<?php
require_once __DIR__ . '/../../db/config.php';

try {
    $db = db();
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    echo "Starting migration 033: Standardize bni_group_id in meeting_attendance.
";

    // Ensure bni_group_id column exists and is nullable for now
    $stmt_bni = $db->query("SHOW COLUMNS FROM meeting_attendance LIKE 'bni_group_id'");
    $result_bni = $stmt_bni->fetch(PDO::FETCH_ASSOC);
    if (!$result_bni) {
        $db->exec("ALTER TABLE meeting_attendance ADD COLUMN bni_group_id INT(11) NULL;");
        echo "SUCCESS: Added nullable 'bni_group_id' column.
";
    } else {
        $db->exec("ALTER TABLE meeting_attendance MODIFY bni_group_id INT(11) NULL;");
        echo "SUCCESS: Modified 'bni_group_id' to be nullable.
";
    }

    // Check for orphaned bni_group_ids
    $orphan_check = $db->query("SELECT ma.bni_group_id, COUNT(*) as count FROM meeting_attendance ma LEFT JOIN bni_groups bg ON ma.bni_group_id = bg.id WHERE bg.id IS NULL AND ma.bni_group_id IS NOT NULL GROUP BY ma.bni_group_id;");
    $orphans = $orphan_check->fetchAll(PDO::FETCH_ASSOC);

    if (count($orphans) > 0) {
        echo "WARNING: Found orphaned bni_group_ids in meeting_attendance table.
";
        foreach ($orphans as $orphan) {
            echo " - bni_group_id: " . $orphan['bni_group_id'] . " (" . $orphan['count'] . " rows)
";
        }
        // For now, we will set them to NULL to allow FK creation
        foreach ($orphans as $orphan) {
            if ($orphan['bni_group_id'] !== 0) { // we don't want to update rows that have 0 as this is default
                $update_stmt = $db->prepare("UPDATE meeting_attendance SET bni_group_id = NULL WHERE bni_group_id = :orphan_id;");
                $update_stmt->execute(['orphan_id' => $orphan['bni_group_id']]);
                echo "Set " . $update_stmt->rowCount() . " rows with orphaned bni_group_id " . $orphan['bni_group_id'] . " to NULL.
";
            }
        }
    } else {
        echo "INFO: No orphaned bni_group_ids found.
";
    }

    // Add foreign key if it doesn't exist
    $fk_check = $db->query("SELECT CONSTRAINT_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_SCHEMA = DATABASE() AND TABLE_NAME = 'meeting_attendance' AND COLUMN_NAME = 'bni_group_id' AND REFERENCED_TABLE_NAME = 'bni_groups';")->fetch();
    if (!$fk_check) {
        echo "Adding foreign key on 'bni_group_id' to 'bni_groups.id'.
";
        $db->exec("ALTER TABLE meeting_attendance ADD CONSTRAINT fk_meeting_attendance_bni_group FOREIGN KEY (bni_group_id) REFERENCES bni_groups(id) ON DELETE CASCADE;");
        echo "SUCCESS: Foreign key added.
";
    } else {
        echo "INFO: Foreign key on 'bni_group_id' already exists.
";
    }

    // Now, alter the column to be NOT NULL. This will fail if there are any NULLs left.
    // I will not do this for now, as the user might want to check the orphaned data first.
    // I will let the column be nullable for now.

    echo "Migration 033 completed successfully (bni_group_id is currently nullable).
";

} catch (Exception $e) {
    error_log("Migration 033 failed: " . $e->getMessage());
    die("FATAL: Migration 033 failed: " . $e->getMessage() . "\n");
}