<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Service;

use TYPO3\CMS\Core\Core\Environment;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Generates 1200×630 OG images using the PHP GD library.
 */
final class OgImageGeneratorService
{
    private const OG_WIDTH  = 1200;
    private const OG_HEIGHT = 630;

    /** Where generated images are stored relative to the web root */
    private const SAVE_DIR = 'fileadmin/og-images/';

    /** Font paths (ordered by preference) */
    private const FONT_BOLD = '/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf';
    private const FONT_REG  = '/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf';

    private const PADDING = 80;

    // ──────────────────────────────────────────────────────────────────
    // Public API
    // ──────────────────────────────────────────────────────────────────

    /**
     * Generate and save an OG image.
     *
     * @return array{0: bool, 1: string, 2: string}  [success, message, publicPath]
     */
    public function generate(array $opts): array
    {
        try {
            $gd = $this->buildImage($opts);

            $saveDir = Environment::getPublicPath() . '/' . self::SAVE_DIR;
            GeneralUtility::mkdir_deep($saveDir);

            $hashSeed = json_encode($opts, JSON_THROW_ON_ERROR) . microtime(true) . random_int(1000, 9999);
            $fileName = 'og-' . substr(sha1($hashSeed), 0, 12) . '.' . ($opts['output_format'] ?? 'jpg');
            $fullPath  = $saveDir . $fileName;

            $this->saveImage($gd, $fullPath, $opts['output_format'] ?? 'jpg', (int)($opts['output_quality'] ?? 90));
            imagedestroy($gd);

            $publicUrl = '/' . self::SAVE_DIR . $fileName;

            return [true, 'Image saved: ' . $publicUrl, $publicUrl];
        } catch (\Throwable $e) {
            return [false, 'Error: ' . $e->getMessage(), ''];
        }
    }

    /**
     * Generate a base64 data-URI preview (no file write).
     *
     * @return array{0: bool, 1: string, 2: string}  [success, message, dataUri]
     */
    public function generatePreview(array $opts): array
    {
        try {
            $gd = $this->buildImage($opts);

            ob_start();
            imagepng($gd);
            $raw = ob_get_clean();
            imagedestroy($gd);

            return [true, 'OK', 'data:image/png;base64,' . base64_encode($raw)];
        } catch (\Throwable $e) {
            return [false, $e->getMessage(), ''];
        }
    }

    /**
     * Return list of previously generated images in the save dir.
     */
    public function getSavedImages(): array
    {
        $dir = Environment::getPublicPath() . '/' . self::SAVE_DIR;
        if (!is_dir($dir)) {
            return [];
        }

        $files = glob($dir . '*.{jpg,jpeg,png}', GLOB_BRACE) ?: [];
        usort($files, static fn($a, $b) => filemtime($b) <=> filemtime($a));

        return array_map(static fn($f) => [
            'path'    => '/' . self::SAVE_DIR . basename($f),
            'name'    => basename($f),
            'created' => date('Y-m-d H:i', filemtime($f)),
        ], array_slice($files, 0, 20));
    }

    /**
     * Return selectable background images from fileadmin/og-backgrounds/.
     */
    public function getBackgroundImages(): array
    {
        $dir = Environment::getPublicPath() . '/fileadmin/og-backgrounds/';
        if (!is_dir($dir)) {
            return [];
        }

        $files = glob($dir . '*.{jpg,jpeg,png,webp}', GLOB_BRACE) ?: [];

        return array_map(static fn($f) => [
            'path'  => '/fileadmin/og-backgrounds/' . basename($f),
            'label' => basename($f),
        ], $files);
    }

    // ──────────────────────────────────────────────────────────────────
    // Core image builder
    // ──────────────────────────────────────────────────────────────────

    /** @return \GdImage */
    private function buildImage(array $opts): \GdImage
    {
        $canvas = imagecreatetruecolor(self::OG_WIDTH, self::OG_HEIGHT);
        if ($canvas === false) {
            throw new \RuntimeException('imagecreatetruecolor failed – GD not available.');
        }

        // Enable alpha blending
        imagealphablending($canvas, true);
        imagesavealpha($canvas, true);

        // 1. Background
        $this->drawBackground($canvas, $opts);

        // 2. Optional dark overlay when bg_image is set
        if (!empty($opts['bg_image']) && ($opts['bg_type'] ?? '') === 'image') {
            $opacity = max(0, min(100, (int)($opts['overlay_opacity'] ?? 40)));
            $this->drawOverlay($canvas, $opacity);
        }

        // 3. Label / badge
        if (!empty(trim($opts['label_text'] ?? ''))) {
            $this->drawLabel($canvas, $opts);
        }

        // 4. Title
        if (!empty(trim($opts['title'] ?? ''))) {
            $this->drawTitle($canvas, $opts);
        }

        // 5. Subtitle
        if (!empty(trim($opts['subtitle'] ?? ''))) {
            $this->drawSubtitle($canvas, $opts);
        }

        // 6. Logo (optional)
        if (!empty($opts['logo_path'])) {
            $this->drawLogo($canvas, $opts['logo_path']);
        }

        return $canvas;
    }

    // ──────────────────────────────────────────────────────────────────
    // Drawing helpers
    // ──────────────────────────────────────────────────────────────────

    private function drawBackground(\GdImage $canvas, array $opts): void
    {
        $bgType = $opts['bg_type'] ?? 'color';

        if ($bgType === 'image' && !empty($opts['bg_image'])) {
            $imagePath = $this->resolvePath($opts['bg_image']);
            $src = $this->loadImageFromPath($imagePath);

            if ($src !== null) {
                imagecopyresampled(
                    $canvas, $src,
                    0, 0, 0, 0,
                    self::OG_WIDTH, self::OG_HEIGHT,
                    imagesx($src), imagesy($src)
                );
                imagedestroy($src);
                return;
            }
        }

        // Solid colour fallback
        $hex = ltrim($opts['bg_color'] ?? '#1a1a2e', '#');
        [$r, $g, $b] = $this->hexToRgb($hex);
        $bg = imagecolorallocate($canvas, $r, $g, $b);
        imagefilledrectangle($canvas, 0, 0, self::OG_WIDTH - 1, self::OG_HEIGHT - 1, $bg);
    }

    private function drawOverlay(\GdImage $canvas, int $opacityPercent): void
    {
        // opacity 0 = fully transparent overlay, 100 = solid black
        $alpha = (int)round(127 - ($opacityPercent / 100 * 127));
        $color = imagecolorallocatealpha($canvas, 0, 0, 0, $alpha);
        imagefilledrectangle($canvas, 0, 0, self::OG_WIDTH - 1, self::OG_HEIGHT - 1, $color);
    }

    private function drawLabel(\GdImage $canvas, array $opts): void
    {
        $text     = strtoupper(trim($opts['label_text'] ?? 'LABEL'));
        $fontSize = 22;
        $font     = $this->fontPath(true);

        $padding  = 14;
        $bbox     = imagettfbbox($fontSize, 0, $font, $text);
        $textW    = abs($bbox[4] - $bbox[0]);
        $textH    = abs($bbox[5] - $bbox[1]);
        $boxW     = $textW + $padding * 2;
        $boxH     = $textH + $padding;

        $position = $opts['label_position'] ?? 'top-left';
        [$bx, $by] = $this->labelCoords($position, $boxW, $boxH);

        [$br, $bg, $bb] = $this->hexToRgb(ltrim($opts['label_bg_color'] ?? '#e63946', '#'));
        $bgColor = imagecolorallocate($canvas, $br, $bg, $bb);
        imagefilledrectangle($canvas, $bx, $by, $bx + $boxW, $by + $boxH, $bgColor);

        [$tr, $tg, $tb] = $this->hexToRgb(ltrim($opts['label_text_color'] ?? '#ffffff', '#'));
        $textColor = imagecolorallocate($canvas, $tr, $tg, $tb);
        imagettftext($canvas, $fontSize, 0, $bx + $padding, $by + $textH + (int)($padding / 2), $textColor, $font, $text);
    }

    private function drawTitle(\GdImage $canvas, array $opts): void
    {
        $text     = trim($opts['title'] ?? '');
        $fontSize = max(20, min(120, (int)($opts['title_size'] ?? 64)));
        $font     = $this->fontPath(true);
        $maxWidth = self::OG_WIDTH - self::PADDING * 2;

        [$r, $g, $b] = $this->hexToRgb(ltrim($opts['title_color'] ?? '#ffffff', '#'));
        $color = imagecolorallocate($canvas, $r, $g, $b);

        $lines   = $this->wrapText($text, $fontSize, $font, $maxWidth);
        $lineH   = (int)($fontSize * 1.3);
        $startY  = $this->titleStartY($opts, count($lines), $lineH, $fontSize);

        foreach ($lines as $i => $line) {
            $y = $startY + $i * $lineH;
            imagettftext($canvas, $fontSize, 0, self::PADDING, $y, $color, $font, $line);
        }
    }

    private function drawSubtitle(\GdImage $canvas, array $opts): void
    {
        $text     = trim($opts['subtitle'] ?? '');
        $fontSize = max(14, min(80, (int)($opts['subtitle_size'] ?? 32)));
        $font     = $this->fontPath(false);
        $maxWidth = self::OG_WIDTH - self::PADDING * 2;

        [$r, $g, $b] = $this->hexToRgb(ltrim($opts['subtitle_color'] ?? '#cccccc', '#'));
        $color = imagecolorallocate($canvas, $r, $g, $b);

        $lines  = $this->wrapText($text, $fontSize, $font, $maxWidth);
        $lineH  = (int)($fontSize * 1.4);
        $startY = $this->subtitleStartY($opts, $fontSize);

        foreach ($lines as $i => $line) {
            $y = $startY + $i * $lineH;
            imagettftext($canvas, $fontSize, 0, self::PADDING, $y, $color, $font, $line);
        }
    }

    private function drawLogo(\GdImage $canvas, string $logoPath): void
    {
        $path = $this->resolvePath($logoPath);
        $src  = $this->loadImageFromPath($path);
        if ($src === null) {
            return;
        }

        $logoW = 200;
        $logoH = (int)(imagesy($src) * ($logoW / imagesx($src)));
        $x     = self::OG_WIDTH  - self::PADDING - $logoW;
        $y     = self::OG_HEIGHT - self::PADDING - $logoH;

        imagecopyresampled($canvas, $src, $x, $y, 0, 0, $logoW, $logoH, imagesx($src), imagesy($src));
        imagedestroy($src);
    }

    // ──────────────────────────────────────────────────────────────────
    // Layout helpers
    // ──────────────────────────────────────────────────────────────────

    private function titleStartY(array $opts, int $lineCount, int $lineH, int $fontSize): int
    {
        $totalH  = $lineCount * $lineH;
        $subH    = empty(trim($opts['subtitle'] ?? '')) ? 0 : (int)($opts['subtitle_size'] ?? 32) + 20;
        $block   = $totalH + $subH;
        $center  = (int)((self::OG_HEIGHT - $block) / 2);
        // nudge up slightly so text block feels centered
        return max(self::PADDING + $fontSize, $center);
    }

    private function subtitleStartY(array $opts, int $fontSize): int
    {
        $titleSize  = max(20, min(120, (int)($opts['title_size'] ?? 64)));
        $titleText  = trim($opts['title'] ?? '');
        $font       = $this->fontPath(true);
        $maxWidth   = self::OG_WIDTH - self::PADDING * 2;
        $titleLines = $this->wrapText($titleText, $titleSize, $font, $maxWidth);
        $titleLineH = (int)($titleSize * 1.3);
        $titleBlock = count($titleLines) * $titleLineH;

        $subH   = empty(trim($opts['subtitle'] ?? '')) ? 0 : $fontSize + 20;
        $block  = $titleBlock + $subH;
        $center = (int)((self::OG_HEIGHT - $block) / 2);
        $topOfTitle = max(self::PADDING + $titleSize, $center);

        return $topOfTitle + $titleBlock + 20;
    }

    private function labelCoords(string $position, int $w, int $h): array
    {
        $pad = self::PADDING;
        return match ($position) {
            'top-right'    => [self::OG_WIDTH  - $pad - $w, $pad],
            'bottom-left'  => [$pad,                         self::OG_HEIGHT - $pad - $h],
            'bottom-right' => [self::OG_WIDTH  - $pad - $w, self::OG_HEIGHT - $pad - $h],
            default        => [$pad, $pad], // top-left
        };
    }

    // ──────────────────────────────────────────────────────────────────
    // Utility helpers
    // ──────────────────────────────────────────────────────────────────

    /** Wrap text to fit within $maxWidth px */
    private function wrapText(string $text, int $fontSize, string $font, int $maxWidth): array
    {
        $words = explode(' ', $text);
        $lines = [];
        $current = '';

        foreach ($words as $word) {
            $test = $current !== '' ? "$current $word" : $word;
            $bbox = imagettfbbox($fontSize, 0, $font, $test);
            $w    = abs($bbox[4] - $bbox[0]);

            if ($w > $maxWidth && $current !== '') {
                $lines[]  = $current;
                $current  = $word;
            } else {
                $current = $test;
            }
        }

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

        return $lines ?: [''];
    }

    private function fontPath(bool $bold): string
    {
        $path = $bold ? self::FONT_BOLD : self::FONT_REG;
        if (!file_exists($path)) {
            $path = self::FONT_REG; // fallback to regular
        }
        if (!file_exists($path)) {
            throw new \RuntimeException("TTF font not found at $path");
        }
        return $path;
    }

    private function hexToRgb(string $hex): array
    {
        $hex = ltrim($hex, '#');
        if (strlen($hex) === 3) {
            $hex = $hex[0] . $hex[0] . $hex[1] . $hex[1] . $hex[2] . $hex[2];
        }
        return [
            hexdec(substr($hex, 0, 2)),
            hexdec(substr($hex, 2, 2)),
            hexdec(substr($hex, 4, 2)),
        ];
    }

    private function resolvePath(string $path): string
    {
        if (str_starts_with($path, '/')) {
            return Environment::getPublicPath() . $path;
        }
        return Environment::getPublicPath() . '/' . ltrim($path, '/');
    }

    /** @return \GdImage|null */
    private function loadImageFromPath(string $path): ?\GdImage
    {
        if (!file_exists($path)) {
            return null;
        }

        $ext = strtolower(pathinfo($path, PATHINFO_EXTENSION));

        return match ($ext) {
            'jpg', 'jpeg' => imagecreatefromjpeg($path) ?: null,
            'png'         => imagecreatefrompng($path) ?: null,
            'gif'         => imagecreatefromgif($path) ?: null,
            'webp'        => imagecreatefromwebp($path) ?: null,
            default       => null,
        };
    }

    private function saveImage(\GdImage $gd, string $path, string $format, int $quality): void
    {
        match (strtolower($format)) {
            'png'  => imagepng($gd, $path, max(0, min(9, (int)(9 - $quality / 11)))),
            default => imagejpeg($gd, $path, $quality),
        };
    }
}