<?php
if (!defined('ABSPATH')) {
    exit;
}

class AIBIMA_PDF {
    private $pages = array();
    private $commands = array();
    private $y = 0;
    private $page_width = 595.28;
    private $page_height = 841.89;
    private $margin = 42;
    private $currency = 'INR';

    public static function invoice($invoice) {
        $pdf = new self();
        return $pdf->build($invoice);
    }

    private function build($invoice) {
        $this->currency = strtoupper($this->clean($invoice['currency'] ?? 'INR')) ?: 'INR';
        $customer = is_array($invoice['customer'] ?? null) ? $invoice['customer'] : array();
        $business = is_array($invoice['business'] ?? null) ? $invoice['business'] : array();
        $items = is_array($invoice['items'] ?? null) ? $invoice['items'] : array();
        $tax_breakup = is_array($invoice['tax_breakup'] ?? null) ? $invoice['tax_breakup'] : array();

        $this->new_page();
        $this->title(__('Invoice', 'aibill-maker'));

        $invoice_number = $this->clean($invoice['invoice_number'] ?? 'INV');
        $this->text(42, 772, $invoice_number, 18, true);
        $this->text(42, 752, __('Generated by AiBill Maker', 'aibill-maker'), 9, false);

        $this->text(402, 790, __('Total due', 'aibill-maker'), 10, true, 'right');
        $this->text(553, 790, $this->money($invoice['grand_total'] ?? 0), 15, true, 'right');
        $this->text(402, 765, __('Issue date', 'aibill-maker') . ': ' . $this->clean($invoice['issue_date'] ?? ''), 9, false);
        $this->text(402, 750, __('Due date', 'aibill-maker') . ': ' . $this->clean($invoice['due_date'] ?? ''), 9, false);
        $this->line(42, 732, 553, 732);
        $this->y = 708;

        $left = 42;
        $right = 310;
        $this->text($left, $this->y, __('From', 'aibill-maker'), 11, true);
        $this->text($right, $this->y, __('Bill to', 'aibill-maker'), 11, true);
        $this->y -= 18;
        $left_end = $this->party($business, $left, $this->y, 230);
        $right_end = $this->party($customer, $right, $this->y, 230);
        $this->y = min($left_end, $right_end) - 24;

        $this->items_table($items);
        $this->summary($invoice, $tax_breakup);
        $this->notes($invoice);

        $this->finish_page();
        return $this->render_pdf();
    }

    private function new_page() {
        if (!empty($this->commands)) {
            $this->finish_page();
        }
        $this->commands = array();
        $this->y = 800;
    }

    private function finish_page() {
        if (empty($this->commands)) {
            return;
        }
        $this->pages[] = implode("\n", $this->commands);
        $this->commands = array();
    }

    private function title($title) {
        $this->text(42, 805, $title, 26, true);
    }

    private function items_table($items) {
        $this->ensure_space(80);
        $this->text(42, $this->y, __('Items', 'aibill-maker'), 12, true);
        $this->y -= 18;
        $this->table_header();

        if (empty($items)) {
            $items = array(array('name' => __('Item', 'aibill-maker'), 'quantity' => 1, 'unit_price' => 0, 'tax_rate' => 0, 'line_total' => 0));
        }

        foreach ($items as $item) {
            $name = $this->clean($item['name'] ?? __('Item', 'aibill-maker'));
            $description = $this->clean($item['description'] ?? '');
            $hsn_sac = $this->clean($item['hsn_sac'] ?? '');
            $lines = $this->wrap($name, 42);
            if ($description !== '') {
                $lines = array_merge($lines, $this->wrap($description, 50));
            }
            if ($hsn_sac !== '') {
                $lines[] = __('HSN/SAC', 'aibill-maker') . ': ' . $hsn_sac;
            }
            $row_height = max(26, 12 + (count($lines) * 11));
            $this->ensure_space($row_height + 20, true);
            $y_top = $this->y;
            $this->line(42, $y_top, 553, $y_top);
            $line_y = $y_top - 14;
            foreach ($lines as $index => $line) {
                $this->text(48, $line_y, $line, $index === 0 ? 9 : 8, $index === 0);
                $line_y -= 10;
            }
            $qty = number_format((float) ($item['quantity'] ?? 0), 2) . ' ' . $this->clean($item['unit'] ?? '');
            $this->text(284, $y_top - 14, $qty, 9, false, 'right');
            $this->text(377, $y_top - 14, $this->money($item['unit_price'] ?? 0), 9, false, 'right');
            $this->text(440, $y_top - 14, number_format((float) ($item['tax_rate'] ?? 0), 2) . '%', 9, false, 'right');
            $this->text(553, $y_top - 14, $this->money($item['line_total'] ?? 0), 9, true, 'right');
            $this->y -= $row_height;
        }
        $this->line(42, $this->y, 553, $this->y);
        $this->y -= 24;
    }

    private function table_header() {
        $this->fill_rect(42, $this->y - 18, 511, 20, 0.94);
        $this->text(48, $this->y - 13, __('Item', 'aibill-maker'), 9, true);
        $this->text(284, $this->y - 13, __('Qty', 'aibill-maker'), 9, true, 'right');
        $this->text(377, $this->y - 13, __('Rate', 'aibill-maker'), 9, true, 'right');
        $this->text(440, $this->y - 13, __('Tax', 'aibill-maker'), 9, true, 'right');
        $this->text(553, $this->y - 13, __('Total', 'aibill-maker'), 9, true, 'right');
        $this->y -= 22;
    }

    private function summary($invoice, $tax_breakup) {
        $this->ensure_space(120);
        $x_label = 360;
        $x_value = 553;
        $this->summary_row(__('Subtotal', 'aibill-maker'), $this->money($invoice['subtotal'] ?? 0), $x_label, $x_value);
        if (!empty($tax_breakup['cgst']) || !empty($tax_breakup['sgst'])) {
            $this->summary_row(__('CGST', 'aibill-maker'), $this->money($tax_breakup['cgst'] ?? 0), $x_label, $x_value);
            $this->summary_row(__('SGST', 'aibill-maker'), $this->money($tax_breakup['sgst'] ?? 0), $x_label, $x_value);
        } elseif (!empty($tax_breakup['igst'])) {
            $this->summary_row(__('IGST', 'aibill-maker'), $this->money($tax_breakup['igst'] ?? 0), $x_label, $x_value);
        } else {
            $this->summary_row(__('Tax', 'aibill-maker'), $this->money($invoice['tax_total'] ?? 0), $x_label, $x_value);
        }
        $this->line($x_label, $this->y - 2, $x_value, $this->y - 2);
        $this->y -= 18;
        $this->summary_row(__('Grand total', 'aibill-maker'), $this->money($invoice['grand_total'] ?? 0), $x_label, $x_value, true);
        $this->y -= 10;
    }

    private function summary_row($label, $value, $x_label, $x_value, $bold = false) {
        $this->text($x_label, $this->y, $label, $bold ? 11 : 9, $bold);
        $this->text($x_value, $this->y, $value, $bold ? 11 : 9, true, 'right');
        $this->y -= 16;
    }

    private function notes($invoice) {
        foreach (array(
            'notes' => __('Notes', 'aibill-maker'),
            'terms' => __('Terms', 'aibill-maker'),
            'payment_instructions' => __('Payment instructions', 'aibill-maker'),
        ) as $key => $label) {
            $value = $this->clean($invoice[$key] ?? '');
            if ($value === '') {
                continue;
            }
            $this->ensure_space(52);
            $this->text(42, $this->y, $label, 10, true);
            $this->y -= 14;
            foreach ($this->wrap($value, 95) as $line) {
                $this->ensure_space(18);
                $this->text(42, $this->y, $line, 9, false);
                $this->y -= 11;
            }
            $this->y -= 6;
        }
    }

    private function party($party, $x, $y, $width_chars) {
        $lines = array();
        $name = $this->clean($party['name'] ?? $party['business_name'] ?? '');
        if ($name === '') {
            $name = __('Not specified', 'aibill-maker');
        }
        $lines[] = array($name, true);
        foreach (array('gstin' => __('GSTIN', 'aibill-maker'), 'email' => __('Email', 'aibill-maker'), 'phone' => __('Phone', 'aibill-maker'), 'address' => __('Address', 'aibill-maker')) as $key => $label) {
            if (!empty($party[$key])) {
                $value = $label . ': ' . $this->clean($party[$key]);
                foreach ($this->wrap($value, (int) ($width_chars / 5)) as $line) {
                    $lines[] = array($line, false);
                }
            }
        }
        $current_y = $y;
        foreach ($lines as $line) {
            $this->text($x, $current_y, $line[0], $line[1] ? 10 : 8, $line[1]);
            $current_y -= $line[1] ? 13 : 10;
        }
        return $current_y;
    }

    private function ensure_space($needed, $repeat_table_header = false) {
        if (($this->y - $needed) > 60) {
            return;
        }
        $this->new_page();
        $this->text(42, 805, __('Invoice continued', 'aibill-maker'), 14, true);
        $this->y = 770;
        if ($repeat_table_header) {
            $this->table_header();
        }
    }

    private function text($x, $y, $text, $size = 10, $bold = false, $align = 'left') {
        $font = $bold ? 'F2' : 'F1';
        $text = $this->clean($text);
        if ('right' === $align) {
            $x -= $this->text_width($text, $size);
        }
        $this->commands[] = sprintf('BT /%s %0.2F Tf %0.2F %0.2F Td (%s) Tj ET', $font, $size, $x, $y, $this->escape($text));
    }

    private function line($x1, $y1, $x2, $y2) {
        $this->commands[] = sprintf('0.75 w %0.2F %0.2F m %0.2F %0.2F l S', $x1, $y1, $x2, $y2);
    }

    private function fill_rect($x, $y, $w, $h, $gray = 0.95) {
        $this->commands[] = sprintf('%0.2F g %0.2F %0.2F %0.2F %0.2F re f 0 g', $gray, $x, $y, $w, $h);
    }

    private function wrap($text, $limit) {
        $text = preg_replace('/\s+/', ' ', $this->clean($text));
        $wrapped = wordwrap($text, max(10, (int) $limit), "\n", true);
        $lines = array_filter(array_map('trim', explode("\n", $wrapped)), static function ($line) {
            return $line !== '';
        });
        return empty($lines) ? array('') : array_values($lines);
    }

    private function money($amount) {
        return $this->currency . ' ' . number_format((float) $amount, 2, '.', ',');
    }

    private function text_width($text, $size) {
        return strlen($this->clean($text)) * $size * 0.48;
    }

    private function clean($text) {
        $text = wp_strip_all_tags((string) $text);
        $text = html_entity_decode($text, ENT_QUOTES, 'UTF-8');
        $replacements = array(
            '₹' => 'INR ',
            '€' => 'EUR ',
            '£' => 'GBP ',
            '…' => '...',
            '—' => '-',
            '–' => '-',
            '“' => '"',
            '”' => '"',
            '‘' => "'",
            '’' => "'",
        );
        $text = strtr($text, $replacements);
        if (function_exists('iconv')) {
            $converted = @iconv('UTF-8', 'ASCII//TRANSLIT//IGNORE', $text);
            if (false !== $converted) {
                $text = $converted;
            }
        }
        return trim(preg_replace('/[^\x09\x0A\x0D\x20-\x7E]/', '', $text));
    }

    private function escape($text) {
        return str_replace(array('\\', '(', ')'), array('\\\\', '\\(', '\\)'), $this->clean($text));
    }

    private function render_pdf() {
        $objects = array();
        $objects[] = '<< /Type /Catalog /Pages 2 0 R >>';
        $objects[] = '';
        $objects[] = '<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>';
        $objects[] = '<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica-Bold >>';

        $kids = array();
        foreach ($this->pages as $index => $content) {
            $page_obj = 5 + ($index * 2);
            $content_obj = $page_obj + 1;
            $kids[] = $page_obj . ' 0 R';
            $objects[$page_obj - 1] = sprintf('<< /Type /Page /Parent 2 0 R /MediaBox [0 0 %0.2F %0.2F] /Resources << /Font << /F1 3 0 R /F2 4 0 R >> >> /Contents %d 0 R >>', $this->page_width, $this->page_height, $content_obj);
            $stream = $content . "\n";
            $objects[$content_obj - 1] = '<< /Length ' . strlen($stream) . " >>\nstream\n" . $stream . "endstream";
        }
        $objects[1] = '<< /Type /Pages /Kids [' . implode(' ', $kids) . '] /Count ' . count($kids) . ' >>';
        ksort($objects);

        $pdf = "%PDF-1.4\n%AiBill Maker\n";
        $offsets = array(0);
        foreach ($objects as $id => $object) {
            $number = $id + 1;
            $offsets[$number] = strlen($pdf);
            $pdf .= $number . " 0 obj\n" . $object . "\nendobj\n";
        }
        $xref = strlen($pdf);
        $pdf .= "xref\n0 " . (count($objects) + 1) . "\n";
        $pdf .= "0000000000 65535 f \n";
        for ($i = 1; $i <= count($objects); $i++) {
            $pdf .= sprintf("%010d 00000 n \n", $offsets[$i]);
        }
        $pdf .= "trailer\n<< /Size " . (count($objects) + 1) . " /Root 1 0 R >>\nstartxref\n" . $xref . "\n%%EOF";
        return $pdf;
    }
}