<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\Book;
use App\Models\Category;
use App\Models\Summary;
use App\Models\Author;
use Illuminate\Http\Request;
use Illuminate\Support\Str;
use Illuminate\Support\Facades\DB;

class IngestController extends Controller
{
    /**
     * Upsert books with summaries and categories.
     * Accepts either a single book object or an array of books under `books`.
     */
    public function upsertBooks(Request $request)
    {
        $payload = $request->all();

        // Normalize to array of items
        $items = [];
        if (isset($payload['books']) && is_array($payload['books'])) {
            $items = $payload['books'];
        } elseif ($this->isAssocArray($payload)) {
            $items = [$payload];
        } elseif (is_array($payload)) {
            $items = $payload;
        }

        if (empty($items)) {
            return response()->json([
                'message' => 'No books provided.',
            ], 422);
        }

        $results = [];

        foreach ($items as $index => $item) {
            // Basic validation (minimal to satisfy requirement)
            $title = $item['title'] ?? null;
            $author = $item['author'] ?? null;
            $authorsArr = $item['authors'] ?? null; // optional array of names
            $hasAuthorInfo = $author || (is_array($authorsArr) && count($authorsArr) > 0);
            if (!$title || !$hasAuthorInfo) {
                $results[] = [
                    'index' => $index,
                    'status' => 'error',
                    'message' => 'title and author/authors are required.',
                ];
                continue;
            }

            $result = DB::transaction(function () use ($item) {
                // Handle category upsert
                $categoryData = $item['category'] ?? null;
                $category = null;
                if ($categoryData) {
                    $catSlug = $categoryData['slug'] ?? null;
                    $catName = $categoryData['name'] ?? null;
                    if (!$catSlug && $catName) {
                        $catSlug = Str::slug($catName);
                    }

                    if ($catSlug) {
                        $category = Category::where('slug', $catSlug)->first();
                    }
                    if (!$category && $catName) {
                        // Try by name
                        $category = Category::where('name', $catName)->first();
                    }

                    if ($category) {
                        // Update existing
                        $category->fill([
                            'name' => $catName ?? $category->name,
                            'slug' => $catSlug ?? ($catName ? Str::slug($catName) : $category->slug),
                            'description' => $categoryData['description'] ?? $category->description,
                        ])->save();
                        $categoryStatus = 'updated';
                    } else {
                        // Create new if enough data
                        $category = Category::create([
                            'name' => $catName ?? 'Uncategorized',
                            'slug' => $catSlug ?? ($catName ? Str::slug($catName) : Str::slug('Uncategorized')),
                            'description' => $categoryData['description'] ?? null,
                        ]);
                        $categoryStatus = 'created';
                    }
                }

                // Handle book upsert
                $bookSlug = $item['slug'] ?? null;
                if (!$bookSlug && !empty($item['title'])) {
                    $bookSlug = Str::slug($item['title']);
                }

                // Determine a primary author name for backward-compatible matching
                $primaryAuthorName = $item['author'] ?? (is_array($item['authors'] ?? null) && count($item['authors']) > 0 ? ($item['authors'][0] ?? null) : null);

                $bookQuery = Book::query();
                if ($bookSlug) {
                    $bookQuery->where('slug', $bookSlug);
                } else {
                    // Fallback: match by title+author (string). If authors[] provided, use first one.
                    $bookQuery->where('title', $item['title'])->where('author', $primaryAuthorName);
                }

                $book = $bookQuery->first();
                $bookData = [
                    'title' => $item['title'] ?? ($book->title ?? null),
                    'slug' => $bookSlug ?? ($book->slug ?? null),
                    'author' => $primaryAuthorName ?? ($book->author ?? null),
                    'description' => $item['description'] ?? ($book->description ?? null),
                    'publication_date' => $item['publication_date'] ?? ($book->publication_date ?? null),
                    'cover_image' => $item['cover_image'] ?? ($book->cover_image ?? null),
                ];
                if ($category) {
                    $bookData['category_id'] = $category->id;
                } elseif (!empty($item['category_id'])) {
                    $bookData['category_id'] = $item['category_id'];
                }

                if ($book) {
                    $book->fill($bookData)->save();
                    $bookStatus = 'updated';
                } else {
                    $book = Book::create($bookData);
                    $bookStatus = 'created';
                }

                // Handle authors upsert and pivot sync
                $names = [];
                if (!empty($item['author'])) {
                    $names[] = $item['author'];
                }
                if (!empty($item['authors']) && is_array($item['authors'])) {
                    $names = array_merge($names, $item['authors']);
                }
                $names = array_values(array_unique(array_filter(array_map(function ($n) { return is_string($n) ? trim($n) : null; }, $names))));
                if (count($names) > 0) {
                    $authorIds = [];
                    foreach ($names as $name) {
                        $slug = Str::slug($name);
                        $author = Author::where('slug', $slug)->first();
                        if (!$author) {
                            $author = Author::where('name', $name)->first();
                        }
                        if ($author) {
                            // ensure slug and name are up to date
                            $author->fill([
                                'name' => $name,
                                'slug' => $author->slug ?: $slug,
                            ])->save();
                        } else {
                            $author = Author::create([
                                'name' => $name,
                                'slug' => $slug,
                            ]);
                        }
                        $authorIds[] = $author->id;
                    }
                    // Replace current authors with provided set
                    $book->authors()->sync($authorIds);
                }

                // Handle summary upsert
                $summaryData = $item['summary'] ?? null;
                $summaryResult = null;
                if ($summaryData && is_array($summaryData)) {
                    $summary = Summary::where('book_id', $book->id)->first();
                    $sumData = [
                        'content' => $summaryData['content'] ?? ($summary->content ?? null),
                        'key_insights' => $summaryData['key_insights'] ?? ($summary->key_insights ?? null),
                        'book_id' => $book->id,
                    ];
                    if ($summary) {
                        $summary->fill($sumData)->save();
                        $summaryResult = ['status' => 'updated', 'id' => $summary->id];
                    } else {
                        $summary = Summary::create($sumData);
                        $summaryResult = ['status' => 'created', 'id' => $summary->id];
                    }
                }

                return [
                    'book' => [
                        'status' => $bookStatus,
                        'id' => $book->id,
                        'slug' => $book->slug,
                    ],
                    'category' => $category ? [
                        'status' => $categoryStatus,
                        'id' => $category->id,
                        'slug' => $category->slug,
                    ] : null,
                    'summary' => $summaryResult,
                ];
            });

            $results[] = $result;
        }

        return response()->json([
            'results' => $results,
        ]);
    }

    private function isAssocArray($arr): bool
    {
        if (!is_array($arr)) return false;
        return array_keys($arr) !== range(0, count($arr) - 1);
    }
}