<?php

require_once __DIR__ . '/../app/bootstrap.php';

use App\Services\CurriculumService;

/**
 * Intelligent Markdown Curriculum Parser
 * Splits a complete textbook markdown into units, lessons, outcomes, and resources.
 */
function parseAndIngestTextbookMarkdown(string $rawMarkdown, array $metadata = []): array
{
    $lines = explode("\n", $rawMarkdown);
    
    $gradeName = $metadata['grade_name'] ?? 'الصف العاشر';
    $gradeKey  = $metadata['grade_key']  ?? 'grade_10';
    $subName   = $metadata['subject_name'] ?? 'الرياضيات';
    $subKey    = $metadata['subject_key']  ?? 'math_10';
    $semName   = $metadata['semester_name'] ?? 'الفصل الدراسي الأول';
    $semKey    = $metadata['semester_key']  ?? 'semester_1';

    $units = [];
    $currentUnit = null;
    $currentLesson = null;
    $lessonBuffer = [];

    $flushLesson = function() use (&$currentUnit, &$currentLesson, &$lessonBuffer) {
        if ($currentUnit && $currentLesson) {
            $content = trim(implode("\n", $lessonBuffer));
            if (!empty($content)) {
                $currentLesson['markdown_content'] = $content;
                $currentUnit['lessons'][] = $currentLesson;
            }
            $currentLesson = null;
            $lessonBuffer = [];
        }
    };

    $flushUnit = function() use (&$units, &$currentUnit, $flushLesson) {
        $flushLesson();
        if ($currentUnit && !empty($currentUnit['lessons'])) {
            $units[] = $currentUnit;
            $currentUnit = null;
        }
    };

    $unitCounter = 0;
    $lessonCounter = 0;

    foreach ($lines as $line) {
        $trimmed = trim($line);

        // Detect Unit (# UNIT or # الوحدة)
        if (preg_match('/^#\s+(UNIT|الوحدة)\s*([0-9\-\:A-Za-z\s]+)(.*)$/ui', $trimmed, $m) || preg_match('/^#\s+([A-Za-z0-9\s]+(?:SPOT|SKILLS|REFERENCE|LIST))/ui', $trimmed, $m2)) {
            $flushUnit();
            $unitCounter++;
            $unitTitle = trim(preg_replace('/^#\s+/u', '', $trimmed));
            $unitKey = sprintf('unit_%02d', $unitCounter);
            
            $currentUnit = [
                'unit_key'  => $unitKey,
                'unit_name' => $unitTitle,
                'lessons'   => []
            ];
            $lessonCounter = 0;
            continue;
        }

        // Detect Lesson (## Lesson or ## الدرس or ## معمل or ## )
        if (preg_match('/^##\s+(Lesson|الدرس|قسم|المحطة|قواعد|تمارين|معمل)\s*([0-9\-\:A-Za-z\s]+)(.*)$/ui', $trimmed, $m) || (preg_match('/^##\s+(.+)$/u', $trimmed, $mAlt) && $currentUnit)) {
            $flushLesson();
            $lessonCounter++;
            $lessonTitle = trim(preg_replace('/^##\s+/u', '', $trimmed));
            $lesId = sprintf('lesson_%02d', $lessonCounter);

            if (!$currentUnit) {
                $unitCounter++;
                $currentUnit = [
                    'unit_key'  => sprintf('unit_%02d', $unitCounter),
                    'unit_name' => 'الوحدة الأولى: المعادلات',
                    'lessons'   => []
                ];
            }

            $currentLesson = [
                'lesson_id' => $lesId,
                'title'     => $lessonTitle,
                'outcomes'  => [$lessonTitle]
            ];
            $lessonBuffer = [$trimmed];
            continue;
        }

        if ($currentLesson) {
            $lessonBuffer[] = $line;
        }
    }

    $flushUnit();

    $extracted = [
        'grade_name'    => $gradeName,
        'grade_key'     => $gradeKey,
        'subject_name'  => $subName,
        'subject_key'   => $subKey,
        'semester_name' => $semName,
        'semester_key'  => $semKey,
        'units'         => $units
    ];

    return CurriculumService::mergeExtractedCurriculum($extracted);
}