<?php

namespace App\Http\Controllers;

use App\Http\Requests\StoreLinkRequest;
use App\Http\Requests\UpdateLinkRequest;
use App\Models\Link;
use App\Models\Tag;
use Illuminate\Support\Facades\Auth;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Validator;
use Illuminate\Http\Request;

class LinkController extends Controller
{
    /**
     * Display a listing of the resource.
     */
    public function index()
    {
        return view('links.index', ['links' => Link::all()]);
    }

    /**
     * Show the form for creating a new resource.
     */
    public function create()
    {
        return view('links.create');
    }

    /**
     * Store a newly created resource in storage.
     */
    public function store(StoreLinkRequest $req)
    {
        $validated = $req->validated();
        $link = Link::create([
            'label' => $validated['label'],
            'url' => $validated['url'],
            'description' => $validated['description'] ?? '',
            'user_id' => Auth::id(),
        ]);

        $redirect = $req->input('_redirect', route('l.index'));
        return redirect($redirect)->with('success', 'Link added');
    }

    /**
     * Display the specified resource.
     */
    public function show($id)
    {
        $link = Link::findOrFail($id);
        return view('links.show', [
            'link' => $link
        ]);
    }

    /**
     * Show the form for editing the specified resource.
     */
    public function edit(Link $link)
    {
        //
    }

    /**
     * Update the specified resource in storage.
     */
    public function update(UpdateLinkRequest $request, Link $link)
    {
        $this->authorize('update', $link);

        $validated = $request->validated();
        $link->update($validated);

        $redirect = $request->input('_redirect', route('l.index'));
        return redirect($redirect)->with('success', 'Link updated');
    }

    /**
     * Remove the specified resource from storage.
     */
    public function destroy(Link $link)
    {
        $this->authorize('delete', $link);

        $link->delete();

        $redirect = request()->input('_redirect', route('l.index'));
        return redirect($redirect)->with('success', 'Link deleted');
    }

    /**
     * Import links from an uploaded JSON file. Admin only.
     */
    public function import(Request $request)
    {
        $request->validate([
            'json_file' => 'required|file|max:2048',
        ]);

        $file = $request->file('json_file');

        if (!in_array($file->getClientOriginalExtension(), ['json', 'txt'])) {
            return back()->withErrors(['json_file' => 'File must be a .json or .txt file.']);
        }

        $contents = file_get_contents($file->getRealPath());
        $entries = json_decode($contents, true);

        if (json_last_error() !== JSON_ERROR_NONE) {
            return back()->withErrors(['json_file' => 'Invalid JSON: ' . json_last_error_msg()]);
        }

        if (!is_array($entries)) {
            return back()->withErrors(['json_file' => 'JSON must contain an array of link objects.']);
        }

        if (count($entries) > 500) {
            return back()->withErrors(['json_file' => 'Too many entries. Maximum is 500 per upload.']);
        }

        $created = 0;
        $skipped = 0;
        $errors = [];

        DB::transaction(function () use ($entries, &$created, &$skipped, &$errors) {
            foreach ($entries as $i => $entry) {
                if (empty($entry['url'])) {
                    $errors[] = "Entry #{$i}: missing url, skipped.";
                    $skipped++;
                    continue;
                }

                $entryValidator = Validator::make($entry, [
                    'url' => 'required|string|url|max:255',
                    'label' => 'nullable|string|min:2|max:255',
                    'description' => 'nullable|string|max:255',
                    'tags' => 'nullable|array|max:20',
                    'tags.*' => 'string|max:50',
                ]);

                if ($entryValidator->fails()) {
                    $reasons = implode(', ', $entryValidator->errors()->all());
                    $errors[] = "Entry #{$i} ({$entry['url']}): {$reasons}";
                    $skipped++;
                    continue;
                }

                $validated = $entryValidator->validated();

                $existing = Link::where('url', $validated['url'])->first();
                if ($existing) {
                    $skipped++;
                    continue;
                }

                $link = Link::create([
                    'url' => $validated['url'],
                    'label' => $validated['label'] ?? $validated['url'],
                    'description' => $validated['description'] ?? '',
                    'user_id' => Auth::id(),
                ]);

                // Attach tags if present
                if (!empty($validated['tags']) && is_array($validated['tags'])) {
                    $tagIds = [];
                    foreach ($validated['tags'] as $tagName) {
                        if (is_string($tagName) && trim($tagName) !== '') {
                            $tag = Tag::firstOrCreate(['label' => trim($tagName)]);
                            $tagIds[] = $tag->id;
                        }
                    }
                    if (!empty($tagIds)) {
                        $link->tags()->syncWithoutDetaching($tagIds);
                    }
                }

                $created++;
            }
        });

        $message = "{$created} link(s) imported, {$skipped} skipped (duplicates or invalid).";
        if (!empty($errors)) {
            $message .= ' Warnings: ' . implode(' ', array_slice($errors, 0, 5));
        }

        return redirect()->route('l.index')->with('success', $message);
    }
}