<?php

namespace app\common\service;

class ShortLinkQrCodeService
{
    private const DATA_CODEWORDS = [1 => 19, 2 => 34, 3 => 55, 4 => 80, 5 => 108];
    private const ECC_CODEWORDS = [1 => 7, 2 => 10, 3 => 15, 4 => 20, 5 => 26];
    private const ALIGNMENT_POSITIONS = [1 => [], 2 => [6, 18], 3 => [6, 22], 4 => [6, 26], 5 => [6, 30]];

    private static array $exp = [];
    private static array $log = [];

    public static function create(string $content, string $code, string $posterUri = '', array $textData = []): array
    {
        $matrix = self::encode($content);
        $svg = self::toSvg($matrix);
        $dirUri = 'uploads/qrcode/shortlink';
        $dir = public_path() . $dirUri;
        if (!is_dir($dir)) {
            mkdir($dir, 0755, true);
        }

        $svgUri = $dirUri . '/' . $code . '.svg';
        $svgPath = public_path() . $svgUri;
        file_put_contents($svgPath, $svg);

        $qrUri = $svgUri;
        $posterCompositeUri = '';
        if (function_exists('imagecreatetruecolor')) {
            $pngUri = $dirUri . '/' . $code . '.png';
            self::toPng($matrix, public_path() . $pngUri);
            $qrUri = $pngUri;

            // 有海报底图时合成完整海报：背景 + 文字层 + 二维码白底
            if ($posterUri !== '' && self::isLocalImage($posterUri)) {
                $posterPath = public_path() . ltrim($posterUri, '/');
                if (is_file($posterPath)) {
                    $compositeUri = $dirUri . '/' . $code . '_poster.png';
                    if (self::composePoster($posterPath, public_path() . $pngUri, public_path() . $compositeUri, $textData)) {
                        $posterCompositeUri = $compositeUri;
                    }
                }
            }
        }

        // uri 用于落库 qrcode 字段：合成海报存在则取合成图，否则取纯二维码
        $uri = $posterCompositeUri !== '' ? $posterCompositeUri : $qrUri;

        return [
            'uri' => $uri,
            'url' => FileService::getFileUrl($uri),
            'qr_uri' => $qrUri,
            'qr_url' => FileService::getFileUrl($qrUri),
            'poster_uri' => $posterCompositeUri,
            'poster_url' => $posterCompositeUri !== '' ? FileService::getFileUrl($posterCompositeUri) : '',
            'data_url' => 'data:image/svg+xml;base64,' . base64_encode($svg),
        ];
    }

    private static function isLocalImage(string $uri): bool
    {
        $ext = strtolower(pathinfo($uri, PATHINFO_EXTENSION));
        return in_array($ext, ['jpg', 'jpeg', 'png'], true);
    }

    /**
     * 合成海报：背景图 + 文字层 + 二维码（带白底圆角）
     */
    private static function composePoster(string $posterPath, string $qrPath, string $outPath, array $textData = []): bool
    {
        $ext = strtolower(pathinfo($posterPath, PATHINFO_EXTENSION));
        $bg = match ($ext) {
            'jpg', 'jpeg' => @imagecreatefromjpeg($posterPath),
            'png' => @imagecreatefrompng($posterPath),
            default => false,
        };
        if (!$bg) {
            return false;
        }

        $qr = @imagecreatefrompng($qrPath);
        if (!$qr) {
            imagedestroy($bg);
            return false;
        }

        $bgW = imagesx($bg);
        $bgH = imagesy($bg);

        // 二维码尺寸：背景宽度的 32%，最小 200，最大 360
        $qrSize = (int) max(200, min(360, $bgW * 0.32));
        $padding = 3;
        $boxSize = $qrSize + $padding * 2;
        // 右下角，距离右边和底部各 5%
        $margin = (int) ($bgW * 0.05);
        $boxX = (int) ($bgW - $boxSize - $margin);
        $boxY = (int) ($bgH - $boxSize - $margin);

        // 文字层：在二维码上方区域绘制
        $font = self::resolveFont();
        if ($font !== null && !empty($textData)) {
            self::drawTextLayer($bg, $font, $bgW, $boxY, $textData);
        }

        // 白色底
        $white = imagecolorallocate($bg, 255, 255, 255);
        imagefilledrectangle($bg, $boxX, $boxY, $boxX + $boxSize, $boxY + $boxSize, $white);

        // 二维码缩放后贴到底框内
        $qrW = imagesx($qr);
        $qrH = imagesy($qr);
        imagecopyresampled(
            $bg,
            $qr,
            $boxX + $padding,
            $boxY + $padding,
            0,
            0,
            $qrSize,
            $qrSize,
            $qrW,
            $qrH
        );

        $ok = imagepng($bg, $outPath);
        imagedestroy($bg);
        imagedestroy($qr);
        return $ok;
    }

    /**
     * 探测可用的中文字体路径，找不到返回 null（此时文字层会被跳过）
     * 注意：不能落到不支持中文的字体（如 DejaVuSans），否则会渲染成豆腐块
     */
    private static function resolveFont(): ?string
    {
        $candidates = [
            public_path() . 'resource/front/cjk.ttf',
            public_path() . 'resource/front/cjk.otf',
            public_path() . 'resource/front/cjk.ttc',
        ];
        foreach ($candidates as $path) {
            if (is_file($path)) {
                return $path;
            }
        }
        return null;
    }

    /**
     * 在海报左上区域绘制文字：标题（加粗+4px）→ 分享内容（+4px）
     * $boundsBottom 为文字区域可使用的底部 y 坐标（即二维码框顶部）
     */
    private static function drawTextLayer($img, string $font, int $bgW, int $boundsBottom, array $textData): void
    {
        $padding = (int) ($bgW * 0.06);
        $maxW = (int) ($bgW - $padding * 2); // 文字区域：全宽（左右留 padding）
        $cursorY = (int) ($bgW * 0.06);

        $textColor = imagecolorallocate($img, 255, 255, 255);
        $shadow = imagecolorallocatealpha($img, 0, 0, 0, 70);

        // 海报标题（居中显示）
        $posterTitle = (string) ($textData['poster_title'] ?? '');
        if ($posterTitle !== '') {
            $size = (int) max(34, $bgW * 0.032 + 18);
            $cursorY = self::drawBoldCenteredLine($img, $font, $size, $textColor, $shadow, $posterTitle, $bgW, $cursorY);
            $cursorY += (int) max(70, $size * 2.0);
        }

        // 分享人
        $nickname = (string) ($textData['sharer']['nickname'] ?? '');
        if ($nickname !== '') {
            $size = (int) max(8, $bgW * 0.022 - 4);
            $cursorY = self::drawBoldLeftLine($img, $font, $size, $textColor, $shadow, '@' . $nickname, $padding, $cursorY);
            $cursorY += (int) max(70, $size * 2.4);
        }

        // 标题：左上角，加粗（双层绘制模拟），字体 +16px
        $title = (string) ($textData['title'] ?? '');
        if ($title !== '') {
            $size = (int) max(32, $bgW * 0.028 + 18);
            $cursorY = self::drawBoldLeftWrappedLines($img, $font, $size, $textColor, $shadow, $title, $maxW, $padding, $cursorY, 3, $boundsBottom);
            $cursorY += (int) max(70, $size * 1.6);
        }

        // 分享内容：在标题下方，字体 +8px，加粗
        $description = (string) ($textData['description'] ?? '');
        if ($description !== '' && $cursorY + 60 < $boundsBottom) {
            $size = (int) max(13, $bgW * 0.02 + 2);
            self::drawBoldLeftWrappedLines($img, $font, $size, $textColor, $shadow, $description, $maxW, $padding, $cursorY, 4, $boundsBottom);
        }
    }

    /**
     * 左对齐单行文字绘制
     */
    private static function drawLeftLine($img, string $font, int $size, int $color, int $shadow, string $text, int $x, int $y): int
    {
        $baseline = $y + $size;
        imagettftext($img, $size, 0, $x + 2, $baseline + 2, $shadow, $font, $text);
        imagettftext($img, $size, 0, $x, $baseline, $color, $font, $text);
        return $baseline;
    }

    /**
     * 左对齐加粗单行文字（三层绘制模拟加粗）
     */
    private static function drawBoldLeftLine($img, string $font, int $size, int $color, int $shadow, string $text, int $x, int $y): int
    {
        $baseline = $y + $size;
        imagettftext($img, $size, 0, $x + 2, $baseline + 2, $shadow, $font, $text);
        imagettftext($img, $size, 0, $x, $baseline, $color, $font, $text);
        imagettftext($img, $size, 0, $x + 1, $baseline, $color, $font, $text);
        imagettftext($img, $size, 0, $x + 2, $baseline, $color, $font, $text);
        return $baseline;
    }

    /**
     * 左对齐换行文字
     */
    private static function drawLeftWrappedLines($img, string $font, int $size, int $color, int $shadow, string $text, int $maxW, int $padding, int $y, int $maxLines, int $maxBottom): int
    {
        $lines = self::wrapByPixel($text, $font, $size, $maxW, $maxLines);
        $lineHeight = (int) ($size * 1.4);
        foreach ($lines as $line) {
            if ($y + $lineHeight > $maxBottom) {
                break;
            }
            $y = self::drawLeftLine($img, $font, $size, $color, $shadow, $line, $padding, $y);
            $y += (int) ($size * 0.4);
        }
        return $y;
    }

    /**
     * 左对齐加粗换行文字
     */
    private static function drawBoldLeftWrappedLines($img, string $font, int $size, int $color, int $shadow, string $text, int $maxW, int $padding, int $y, int $maxLines, int $maxBottom): int
    {
        $lines = self::wrapByPixel($text, $font, $size, $maxW, $maxLines);
        $lineHeight = (int) ($size * 1.6);
        foreach ($lines as $line) {
            if ($y + $lineHeight > $maxBottom) {
                break;
            }
            $y = self::drawBoldLeftLine($img, $font, $size, $color, $shadow, $line, $padding, $y);
            $y += (int) ($size * 1.6);
        }
        return $y;
    }

    private static function drawCenteredLine($img, string $font, int $size, int $color, int $shadow, string $text, int $bgW, int $y): int
    {
        $box = imagettfbbox($size, 0, $font, $text);
        $w = abs($box[2] - $box[0]);
        $x = (int) (($bgW - $w) / 2);
        $baseline = $y + $size;
        imagettftext($img, $size, 0, $x + 2, $baseline + 2, $shadow, $font, $text);
        imagettftext($img, $size, 0, $x, $baseline, $color, $font, $text);
        return $baseline;
    }

    /**
     * 居中加粗单行文字（三层绘制模拟加粗）
     */
    private static function drawBoldCenteredLine($img, string $font, int $size, int $color, int $shadow, string $text, int $bgW, int $y): int
    {
        $box = imagettfbbox($size, 0, $font, $text);
        $w = abs($box[2] - $box[0]);
        $x = (int) (($bgW - $w) / 2);
        $baseline = $y + $size;
        imagettftext($img, $size, 0, $x + 2, $baseline + 2, $shadow, $font, $text);
        imagettftext($img, $size, 0, $x, $baseline, $color, $font, $text);
        imagettftext($img, $size, 0, $x + 1, $baseline, $color, $font, $text);
        imagettftext($img, $size, 0, $x + 2, $baseline, $color, $font, $text);
        return $baseline;
    }

    private static function drawWrappedLines($img, string $font, int $size, int $color, int $shadow, string $text, int $maxW, int $bgW, int $y, int $maxLines, int $maxBottom): int
    {
        $lines = self::wrapByPixel($text, $font, $size, $maxW, $maxLines);
        $lineHeight = (int) ($size * 1.4);
        foreach ($lines as $line) {
            if ($y + $lineHeight > $maxBottom) {
                break;
            }
            $y = self::drawCenteredLine($img, $font, $size, $color, $shadow, $line, $bgW, $y);
            $y += (int) ($size * 0.4);
        }
        return $y;
    }

    /**
     * 按像素宽度对文本断行，超过 $maxLines 时末尾追加省略号
     */
    private static function wrapByPixel(string $text, string $font, int $size, int $maxW, int $maxLines): array
    {
        $chars = preg_split('//u', $text, -1, PREG_SPLIT_NO_EMPTY) ?: [];
        $lines = [];
        $current = '';
        foreach ($chars as $ch) {
            $candidate = $current . $ch;
            $box = imagettfbbox($size, 0, $font, $candidate);
            $w = abs($box[2] - $box[0]);
            if ($w > $maxW) {
                if ($current !== '') {
                    $lines[] = $current;
                }
                $current = $ch;
                if (count($lines) >= $maxLines) {
                    $lastIdx = count($lines) - 1;
                    $lines[$lastIdx] = mb_substr($lines[$lastIdx], 0, max(0, mb_strlen($lines[$lastIdx]) - 1)) . '…';
                    return $lines;
                }
            } else {
                $current = $candidate;
            }
        }
        if ($current !== '') {
            $lines[] = $current;
        }
        return array_slice($lines, 0, $maxLines);
    }

    private static function toPng(array $matrix, string $path): void
    {
        $quiet = 1;
        $scale = 10;
        $size = count($matrix);
        $imageSize = ($size + $quiet * 2) * $scale;
        $image = imagecreatetruecolor($imageSize, $imageSize);
        $white = imagecolorallocate($image, 255, 255, 255);
        $black = imagecolorallocate($image, 0, 0, 0);
        imagefill($image, 0, 0, $white);

        for ($y = 0; $y < $size; $y++) {
            for ($x = 0; $x < $size; $x++) {
                if ($matrix[$y][$x]) {
                    imagefilledrectangle(
                        $image,
                        ($x + $quiet) * $scale,
                        ($y + $quiet) * $scale,
                        ($x + $quiet + 1) * $scale - 1,
                        ($y + $quiet + 1) * $scale - 1,
                        $black
                    );
                }
            }
        }

        imagepng($image, $path);
        imagedestroy($image);
    }

    public static function get(string $content, string $code): array
    {
        $pngUri = 'uploads/qrcode/shortlink/' . $code . '.png';
        $svgUri = 'uploads/qrcode/shortlink/' . $code . '.svg';
        if (is_file(public_path() . $pngUri)) {
            return [
                'uri' => $pngUri,
                'url' => FileService::getFileUrl($pngUri),
                'data_url' => '',
            ];
        }
        if (is_file(public_path() . $svgUri)) {
            return [
                'uri' => $svgUri,
                'url' => FileService::getFileUrl($svgUri),
                'data_url' => '',
            ];
        }
        return self::create($content, $code);
    }

    private static function encode(string $content): array
    {
        $version = self::getVersion(strlen($content));
        $data = self::buildData($content, $version);
        $codewords = array_merge($data, self::reedSolomonRemainder($data, self::ECC_CODEWORDS[$version]));
        $size = 17 + 4 * $version;
        $modules = array_fill(0, $size, array_fill(0, $size, false));
        $isFunction = array_fill(0, $size, array_fill(0, $size, false));

        self::drawFunctionPatterns($modules, $isFunction, $version);
        self::drawCodewords($modules, $isFunction, $codewords);
        self::applyMask($modules, $isFunction);
        self::drawFormatBits($modules, $isFunction);

        return $modules;
    }

    private static function getVersion(int $length): int
    {
        foreach (self::DATA_CODEWORDS as $version => $capacity) {
            if ($length <= $capacity) {
                return $version;
            }
        }
        return 5;
    }

    private static function buildData(string $content, int $version): array
    {
        $bits = [];
        self::appendBits($bits, 0x4, 4);
        self::appendBits($bits, strlen($content), 8);
        foreach (unpack('C*', $content) as $byte) {
            self::appendBits($bits, $byte, 8);
        }

        $capacity = self::DATA_CODEWORDS[$version] * 8;
        self::appendBits($bits, 0, min(4, $capacity - count($bits)));
        while (count($bits) % 8 !== 0) {
            $bits[] = 0;
        }

        $data = self::bitsToBytes($bits);
        for ($pad = 0xec; count($data) < self::DATA_CODEWORDS[$version]; $pad ^= 0xfd) {
            $data[] = $pad;
        }

        return $data;
    }

    private static function appendBits(array &$bits, int $value, int $length): void
    {
        for ($i = $length - 1; $i >= 0; $i--) {
            $bits[] = ($value >> $i) & 1;
        }
    }

    private static function bitsToBytes(array $bits): array
    {
        $bytes = [];
        for ($i = 0; $i < count($bits); $i += 8) {
            $byte = 0;
            for ($j = 0; $j < 8; $j++) {
                $byte = ($byte << 1) | ($bits[$i + $j] ?? 0);
            }
            $bytes[] = $byte;
        }
        return $bytes;
    }

    private static function initGalois(): void
    {
        if (self::$exp) {
            return;
        }

        self::$exp = array_fill(0, 512, 0);
        self::$log = array_fill(0, 256, 0);
        $x = 1;
        for ($i = 0; $i < 255; $i++) {
            self::$exp[$i] = $x;
            self::$log[$x] = $i;
            $x <<= 1;
            if ($x & 0x100) {
                $x ^= 0x11d;
            }
        }
        for ($i = 255; $i < 512; $i++) {
            self::$exp[$i] = self::$exp[$i - 255];
        }
    }

    private static function multiply(int $x, int $y): int
    {
        if ($x === 0 || $y === 0) {
            return 0;
        }
        self::initGalois();
        return self::$exp[self::$log[$x] + self::$log[$y]];
    }

    private static function reedSolomonDivisor(int $degree): array
    {
        self::initGalois();
        $result = [1];
        for ($i = 0; $i < $degree; $i++) {
            $next = array_fill(0, count($result) + 1, 0);
            foreach ($result as $j => $coefficient) {
                $next[$j] ^= self::multiply($coefficient, 1);
                $next[$j + 1] ^= self::multiply($coefficient, self::$exp[$i]);
            }
            $result = $next;
        }
        return $result;
    }

    private static function reedSolomonRemainder(array $data, int $degree): array
    {
        $divisor = self::reedSolomonDivisor($degree);
        $result = array_fill(0, $degree, 0);
        foreach ($data as $byte) {
            $factor = $byte ^ $result[0];
            array_shift($result);
            $result[] = 0;
            for ($i = 0; $i < $degree; $i++) {
                $result[$i] ^= self::multiply($divisor[$i + 1], $factor);
            }
        }
        return $result;
    }

    private static function drawFunctionPatterns(array &$modules, array &$isFunction, int $version): void
    {
        $size = count($modules);
        self::drawFinderPattern($modules, $isFunction, 3, 3);
        self::drawFinderPattern($modules, $isFunction, $size - 4, 3);
        self::drawFinderPattern($modules, $isFunction, 3, $size - 4);

        for ($i = 8; $i < $size - 8; $i++) {
            self::setFunctionModule($modules, $isFunction, 6, $i, $i % 2 === 0);
            self::setFunctionModule($modules, $isFunction, $i, 6, $i % 2 === 0);
        }

        foreach (self::ALIGNMENT_POSITIONS[$version] as $x) {
            foreach (self::ALIGNMENT_POSITIONS[$version] as $y) {
                if (!$isFunction[$y][$x]) {
                    self::drawAlignmentPattern($modules, $isFunction, $x, $y);
                }
            }
        }

        for ($i = 0; $i <= 8; $i++) {
            self::setFunctionModule($modules, $isFunction, 8, $i, false);
            self::setFunctionModule($modules, $isFunction, $i, 8, false);
        }
        for ($i = 0; $i < 8; $i++) {
            self::setFunctionModule($modules, $isFunction, $size - 1 - $i, 8, false);
            self::setFunctionModule($modules, $isFunction, 8, $size - 1 - $i, false);
        }
        self::setFunctionModule($modules, $isFunction, 8, $size - 8, true);
    }

    private static function drawFinderPattern(array &$modules, array &$isFunction, int $x, int $y): void
    {
        $size = count($modules);
        for ($dy = -4; $dy <= 4; $dy++) {
            for ($dx = -4; $dx <= 4; $dx++) {
                $xx = $x + $dx;
                $yy = $y + $dy;
                if ($xx < 0 || $xx >= $size || $yy < 0 || $yy >= $size) {
                    continue;
                }
                $distance = max(abs($dx), abs($dy));
                self::setFunctionModule($modules, $isFunction, $xx, $yy, $distance !== 2 && $distance !== 4);
            }
        }
    }

    private static function drawAlignmentPattern(array &$modules, array &$isFunction, int $x, int $y): void
    {
        for ($dy = -2; $dy <= 2; $dy++) {
            for ($dx = -2; $dx <= 2; $dx++) {
                self::setFunctionModule($modules, $isFunction, $x + $dx, $y + $dy, max(abs($dx), abs($dy)) !== 1);
            }
        }
    }

    private static function setFunctionModule(array &$modules, array &$isFunction, int $x, int $y, bool $dark): void
    {
        $modules[$y][$x] = $dark;
        $isFunction[$y][$x] = true;
    }

    private static function drawCodewords(array &$modules, array $isFunction, array $codewords): void
    {
        $size = count($modules);
        $bitIndex = 0;
        $totalBits = count($codewords) * 8;
        $upward = true;
        for ($right = $size - 1; $right >= 1; $right -= 2) {
            if ($right === 6) {
                $right--;
            }
            for ($vert = 0; $vert < $size; $vert++) {
                $y = $upward ? $size - 1 - $vert : $vert;
                for ($j = 0; $j < 2; $j++) {
                    $x = $right - $j;
                    if ($isFunction[$y][$x]) {
                        continue;
                    }
                    $dark = false;
                    if ($bitIndex < $totalBits) {
                        $dark = (($codewords[intdiv($bitIndex, 8)] >> (7 - ($bitIndex % 8))) & 1) !== 0;
                    }
                    $modules[$y][$x] = $dark;
                    $bitIndex++;
                }
            }
            $upward = !$upward;
        }
    }

    private static function applyMask(array &$modules, array $isFunction): void
    {
        $size = count($modules);
        for ($y = 0; $y < $size; $y++) {
            for ($x = 0; $x < $size; $x++) {
                if (!$isFunction[$y][$x] && (($x + $y) % 2 === 0)) {
                    $modules[$y][$x] = !$modules[$y][$x];
                }
            }
        }
    }

    private static function drawFormatBits(array &$modules, array &$isFunction): void
    {
        $size = count($modules);
        $bits = self::getFormatBits();
        for ($i = 0; $i <= 5; $i++) {
            self::setFunctionModule($modules, $isFunction, 8, $i, self::getBit($bits, $i));
        }
        self::setFunctionModule($modules, $isFunction, 8, 7, self::getBit($bits, 6));
        self::setFunctionModule($modules, $isFunction, 8, 8, self::getBit($bits, 7));
        self::setFunctionModule($modules, $isFunction, 7, 8, self::getBit($bits, 8));
        for ($i = 9; $i < 15; $i++) {
            self::setFunctionModule($modules, $isFunction, 14 - $i, 8, self::getBit($bits, $i));
        }
        for ($i = 0; $i < 8; $i++) {
            self::setFunctionModule($modules, $isFunction, $size - 1 - $i, 8, self::getBit($bits, $i));
        }
        for ($i = 8; $i < 15; $i++) {
            self::setFunctionModule($modules, $isFunction, 8, $size - 15 + $i, self::getBit($bits, $i));
        }
        self::setFunctionModule($modules, $isFunction, 8, $size - 8, true);
    }

    private static function getFormatBits(): int
    {
        $data = 1 << 3;
        $remainder = $data << 10;
        for ($i = 14; $i >= 10; $i--) {
            if ((($remainder >> $i) & 1) !== 0) {
                $remainder ^= 0x537 << ($i - 10);
            }
        }
        return (($data << 10) | $remainder) ^ 0x5412;
    }

    private static function getBit(int $value, int $index): bool
    {
        return (($value >> $index) & 1) !== 0;
    }

    private static function toSvg(array $matrix): string
    {
        $quiet = 1;
        $size = count($matrix);
        $viewBox = $size + $quiet * 2;
        $path = '';
        for ($y = 0; $y < $size; $y++) {
            for ($x = 0; $x < $size; $x++) {
                if ($matrix[$y][$x]) {
                    $path .= 'M' . ($x + $quiet) . ',' . ($y + $quiet) . 'h1v1h-1z';
                }
            }
        }

        return '<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 ' . $viewBox . ' ' . $viewBox . '" width="360" height="360" shape-rendering="crispEdges"><rect width="100%" height="100%" fill="#fff"/><path d="' . $path . '" fill="#000"/></svg>';
    }
}