<?php
/**
 * Update Selection Quota Limit (AJAX handler)
 * Location: /clients/update-selection-quota.php
 * 
 * Created 2026-02-26: Allows clients to set/edit quota limit per selection.
 * 
 * Rules:
 *   - Quota can be set to any value >= 0 (0 or null = no limit)
 *   - If quota not yet achieved, client can set any value
 *   - If quota already achieved, client can only INCREASE (not decrease)
 *   - Sum of all selection quotas cannot exceed project sample_size
 *   - Increasing quota after it was achieved will re-activate remaining URLs
 */
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 {
    $data = json_decode(file_get_contents('php://input'), true);
    $selection_id = (int)($data['selection_id'] ?? 0);
    $quota_limit = isset($data['quota_limit']) ? (int)$data['quota_limit'] : null;
    
    if (!$selection_id) {
        throw new Exception('Invalid selection ID');
    }
    
    // Treat 0 or empty as NULL (no limit)
    if ($quota_limit !== null && $quota_limit <= 0) {
        $quota_limit = null;
    }
    
    $pdo = getClientDBConnection();
    
    // Get selection with project info
    $stmt = $pdo->prepare("
        SELECT ps.*, p.project_id AS project_code, p.sample_size AS project_sample_size, p.id AS proj_db_id
        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');
    }
    
    $currentQuota = $selection['quota_limit'] !== null ? (int)$selection['quota_limit'] : null;
    
    // Count current completes in this selection
    $stmt = $pdo->prepare("
        SELECT COUNT(*) FROM survey_urls 
        WHERE assigned_to_selection_id = ? AND status = 'complete'
    ");
    $stmt->execute([$selection_id]);
    $selCompletes = (int)$stmt->fetchColumn();
    
    // RULE: If quota was already achieved, only allow increase
    if ($currentQuota !== null && $selCompletes >= $currentQuota) {
        if ($quota_limit !== null && $quota_limit < $selCompletes) {
            throw new Exception("Cannot set quota below current completes ($selCompletes). You can only increase the quota.");
        }
        if ($quota_limit !== null && $quota_limit < $currentQuota) {
            throw new Exception("Quota was already achieved ($selCompletes completes). You can only increase from $currentQuota.");
        }
    }
    
    // RULE: Sum of all selection quotas cannot exceed project sample_size
    if ($quota_limit !== null && $selection['project_sample_size'] > 0) {
        // Get sum of quotas for OTHER selections in this project
        $stmt = $pdo->prepare("
            SELECT COALESCE(SUM(quota_limit), 0) as other_quota_sum
            FROM project_selections 
            WHERE project_id = ? AND id != ? AND quota_limit IS NOT NULL
        ");
        $stmt->execute([$selection['project_id'], $selection_id]);
        $otherQuotaSum = (int)$stmt->fetchColumn();
        
        if (($otherQuotaSum + $quota_limit) > $selection['project_sample_size']) {
            $remaining = $selection['project_sample_size'] - $otherQuotaSum;
            throw new Exception("Total quotas across all selections cannot exceed project sample size ({$selection['project_sample_size']}). Other selections use $otherQuotaSum. Maximum for this selection: $remaining.");
        }
    }
    
    // Update the quota
    $pdo->beginTransaction();
    
    try {
        $stmt = $pdo->prepare("
            UPDATE project_selections 
            SET quota_limit = ?, updated_at = NOW()
            WHERE id = ?
        ");
        $stmt->execute([$quota_limit, $selection_id]);
        
        // If quota was INCREASED after being reached, re-activate quotafull URLs
        if ($quota_limit !== null && $currentQuota !== null && $selCompletes >= $currentQuota && $quota_limit > $currentQuota) {
            // Re-activate URLs that were marked quotafull in this selection
            // Change them back to 'assigned' (they were assigned before being marked quotafull)
            $stmt = $pdo->prepare("
                UPDATE survey_urls 
                SET status = 'assigned', completed_at = NULL
                WHERE assigned_to_selection_id = ? 
                AND status = 'quotafull'
            ");
            $stmt->execute([$selection_id]);
            $reactivated = $stmt->rowCount();
            
            // Re-activate selection members that were marked quota_full
            $stmt = $pdo->prepare("
                UPDATE selection_members 
                SET sample_status = 'pending'
                WHERE selection_id = ? 
                AND sample_status = 'quota_full'
            ");
            $stmt->execute([$selection_id]);
            
            if ($reactivated > 0) {
                error_log("Quota increased: SelectionID=$selection_id, OldQuota=$currentQuota, NewQuota=$quota_limit, Reactivated=$reactivated URLs");
            }
        }
        
        // Log activity
        $desc = $quota_limit !== null 
            ? "Quota limit set to $quota_limit (was " . ($currentQuota ?? 'none') . ")" 
            : "Quota limit removed (was " . ($currentQuota ?? 'none') . ")";
        
        $stmt = $pdo->prepare("
            INSERT INTO selection_activity_log (selection_id, action, description, performed_by, created_at)
            VALUES (?, 'quota_updated', ?, ?, NOW())
        ");
        $stmt->execute([$selection_id, $desc, $_SESSION['client_id']]);
        
        $pdo->commit();
        
        echo json_encode([
            'success' => true,
            'message' => $quota_limit !== null 
                ? "Quota limit set to $quota_limit" 
                : "Quota limit removed",
            'quota_limit' => $quota_limit,
            'completes' => $selCompletes
        ]);
        
    } catch (Exception $e) {
        $pdo->rollBack();
        throw $e;
    }
    
} catch (Exception $e) {
    error_log("Update selection quota error: " . $e->getMessage());
    echo json_encode([
        'success' => false,
        'message' => $e->getMessage()
    ]);
}