<?php
namespace App\Services\SupplyDemand;
use App\Models\SupplyDemand;
use App\Models\Dialogue;
use App\Models\Message;
use Illuminate\Support\Facades\DB;
class Conversations
{
    public static function key($demandId, $a, $b) { return (int) $demandId . ':' . min((int) $a, (int) $b) . ':' . max((int) $a, (int) $b); }
    public static function resolve($viewer, array $input, $create = false) {
        if (!empty($input['dialogue_id'])) {
            return Dialogue::whereKey($input['dialogue_id'])->where(function ($q) use ($viewer) {
                $q->where('user_id', $viewer)->orWhere('to_user_id', $viewer);
            })->firstOrFail();
        }
        $demandId = (int) ($input['supply_demand_id'] ?? 0);
        $other = (int) ($input['to_user_id'] ?? 0);
        if ($demandId) {
            $query = SupplyDemand::whereKey($demandId);
            if ($create) $query->lockForUpdate();
            $d = $query->firstOrFail();
            // 接收人由需求归属确定，不能由请求伪造；发布人回复须指定已有会话。
            if ((int) $d->user_id === (int) $viewer) {
                if (!$other || $other === (int) $viewer) throw new \InvalidArgumentException('不能给自己发信息');
                $existing = Dialogue::where('supply_demand_id', $demandId)->where('user_id', $other)->where('to_user_id', $viewer)->first();
                if (!$existing) throw new \InvalidArgumentException('对接记录不存在');
                return $existing;
            }
            if ((int) $d->status !== 1) throw new \InvalidArgumentException('该供需信息尚未发布或已下架');
            if ($d->expire_time && \Illuminate\Support\Carbon::parse($d->expire_time)->isPast()) throw new \InvalidArgumentException('该信息已过期，不能发起对接');
            if ((!$d->user_id && !$d->is_proxy) || ($d->user_id && !\App\Models\User::whereKey($d->user_id)->exists())) throw new \InvalidArgumentException('发布人资料暂不可用，请联系平台');
            $other = (int) $d->user_id;
        } elseif (!$other || $other === (int) $viewer || !\App\Models\User::whereKey($other)->exists()) {
            throw new \InvalidArgumentException('请选择有效的对接人，不能给自己发信息');
        }
        $key = self::key($demandId, $viewer, $other);
        $q = Dialogue::where('conversation_key', $key);
        if (!$create) return $q->first();
        return Dialogue::firstOrCreate(['conversation_key' => $key], ['user_id' => $viewer, 'to_user_id' => $other, 'supply_demand_id' => $demandId ?: null]);
    }
    public static function send($viewer, array $input) {
        $content = trim((string) ($input['content'] ?? ''));
        if ($content === '' || mb_strlen($content) > 2000) throw new \InvalidArgumentException('请输入1至2000字的对接内容');
        return DB::transaction(function () use ($viewer, $input, $content) {
            // 同一用户并发发送时串行检查每日限额。
            \App\Models\User::whereKey($viewer)->lockForUpdate()->firstOrFail();
            $dialogue = self::resolve($viewer, $input, true);
            $dialogue = Dialogue::whereKey($dialogue->id)->lockForUpdate()->firstOrFail();
            $other = (int) $dialogue->user_id === (int) $viewer ? (int) $dialogue->to_user_id : (int) $dialogue->user_id;
            if ($other === (int) $viewer) throw new \InvalidArgumentException('不能给自己发信息');
            $d = $dialogue->supplyDemand;
            if ($d && $d->expire_time && \Illuminate\Support\Carbon::parse($d->expire_time)->isPast()) throw new \InvalidArgumentException('该信息已过期，不能发送对接');
            $limit = \App\Models\Config::getValueByKey('message_limit');
            if (is_numeric($limit) && $limit > 0 && Message::where('user_id', $viewer)->whereBetween('created_at', [now()->startOfDay(), now()->endOfDay()])->count() >= $limit) throw new \InvalidArgumentException('今天私信次数已达上限');
            // 未回复前只允许一条，系统代管期间同样适用。
            if ($dialogue->messages()->where('user_id', $viewer)->exists() && !$dialogue->messages()->where('user_id', $other)->exists()) throw new \InvalidArgumentException('对方回复以后才可以再次发送消息');
            $first = !$dialogue->messages()->exists();
            $m = Message::create(['dialogue_id' => $dialogue->id, 'user_id' => $viewer, 'to_user_id' => $other,
                'supply_demand_id' => $dialogue->supply_demand_id ?: 0, 'content' => $content, 'is_read' => 0]);
            $dialogue->last_content = $content; $dialogue->last_datetime = now()->toDateTimeString(); $dialogue->save();
            if ($first && $d) $d->increment('contact_count');
            if ($d && $other && (int) $d->user_id === $other) Notices::queue($other);
            return ['id' => $m->id, 'dialogue_id' => $dialogue->id, 'is_managed' => $d && $d->is_proxy && !$d->user_id];
        });
    }
    public static function summary(Dialogue $d, $viewer, $private = false) {
        $d->loadMissing(['user', 'toUser', 'supplyDemand']);
        $out = $d->attributesToArray();
        $out['user'] = Profiles::user($d->user, $private);
        $out['to_user'] = Profiles::user($d->toUser, $private);
        $out['supply_demand'] = $d->supplyDemand ? Profiles::demand($d->supplyDemand, $private, $viewer) : null;
        $out['unread_count'] = $d->messages()->where('to_user_id', $viewer)->where('is_read', 0)->count();
        $out['other_profile'] = (int) $d->user_id === (int) $viewer ? $out['to_user'] : $out['user'];
        if (!$out['other_profile'] && $d->supplyDemand) $out['other_profile'] = Profiles::publisher($d->supplyDemand, $private);
        return $out;
    }
}