<?php

declare(strict_types=1);

class BookManager
{
    public function __construct(private string $booksDir)
    {
    }

    // ------------------------------------------------------------------ //
    //  Lecture
    // ------------------------------------------------------------------ //

    public function getAll(): array
    {
        $books = [];
        if (!is_dir($this->booksDir)) {
            return $books;
        }
        foreach (scandir($this->booksDir) as $file) {
            if (!str_ends_with($file, '.json')) {
                continue;
            }
            $raw = file_get_contents($this->booksDir . '/' . $file);
            if ($raw === false) {
                continue;
            }
            $book = json_decode($raw, true);
            if (!is_array($book) || empty($book['slug'])) {
                continue;
            }
            $books[] = $book;
        }
        usort($books, static fn ($a, $b) => strcmp($a['title'] ?? '', $b['title'] ?? ''));
        return $books;
    }

    public function getBySlug(string $slug): ?array
    {
        $path = $this->bookPath($slug);
        if (!file_exists($path)) {
            return null;
        }
        $raw = file_get_contents($path);
        if ($raw === false) {
            return null;
        }
        $book = json_decode($raw, true);
        return is_array($book) && !empty($book['slug']) ? $book : null;
    }

    /**
     * Cherche dans quel livre se trouve un article (par son slug).
     * Retourne le contexte complet ou null si l'article n'appartient à aucun livre.
     *
     * @return array{book: array, position: int, total: int, prev: ?string, next: ?string}|null
     */
    public function findForArticle(string $articleSlug): ?array
    {
        foreach ($this->getAll() as $book) {
            $arts = $book['articles'] ?? [];
            $pos  = array_search($articleSlug, $arts, true);
            if ($pos === false) {
                continue;
            }
            $pos = (int) $pos;
            return [
                'book'     => $book,
                'position' => $pos + 1,
                'total'    => count($arts),
                'prev'     => $pos > 0 ? $arts[$pos - 1] : null,
                'next'     => $pos < count($arts) - 1 ? $arts[$pos + 1] : null,
            ];
        }
        return null;
    }

    // ------------------------------------------------------------------ //
    //  Écriture
    // ------------------------------------------------------------------ //

    public function save(array $book): void
    {
        $slug = $this->sanitizeSlug($book['slug'] ?? '');
        if ($slug === '') {
            return;
        }
        $book['slug']     = $slug;
        $book['articles'] = array_values(array_filter(array_map('strval', $book['articles'] ?? [])));
        if (!is_dir($this->booksDir)) {
            mkdir($this->booksDir, 0755, true);
        }
        file_put_contents(
            $this->bookPath($slug),
            json_encode($book, JSON_PRETTY_PRINT | JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES) . "\n"
        );
    }

    public function delete(string $slug): void
    {
        $path = $this->bookPath($slug);
        if (file_exists($path)) {
            @unlink($path);
        }
    }

    // ------------------------------------------------------------------ //
    //  Helpers
    // ------------------------------------------------------------------ //

    private function bookPath(string $slug): string
    {
        return $this->booksDir . '/' . $slug . '.json';
    }

    private function sanitizeSlug(string $slug): string
    {
        $map = [
            'à' => 'a', 'â' => 'a', 'ä' => 'a',
            'é' => 'e', 'è' => 'e', 'ê' => 'e', 'ë' => 'e',
            'î' => 'i', 'ï' => 'i',
            'ô' => 'o', 'ö' => 'o',
            'ù' => 'u', 'û' => 'u', 'ü' => 'u',
            'ç' => 'c', 'æ' => 'ae', 'œ' => 'oe',
        ];
        $slug = mb_strtolower(strtr(trim($slug), $map), 'UTF-8');
        $slug = (string) preg_replace('/[^a-z0-9]+/', '-', $slug);
        return trim($slug, '-');
    }
}