<?php

namespace app\support;

class ReportPdfGenerator
{
    public function generate(array $payload): string
    {
        $content = $this->buildContentStream($payload);

        $objects = [
            1 => '<< /Type /Catalog /Pages 2 0 R >>',
            2 => '<< /Type /Pages /Kids [3 0 R] /Count 1 >>',
            3 => '<< /Type /Page /Parent 2 0 R /MediaBox [0 0 595 842] /Resources << /Font << /F1 5 0 R >> >> /Contents 4 0 R >>',
            4 => sprintf("<< /Length %d >>\nstream\n%s\nendstream", strlen($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 >>',
        ];

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

    private function buildContentStream(array $payload): 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'] ?? '-'));
        $resultText = $this->normalizeText((string)($payload['result_text'] ?? '-'));
        $resultDesc = $this->normalizeText((string)($payload['result_desc'] ?? '-'));
        $productName = $this->normalizeText((string)($payload['product_name'] ?? '-'));
        $categoryBrand = $this->normalizeText((string)($payload['category_brand'] ?? '-'));
        $specInfo = $this->normalizeText((string)($payload['spec_info'] ?? '-'));
        $appraisers = $this->normalizeText((string)($payload['appraisers'] ?? '-'));
        $conditionGrade = $this->normalizeText((string)($payload['condition_grade'] ?? '-'));
        $valuationRange = $this->normalizeText((string)($payload['valuation_range'] ?? '-'));
        $verifyInfo = $this->normalizeText((string)($payload['verify_info'] ?? '-'));
        $riskNotice = $this->normalizeText((string)($payload['risk_notice_text'] ?? '-'));

        $blocks = [];
        $y = 790;

        $blocks[] = $this->textBlock($title, 52, $y, 20);
        $y -= 32;
        $blocks[] = $this->textBlock('正式报告凭证，请以编号验真结果为准。', 52, $y, 10);
        $y -= 30;

        foreach ([
            sprintf('报告编号：%s', $reportNo),
            sprintf('出具机构：%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;
        }

        $y -= 8;
        $blocks[] = $this->textBlock(sprintf('鉴定结论：%s', $resultText), 52, $y, 16);
        $y -= 26;

        foreach ($this->wrapText('结果说明：' . $resultDesc, 30) as $line) {
            $blocks[] = $this->textBlock($line, 52, $y, 11);
            $y -= 18;
        }

        $y -= 8;
        foreach ([
            sprintf('商品名称：%s', $productName),
            sprintf('品类 / 品牌：%s', $categoryBrand),
            sprintf('颜色 / 规格：%s', $specInfo),
            sprintf('鉴定师：%s', $appraisers),
            sprintf('成色评级：%s', $conditionGrade),
            sprintf('估值区间：%s', $valuationRange),
            sprintf('验真信息：%s', $verifyInfo),
        ] as $line) {
            $blocks[] = $this->textBlock($line, 52, $y, 11);
            $y -= 20;
        }

        $y -= 8;
        foreach ($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('安心验鉴定平台', 52, 42, 9);
        }

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

    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 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;
    }
}