<?php

declare(strict_types=1);

namespace App\Support\Batch;

use App\Support\AdminContent;
use Illuminate\Http\UploadedFile;
use Illuminate\Support\Arr;
use Illuminate\Validation\ValidationException;
use Spatie\Translatable\HasTranslations;

/**
 * Turns rows — from a JSON array or a CSV file — into the create and update
 * calls the API already has, and hands them to the batch runner.
 *
 * A row that names an existing record, by `id` or by the field given as
 * `match`, updates it; any other row creates one. In a CSV, a column called
 * `title.es` fills the Spanish title, a list is written `1|2|3`, `true` and
 * `false` are booleans, and an empty cell is left out rather than erasing
 * what is there.
 */
final class Importer
{
    public const MAX_ROWS = BatchRunner::MAX_OPERATIONS;

    /**
     * Fields a CSV writes as `a|b|c`.
     */
    protected const LISTS = ['technology_ids', 'service_ids', 'project_ids'];

    /**
     * @return array<int, array<string, mixed>>
     */
    public function rowsFromCsv(UploadedFile $file): array
    {
        $handle = fopen($file->getRealPath(), 'r');
        $header = null;
        $rows = [];

        while (($line = fgetcsv($handle, escape: '\\')) !== false) {
            if ($line === [null]) {
                continue;
            }

            if ($header === null) {
                // A byte-order mark is what a spreadsheet saving "CSV UTF-8"
                // puts before the first column's name.
                $header = array_map(fn ($name) => trim((string) preg_replace('/^\xEF\xBB\xBF/', '', (string) $name)), $line);

                continue;
            }

            $row = [];

            foreach ($header as $i => $column) {
                $value = $line[$i] ?? '';

                if ($column === '' || $value === '') {
                    continue;
                }

                Arr::set($row, $column, $this->cell($column, $value));
            }

            $rows[] = $row;
        }

        fclose($handle);

        return $rows;
    }

    /**
     * @param  array<int, array<string, mixed>>  $rows
     * @return array<int, array{method: string, path: string, body: array<string, mixed>}>
     */
    public function operations(string $resource, array $rows, ?string $match = null): array
    {
        if (count($rows) > self::MAX_ROWS) {
            throw ValidationException::withMessages(['rows' => [__('rules.batch.too_many', ['max' => self::MAX_ROWS])]]);
        }

        return array_map(function (array $row) use ($resource, $match): array {
            $id = $row['id'] ?? $this->existing($resource, $row, $match);
            unset($row['id']);

            return $id === null
                ? ['method' => 'POST', 'path' => "/v1/{$resource}", 'body' => $row]
                : ['method' => 'PATCH', 'path' => "/v1/{$resource}/{$id}", 'body' => $row];
        }, $rows);
    }

    /**
     * The record a row names through its `match` field, if any: a slug is
     * looked up in the default language when it is translated.
     *
     * @param  array<string, mixed>  $row
     */
    protected function existing(string $resource, array $row, ?string $match): mixed
    {
        if ($match === null || ! array_key_exists($match, $row)) {
            return null;
        }

        $model = AdminContent::model($resource);
        $instance = new $model;
        $value = $row[$match];
        $translated = in_array(HasTranslations::class, class_uses_recursive($model), true)
            && in_array($match, $instance->translatable, true);

        if ($translated) {
            $locale = (string) config('locales.default');
            $value = is_array($value) ? ($value[$locale] ?? null) : $value;
            $column = "{$match}->{$locale}";
        } else {
            $column = $match;
        }

        if ($value === null || is_array($value)) {
            return null;
        }

        $query = $model::query();

        if (method_exists($instance, 'bootSoftDeletes')) {
            $query->withTrashed();
        }

        return $query->where($column, $value)->value($instance->getKeyName());
    }

    protected function cell(string $column, string $value): mixed
    {
        $base = explode('.', $column)[0];

        return match (true) {
            in_array($base, self::LISTS, true) => array_map(
                fn ($item) => is_numeric($item) ? (int) $item : $item,
                array_values(array_filter(array_map('trim', explode('|', $value)), fn ($item) => $item !== '')),
            ),
            strtolower($value) === 'true' => true,
            strtolower($value) === 'false' => false,
            strtolower($value) === 'null' => null,
            default => $value,
        };
    }
}