<?php

namespace App\Services;

class CsvImportService
{
    /**
     * Read the first line of a file; returns null on failure.
     */
    public function readFirstLine(string $path): ?string
    {
        $fh = @fopen($path, 'r');
        if (!$fh) return null;
        $line = fgets($fh);
        fclose($fh);
        return $line === false ? null : $line;
    }

    /**
     * Detect delimiter and return columns for first row.
     * If $hasHeader is false, returns positional indices instead of header names.
     * Returns [delimiter, columns].
     */
    public function detectColumnsFromCsv(string $path, bool $hasHeader): array
    {
        // Use actual tab character for TSV; keep other common delimiters
        $delims = [',',';','|',"\t"]; 
        $bestDelim = ',';
        $bestCols = [];

        $firstLine = $this->readFirstLine($path);
        if ($firstLine === null) {
            return [$bestDelim, []];
        }

        $maxCount = 0;
        foreach ($delims as $d) {
            $row = str_getcsv($firstLine, $d);
            $count = is_array($row) ? count($row) : 0;
            if ($count > $maxCount) {
                $maxCount = $count;
                $bestDelim = $d;
                $bestCols = $row;
            }
        }

        if (!$hasHeader) {
            // return positional indices 0..N-1
            $cols = [];
            for ($i = 0; $i < $maxCount; $i++) {
                $cols[] = (string) $i;
            }
            return [$bestDelim, $cols];
        }

        // Clean header names
        $clean = array_map(function ($v) {
            $v = trim((string) $v);
            $v = preg_replace('/\s+/', ' ', $v);
            return $v;
        }, $bestCols);

        return [$bestDelim, $clean];
    }
}