<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Controller\Backend;

use Evomedien\Vitec\Import\CsvReader;
use Evomedien\Vitec\Import\ImportModelRegistry;
use Evomedien\Vitec\Import\MappingRepository;
use Evomedien\Vitec\Import\SeoResearchRepository;
use Evomedien\Vitec\Import\SeoResearchService;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use TYPO3\CMS\Backend\Attribute\AsController;
use TYPO3\CMS\Backend\Routing\UriBuilder;
use TYPO3\CMS\Backend\Template\ModuleTemplateFactory;
use TYPO3\CMS\Core\DataHandling\DataHandler;
use TYPO3\CMS\Core\Http\RedirectResponse;
use TYPO3\CMS\Core\Messaging\FlashMessage;
use TYPO3\CMS\Core\Messaging\FlashMessageService;
use TYPO3\CMS\Core\Page\PageRenderer;
use TYPO3\CMS\Core\Type\ContextualFeedbackSeverity;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Backend module: CSV import for the VITEC domain models.
 *
 * Workflow per model page (decisions 2026-08-06):
 *   1. Upload a CSV; delimiter and encoding are auto-detected.
 *   2. Map CSV columns to DB fields; the mapping (and the identity field
 *      used for matching) is persisted per model via MappingRepository.
 *   3. A unified list shows CSV rows matched against the DB records:
 *      new / update (with the differing fields) / unchanged / db-only.
 *      Each importable row carries an editable JSON payload textarea -
 *      what is applied is the textarea, not the raw CSV.
 *   4. Checked rows are written through DataHandler (BE user permissions
 *      apply). New records are created on the configured pid.
 *
 * The parsed CSV travels through the form as a hidden JSON field, so the
 * module needs no server-side session state.
 */
#[AsController]
final class ImportController
{
    public function __construct(
        private readonly ModuleTemplateFactory $moduleTemplateFactory,
        private readonly ImportModelRegistry $registry,
        private readonly MappingRepository $mappingRepository,
        private readonly CsvReader $csvReader,
        private readonly SeoResearchRepository $seoResearchRepository,
        private readonly SeoResearchService $seoResearchService,
        private readonly FlashMessageService $flashMessageService,
        private readonly PageRenderer $pageRenderer,
        private readonly UriBuilder $uriBuilder,
    ) {}

    public function indexAction(ServerRequestInterface $request): ResponseInterface
    {
        $modelKey = (string)($request->getQueryParams()['model'] ?? 'market');
        if (!$this->registry->has($modelKey)) {
            $modelKey = 'market';
        }
        return $this->render($request, $modelKey, null, null, null);
    }

    public function processAction(ServerRequestInterface $request): ResponseInterface
    {
        $body = (array)$request->getParsedBody();
        $modelKey = (string)($body['model'] ?? '');
        if (!$this->registry->has($modelKey)) {
            return new RedirectResponse((string)$this->uriBuilder->buildUriFromRoute('web_vitecimport'), 303);
        }
        $op = (string)($body['op'] ?? 'preview');

        // CSV: fresh upload wins, otherwise the hidden state field.
        $csv = null;
        $files = $request->getUploadedFiles();
        $upload = $files['csvfile'] ?? null;
        if ($upload !== null && $upload->getError() === UPLOAD_ERR_OK) {
            $csv = $this->csvReader->parse((string)$upload->getStream());
            if ($csv['columns'] === []) {
                $this->flash('The file could not be parsed as CSV.', 'Upload', false);
                $csv = null;
            } else {
                $this->flash(
                    sprintf('%d rows, %d columns detected.', count($csv['rows']), count($csv['columns'])),
                    'CSV loaded',
                    true
                );
            }
        } elseif (($body['csvstate'] ?? '') !== '') {
            $decoded = json_decode((string)$body['csvstate'], true);
            if (is_array($decoded) && isset($decoded['columns'], $decoded['rows'])) {
                $csv = $decoded;
            }
        }

        // Mapping from the form, when present.
        $mapping = null;
        $identity = null;
        if (isset($body['map']) && is_array($body['map'])) {
            $mapping = [];
            foreach ($body['map'] as $column => $field) {
                if ((string)$field !== '') {
                    $mapping[(string)$column] = (string)$field;
                }
            }
            $identity = (string)($body['identity'] ?? '');
        }

        if ($op === 'saveMapping' && $mapping !== null && $identity !== '') {
            $this->mappingRepository->save($modelKey, $mapping, $identity);
            $this->flash('Mapping stored for this model - it will be preselected on the next upload.', 'Mapping saved', true);
        }

        if ($op === 'apply') {
            $this->apply($modelKey, $body);
        }

        return $this->render($request, $modelKey, $csv, $mapping, $identity);
    }

    // --------------------------------------------------- SEO research tab

    public function seoAction(ServerRequestInterface $request): ResponseInterface
    {
        $latest = $this->seoResearchRepository->latest(0);
        $previous = $this->seoResearchRepository->latest(1);
        $analysis = $latest !== null
            ? $this->seoResearchService->analyze($latest['rows'], $previous !== null ? $previous['rows'] : null)
            : null;

        $this->pageRenderer->addCssFile('EXT:vitec/Resources/Public/Css/backend-import.css');
        $view = $this->moduleTemplateFactory->create($request);
        $view->assignMultiple([
            'models' => $this->registry->all(),
            'latest' => $latest,
            'previous' => $previous,
            'analysis' => $analysis,
        ]);
        return $view->renderResponse('Import/Seo');
    }

    public function seoUploadAction(ServerRequestInterface $request): ResponseInterface
    {
        $files = $request->getUploadedFiles();
        $upload = $files['csvfile'] ?? null;
        if ($upload !== null && $upload->getError() === UPLOAD_ERR_OK) {
            $csv = $this->csvReader->parse((string)$upload->getStream());
            $rows = $this->seoResearchService->normalizeRows($csv['rows']);
            if ($rows === []) {
                $this->flash('No usable rows found - is the "Potential URL" column present?', 'Upload', false);
            } else {
                $this->seoResearchRepository->add((string)($upload->getClientFilename() ?? 'upload.csv'), $rows);
                $this->flash(sprintf('%d rows stored as new delivery.', count($rows)), 'Delivery stored', true);
            }
        } else {
            $this->flash('No file received.', 'Upload', false);
        }
        return new RedirectResponse((string)$this->uriBuilder->buildUriFromRoute('web_vitecimport.seo'), 303);
    }

    // ------------------------------------------------------------ rendering

    /**
     * @param array{columns:array<int,string>,rows:array<int,array<string,string>>}|null $csv
     * @param array<string,string>|null $mapping
     */
    private function render(
        ServerRequestInterface $request,
        string $modelKey,
        ?array $csv,
        ?array $mapping,
        ?string $identity
    ): ResponseInterface {
        $model = $this->registry->get($modelKey);
        $fields = $this->registry->importableFields($model['table']);
        $saved = $this->mappingRepository->load($modelKey);

        if ($mapping === null) {
            $mapping = $saved['mapping'] ?? [];
            if ($mapping === [] && $csv !== null) {
                $mapping = $this->guessMapping($csv['columns'], $fields);
            }
        }
        if ($identity === null || $identity === '') {
            $identity = $saved['identity'] ?? (isset($fields['slug']) ? 'slug' : 'title');
        }

        $union = $this->buildUnion($model['table'], $fields, $csv, $mapping, $identity);

        $counts = ['new' => 0, 'update' => 0, 'unchanged' => 0, 'dbonly' => 0];
        foreach ($union as $row) {
            $counts[$row['status']]++;
        }

        // Column meta for the mapping panel: sample value + current target.
        $columns = [];
        foreach ($csv['columns'] ?? [] as $column) {
            $columns[] = [
                'name' => $column,
                'sample' => (string)($csv['rows'][0][$column] ?? ''),
                'target' => $mapping[$column] ?? '',
            ];
        }

        $this->pageRenderer->addCssFile('EXT:vitec/Resources/Public/Css/backend-import.css');
        $view = $this->moduleTemplateFactory->create($request);
        $view->assignMultiple([
            'models' => $this->registry->all(),
            'model' => $model,
            'fields' => $fields,
            'columns' => $columns,
            'hasCsv' => $csv !== null,
            'csvRowCount' => count($csv['rows'] ?? []),
            'csvstate' => $csv !== null ? (string)json_encode($csv, JSON_UNESCAPED_UNICODE) : '',
            'identity' => $identity,
            'mappingSaved' => $saved !== null,
            'union' => $union,
            'counts' => $counts,
            'pid' => $this->registry->detectPid($model['table']),
        ]);

        return $view->renderResponse('Import/Index');
    }

    /**
     * Name-equality guess for a first-time mapping.
     *
     * @param array<int,string> $columns
     * @param array<string,string> $fields
     * @return array<string,string>
     */
    private function guessMapping(array $columns, array $fields): array
    {
        $mapping = [];
        foreach ($columns as $column) {
            $normalized = mb_strtolower(trim($column));
            if (isset($fields[$normalized])) {
                $mapping[$column] = $normalized;
            }
        }
        return $mapping;
    }

    /**
     * Merge CSV rows and DB records into one status-annotated list.
     *
     * @param array<string,string> $fields
     * @param array{columns:array<int,string>,rows:array<int,array<string,string>>}|null $csv
     * @param array<string,string> $mapping
     * @return array<int,array<string,mixed>>
     */
    private function buildUnion(string $table, array $fields, ?array $csv, array $mapping, string $identity): array
    {
        $mappedFields = array_values(array_unique(array_values($mapping)));
        $records = $this->registry->loadRecords($table, array_keys($fields));

        $byIdentity = [];
        foreach ($records as $uid => $record) {
            $key = mb_strtolower(trim((string)($record[$identity] ?? '')));
            if ($key !== '' && !isset($byIdentity[$key])) {
                $byIdentity[$key] = $uid;
            }
        }

        $union = [];
        $matchedUids = [];
        $index = 0;

        foreach ($csv['rows'] ?? [] as $raw) {
            $payload = [];
            foreach ($mapping as $column => $field) {
                $payload[$field] = (string)($raw[$column] ?? '');
            }
            $identityValue = mb_strtolower(trim((string)($payload[$identity] ?? '')));
            $uid = $identityValue !== '' ? ($byIdentity[$identityValue] ?? 0) : 0;

            if ($uid > 0) {
                $matchedUids[$uid] = true;
                $record = $records[$uid];
                $diff = [];
                foreach ($payload as $field => $value) {
                    if (trim($value) !== trim((string)($record[$field] ?? ''))) {
                        $diff[] = $field;
                    }
                }
                $status = $diff === [] ? 'unchanged' : 'update';
            } else {
                $diff = array_keys($payload);
                $status = 'new';
            }

            $union[] = [
                'index' => $index++,
                'status' => $status,
                'uid' => $uid,
                'label' => (string)($payload['title'] ?? ($payload[$identity] ?? 'row')),
                'diff' => implode(', ', $diff),
                'payload' => (string)json_encode($payload, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES),
                'checked' => $status === 'new' || $status === 'update',
            ];
        }

        foreach ($records as $uid => $record) {
            if (isset($matchedUids[$uid])) {
                continue;
            }
            $union[] = [
                'index' => $index++,
                'status' => 'dbonly',
                'uid' => $uid,
                'label' => (string)($record['title'] ?? $uid),
                'diff' => '',
                'payload' => '',
                'checked' => false,
            ];
        }

        return $union;
    }

    // ---------------------------------------------------------------- apply

    /** @param array<string,mixed> $body */
    private function apply(string $modelKey, array $body): void
    {
        $model = $this->registry->get($modelKey);
        $fields = $this->registry->importableFields($model['table']);
        $pid = (int)($body['pid'] ?? 0);
        $rows = is_array($body['rows'] ?? null) ? $body['rows'] : [];

        $datamap = [];
        $errors = [];
        foreach ($rows as $i => $row) {
            if (empty($row['selected'])) {
                continue;
            }
            $payload = json_decode((string)($row['payload'] ?? ''), true);
            if (!is_array($payload)) {
                $errors[] = sprintf('Row %s: payload is not valid JSON - skipped.', $i);
                continue;
            }
            // Whitelist against the TCA-derived field list.
            $payload = array_intersect_key($payload, $fields);
            $payload = array_map(static fn($v): string => is_scalar($v) ? (string)$v : '', $payload);
            if ($payload === []) {
                continue;
            }
            $uid = (int)($row['uid'] ?? 0);
            if ($uid > 0) {
                $datamap[(string)$uid] = $payload;
            } elseif ($pid > 0) {
                $datamap['NEW' . $i] = ['pid' => $pid] + $payload;
            } else {
                $errors[] = sprintf('Row %s: no storage pid for a new record - skipped.', $i);
            }
        }

        $created = 0;
        $updated = 0;
        if ($datamap !== []) {
            $dataHandler = GeneralUtility::makeInstance(DataHandler::class);
            $dataHandler->start([$model['table'] => $datamap], []);
            $dataHandler->process_datamap();
            $errors = array_merge($errors, $dataHandler->errorLog);
            $created = count($dataHandler->substNEWwithIDs);
            $updated = count(array_filter(array_keys($datamap), 'is_numeric'));
        }

        $this->flash(
            sprintf('%d created, %d updated, %d error(s).', $created, $updated, count($errors))
            . ($errors !== [] ? ' ' . implode(' | ', array_slice($errors, 0, 5)) : ''),
            'Import finished',
            $errors === []
        );
    }

    private function flash(string $message, string $title, bool $ok): void
    {
        $flashMessage = GeneralUtility::makeInstance(
            FlashMessage::class,
            $message,
            $title,
            $ok ? ContextualFeedbackSeverity::OK : ContextualFeedbackSeverity::ERROR,
            true
        );
        $this->flashMessageService->getMessageQueueByIdentifier()->addMessage($flashMessage);
    }
}