<?php
/**
 * Send Invitations - AJAX Handler
 * Location: /clients/send-invitations.php
 * 
 * Sends email invitations to all members of a selection via SendGrid.
 * Updates survey_urls, selection, and project statuses.
 * 
 * POST params: selection_id, incentive_amount (optional override)
 * Returns: JSON { success, sent_count, failed_count, errors[] }
 * 
 * BUG FIX 2026-02-06: Fixed selection_activity_log INSERT to use correct
 * column names (description, performed_by) instead of (client_id, details, ip_address)
 */
ini_set('display_errors', 0);
error_reporting(E_ALL);
ini_set('log_errors', 1);

require_once 'client-session.php';
require_once 'panel-db-config.php';
require_once 'sendgrid-config.php';
requireClientLogin();

header('Content-Type: application/json');

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    echo json_encode(['success' => false, 'message' => 'Invalid request method']);
    exit;
}

try {
    $pdo = getClientDBConnection();
    $panelPdo = getPanelDBConnection();

    $selection_id = isset($_POST['selection_id']) ? (int)$_POST['selection_id'] : 0;
    $incentive_override = isset($_POST['incentive_amount']) ? (float)$_POST['incentive_amount'] : 0;

    if (!$selection_id) {
        throw new Exception('Invalid selection ID');
    }

    // 1. Get selection + project details
    $stmt = $pdo->prepare("
        SELECT ps.*, p.project_name, p.project_id AS project_code, p.eloi, p.id AS proj_id,
               p.status AS project_status, p.made_live_at
        FROM project_selections ps
        JOIN projects p ON ps.project_id = p.id
        WHERE ps.id = ? AND ps.client_id = ?
    ");
    $stmt->execute([$selection_id, $_SESSION['client_id']]);
    $selection = $stmt->fetch(PDO::FETCH_ASSOC);

    if (!$selection) {
        throw new Exception('Selection not found or unauthorized');
    }

    // 2. Validate selection status — must be 'targeted' (URLs fully assigned)
    if (!in_array($selection['status'], ['targeted', 'draft'])) {
        // Allow re-check: if already live, block
        if ($selection['status'] === 'live') {
            throw new Exception('Invitations have already been sent for this selection');
        }
        throw new Exception('Selection must be in "targeted" status to send invitations. Current: ' . $selection['status']);
    }

    // 3. Get member count
    $stmt = $pdo->prepare("SELECT COUNT(*) FROM selection_members WHERE selection_id = ?");
    $stmt->execute([$selection_id]);
    $member_count = (int)$stmt->fetchColumn();

    if ($member_count === 0) {
        throw new Exception('No members in this selection');
    }

    // 4. Get assigned URL count for this selection
    $stmt = $pdo->prepare("
        SELECT COUNT(*) FROM survey_urls 
        WHERE assigned_to_selection_id = ? AND status = 'assigned'
    ");
    $stmt->execute([$selection_id]);
    $assigned_count = (int)$stmt->fetchColumn();

    if ($assigned_count < $member_count) {
        throw new Exception("Not all members have URLs assigned. Members: $member_count, URLs assigned: $assigned_count");
    }

    // 5. Calculate & validate incentive
    $eloi = (int)$selection['eloi'];
    $default_incentive = calculateDefaultIncentive($eloi);
    $incentive = $incentive_override > 0 ? $incentive_override : $default_incentive;

    if ($incentive < $default_incentive) {
        throw new Exception("Incentive cannot be less than ₹" . number_format($default_incentive, 0) . " (default for {$eloi} min LOI)");
    }

    // 6. Get all assigned URLs for this selection
    $stmt = $pdo->prepare("
        SELECT id, rr_proxy_url, unique_identifier
        FROM survey_urls
        WHERE assigned_to_selection_id = ? AND status = 'assigned'
        ORDER BY id ASC
    ");
    $stmt->execute([$selection_id]);
    $urls = $stmt->fetchAll(PDO::FETCH_ASSOC);

    // 7. Get all member user_ids for this selection (ordered to pair with URLs)
    $stmt = $pdo->prepare("
        SELECT user_id FROM selection_members 
        WHERE selection_id = ? 
        ORDER BY id ASC
    ");
    $stmt->execute([$selection_id]);
    $members = $stmt->fetchAll(PDO::FETCH_COLUMN);

    // 8. Pair members with URLs
    $send_queue = [];
    for ($i = 0; $i < count($members); $i++) {
        if (!isset($urls[$i])) break;
        $send_queue[] = [
            'user_id'    => $members[$i],
            'url_id'     => $urls[$i]['id'],
            'proxy_url'  => $urls[$i]['rr_proxy_url'],
            'unique_id'  => $urls[$i]['unique_identifier']
        ];
    }

    if (empty($send_queue)) {
        throw new Exception('No URL-member pairs available to send');
    }

    // 9. Look up member emails from panel DB
    $user_ids = array_column($send_queue, 'user_id');
    $placeholders = implode(',', array_fill(0, count($user_ids), '?'));
    $stmt = $panelPdo->prepare("SELECT id, email FROM users WHERE id IN ($placeholders) AND status = 'active'");
    $stmt->execute($user_ids);
    $email_map = $stmt->fetchAll(PDO::FETCH_KEY_PAIR); // id => email

    // 10. Send emails
    $subject = 'Invitation: Your Online Survey Opportunity from Relevant Reflex India';
    $sent_count = 0;
    $failed_count = 0;
    $errors = [];

    $pdo->beginTransaction();

    foreach ($send_queue as $item) {
        $user_id = $item['user_id'];
        $url_id  = $item['url_id'];

        if (!isset($email_map[$user_id])) {
            $failed_count++;
            $errors[] = "User ID $user_id: email not found or inactive";
            continue;
        }

        $email = $email_map[$user_id];
        $html  = buildInvitationEmail($item['proxy_url'], $eloi, $incentive);

        $result = sendEmailViaSendGrid($email, $subject, $html);

        if ($result['success']) {
            // Update survey_url: status → sent, link to user
            $stmt = $pdo->prepare("
                UPDATE survey_urls 
                SET status = 'sent', 
                    is_sent = 1, 
                    sent_to_user_id = ?, 
                    sent_at = NOW()
                WHERE id = ?
            ");
            $stmt->execute([$user_id, $url_id]);
            $sent_count++;
        } else {
            $failed_count++;
            $errors[] = "User ID $user_id ($email): " . $result['message'];
            error_log("SendGrid error for $email: " . $result['message']);
        }
    }

    // 11. Update selection status
    $stmt = $pdo->prepare("
        UPDATE project_selections 
        SET status = 'live',
            incentive_amount = ?,
            invitations_sent_at = NOW(),
            launched_at = CASE WHEN launched_at IS NULL THEN NOW() ELSE launched_at END
        WHERE id = ?
    ");
    $stmt->execute([$incentive, $selection_id]);

    // 12. Update project status to 'Live' if not already
    if ($selection['project_status'] !== 'Live') {
        $stmt = $pdo->prepare("
            UPDATE projects 
            SET status = 'Live',
                made_live_at = CASE WHEN made_live_at IS NULL THEN NOW() ELSE made_live_at END
            WHERE id = ?
        ");
        $stmt->execute([$selection['proj_id']]);
    }

    // 13. Log activity
    // ✅ FIX: selection_activity_log uses: description (not details), performed_by (not client_id), NO ip_address
    $details = json_encode([
        'sent' => $sent_count,
        'failed' => $failed_count,
        'incentive' => $incentive,
        'eloi' => $eloi
    ]);

    $stmt = $pdo->prepare("
        INSERT INTO selection_activity_log (selection_id, action, description, performed_by, created_at)
        VALUES (?, 'invitations_sent', ?, ?, NOW())
    ");
    $stmt->execute([$selection_id, $details, $_SESSION['client_id']]);

    // project_activity_log schema is correct as-is (has client_id, details, ip_address)
    $stmt = $pdo->prepare("
        INSERT INTO project_activity_log (project_id, client_id, action, details, ip_address, created_at)
        VALUES (?, ?, 'invitations_sent', ?, ?, NOW())
    ");
    $stmt->execute([$selection['proj_id'], $_SESSION['client_id'], $details, $_SERVER['REMOTE_ADDR'] ?? '']);

    $pdo->commit();

    echo json_encode([
        'success'      => true,
        'sent_count'   => $sent_count,
        'failed_count' => $failed_count,
        'errors'       => $errors,
        'incentive'    => $incentive,
        'message'      => "Successfully sent $sent_count invitation(s)" . ($failed_count > 0 ? ", $failed_count failed" : '')
    ]);

} catch (Exception $e) {
    if (isset($pdo) && $pdo->inTransaction()) {
        $pdo->rollBack();
    }
    error_log("Send invitations error: " . $e->getMessage());
    echo json_encode([
        'success' => false,
        'message' => $e->getMessage()
    ]);
}