<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Import;

/**
 * Tolerant CSV parser for editor-supplied files.
 *
 * German Excel exports ship with semicolon delimiters and Windows-1252
 * encoding; other tools use comma/UTF-8. Both are detected instead of
 * configured: encoding by BOM/UTF-8 validity, delimiter by counting
 * candidates in the header line. Multiline quoted values (e.g. RTE
 * descriptions) are handled by fgetcsv on a temp stream.
 */
final class CsvReader
{
    /**
     * @return array{columns: array<int,string>, rows: array<int,array<string,string>>}
     */
    public function parse(string $content): array
    {
        if (str_starts_with($content, "\xEF\xBB\xBF")) {
            $content = substr($content, 3);
        }
        if (!mb_check_encoding($content, 'UTF-8')) {
            $content = mb_convert_encoding($content, 'UTF-8', 'Windows-1252');
        }

        $firstLine = strtok($content, "\r\n") ?: '';
        $delimiter = ';';
        $best = 0;
        foreach ([';', ',', "\t"] as $candidate) {
            $count = substr_count($firstLine, $candidate);
            if ($count > $best) {
                $best = $count;
                $delimiter = $candidate;
            }
        }

        $stream = fopen('php://temp', 'r+');
        fwrite($stream, $content);
        rewind($stream);

        $header = fgetcsv($stream, null, $delimiter, '"', '');
        if (!is_array($header)) {
            fclose($stream);
            return ['columns' => [], 'rows' => []];
        }
        $columns = [];
        $seen = [];
        foreach ($header as $i => $name) {
            $name = trim((string)$name);
            if ($name === '') {
                $name = 'column_' . ($i + 1);
            }
            // Duplicate headers (e.g. the keyword research CSV repeats
            // "Vol (Global)" for the secondary block) get a _2/_3 suffix -
            // otherwise the later block silently overwrites the earlier one.
            if (isset($seen[$name])) {
                $seen[$name]++;
                $name .= '_' . $seen[$name];
            } else {
                $seen[$name] = 1;
            }
            $columns[$i] = $name;
        }

        $rows = [];
        while (($data = fgetcsv($stream, null, $delimiter, '"', '')) !== false) {
            if ($data === [null] || $data === ['']) {
                continue; // blank line
            }
            $row = [];
            $hasContent = false;
            foreach ($columns as $i => $name) {
                $value = trim((string)($data[$i] ?? ''));
                $row[$name] = $value;
                if ($value !== '') {
                    $hasContent = true;
                }
            }
            if ($hasContent) {
                $rows[] = $row;
            }
        }
        fclose($stream);

        return ['columns' => array_values($columns), 'rows' => $rows];
    }
}