<?php

declare(strict_types=1);

namespace Evomedien\Vitec\Import;

use TYPO3\CMS\Core\Database\ConnectionPool;
use TYPO3\CMS\Core\Utility\GeneralUtility;

/**
 * Evaluates one keyword-research delivery:
 *
 *  - work lists from the SEO flags (quick wins, shared terms, already ranking)
 *  - structure check: does the CSV tree exist in TYPO3?
 *      pages     -> every row's URL against pages.slug (slug = full path)
 *      markets   -> level-1.x rows against tx_vitec_domain_model_market
 *      solutions -> level-2.x rows against tx_vitec_domain_model_solution
 *      products  -> level-3.x.y+ rows against tx_vitec_domain_model_product
 *                   (3.x rows are categories, not products - skipped)
 *    Record matching: slug == last URL segment, falling back to a
 *    normalized title comparison (parentheses stripped, & -> and), and
 *    finally the hand-made record links (record_aliases per model in
 *    tx_vitec_import_mapping - the same store the import tabs use, so
 *    one link serves both views and vitec:create-markets).
 *  - diff against the previous delivery, keyed by URL
 *
 * Works on the normalized row schema produced by normalizeRows(). Read-only:
 * this class never writes anything.
 */
final class SeoResearchService
{
    private const SECTION_MODELS = [
        // Markets/Solutions: every row below the section root is a record
        // candidate - sub-markets ("Traffic & Smart Mobility" under
        // "Transport & Infrastructure") and sub-solutions are records of the
        // same (flat) model. Products: 3.x rows are categories, records
        // start at 3.x.y.
        'Markets' => ['key' => 'market', 'table' => 'tx_vitec_domain_model_market', 'depth' => [2, 9]],
        'Solutions' => ['key' => 'solution', 'table' => 'tx_vitec_domain_model_solution', 'depth' => [2, 9]],
        'Products' => ['key' => 'product', 'table' => 'tx_vitec_domain_model_product', 'depth' => [3, 9]],
    ];

    /**
     * Map raw CSV rows (deduplicated headers) onto a stable schema, so stored
     * deliveries stay comparable even if the CSV gains columns.
     *
     * @param array<int,array<string,string>> $raw
     * @return array<int,array<string,string>>
     */
    public function normalizeRows(array $raw): array
    {
        $rows = [];
        foreach ($raw as $r) {
            $url = trim((string)($r['Potential URL'] ?? ''));
            if ($url === '') {
                continue;
            }
            $rows[] = [
                'section' => trim((string)($r['Section'] ?? '')),
                'ref' => trim((string)($r['Page Ref'] ?? '')),
                'name' => trim((string)($r['Page Name'] ?? '')),
                'url' => $url,
                'primary' => trim((string)($r['Primary Keyword'] ?? '')),
                'volGlobal' => trim((string)($r['Vol (Global)'] ?? '')),
                'intent' => trim((string)($r['Intent'] ?? '')),
                'kd' => trim((string)($r['KD'] ?? '')),
                'gscPos' => trim((string)($r['GSC Pos (blended)'] ?? '')),
                'gscImpr' => trim((string)($r['GSC Impr'] ?? '')),
                'flag' => trim((string)($r['Flag'] ?? '')),
                'secondary' => trim((string)($r['Secondary Keyword'] ?? '')),
                'secVolGlobal' => trim((string)($r['Vol (Global)_2'] ?? '')),
            ];
        }
        return $rows;
    }

    /**
     * @param array<int,array<string,string>> $rows
     * @param array<int,array<string,string>>|null $previousRows
     * @return array<string,mixed>
     */
    public function analyze(array $rows, ?array $previousRows): array
    {
        return [
            'quickWins' => $this->quickWins($rows),
            'sharedTerms' => $this->sharedTerms($rows),
            'alreadyRanking' => array_values(array_filter($rows, fn(array $r): bool => str_contains($r['flag'], 'Already ranking'))),
            'structure' => $this->structure($rows),
            'diff' => $previousRows !== null ? $this->diff($previousRows, $rows) : null,
        ];
    }

    // ------------------------------------------------------------ work lists

    /** @param array<int,array<string,string>> $rows
     *  @return array<int,array<string,string>> */
    private function quickWins(array $rows): array
    {
        $wins = array_values(array_filter($rows, fn(array $r): bool => str_contains($r['flag'], 'Quick win')));
        usort($wins, static function (array $a, array $b): int {
            return (int)preg_replace('/\D/', '', $b['gscImpr']) <=> (int)preg_replace('/\D/', '', $a['gscImpr']);
        });
        return $wins;
    }

    /**
     * Shared-term rows grouped by primary keyword - each group is one
     * cannibalization risk: several pages targeting the same term.
     *
     * @param array<int,array<string,string>> $rows
     * @return array<int,array{keyword:string,pages:array<int,array<string,string>>}>
     */
    private function sharedTerms(array $rows): array
    {
        $groups = [];
        foreach ($rows as $r) {
            if (!str_contains($r['flag'], 'Shared term')) {
                continue;
            }
            $groups[mb_strtolower($r['primary'])]['keyword'] = $r['primary'];
            $groups[mb_strtolower($r['primary'])]['pages'][] = $r;
        }
        // Pages sharing the keyword without carrying the flag themselves:
        foreach ($groups as $kw => $group) {
            foreach ($rows as $r) {
                if (mb_strtolower($r['primary']) === $kw && !in_array($r, $group['pages'], true)) {
                    $groups[$kw]['pages'][] = $r;
                }
            }
        }
        return array_values($groups);
    }

    // ------------------------------------------------------- structure check

    /** @param array<int,array<string,string>> $rows
     *  @return array<string,mixed> */
    private function structure(array $rows): array
    {
        $out = ['pages' => $this->pagesCheck($rows)];

        foreach (self::SECTION_MODELS as $section => $cfg) {
            $candidates = array_values(array_filter($rows, function (array $r) use ($section, $cfg): bool {
                $depth = substr_count($r['ref'], '.') + 1;
                return $r['section'] === $section && $depth >= $cfg['depth'][0] && $depth <= $cfg['depth'][1];
            }));
            $aliases = GeneralUtility::makeInstance(MappingRepository::class)->load($cfg['key'])['aliases'] ?? [];
            $out[$cfg['key']] = $this->recordsCheck($candidates, $cfg['table'], $aliases);
        }
        return $out;
    }

    /** @param array<int,array<string,string>> $rows
     *  @return array{total:int,found:int,missing:array<int,array<string,string>>} */
    private function pagesCheck(array $rows): array
    {
        $qb = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable('pages');
        $slugs = $qb->select('slug')->from('pages')
            ->where(
                $qb->expr()->eq('deleted', 0),
                $qb->expr()->eq('sys_language_uid', 0)
            )
            ->executeQuery()->fetchFirstColumn();
        $existing = array_flip(array_map(static fn($s): string => rtrim((string)$s, '/') ?: '/', $slugs));

        $missing = [];
        $found = 0;
        foreach ($rows as $r) {
            $slug = rtrim($r['url'], '/') ?: '/';
            if (isset($existing[$slug])) {
                $found++;
            } else {
                $missing[] = $r;
            }
        }
        return ['total' => count($rows), 'found' => $found, 'missing' => $missing];
    }

    /**
     * @param array<int,array<string,string>> $candidates
     * @param array<string,int> $aliases lowercased CSV name -> record uid
     * @return array{total:int,matched:int,both:array<int,array<string,string>>,missing:array<int,array<string,string>>,extra:array<int,array<string,string>>,linkable:array<int,array<string,string>>}
     */
    private function recordsCheck(array $candidates, string $table, array $aliases): array
    {
        $qb = GeneralUtility::makeInstance(ConnectionPool::class)->getQueryBuilderForTable($table);
        $records = $qb->select('uid', 'title', 'slug')->from($table)
            ->where($qb->expr()->eq('deleted', 0))
            ->executeQuery()->fetchAllAssociative();

        $bySlug = [];
        $byTitle = [];
        $byUid = [];
        foreach ($records as $rec) {
            $slug = mb_strtolower(trim((string)($rec['slug'] ?? '')));
            if ($slug !== '') {
                $bySlug[$slug] = $rec;
            }
            $byTitle[$this->normalizeTitle((string)$rec['title'])] = $rec;
            $byUid[(int)$rec['uid']] = $rec;
        }

        $missing = [];
        $both = [];
        $matchedUids = [];
        $directUids = [];
        foreach ($candidates as $r) {
            $segment = mb_strtolower(trim((string)basename(rtrim($r['url'], '/'))));
            $rec = $bySlug[$segment] ?? $byTitle[$this->normalizeTitle($r['name'])] ?? null;
            $via = '';
            if ($rec === null) {
                $aliasUid = (int)($aliases[mb_strtolower(trim($r['name']))] ?? 0);
                if ($aliasUid > 0 && isset($byUid[$aliasUid])) {
                    $rec = $byUid[$aliasUid];
                    $via = 'link';
                }
            }
            if ($rec !== null) {
                $matchedUids[(int)$rec['uid']] = true;
                if ($via === '') {
                    $directUids[(int)$rec['uid']] = true;
                }
                $both[] = [
                    'ref' => $r['ref'],
                    'name' => $r['name'],
                    'url' => $r['url'],
                    'uid' => (string)$rec['uid'],
                    'title' => (string)$rec['title'],
                    'via' => $via,
                ];
            } else {
                $missing[] = $r;
            }
        }

        $extra = [];
        $linkable = [];
        foreach ($records as $rec) {
            if (!isset($matchedUids[(int)$rec['uid']])) {
                $extra[] = ['uid' => (string)$rec['uid'], 'title' => (string)$rec['title']];
            }
            // Select options for the hand-made links: everything the direct
            // match (slug/title) did not claim - alias-linked records stay in
            // here so a linked row can be re-pointed or unlinked.
            if (!isset($directUids[(int)$rec['uid']])) {
                $linkable[] = ['uid' => (string)$rec['uid'], 'title' => (string)$rec['title']];
            }
        }
        usort($linkable, static fn(array $a, array $b): int => strcasecmp($a['title'], $b['title']));

        return [
            'total' => count($candidates),
            'matched' => count($matchedUids),
            'both' => $both,
            'missing' => $missing,
            'extra' => $extra,
            'linkable' => $linkable,
        ];
    }

    private function normalizeTitle(string $title): string
    {
        $title = (string)preg_replace('/\s*\(.*?\)/', '', $title);       // drop parenthetical suffixes
        $title = str_replace('&', 'and', mb_strtolower($title));
        $title = (string)preg_replace('/[^a-z0-9]+/', ' ', $title);
        return trim((string)preg_replace('/\s+/', ' ', $title));
    }

    // ------------------------------------------------------------------ diff

    /**
     * @param array<int,array<string,string>> $old
     * @param array<int,array<string,string>> $new
     * @return array{added:array<int,string>,removed:array<int,string>,changed:array<int,string>}
     */
    private function diff(array $old, array $new): array
    {
        $byUrlOld = [];
        foreach ($old as $r) {
            $byUrlOld[$r['url']] = $r;
        }
        $byUrlNew = [];
        foreach ($new as $r) {
            $byUrlNew[$r['url']] = $r;
        }

        $added = [];
        $changed = [];
        foreach ($byUrlNew as $url => $r) {
            $o = $byUrlOld[$url] ?? null;
            if ($o === null) {
                $added[] = sprintf('%s (%s)', $url, $r['name']);
                continue;
            }
            $changes = [];
            foreach (['primary' => 'primary keyword', 'secondary' => 'secondary keyword', 'flag' => 'flag'] as $field => $label) {
                if ($r[$field] !== $o[$field]) {
                    $changes[] = sprintf('%s "%s" -> "%s"', $label, $o[$field], $r[$field]);
                }
            }
            if ($changes !== []) {
                $changed[] = $url . ': ' . implode('; ', $changes);
            }
        }
        $removed = [];
        foreach ($byUrlOld as $url => $r) {
            if (!isset($byUrlNew[$url])) {
                $removed[] = sprintf('%s (%s)', $url, $r['name']);
            }
        }

        return ['added' => $added, 'removed' => $removed, 'changed' => $changed];
    }
}