<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Models\User;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;

class ConversationApiController extends Controller
{
    private function ensureUserConversation($user)
    {
        // Return existing conversation ID for user, or null if none created
        return DB::table('mobile_conversation_participants')
            ->where('user_id', $user->id)
            ->value('conversation_id');
    }

    public function conversations(Request $request)
    {
        $user = $request->user();

        $convIds = DB::table('mobile_conversation_participants')
            ->where('user_id', $user->id)
            ->pluck('conversation_id');

        $conversations = DB::table('mobile_conversations')
            ->whereIn('id', $convIds)
            ->get()
            ->map(function ($c) use ($user) {
                $lastMsg = DB::table('mobile_messages')
                    ->where('conversation_id', $c->id)
                    ->latest()
                    ->first();

                $unreadCount = DB::table('mobile_messages')
                    ->where('conversation_id', $c->id)
                    ->where('sender_id', '!=', $user->id)
                    ->where('is_read', false)
                    ->count();

                $participantIds = DB::table('mobile_conversation_participants')
                    ->where('conversation_id', $c->id)
                    ->pluck('user_id');

                $participants = User::whereIn('id', $participantIds)
                    ->select('id', 'name', 'email', 'avatar', 'type')
                    ->get();

                return [
                    'id' => $c->id,
                    'type' => $c->type,
                    'name' => $c->name ?? 'Direct Chat',
                    'last_message' => $lastMsg ? $lastMsg->content : 'No messages yet',
                    'last_message_at' => $lastMsg && $lastMsg->created_at ? date('h:i A', strtotime($lastMsg->created_at)) : date('h:i A'),
                    'unread_count' => $unreadCount,
                    'participants' => $participants,
                ];
            });

        return response()->json([
            'success' => true,
            'data' => $conversations,
            'message' => null,
            'errors' => null,
        ]);
    }

    public function store(Request $request)
    {
        $isGroup = $request->boolean('is_group') || $request->filled('name') || (is_array($request->participant_ids) && count($request->participant_ids) > 1);

        if ($isGroup) {
            return $this->createGroup($request);
        }

        return $this->createDirect($request);
    }

    public function createDirect(Request $request)
    {
        $recipientId = $request->recipient_id ?? ($request->participant_ids[0] ?? null);

        if (!$recipientId) {
            return response()->json([
                'success' => false,
                'data' => null,
                'message' => 'The recipient_id or participant_ids field is required.',
                'errors' => ['recipient_id' => ['Recipient required']],
            ], 422);
        }

        $user = $request->user();
        $recipient = User::find($recipientId);

        if (!$recipient) {
            return response()->json([
                'success' => false,
                'data' => null,
                'message' => 'Recipient user not found',
                'errors' => null,
            ], 404);
        }

        $myConvs = DB::table('mobile_conversation_participants')
            ->where('user_id', $user->id)
            ->pluck('conversation_id');

        $existing = DB::table('mobile_conversation_participants')
            ->whereIn('conversation_id', $myConvs)
            ->where('user_id', $recipientId)
            ->first();

        if ($existing) {
            $conv = DB::table('mobile_conversations')->where('id', $existing->conversation_id)->first();
            $participants = User::whereIn('id', [$user->id, $recipientId])->select('id', 'name', 'email', 'avatar', 'type')->get();

            return response()->json([
                'id' => $conv->id,
                'name' => $recipient->name,
                'type' => 'direct',
                'participants' => $participants,
                'success' => true,
                'data' => [
                    'id' => $conv->id,
                    'name' => $recipient->name,
                    'type' => 'direct',
                    'participants' => $participants,
                ],
                'message' => 'Conversation existing',
                'errors' => null,
            ]);
        }

        $convId = DB::table('mobile_conversations')->insertGetId([
            'name' => $recipient->name,
            'type' => 'direct',
            'created_by' => $user->id,
            'created_at' => now(),
            'updated_at' => now(),
        ]);

        DB::table('mobile_conversation_participants')->insert([
            ['conversation_id' => $convId, 'user_id' => $user->id, 'created_at' => now(), 'updated_at' => now()],
            ['conversation_id' => $convId, 'user_id' => $recipientId, 'created_at' => now(), 'updated_at' => now()],
        ]);

        $participants = User::whereIn('id', [$user->id, $recipientId])->select('id', 'name', 'email', 'avatar', 'type')->get();

        return response()->json([
            'id' => $convId,
            'name' => $recipient->name,
            'type' => 'direct',
            'participants' => $participants,
            'success' => true,
            'data' => [
                'id' => $convId,
                'name' => $recipient->name,
                'type' => 'direct',
                'participants' => $participants,
            ],
            'message' => 'Direct conversation created',
            'errors' => null,
        ], 201);
    }

    public function createGroup(Request $request)
    {
        $request->validate([
            'name' => 'nullable|string|max:255',
            'participant_ids' => 'required|array',
            'participant_ids.*' => 'integer|exists:users,id',
        ]);

        $user = $request->user();
        $groupName = $request->name ?? 'New Team Group';

        $convId = DB::table('mobile_conversations')->insertGetId([
            'name' => $groupName,
            'type' => 'group',
            'created_by' => $user->id,
            'created_at' => now(),
            'updated_at' => now(),
        ]);

        $participants = array_unique(array_merge([$user->id], $request->participant_ids));
        foreach ($participants as $pId) {
            DB::table('mobile_conversation_participants')->insert([
                'conversation_id' => $convId,
                'user_id' => $pId,
                'created_at' => now(),
                'updated_at' => now(),
            ]);
        }

        $participantUsers = User::whereIn('id', $participants)->select('id', 'name', 'email', 'avatar', 'type')->get();

        return response()->json([
            'id' => $convId,
            'name' => $groupName,
            'type' => 'group',
            'participants' => $participantUsers,
            'success' => true,
            'data' => [
                'id' => $convId,
                'name' => $groupName,
                'type' => 'group',
                'participant_count' => count($participants),
                'participants' => $participantUsers,
            ],
            'message' => 'Group conversation created',
            'errors' => null,
        ], 201);
    }

    public function messages(Request $request, $id)
    {
        $user = $request->user();

        $isParticipant = DB::table('mobile_conversation_participants')
            ->where('conversation_id', $id)
            ->where('user_id', $user->id)
            ->exists();

        if (!$isParticipant) {
            return response()->json([
                'success' => false,
                'data' => [],
                'message' => 'Unauthorized access to this conversation',
                'errors' => null,
            ], 403);
        }

        DB::table('mobile_messages')
            ->where('conversation_id', $id)
            ->where('sender_id', '!=', $user->id)
            ->update(['is_read' => true]);

        $messages = DB::table('mobile_messages')
            ->where('conversation_id', $id)
            ->orderBy('created_at', 'asc')
            ->get()
            ->map(function ($m) {
                $sender = User::find($m->sender_id);
                return [
                    'id' => $m->id,
                    'conversation_id' => (int)$m->conversation_id,
                    'sender_id' => $m->sender_id,
                    'sender_name' => $sender ? $sender->name : 'User',
                    'content' => $m->content,
                    'created_at' => date('h:i A', strtotime($m->created_at)),
                ];
            });

        return response()->json([
            'success' => true,
            'data' => $messages,
            'message' => null,
            'errors' => null,
        ]);
    }

    public function sendMessage(Request $request, $id)
    {
        $request->validate([
            'content' => 'required|string',
        ]);

        $user = $request->user();

        $isParticipant = DB::table('mobile_conversation_participants')
            ->where('conversation_id', $id)
            ->where('user_id', $user->id)
            ->exists();

        if (!$isParticipant) {
            return response()->json([
                'success' => false,
                'data' => null,
                'message' => 'Unauthorized access to this conversation',
                'errors' => null,
            ], 403);
        }

        $messageId = DB::table('mobile_messages')->insertGetId([
            'conversation_id' => $id,
            'sender_id' => $user->id,
            'content' => $request->content,
            'is_read' => false,
            'created_at' => now(),
            'updated_at' => now(),
        ]);

        return response()->json([
            'success' => true,
            'message' => 'Message sent',
            'data' => [
                'id' => $messageId,
                'conversation_id' => (int)$id,
                'sender_id' => $user->id,
                'sender_name' => $user->name,
                'content' => $request->content,
                'created_at' => date('h:i A'),
            ],
            'errors' => null,
        ], 201);
    }

    public function unreadCount(Request $request)
    {
        $user = $request->user();
        $convIds = DB::table('mobile_conversation_participants')
            ->where('user_id', $user->id)
            ->pluck('conversation_id');

        $unreadCount = DB::table('mobile_messages')
            ->whereIn('conversation_id', $convIds)
            ->where('sender_id', '!=', $user->id)
            ->where('is_read', false)
            ->count();

        return response()->json([
            'success' => true,
            'unread_count' => $unreadCount,
            'data' => ['unread_count' => $unreadCount],
            'message' => null,
            'errors' => null,
        ]);
    }

    public function users(Request $request)
    {
        $users = User::where('id', '!=', $request->user()->id)
            ->select('id', 'name', 'email', 'type', 'avatar')
            ->limit(20)
            ->get();

        return response()->json([
            'success' => true,
            'data' => $users,
            'message' => null,
            'errors' => null,
        ]);
    }
}