<?php
/**
 * Deterministic fixed-template renderer for the Free Basic order confirmation.
 *
 * This intentionally supports the fixed Free template only. Versioned HTML template
 * rendering is outside the Free Basic PDF module.
 *
 * @package Leanmerce\CommerceCompliance
 */

namespace Leanmerce\CommerceCompliance\Infrastructure\Pdf;

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

use Leanmerce\CommerceCompliance\Application\Document\BasicDocumentTextCatalog;
use Leanmerce\CommerceCompliance\Domain\Document\BasicOrderDocument;
use Leanmerce\CommerceCompliance\Domain\Document\PdfRendererInterface;

final class FixedBasicPdfRenderer implements PdfRendererInterface {
	private const PAGE_WIDTH  = 595.28;
	private const PAGE_HEIGHT = 841.89;
	private const MARGIN      = 42.0;
	private const FOOTER_Y    = 24.0;

	/** Helvetica AFM advance widths (1000 units/em), WinAnsi plus our six Differences glyphs. */
	private const FONT_WIDTHS = array(
		0,
		722,
		500,
		722,
		500,
		722,
		556,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		0,
		278,
		278,
		355,
		556,
		556,
		889,
		667,
		191,
		333,
		333,
		389,
		584,
		278,
		333,
		278,
		278,
		556,
		556,
		556,
		556,
		556,
		556,
		556,
		556,
		556,
		556,
		278,
		278,
		584,
		584,
		584,
		556,
		1015,
		667,
		667,
		722,
		722,
		667,
		611,
		778,
		722,
		278,
		500,
		667,
		556,
		833,
		722,
		778,
		667,
		778,
		722,
		667,
		611,
		722,
		667,
		944,
		667,
		667,
		611,
		278,
		278,
		278,
		469,
		556,
		333,
		556,
		556,
		500,
		556,
		556,
		278,
		556,
		556,
		222,
		222,
		500,
		222,
		833,
		556,
		556,
		556,
		556,
		333,
		500,
		278,
		556,
		500,
		722,
		500,
		500,
		500,
		334,
		260,
		334,
		584,
		350,
		556,
		350,
		222,
		556,
		333,
		1000,
		556,
		556,
		333,
		1000,
		667,
		333,
		1000,
		350,
		611,
		350,
		350,
		222,
		222,
		333,
		333,
		350,
		556,
		1000,
		333,
		1000,
		500,
		333,
		944,
		350,
		500,
		667,
		278,
		333,
		556,
		556,
		556,
		556,
		260,
		556,
		333,
		737,
		370,
		556,
		584,
		333,
		737,
		333,
		400,
		584,
		333,
		333,
		333,
		556,
		537,
		278,
		333,
		333,
		365,
		556,
		834,
		834,
		834,
		611,
		667,
		667,
		667,
		667,
		667,
		667,
		1000,
		722,
		667,
		667,
		667,
		667,
		278,
		278,
		278,
		278,
		722,
		722,
		778,
		778,
		778,
		778,
		778,
		584,
		778,
		722,
		722,
		722,
		722,
		667,
		667,
		611,
		556,
		556,
		556,
		556,
		556,
		556,
		889,
		500,
		556,
		556,
		556,
		556,
		278,
		278,
		278,
		278,
		556,
		556,
		556,
		556,
		556,
		556,
		556,
		584,
		611,
		556,
		556,
		556,
		556,
		500,
		556,
		500,
	);

	/** @var array<int,int> */
	private const CUSTOM_UNICODE_TO_BYTE = array(
		0x0106 => 1, // Ć.
		0x0107 => 2, // ć.
		0x010C => 3, // Č.
		0x010D => 4, // č.
		0x0110 => 5, // Đ.
		0x0111 => 6, // đ.
	);

	/** @var array<int,int> */
	private const CP1252_SPECIALS = array(
		0x20AC => 0x80,
		0x201A => 0x82,
		0x0192 => 0x83,
		0x201E => 0x84,
		0x2026 => 0x85,
		0x2020 => 0x86,
		0x2021 => 0x87,
		0x02C6 => 0x88,
		0x2030 => 0x89,
		0x0160 => 0x8A,
		0x2039 => 0x8B,
		0x0152 => 0x8C,
		0x017D => 0x8E,
		0x2018 => 0x91,
		0x2019 => 0x92,
		0x201C => 0x93,
		0x201D => 0x94,
		0x2022 => 0x95,
		0x2013 => 0x96,
		0x2014 => 0x97,
		0x02DC => 0x98,
		0x2122 => 0x99,
		0x0161 => 0x9A,
		0x203A => 0x9B,
		0x0153 => 0x9C,
		0x017E => 0x9E,
		0x0178 => 0x9F,
	);

	public function __construct( private readonly BasicDocumentTextCatalog $texts ) {}

	public function render( BasicOrderDocument $document ): string {
		$pages = $this->layout( $document );
		if ( empty( $pages ) ) {
			throw new \RuntimeException( 'The Basic PDF renderer produced no pages.' );
		}
		return $this->build_pdf( $pages, $document );
	}

	/**
	 * @return string[] Page content streams.
	 */
	private function layout( BasicOrderDocument $document ): array {
		$pages    = array();
		$commands = array();
		$page     = 1;
		$y        = self::PAGE_HEIGHT - self::MARGIN;

		$start_page = function ( bool $continuation = false ) use ( &$commands, &$y, $document ): void {
			$commands = array();
			$y        = self::PAGE_HEIGHT - self::MARGIN;
			if ( ! $continuation ) {
				$headline = $this->texts->get( $document->language(), 'document_title' ) . ' ' . $document->order_number();
				foreach ( $this->wrap_text( $headline, 58 ) as $line ) {
					$this->text( $commands, self::MARGIN, $y, 16, true, $line );
					$y -= 19;
				}
				$y -= 5;
				if ( '' !== $document->preview_label() ) {
					$this->text( $commands, self::MARGIN, $y, 10, true, $document->preview_label() );
					$y -= 17;
				}
				$this->text( $commands, self::MARGIN, $y, 9, false, $this->texts->get( $document->language(), 'order_date' ) . ': ' . $document->order_date() );
				$y -= 14;
				$this->line( $commands, self::MARGIN, $y, self::PAGE_WIDTH - self::MARGIN, $y );
				$y -= 18;
			} elseif ( '' !== $document->preview_label() ) {
				$this->text( $commands, self::MARGIN, $y, 9, true, $document->preview_label() );
				$y -= 16;
				$this->line( $commands, self::MARGIN, $y, self::PAGE_WIDTH - self::MARGIN, $y );
				$y -= 18;
			}
		};

		$finish_page = function () use ( &$pages, &$commands, &$page ): void {
			$commands[] = '__LMCC_PAGE_FOOTER_' . $page . '__';
			$pages[]    = implode( "\n", $commands );
			++$page;
		};

		$start_page();
		$merchant_lines = $this->wrap_lines( $this->merchant_lines( $document ), 41 );
		$billing_lines  = $this->wrap_lines( $this->customer_lines( $document->billing() ), 41 );
		$merchant_count = count( $merchant_lines );
		$billing_count  = count( $billing_lines );
		$merchant_index = 0;
		$billing_index  = 0;
		$left_x         = self::MARGIN;
		$right_x        = 307.0;
		$column_width   = 246.0;
		do {
			$capacity       = max( 1, (int) floor( ( $y - 112 ) / 11 ) - 3 );
			$merchant_chunk = array_slice( $merchant_lines, $merchant_index, $capacity );
			$billing_chunk  = array_slice( $billing_lines, $billing_index, $capacity );
			$line_count     = max( 1, count( $merchant_chunk ), count( $billing_chunk ) );
			$row_height     = 29 + ( $line_count * 11 );
			$this->rect_fill( $commands, $left_x, $y - $row_height, $column_width, $row_height, 0.97 );
			$this->rect_fill( $commands, $right_x, $y - $row_height, $column_width, $row_height, 0.97 );
			$this->text( $commands, $left_x + 8, $y - 16, 10, true, $this->texts->get( $document->language(), 'seller' ) );
			$this->text( $commands, $right_x + 8, $y - 16, 10, true, $this->texts->get( $document->language(), 'customer' ) );
			foreach ( $merchant_chunk as $index => $line ) {
				$this->text( $commands, $left_x + 8, $y - 31 - ( $index * 11 ), 8.3, false, $line );
			}
			foreach ( $billing_chunk as $index => $line ) {
				$this->text( $commands, $right_x + 8, $y - 31 - ( $index * 11 ), 8.3, false, $line );
			}
			$merchant_index += count( $merchant_chunk );
			$billing_index  += count( $billing_chunk );
			$y              -= $row_height + 10;
			if ( $merchant_index < $merchant_count || $billing_index < $billing_count ) {
				$finish_page();
				$start_page( true );
			}
		} while ( $merchant_index < $merchant_count || $billing_index < $billing_count );

		$shipping_lines = $this->wrap_lines( $this->customer_lines( $document->shipping() ), 88 );
		if ( ! empty( $shipping_lines ) ) {
			$shipping_height = 20 + ( count( $shipping_lines ) * 11 );
			if ( $y - $shipping_height < 105 ) {
				$finish_page();
				$start_page( true );
			}
			$this->identity_section( $commands, $y, $this->texts->get( $document->language(), 'shipping' ), $shipping_lines );
		}

		$y -= 4;
		if ( $y < 145 ) {
			$finish_page();
			$start_page( true );
		}
		$this->table_header( $commands, $y, $document );

		foreach ( $document->items() as $item ) {
			$name_lines = $this->wrap_text( (string) ( $item['name'] ?? '' ), 37 );
			$row_height = max( 18, 12 * count( $name_lines ) + 6 );
			if ( $y - $row_height < 92 ) {
				$finish_page();
				$start_page( true );
				$this->table_header( $commands, $y, $document );
			}

			$row_top = $y;
			foreach ( $name_lines as $index => $line ) {
				$this->text( $commands, self::MARGIN + 4, $row_top - 13 - ( $index * 11 ), 8.5, false, $line );
			}
			$this->text( $commands, 300, $row_top - 13, 8.0, false, (string) ( $item['sku'] ?? '' ) );
			$this->text( $commands, 380, $row_top - 13, 8.5, false, (string) ( $item['quantity'] ?? 0 ) );
			$this->text( $commands, 420, $row_top - 13, 8.5, false, (string) ( $item['unit_price'] ?? '' ) );
			$this->text( $commands, 500, $row_top - 13, 8.5, false, (string) ( $item['line_total'] ?? '' ) );
			$y -= $row_height;
			$this->line( $commands, self::MARGIN, $y, self::PAGE_WIDTH - self::MARGIN, $y, 0.5 );
		}

		if ( $y < 260 ) {
			$finish_page();
			$start_page( true );
		}
		$y -= 16;
		$this->summary( $commands, $y, $document );
		$y -= 18;
		$this->labeled_value( $commands, $y, $this->texts->get( $document->language(), 'payment_method' ), $document->payment_method(), $finish_page, $start_page );
		$this->labeled_value( $commands, $y, $this->texts->get( $document->language(), 'shipping_method' ), $document->shipping_method(), $finish_page, $start_page );
		$y -= 8;
		foreach ( $this->wrap_measured( $this->texts->get( $document->language(), 'notice' ), self::PAGE_WIDTH - ( 2 * self::MARGIN ), 8 ) as $line ) {
			if ( $y < 72 ) {
				$finish_page();
				$start_page( true );
			}
			$this->text( $commands, self::MARGIN, $y, 8, false, $line );
			$y -= 10;
		}
		$finish_page();

		$total_pages = count( $pages );
		foreach ( $pages as $index => $content ) {
			$page_number     = $index + 1;
			$footer_text     = $this->texts->get( $document->language(), 'page' ) . ' ' . $page_number . '/' . $total_pages;
			$footer          = $this->gray_text_command( self::PAGE_WIDTH - 100, self::FOOTER_Y, 7.5, false, $footer_text );
			$pages[ $index ] = str_replace( '__LMCC_PAGE_FOOTER_' . $page_number . '__', $footer, $content );
		}

		return $pages;
	}

	/** @return string[] */
	private function merchant_lines( BasicOrderDocument $document ): array {
		$m     = $document->merchant();
		$lines = array();
		if ( '' !== (string) ( $m['name'] ?? '' ) ) {
			$lines[] = (string) $m['name']; }
		if ( '' !== (string) ( $m['address'] ?? '' ) ) {
			$lines[] = (string) $m['address']; }
		if ( '' !== (string) ( $m['registration_number'] ?? '' ) ) {
			$lines[] = $this->texts->get( $document->language(), 'registration' ) . ': ' . (string) $m['registration_number']; }
		if ( '' !== (string) ( $m['tax_id'] ?? '' ) ) {
			$lines[] = $this->texts->get( $document->language(), 'tax_id' ) . ': ' . (string) $m['tax_id']; }
		if ( '' !== (string) ( $m['vat_number'] ?? '' ) ) {
			$lines[] = $this->texts->get( $document->language(), 'vat_number' ) . ': ' . (string) $m['vat_number']; }
		if ( '' !== (string) ( $m['email'] ?? '' ) ) {
			$lines[] = $this->texts->get( $document->language(), 'email' ) . ': ' . (string) $m['email']; }
		if ( '' !== (string) ( $m['phone'] ?? '' ) ) {
			$lines[] = $this->texts->get( $document->language(), 'phone' ) . ': ' . (string) $m['phone']; }
		return $lines;
	}

	/** @param array<string,string> $identity @return string[] */
	private function customer_lines( array $identity ): array {
		$lines = array();
		foreach ( array( 'name', 'company', 'address', 'email', 'phone' ) as $key ) {
			$value = trim( (string) ( $identity[ $key ] ?? '' ) );
			if ( '' !== $value ) {
				$lines[] = $value;
			}
		}
		return $lines;
	}

	/** @param string[] $lines */
	private function identity_section( array &$commands, float &$y, string $heading, array $lines ): void {
		$this->text( $commands, self::MARGIN, $y, 10, true, $heading );
		$y -= 13;
		foreach ( $lines as $line ) {
			$this->text( $commands, self::MARGIN + 8, $y, 8.5, false, $line );
			$y -= 11;
		}
		$y -= 7;
	}

	/** @param string[] $lines @return string[] */
	private function wrap_lines( array $lines, int $max_chars ): array {
		$wrapped = array();
		foreach ( $lines as $line ) {
			foreach ( $this->wrap_text( $line, $max_chars ) as $part ) {
				$wrapped[] = $part;
			}
		}
		return $wrapped;
	}

	private function table_header( array &$commands, float &$y, BasicOrderDocument $document ): void {
		$this->rect_fill( $commands, self::MARGIN, $y - 18, self::PAGE_WIDTH - ( 2 * self::MARGIN ), 18, 0.94 );
		$this->text( $commands, self::MARGIN + 4, $y - 12, 8.3, true, $this->texts->get( $document->language(), 'product' ) );
		$this->text( $commands, 296, $y - 12, 8.0, true, $this->texts->get( $document->language(), 'sku' ) );
		$this->text( $commands, 374, $y - 12, 8.3, true, $this->texts->get( $document->language(), 'quantity' ) );
		$this->text( $commands, 414, $y - 12, 8.3, true, $this->texts->get( $document->language(), 'unit_price' ) );
		$this->text( $commands, 494, $y - 12, 8.3, true, $this->texts->get( $document->language(), 'line_total' ) );
		$y -= 18;
	}

	private function summary( array &$commands, float &$y, BasicOrderDocument $document ): void {
		$rows = array(
			array( $this->texts->get( $document->language(), 'subtotal' ), $document->subtotal(), false ),
			array( $this->texts->get( $document->language(), 'discount' ), $document->discount(), false ),
			array( $this->texts->get( $document->language(), 'shipping_total' ), $document->shipping_total(), false ),
			array( $this->texts->get( $document->language(), 'tax' ), $document->tax_total(), false ),
			array( $this->texts->get( $document->language(), 'grand_total' ), $document->total(), true ),
		);
		foreach ( $rows as $row ) {
			$this->text( $commands, 340, $y, 9, (bool) $row[2], (string) $row[0] );
			$this->text( $commands, 470, $y, 9, (bool) $row[2], (string) $row[1] );
			$y -= 13;
		}
	}

	private function labeled_value( array &$commands, float &$y, string $label, string $value, callable $finish_page, callable $start_page ): void {
		if ( '' === trim( $value ) ) {
			return;
		}
		foreach ( $this->wrap_measured( $value, self::PAGE_WIDTH - self::MARGIN - 155, 8.5 ) as $index => $line ) {
			if ( $y < 84 ) {
				$finish_page();
				$start_page( true );
			}
			if ( 0 === $index ) {
				$this->text( $commands, self::MARGIN, $y, 8.5, true, $label . ':' );
			}
			$this->text( $commands, 155, $y, 8.5, false, $line );
			$y -= 12;
		}
	}

	/** @return string[] Greedy wrapping by the actual font advances, including unbroken words. */
	private function wrap_measured( string $text, float $width, float $size ): array {
		$text  = trim( preg_replace( '/\s+/u', ' ', $text ) ?? $text );
		$words = preg_split( '/\s+/u', $text );
		$words = false !== $words ? $words : array( $text );
		$lines = array();
		$line  = '';
		foreach ( $words as $word ) {
			$candidate = '' === $line ? $word : $line . ' ' . $word;
			if ( $this->text_width( $candidate, $size ) <= $width ) {
				$line = $candidate;
				continue;
			}
			if ( '' !== $line ) {
				$lines[] = $line;
			}
			$line       = '';
			$characters = preg_split( '//u', $word, -1, PREG_SPLIT_NO_EMPTY );
			foreach ( false !== $characters ? $characters : array() as $character ) {
				if ( '' !== $line && $this->text_width( $line . $character, $size ) > $width ) {
					$lines[] = $line;
					$line    = '';
				}
				$line .= $character;
			}
		}
		if ( '' !== $line ) {
			$lines[] = $line;
		}
		return $lines;
	}

	/** @return string[] */
	private function wrap_text( string $text, int $max_chars ): array {
		$text = trim( preg_replace( '/\s+/u', ' ', $text ) ?? $text );
		if ( '' === $text ) {
			return array( '' );
		}
		$words = preg_split( '/\s+/u', $text );
		$words = false !== $words ? $words : array( $text );
		$lines = array();
		$line  = '';
		foreach ( $words as $word ) {
			while ( $this->unicode_length( $word ) > $max_chars ) {
				if ( '' !== $line ) {
					$lines[] = $line;
					$line    = '';
				}
				$parts   = preg_split( '//u', $word, -1, PREG_SPLIT_NO_EMPTY );
				$parts   = false !== $parts ? $parts : str_split( $word );
				$lines[] = implode( '', array_slice( $parts, 0, $max_chars ) );
				$word    = implode( '', array_slice( $parts, $max_chars ) );
			}
			$candidate = '' === $line ? $word : $line . ' ' . $word;
			if ( $this->unicode_length( $candidate ) <= $max_chars ) {
				$line = $candidate;
				continue;
			}
			if ( '' !== $line ) {
				$lines[] = $line;
			}
			$line = $word;
		}
		if ( '' !== $line ) {
			$lines[] = $line;
		}
		return $lines;
	}

	private function unicode_length( string $text ): int {
		$count = preg_match_all( '/./us', $text, $matches );
		return false === $count ? strlen( $text ) : $count;
	}

	private function text( array &$commands, float $x, float $y, float $size, bool $bold, string $text ): void {
		$commands[] = $this->text_command( $x, $y, $size, $bold, $text );
	}

	private function text_command( float $x, float $y, float $size, bool $bold, string $text ): string {
		$font = $bold ? 'F2' : 'F1';
		return sprintf( 'BT /%s %.2F Tf %.2F %.2F Td (%s) Tj ET', $font, $size, $x, $y, $this->pdf_text( $text ) );
	}

	private function gray_text_command( float $x, float $y, float $size, bool $bold, string $text ): string {
		return 'q 0.42 g ' . $this->text_command( $x, $y, $size, $bold, $text ) . ' Q';
	}

	private function text_width( string $text, float $size ): float {
		$units = 0;
		foreach ( $this->utf8_codepoints( $text ) as $codepoint ) {
			$byte = $this->codepoint_to_byte( $codepoint );
			if ( null === $byte ) {
				throw new \RuntimeException( 'Unsupported Basic PDF font character.' );
			}
			$units += self::FONT_WIDTHS[ $byte ];
		}
		return $units * $size / 1000;
	}

	private function line( array &$commands, float $x1, float $y1, float $x2, float $y2, float $width = 0.8 ): void {
		$commands[] = sprintf( 'q %.2F w 0.70 G %.2F %.2F m %.2F %.2F l S Q', $width, $x1, $y1, $x2, $y2 );
	}

	private function rect_fill( array &$commands, float $x, float $y, float $w, float $h, float $gray ): void {
		$commands[] = sprintf( 'q %.2F g %.2F %.2F %.2F %.2F re f Q', $gray, $x, $y, $w, $h );
	}

	private function pdf_text( string $text ): string {
		$encoded = '';
		foreach ( $this->utf8_codepoints( $text ) as $codepoint ) {
			$byte = $this->codepoint_to_byte( $codepoint );
			if ( null === $byte ) {
				// phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped -- Exception text is not rendered; codepoint is an integer.
				throw new \RuntimeException( sprintf( 'Basic PDF fixed-font renderer cannot safely encode Unicode code point U+%04X.', $codepoint ) );
			}
			if ( 0x5C === $byte || 0x28 === $byte || 0x29 === $byte ) {
				$encoded .= '\\' . chr( $byte );
			} elseif ( $byte < 32 || $byte > 126 ) {
				$encoded .= sprintf( '\\%03o', $byte );
			} else {
				$encoded .= chr( $byte );
			}
		}
		return $encoded;
	}

	private function codepoint_to_byte( int $codepoint ): ?int {
		if ( isset( self::CUSTOM_UNICODE_TO_BYTE[ $codepoint ] ) ) {
			return self::CUSTOM_UNICODE_TO_BYTE[ $codepoint ];
		}
		if ( $codepoint >= 0x20 && $codepoint <= 0x7E ) {
			return $codepoint;
		}
		if ( isset( self::CP1252_SPECIALS[ $codepoint ] ) ) {
			return self::CP1252_SPECIALS[ $codepoint ];
		}
		if ( $codepoint >= 0x00A0 && $codepoint <= 0x00FF ) {
			return $codepoint;
		}
		return null;
	}

	/** @return int[] */
	private function utf8_codepoints( string $text ): array {
		$unpacked = unpack( 'C*', $text );
		$bytes    = array_values( false !== $unpacked ? $unpacked : array() );
		$result   = array();
		$count    = count( $bytes );
		for ( $i = 0; $i < $count; ++$i ) {
			$b1 = $bytes[ $i ];
			if ( $b1 < 0x80 ) {
				$result[] = $b1;
				continue;
			}
			if ( ( $b1 & 0xE0 ) === 0xC0 && isset( $bytes[ $i + 1 ] ) ) {
				$result[] = ( ( $b1 & 0x1F ) << 6 ) | ( $bytes[ ++$i ] & 0x3F );
				continue;
			}
			if ( ( $b1 & 0xF0 ) === 0xE0 && isset( $bytes[ $i + 2 ] ) ) {
				$b2       = $bytes[ ++$i ];
				$b3       = $bytes[ ++$i ];
				$result[] = ( ( $b1 & 0x0F ) << 12 ) | ( ( $b2 & 0x3F ) << 6 ) | ( $b3 & 0x3F );
				continue;
			}
			if ( ( $b1 & 0xF8 ) === 0xF0 && isset( $bytes[ $i + 3 ] ) ) {
				$b2       = $bytes[ ++$i ];
				$b3       = $bytes[ ++$i ];
				$b4       = $bytes[ ++$i ];
				$result[] = ( ( $b1 & 0x07 ) << 18 ) | ( ( $b2 & 0x3F ) << 12 ) | ( ( $b3 & 0x3F ) << 6 ) | ( $b4 & 0x3F );
				continue;
			}
			throw new \RuntimeException( 'Invalid UTF-8 input in Basic PDF data.' );
		}
		return $result;
	}

	/** @param string[] $page_streams */
	private function build_pdf( array $page_streams, BasicOrderDocument $document ): string {
		$objects    = array();
		$objects[1] = '<< /Type /Catalog /Pages 2 0 R >>';
		$objects[3] = '<< /Type /Encoding /BaseEncoding /WinAnsiEncoding /Differences [1 /Cacute /cacute /Ccaron /ccaron /Dcroat /dcroat] >>';
		$objects[4] = '<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding 3 0 R >>';
		$objects[5] = '<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica-Bold /Encoding 3 0 R >>';

		$kids = array();
		foreach ( $page_streams as $index => $stream ) {
			$content_id             = 6 + ( $index * 2 );
			$page_id                = 7 + ( $index * 2 );
			$kids[]                 = $page_id . ' 0 R';
			$objects[ $content_id ] = '<< /Length ' . strlen( $stream ) . ">>\nstream\n" . $stream . "\nendstream";
			$objects[ $page_id ]    = sprintf(
				'<< /Type /Page /Parent 2 0 R /MediaBox [0 0 %.2F %.2F] /Resources << /Font << /F1 4 0 R /F2 5 0 R >> >> /Contents %d 0 R >>',
				self::PAGE_WIDTH,
				self::PAGE_HEIGHT,
				$content_id
			);
		}
		$objects[2] = '<< /Type /Pages /Kids [' . implode( ' ', $kids ) . '] /Count ' . count( $kids ) . ' >>';
		ksort( $objects );

		$pdf     = "%PDF-1.4\n%\xE2\xE3\xCF\xD3\n";
		$offsets = array( 0 => 0 );
		foreach ( $objects as $id => $body ) {
			$offsets[ $id ] = strlen( $pdf );
			$pdf           .= $id . " 0 obj\n" . $body . "\nendobj\n";
		}

		$xref_offset = strlen( $pdf );
		$max_id      = max( array_keys( $objects ) );
		$pdf        .= "xref\n0 " . ( $max_id + 1 ) . "\n";
		$pdf        .= "0000000000 65535 f \n";
		for ( $id = 1; $id <= $max_id; ++$id ) {
			$offset = $offsets[ $id ] ?? 0;
			$pdf   .= sprintf( "%010d 00000 n \n", $offset );
		}
		$pdf .= "trailer\n<< /Size " . ( $max_id + 1 ) . " /Root 1 0 R >>\nstartxref\n" . $xref_offset . "\n%%EOF\n";
		return $pdf;
	}
}