<?php
declare(strict_types=1);

require_once __DIR__ . '/_bootstrap.php';
api_method('GET');

$planUuid = $_GET['id'] ?? null;
if ($planUuid !== null && (!is_string($planUuid) || !preg_match('/^[0-9a-f-]{36}$/i', $planUuid))) {
    api_json(['error' => 'invalid_plan_id'], 400);
}

try {
    $database = Database::getInstance();
    $connection = $database->getConnection();
    if ($planUuid !== null) {
        $planQuery = $database->prepare(
            'SELECT plan_uuid, slug, title_ar, summary_ar, goal, level, weeks_duration, source_notes, safety_notes_ar, content_revision FROM training_plans WHERE is_published = 1 AND plan_uuid = ? LIMIT 1'
        );
        $planQuery->bind_param('s', $planUuid);
    } else {
        $planQuery = $database->prepare(
            'SELECT plan_uuid, slug, title_ar, summary_ar, goal, level, weeks_duration, source_notes, safety_notes_ar, content_revision FROM training_plans WHERE is_published = 1 ORDER BY title_ar'
        );
    }
    $planQuery->execute();
    $planResult = $planQuery->get_result();
    $plans = [];
    while ($plan = $planResult->fetch_assoc()) {
        $plan['weeks_duration'] = (int) $plan['weeks_duration'];
        $plan['content_revision'] = (int) $plan['content_revision'];
        $plan['source_notes'] = json_decode($plan['source_notes'] ?? '[]', true) ?? [];
        $plan['safety_notes_ar'] = json_decode($plan['safety_notes_ar'], true) ?? [];
        $plans[$plan['plan_uuid']] = $plan;
    }
    $planQuery->close();

    if ($planUuid !== null && !$plans) {
        api_json(['error' => 'plan_not_found'], 404);
    }
    if (!$plans) {
        header('Cache-Control: public, max-age=60, stale-while-revalidate=300');
        api_json(['plans' => []]);
    }

    $planUuids = array_keys($plans);
    $ids = array_fill(0, count($planUuids), '?');
    $sessionQuery = $database->prepare(
        'SELECT s.plan_id, p.plan_uuid, s.week_number, s.day_number, s.title_ar, s.session_type, s.duration_minutes, s.intensity, s.notes_ar, e.exercise_uuid, e.slug AS exercise_slug, e.title_ar AS exercise_title_ar, e.instructions_ar, e.target_muscles, e.equipment, e.gif_url, e.gif_poster_url, e.duration_seconds AS exercise_duration_seconds, e.repetitions, e.safety_notes_ar AS exercise_safety_notes_ar, alt.exercise_uuid AS alternative_exercise_uuid, se.sort_order AS exercise_sort_order, se.sets, se.reps, se.duration_seconds, se.rest_seconds FROM training_plan_sessions s JOIN training_plans p ON p.id = s.plan_id LEFT JOIN training_session_exercises se ON se.session_id = s.id LEFT JOIN exercises e ON e.id = se.exercise_id AND e.is_published = 1 LEFT JOIN exercises alt ON alt.id = e.alternative_exercise_id AND alt.is_published = 1 WHERE p.plan_uuid IN (' . implode(',', $ids) . ') AND p.is_published = 1 ORDER BY p.title_ar, s.week_number, s.day_number, se.sort_order'
    );
    $bindArguments = [str_repeat('s', count($planUuids))];
    foreach ($planUuids as $index => $_planUuid) {
        $bindArguments[] = &$planUuids[$index];
    }
    call_user_func_array([$sessionQuery, 'bind_param'], $bindArguments);
    $sessionQuery->execute();
    $sessionResult = $sessionQuery->get_result();

    foreach ($plans as &$plan) {
        $plan['sessions'] = [];
    }
    unset($plan);

    while ($row = $sessionResult->fetch_assoc()) {
        $uuid = $row['plan_uuid'];
        $week = (int) $row['week_number'];
        $day = (int) $row['day_number'];
        $key = $week . ':' . $day;
        if (!isset($plans[$uuid]['sessions'][$key])) {
            $plans[$uuid]['sessions'][$key] = [
                'week' => $week,
                'day' => $day,
                'title_ar' => $row['title_ar'],
                'type' => $row['session_type'],
                'duration_minutes' => (int) $row['duration_minutes'],
                'intensity' => $row['intensity'],
                'notes_ar' => $row['notes_ar'],
                'exercises' => [],
            ];
        }
        if ($row['exercise_uuid'] !== null) {
            $plans[$uuid]['sessions'][$key]['exercises'][] = [
                'exercise_uuid' => $row['exercise_uuid'],
                'slug' => $row['exercise_slug'],
                'title_ar' => $row['exercise_title_ar'],
                'instructions_ar' => json_decode($row['instructions_ar'], true) ?? [],
                'target_muscles' => json_decode($row['target_muscles'], true) ?? [],
                'equipment' => json_decode($row['equipment'], true) ?? [],
                'gif_url' => $row['gif_url'],
                'gif_poster_url' => $row['gif_poster_url'],
                'duration_seconds' => $row['duration_seconds'] === null ? null : (int) $row['duration_seconds'],
                'repetitions' => $row['repetitions'],
                'safety_notes_ar' => json_decode($row['exercise_safety_notes_ar'] ?? '[]', true) ?? [],
                'alternative_exercise_uuid' => $row['alternative_exercise_uuid'],
                'prescription' => [
                    'sets' => $row['sets'] === null ? null : (int) $row['sets'],
                    'reps' => $row['reps'],
                    'duration_seconds' => $row['duration_seconds'] === null ? null : (int) $row['duration_seconds'],
                    'rest_seconds' => (int) $row['rest_seconds'],
                ],
            ];
        }
    }
    $sessionQuery->close();

    foreach ($plans as &$plan) {
        $plan['sessions'] = array_values($plan['sessions']);
    }
    unset($plan);
    header('Cache-Control: public, max-age=60, stale-while-revalidate=300');
    api_json(['plans' => array_values($plans)]);
} catch (Throwable $exception) {
    error_log('Training plans unavailable: ' . $exception->getMessage());
    api_json(['error' => 'service_unavailable'], 503);
}