<?php
/**
 * Assign Survey URLs to a Selection - AJAX Handler
 * Location: /clients/assign-selection-urls.php
 * 
 * Pulls available survey URLs from the project's batches and assigns them
 * to the selection's members. After assigning, auto-updates:
 *   - Selection status → 'targeted' (if fully assigned)
 *   - Project status → 'Targeted' (if ALL selections fully assigned)
 * 
 * POST (JSON body): { selection_id }
 * Returns: JSON { success, assigned_count, total_assigned, member_count, fully_assigned, message }
 * 
 * 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';
requireClientLogin();

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

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

try {
    $input = file_get_contents('php://input');
    $data = json_decode($input, true);

    if (!$data) {
        throw new Exception('Invalid JSON input');
    }

    $selection_id = (int)($data['selection_id'] ?? 0);

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

    $pdo = getClientDBConnection();

    // 1. Get selection details + project info
    $stmt = $pdo->prepare("
        SELECT ps.*, p.project_id AS project_code, p.project_name, p.id AS proj_id, p.status AS project_status
        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 access denied');
    }

    $project_code = $selection['project_code'];

    // 2. Count members in this selection
    $stmt = $pdo->prepare("SELECT COUNT(*) FROM selection_members WHERE selection_id = ?");
    $stmt->execute([$selection_id]);
    $member_count = (int)$stmt->fetchColumn();

    if ($member_count === 0) {
        echo json_encode([
            'success' => false,
            'message' => 'No members in this selection. Create the selection with members first.'
        ]);
        exit;
    }

    // 3. Count URLs already assigned to THIS selection
    $stmt = $pdo->prepare("
        SELECT COUNT(*) FROM survey_urls 
        WHERE project_id = ? AND assigned_to_selection_id = ?
    ");
    $stmt->execute([$project_code, $selection_id]);
    $already_assigned = (int)$stmt->fetchColumn();

    // 4. Calculate how many more URLs we need
    $needed = $member_count - $already_assigned;

    if ($needed <= 0) {
        echo json_encode([
            'success'        => true,
            'message'        => 'All members already have URLs assigned.',
            'assigned_count' => 0,
            'total_assigned' => $already_assigned,
            'member_count'   => $member_count,
            'fully_assigned' => true,
            'shortfall'      => 0
        ]);
        exit;
    }

    // 5. Get available URLs — use intval inline for LIMIT (PDO param binding fails for LIMIT on many MySQL configs)
    $needed_int = intval($needed);
    $stmt = $pdo->prepare("
        SELECT id FROM survey_urls 
        WHERE project_id = ? 
        AND status = 'available'
        AND assigned_to_selection_id IS NULL
        ORDER BY batch_number ASC, id ASC
        LIMIT {$needed_int}
    ");
    $stmt->execute([$project_code]);
    $available_url_ids = $stmt->fetchAll(PDO::FETCH_COLUMN);

    $available_count = count($available_url_ids);
    $shortfall = $needed - $available_count;

    // 6. Assign the URLs within a transaction
    if ($available_count > 0) {
        $pdo->beginTransaction();

        try {
            $update_stmt = $pdo->prepare("
                UPDATE survey_urls 
                SET status = 'assigned', 
                    assigned_to_selection_id = ?
                WHERE id = ?
                AND status = 'available'
                AND assigned_to_selection_id IS NULL
            ");

            $assigned_count = 0;
            foreach ($available_url_ids as $url_id) {
                $update_stmt->execute([$selection_id, $url_id]);
                $assigned_count += $update_stmt->rowCount();
            }

            $total_assigned = $already_assigned + $assigned_count;
            $fully_assigned = ($total_assigned >= $member_count);

            // Auto-update selection status to 'targeted' if fully assigned
            if ($fully_assigned && in_array($selection['status'], ['draft'])) {
                $stmt = $pdo->prepare("UPDATE project_selections SET status = 'targeted' WHERE id = ?");
                $stmt->execute([$selection_id]);
            }

            // Check if ALL selections for this project are fully assigned → project 'Targeted'
            if ($fully_assigned) {
                $stmt = $pdo->prepare("
                    SELECT ps.id, 
                           COUNT(DISTINCT sm.user_id) AS member_count,
                           COUNT(DISTINCT su.id) AS url_count
                    FROM project_selections ps
                    LEFT JOIN selection_members sm ON ps.id = sm.selection_id
                    LEFT JOIN survey_urls su ON ps.id = su.assigned_to_selection_id
                    WHERE ps.project_id = ? AND ps.client_id = ?
                    GROUP BY ps.id
                ");
                $stmt->execute([$selection['project_id'], $_SESSION['client_id']]);
                $all_selections = $stmt->fetchAll(PDO::FETCH_ASSOC);

                $all_targeted = true;
                foreach ($all_selections as $s) {
                    if ($s['member_count'] > 0 && $s['url_count'] < $s['member_count']) {
                        $all_targeted = false;
                        break;
                    }
                }

                if ($all_targeted && $selection['project_status'] === 'Created') {
                    $stmt = $pdo->prepare("UPDATE projects SET status = 'Targeted' WHERE id = ?");
                    $stmt->execute([$selection['proj_id']]);
                }
            }

            // ✅ FIX: selection_activity_log uses: description (not details), performed_by (not client_id), NO ip_address
            $details = json_encode(['assigned' => $assigned_count, 'total' => $total_assigned, 'members' => $member_count]);
            $stmt = $pdo->prepare("
                INSERT INTO selection_activity_log (selection_id, action, description, performed_by, created_at)
                VALUES (?, 'urls_assigned', ?, ?, NOW())
            ");
            $stmt->execute([$selection_id, $details, $_SESSION['client_id']]);

            $pdo->commit();

            // Build response message
            $remaining = max(0, $member_count - $total_assigned);
            $msg = "Assigned $assigned_count URL(s)";
            if ($remaining > 0) {
                $msg .= ". Still need $remaining more URL(s).";
            } else {
                $msg .= ". All members have URLs assigned!";
                if ($fully_assigned) {
                    $msg .= " Selection status updated to 'targeted'.";
                }
            }

            echo json_encode([
                'success'        => true,
                'assigned_count' => $assigned_count,
                'total_assigned' => $total_assigned,
                'member_count'   => $member_count,
                'fully_assigned' => $fully_assigned,
                'shortfall'      => max(0, $shortfall),
                'message'        => $msg
            ]);

        } catch (Exception $e) {
            $pdo->rollBack();
            throw $e;
        }
    } else {
        echo json_encode([
            'success'        => false,
            'message'        => sprintf(
                'No available survey URLs found for this project. %d URLs are required for %d members. Please upload survey URL batches first.',
                $needed, $member_count
            ),
            'assigned_count' => 0,
            'total_assigned' => $already_assigned,
            'member_count'   => $member_count,
            'fully_assigned' => false,
            'shortfall'      => $needed
        ]);
    }

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