(): array
    {
        $names = [];
        $collect = function (array $node) use (&$collect, &$names): void {
            if (in_array($node['type'] ?? '', ['COMPONENT', 'COMPONENT_SET', 'INSTANCE'], true)) {
                $names[$node['name']] = ['role' => '', 'target' => '', 'overrides' => []];
            }

            foreach ($node['children'] ?? [] as $child) {
                $collect($child);
            }
        };

        $collect($this->document);

        return array_slice($names, 0, 100, true);
    }

    /** Top-level frames wide enough to be pages, in canvas order. */
    public function frames(): array
    {
        $frames = [];

        foreach ($this->document['children'] ?? [] as $canvas) {
            $nodes = ($canvas['type'] ?? '') === 'CANVAS' ? ($canvas['children'] ?? []) : [$canvas];

            foreach ($nodes as $node) {
                if (($node['type'] ?? '') === 'FRAME' && ($node['absoluteBoundingBox']['width'] ?? 0) >= 600) {
                    $frames[] = $node;
                }
            }
        }

        if (!$frames && ($this->document['type'] ?? '') === 'FRAME') {
            $frames[] = $this->document;
        }

        return $frames;
    }
}