<?php

namespace app\support;

class ReportPdfGenerator
{
    public function generate(array $payload): string
    {
        $heroImage = $this->normalizeHeroImage($payload['hero_image'] ?? null);
        $content = $this->buildContentStream($payload, $heroImage);
        $resources = '<< /Font << /F1 5 0 R >>';
        if ($heroImage) {
            $resources .= ' /XObject << /Im1 7 0 R >>';
        }
        $resources .= ' >>';

        $objects = [
            1 => '<< /Type /Catalog /Pages 2 0 R >>',
            2 => '<< /Type /Pages /Kids [3 0 R] /Count 1 >>',
            3 => sprintf('<< /Type /Page /Parent 2 0 R /MediaBox [0 0 595 842] /Resources %s /Contents 4 0 R >>', $resources),
            4 => sprintf("<< /Length %d >>\nstream\n%s\nendstream", strlen($content), $content),
            5 => '<< /Type /Font /Subtype /Type0 /BaseFont /STSong-Light /Encoding /UniGB-UCS2-H /DescendantFonts [6 0 R] >>',
            6 => '<< /Type /Font /Subtype /CIDFontType0 /BaseFont /STSong-Light /CIDSystemInfo << /Registry (Adobe) /Ordering (GB1) /Supplement 4 >> /DW 1000 >>',
        ];
        if ($heroImage) {
            $objects[7] = sprintf(
                "<< /Type /XObject /Subtype /Image /Width %d /Height %d /ColorSpace /DeviceRGB /BitsPerComponent 8 /Filter /DCTDecode /Length %d >>\nstream\n%s\nendstream",
                $heroImage['width'],
                $heroImage['height'],
                strlen($heroImage['data']),
                $heroImage['data']
            );
        }

        return $this->renderPdf($objects);
    }

    private function buildContentStream(array $payload, ?array $heroImage): string
    {
        $title = $this->normalizeText((string)($payload['report_title'] ?? '鉴定报告'));
        $serviceProviderText = $this->normalizeText((string)($payload['service_provider_text'] ?? '-'));
        $institutionName = $this->normalizeText((string)($payload['institution_name'] ?? '-'));
        $reportNo = $this->normalizeText((string)($payload['report_no'] ?? '-'));
        $publishTime = $this->normalizeText((string)($payload['publish_time'] ?? '-'));
        $productName = $this->normalizeText((string)($payload['product_name'] ?? '-'));
        $verifyInfo = $this->normalizeText((string)($payload['verify_info'] ?? '-'));
        $riskNotice = $this->normalizeText((string)($payload['risk_notice_text'] ?? '-'));
        $productItems = is_array($payload['product_items'] ?? null) ? $payload['product_items'] : [];
        $heroImageLabels = is_array($payload['hero_image_labels'] ?? null) ? $payload['hero_image_labels'] : [];

        $blocks = [];
        $y = 790;

        $blocks[] = $this->textBlock($title, 52, $y, 20);
        $y -= 32;
        $blocks[] = $this->textBlock('正式报告凭证，请以报告页防伪查询结果为准。', 52, $y, 10);
        $y -= 30;

        foreach ([
            sprintf('报告编号：%s', $reportNo),
            sprintf('检测机构：%s', $institutionName),
            sprintf('出具时间：%s', $publishTime),
            sprintf('服务类型：%s', $serviceProviderText),
        ] as $line) {
            $blocks[] = $this->textBlock($line, 52, $y, 12);
            $y -= 22;
        }

        if ($heroImage) {
            $maxWidth = 230;
            $maxHeight = 150;
            $scale = min($maxWidth / $heroImage['width'], $maxHeight / $heroImage['height'], 1);
            $drawWidth = (int)round($heroImage['width'] * $scale);
            $drawHeight = (int)round($heroImage['height'] * $scale);
            $y -= $drawHeight + 6;
            $blocks[] = $this->imageBlock('Im1', 52, $y, $drawWidth, $drawHeight);
            $y -= 24;
        } elseif ($heroImageLabels) {
            foreach ($this->wrapText('鉴定图片：' . implode('、', array_slice($heroImageLabels, 0, 3)), 34) as $line) {
                $blocks[] = $this->textBlock($line, 52, $y, 11);
                $y -= 18;
            }
            $y -= 8;
        }

        $y -= 8;
        $blocks[] = $this->textBlock('产品信息', 52, $y, 15);
        $y -= 24;
        $blocks[] = $this->textBlock(sprintf('产品名称：%s', $productName), 52, $y, 12);
        $y -= 22;

        foreach ($productItems as $item) {
            if (!is_array($item)) {
                continue;
            }
            $label = $this->normalizeText((string)($item['label'] ?? ''));
            if ($label === '') {
                continue;
            }
            $value = $this->normalizeText((string)($item['value'] ?? '-'));
            $remark = $this->normalizeText((string)($item['remark'] ?? ''));
            foreach ($this->wrapText(sprintf('%s：%s', $label, $value !== '' ? $value : '-'), 34) as $line) {
                $blocks[] = $this->textBlock($line, 52, $y, 11);
                $y -= 18;
            }
            if ($remark !== '') {
                foreach ($this->wrapText('说明：' . $remark, 34) as $line) {
                    $blocks[] = $this->textBlock($line, 72, $y, 10);
                    $y -= 16;
                }
            }
            $y -= 2;
        }

        $y -= 6;
        $blocks[] = $this->textBlock(sprintf('验真信息：%s', $verifyInfo), 52, $y, 11);
        $y -= 22;

        $y -= 8;
        foreach ($this->wrapText('风险说明：' . $riskNotice, 30) as $line) {
            $blocks[] = $this->textBlock($line, 52, $y, 10);
            $y -= 17;
        }

        if ($y > 48) {
            $blocks[] = $this->textBlock('安心检验鉴定平台', 52, 42, 9);
        }

        return implode("\n", array_filter($blocks));
    }

    private function normalizeHeroImage(mixed $image): ?array
    {
        if (!is_array($image)) {
            return null;
        }

        $data = (string)($image['data'] ?? '');
        $width = (int)($image['width'] ?? 0);
        $height = (int)($image['height'] ?? 0);
        if ($data === '' || $width <= 0 || $height <= 0) {
            return null;
        }

        return [
            'data' => $data,
            'width' => $width,
            'height' => $height,
        ];
    }

    private function wrapText(string $text, int $maxUnits): array
    {
        $normalized = $this->normalizeText($text);
        if ($normalized === '') {
            return ['-'];
        }

        $chars = preg_split('//u', $normalized, -1, PREG_SPLIT_NO_EMPTY) ?: [];
        $lines = [];
        $current = '';
        $width = 0.0;

        foreach ($chars as $char) {
            $charWidth = strlen($char) === 1 && ord($char) < 128 ? 0.5 : 1.0;
            if ($current !== '' && $width + $charWidth > $maxUnits) {
                $lines[] = $current;
                $current = '';
                $width = 0.0;
            }
            $current .= $char;
            $width += $charWidth;
        }

        if ($current !== '') {
            $lines[] = $current;
        }

        return $lines ?: ['-'];
    }

    private function textBlock(string $text, int $x, int $y, int $fontSize): string
    {
        if ($text === '') {
            return '';
        }

        return sprintf(
            "BT\n/F1 %d Tf\n1 0 0 1 %d %d Tm\n<%s> Tj\nET",
            $fontSize,
            $x,
            $y,
            strtoupper(bin2hex(mb_convert_encoding($text, 'UCS-2BE', 'UTF-8')))
        );
    }

    private function imageBlock(string $name, int $x, int $y, int $width, int $height): string
    {
        return sprintf("q\n%d 0 0 %d %d %d cm\n/%s Do\nQ", $width, $height, $x, $y, $name);
    }

    private function normalizeText(string $text): string
    {
        $text = trim(str_replace(["\r\n", "\r", "\n", "\t"], [' ', ' ', ' ', ' '], $text));
        return preg_replace('/\s+/u', ' ', $text) ?: '';
    }

    private function renderPdf(array $objects): string
    {
        $pdf = "%PDF-1.4\n%\xE2\xE3\xCF\xD3\n";
        $offsets = [];

        foreach ($objects as $id => $body) {
            $offsets[$id] = strlen($pdf);
            $pdf .= sprintf("%d 0 obj\n%s\nendobj\n", $id, $body);
        }

        $xrefPosition = strlen($pdf);
        $pdf .= sprintf("xref\n0 %d\n", count($objects) + 1);
        $pdf .= "0000000000 65535 f \n";

        foreach ($objects as $id => $_body) {
            $pdf .= sprintf("%010d 00000 n \n", $offsets[$id]);
        }

        $pdf .= sprintf(
            "trailer\n<< /Size %d /Root 1 0 R >>\nstartxref\n%d\n%%%%EOF",
            count($objects) + 1,
            $xrefPosition
        );

        return $pdf;
    }
}