<?php
session_start();

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

function redirect_with_message($status, $message) {
    header("Location: index.php?import_status=$status&import_message=" . urlencode($message));
    exit();
}

if ($_SERVER['REQUEST_METHOD'] !== 'POST' || !isset($_FILES['importFile'])) {
    redirect_with_message('error', 'Invalid request.');
}

$file = $_FILES['importFile'];

if ($file['error'] !== UPLOAD_ERR_OK) {
    redirect_with_message('error', 'File upload failed with error code: ' . $file['error']);
}

$file_ext = strtolower(pathinfo($file['name'], PATHINFO_EXTENSION));
if ($file_ext !== 'csv') {
    redirect_with_message('error', 'Invalid file type. Only .csv files are accepted.');
}

$handle = fopen($file['tmp_name'], 'r');
if ($handle === false) {
    redirect_with_message('error', 'Could not open the uploaded file.');
}

try {
    $pdo = db();
    $pdo->beginTransaction();

    $header = fgetcsv($handle);
    if ($header === false) {
        redirect_with_message('error', 'Could not read the CSV header.');
    }

    // Normalize headers to camelCase
    $normalized_header = array_map(function($h) {
        $h = trim($h);
        $h = preg_replace('/[^a-zA-Z0-9_\s]/', '', $h); // Remove special chars
        $h = preg_replace('/\s+/', ' ', $h); // Normalize whitespace
        $h = str_replace(' ', '', ucwords(strtolower($h))); // To PascalCase
        return lcfirst($h); // To camelCase
    }, $header);
    
    $expected_headers = [
        'sapCode', 'fullNameEn', 'legalEntity', 'functionBusinessUnit', 'costCenterCode', 'level',
        'newAmendedSalary', 'employerContributions', 'cars', 'ticketRestaurant', 'metlife', 'topusPerMonth'
    ];

    $col_map = array_flip($normalized_header);

    foreach ($expected_headers as $expected) {
        if (!isset($col_map[$expected])) {
            redirect_with_message('error', "Missing required column: '{$expected}'. Please check the CSV file header.");
        }
    }

    $sql = "INSERT INTO roster (sapCode, fullNameEn, legalEntity, functionBusinessUnit, costCenterCode, `level`, newAmendedSalary, employerContributions, cars, ticketRestaurant, metlife, topusPerMonth, totalSalaryCostWithLabor, totalMonthlyCost, totalAnnualCost) 
            VALUES (:sapCode, :fullNameEn, :legalEntity, :functionBusinessUnit, :costCenterCode, :level, :newAmendedSalary, :employerContributions, :cars, :ticketRestaurant, :metlife, :topusPerMonth, :totalSalaryCostWithLabor, :totalMonthlyCost, :totalAnnualCost)
            ON DUPLICATE KEY UPDATE 
                fullNameEn = VALUES(fullNameEn),
                legalEntity = VALUES(legalEntity),
                functionBusinessUnit = VALUES(functionBusinessUnit),
                costCenterCode = VALUES(costCenterCode),
                `level` = VALUES(`level`),
                newAmendedSalary = VALUES(newAmendedSalary),
                employerContributions = VALUES(employerContributions),
                cars = VALUES(cars),
                ticketRestaurant = VALUES(ticketRestaurant),
                metlife = VALUES(metlife),
                topusPerMonth = VALUES(topusPerMonth),
                totalSalaryCostWithLabor = VALUES(totalSalaryCostWithLabor),
                totalMonthlyCost = VALUES(totalMonthlyCost),
                totalAnnualCost = VALUES(totalAnnualCost)";

    $stmt = $pdo->prepare($sql);
    
    $rows_processed = 0;
    while (($row = fgetcsv($handle)) !== false) {
        $data = array_combine(array_keys($col_map), $row);

        $sapCode = $data['sapCode'] ?? null;
        if (empty($sapCode)) {
            continue; // Skip rows without a SAP Code
        }

        // Prepare data and perform calculations
        $newAmendedSalary = (float)($data['newAmendedSalary'] ?? 0);
        $employerContributions = (float)($data['employerContributions'] ?? 0);
        $cars = (float)($data['cars'] ?? 0);
        $ticketRestaurant = (float)($data['ticketRestaurant'] ?? 0);
        $metlife = (float)($data['metlife'] ?? 0);
        $topusPerMonth = (float)($data['topusPerMonth'] ?? 0);

        $totalSalaryCostWithLabor = $newAmendedSalary + $employerContributions;
        $totalMonthlyCost = $totalSalaryCostWithLabor + $cars + $ticketRestaurant + $metlife + $topusPerMonth;
        $totalAnnualCost = $totalMonthlyCost * 14;

        $stmt->execute([
            ':sapCode' => $sapCode,
            ':fullNameEn' => $data['fullNameEn'] ?? null,
            ':legalEntity' => $data['legalEntity'] ?? null,
            ':functionBusinessUnit' => $data['functionBusinessUnit'] ?? null,
            ':costCenterCode' => $data['costCenterCode'] ?? null,
            ':level' => $data['level'] ?? null,
            ':newAmendedSalary' => $newAmendedSalary,
            ':employerContributions' => $employerContributions,
            ':cars' => $cars,
            ':ticketRestaurant' => $ticketRestaurant,
            ':metlife' => $metlife,
            ':topusPerMonth' => $topusPerMonth,
            ':totalSalaryCostWithLabor' => $totalSalaryCostWithLabor,
            ':totalMonthlyCost' => $totalMonthlyCost,
            ':totalAnnualCost' => $totalAnnualCost
        ]);
        $rows_processed++;
    }

    $pdo->commit();
    fclose($handle);
    redirect_with_message('success', "Successfully imported {$rows_processed} records.");

} catch (Exception $e) {
    if ($pdo->inTransaction()) {
        $pdo->rollBack();
    }
    fclose($handle);
    error_log("Import Error: " . $e->getMessage());
    redirect_with_message('error', 'An error occurred during the import process. Details: ' . $e->getMessage());
}