<?php

namespace App\Services;

use Carbon\CarbonImmutable;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Validator;
use Illuminate\Validation\ValidationException;

class TelegramChannelMessageService
{
    private const TABLE = 'telegram_channel_messages';

    public function __construct(private TelegramChannelService $channels) {}

    public function list(int $page): array
    {
        $items = DB::table(self::TABLE)->orderByDesc('id')->paginate(20, ['*'], 'page', $page);
        return ['list' => array_map($this->present(...), $items->items()), 'total' => $items->total()];
    }

    public function create(array $input): array
    {
        $fields = Validator::make($input, [
            'channel_id' => 'required|integer|min:1',
            'scheduled_at' => 'nullable|date_format:Y-m-d\TH:i:sP',
            'is_top' => 'sometimes|boolean',
        ])->validate();
        $message = TelegramChannelService::message($input);
        $channel = $this->channels->detail((int) $fields['channel_id']);
        if (!$channel['enabled']) {
            throw ValidationException::withMessages(['channel_id' => '请先启用频道']);
        }
        $scheduled = isset($fields['scheduled_at']) ? CarbonImmutable::parse($fields['scheduled_at'])->utc() : null;
        if ($scheduled !== null && $scheduled->lessThanOrEqualTo(now('UTC'))) {
            throw ValidationException::withMessages(['scheduled_at' => '定时发送时间必须晚于当前时间']);
        }

        $id = (int) DB::table(self::TABLE)->insertGetId([
            'channel_id' => $channel['id'],
            'channel_name' => $channel['name'],
            'target' => $channel['telegram_chat_id'] ?? $channel['chatId'],
            'message' => json_encode($message, JSON_THROW_ON_ERROR | JSON_UNESCAPED_UNICODE),
            'is_top' => $fields['is_top'] ?? false,
            'status' => 'scheduled',
            'scheduled_at' => $scheduled ?? now('UTC'),
            'created_at' => now('UTC'),
            'updated_at' => now('UTC'),
        ]);
        if ($scheduled === null) {
            $this->dispatch($id);
        }
        return $this->present(DB::table(self::TABLE)->find($id));
    }

    public function cancel(int $id): void
    {
        if (!DB::table(self::TABLE)->where('id', $id)->where('status', 'scheduled')->update([
            'status' => 'cancelled',
            'updated_at' => now('UTC'),
        ])) {
            throw ValidationException::withMessages(['id' => '只有待发送消息可以取消']);
        }
    }

    public function dispatchDue(): void
    {
        DB::table(self::TABLE)->where('status', 'sending')
            ->where('attempted_at', '<=', now('UTC')->subMinutes(10))->update([
                'status' => 'unknown', 'error' => '发送中断，结果未知，请到频道核对', 'updated_at' => now('UTC'),
            ]);

        $ids = DB::table(self::TABLE)->where('status', 'scheduled')
            ->where('scheduled_at', '<=', now('UTC'))->orderBy('scheduled_at')->orderBy('id')->limit(20)->pluck('id');
        foreach ($ids as $id) {
            $this->dispatch((int) $id);
        }
    }

    private function dispatch(int $id): void
    {
        $claimed = DB::table(self::TABLE)->where('id', $id)->where('status', 'scheduled')
            ->where('scheduled_at', '<=', now('UTC'))->update([
                'status' => 'sending', 'attempted_at' => now('UTC'), 'updated_at' => now('UTC'),
            ]);
        if (!$claimed) {
            return;
        }
        $row = DB::table(self::TABLE)->find($id);
        try {
            $result = $this->channels->publishMessage(
                (int) $row->channel_id,
                json_decode($row->message, true, 512, JSON_THROW_ON_ERROR),
                (bool) $row->is_top,
                $row->target,
            );
        } catch (ValidationException $e) {
            $result = ['sent' => false, 'pinned' => null, 'message_id' => null, 'error' => $e->validator->errors()->first()];
        }
        DB::table(self::TABLE)->where('id', $id)->where('status', 'sending')->update([
            'status' => match ($result['sent']) { true => 'sent', false => 'failed', null => 'unknown' },
            'telegram_message_id' => $result['message_id'],
            'pinned' => $result['pinned'],
            'error' => $result['error'],
            'updated_at' => now('UTC'),
        ]);
    }

    private function present(object $row): array
    {
        $data = (array) $row;
        $data['message'] = json_decode($row->message, true);
        $data['is_top'] = (bool) $row->is_top;
        $data['pinned'] = $row->pinned === null ? null : (bool) $row->pinned;
        foreach (['scheduled_at', 'attempted_at', 'created_at', 'updated_at'] as $key) {
            $data[$key] = $row->$key === null ? null : CarbonImmutable::parse($row->$key, 'UTC')->toIso8601String();
        }
        return $data;
    }
}