<?php

namespace App\Http\Controllers\Admin;

use App\Http\Controllers\Concerns\PortalAware;
use App\Http\Controllers\Controller;
use App\Models\Channel;
use App\Models\User;
use App\Services\ChannelProjectService;
use Illuminate\Http\Request;
use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Log;
use Illuminate\Validation\Rule;
use Illuminate\Validation\ValidationException;

class ChannelController extends Controller
{
    use PortalAware;

    public function index()
    {
        $agents = $this->isAgentPortal()
            ? collect()
            : User::query()->orderBy('username')->get(['id', 'username']);

        return view('admin.channels.index', [
            'portal' => $this->portal(),
            'agents' => $agents,
            'maxPerAgent' => Channel::maxPerAgent(),
        ]);
    }

    public function data(Request $request)
    {
        $q = Channel::query()->with('user:id,username');

        if ($agent = $this->agent()) {
            $q->where('user_id', $agent->id);
        }

        $channelId = trim((string) $request->query('channel_id', ''));
        $agentUserId = $request->query('agent_user_id');
        $status = $request->query('status');

        if ($channelId !== '') {
            $q->where('channel_id', 'like', '%'.$channelId.'%');
        }
        if (! $this->isAgentPortal() && $agentUserId !== null && $agentUserId !== '') {
            $q->where('user_id', (int) $agentUserId);
        }
        if ($status !== null && $status !== '') {
            $q->where('status', (int) $status);
        }

        $sortable = ['id', 'channel_id', 'status', 'user_id', 'created_at', 'updated_at'];
        $field = (string) $request->query('field', 'id');
        $order = strtolower((string) $request->query('order', 'desc')) === 'asc' ? 'asc' : 'desc';
        if (! in_array($field, $sortable, true)) {
            $field = 'id';
        }
        $q->orderBy($field, $order);

        $limit = max(1, min(100, (int) $request->query('limit', 15)));
        $page = max(1, (int) $request->query('page', 1));
        $paginator = $q->paginate($limit, ['*'], 'page', $page);

        $data = collect($paginator->items())->map(function (Channel $c) {
            return [
                'id' => $c->id,
                'channel_id' => $c->channel_id,
                'user_id' => (int) $c->user_id,
                'agent_username' => $c->agentLabel(),
                'remark' => $c->remark ?: '',
                'status' => (int) $c->status,
                'links' => $c->supportLinks(),
                'created_at' => optional($c->created_at)->format('Y-m-d H:i:s'),
                'updated_at' => optional($c->updated_at)->format('Y-m-d H:i:s'),
            ];
        })->values();

        return response()->json([
            'code' => 0,
            'msg' => '',
            'count' => $paginator->total(),
            'data' => $data,
        ]);
    }

    public function randomId()
    {
        return response()->json([
            'code' => 0,
            'msg' => '',
            'data' => ['channel_id' => Channel::randomChannelId()],
        ]);
    }

    public function store(Request $request, ChannelProjectService $projects)
    {
        abort_if($this->isAgentPortal(), 403);

        $data = $request->validate([
            'channel_id' => ['required', 'string', 'size:32', 'regex:/^[a-z0-9]+$/', Rule::unique('channels', 'channel_id')],
            'user_id' => ['nullable', 'integer', 'min:0'],
            'support_template' => ['nullable', 'string', Rule::in(ChannelProjectService::SUPPORT_TEMPLATES)],
            'deployment_seed' => ['nullable', 'string', 'min:1', 'max:32'],
            'reporting_seed' => ['nullable', 'string', 'min:1', 'max:32'],
            'remark' => ['nullable', 'string', 'max:255'],
            'status' => ['nullable', 'integer', Rule::in([0, 1])],
        ]);

        $userId = (int) ($data['user_id'] ?? Channel::OFFICIAL_USER_ID);
        if ($userId > 0 && ! User::query()->whereKey($userId)->exists()) {
            throw ValidationException::withMessages(['user_id' => '代理用户不存在']);
        }

        $supportTemplate = (string) ($data['support_template'] ?? ChannelProjectService::DEFAULT_SUPPORT_TEMPLATE);
        $this->assertAgentChannelQuota($userId);

        try {
            $build = $projects->generate(
                $data['channel_id'],
                $supportTemplate,
                $data['deployment_seed'] ?? null,
                $data['reporting_seed'] ?? null,
            );
        } catch (\Throwable $e) {
            return response()->json([
                'code' => 1,
                'msg' => $e->getMessage() ?: '渠道资源生成失败',
            ], 422);
        }

        try {
            $channel = DB::transaction(function () use ($data, $userId) {
                if ($userId > 0) {
                    $userExists = User::query()->lockForUpdate()->whereKey($userId)->exists();
                    if (! $userExists) {
                        throw ValidationException::withMessages(['user_id' => '代理用户不存在']);
                    }
                    // The user row lock serializes quota checks for this agent.
                    $this->assertAgentChannelQuota($userId);
                }

                return Channel::query()->create([
                    'channel_id' => $data['channel_id'],
                    'user_id' => $userId,
                    'domains' => [],
                    'remark' => $data['remark'] ?? null,
                    'status' => (int) ($data['status'] ?? 1),
                ]);
            });
        } catch (\Throwable $e) {
            $this->compensateBuildUnlessChannelExists($projects, $data['channel_id']);

            return response()->json([
                'code' => 1,
                'msg' => $e->getMessage() ?: '创建失败',
            ], 422);
        }

        return response()->json([
            'code' => 0,
            'msg' => 'ok',
            'data' => [
                'id' => $channel->id,
                'links' => $channel->supportLinks(),
                'seeds' => $build['seeds'],
                'domains' => $build['domains'],
                'seeds_initialized' => $build['seeds_initialized'],
                'sync_rebuilt' => $build['sync_rebuilt'],
                'support_path' => $build['support_path'],
                'daily_path' => $build['daily_path'],
            ],
        ]);
    }

    public function update(Request $request, Channel $channel)
    {
        $this->authorizeChannel($channel);

        if ($this->isAgentPortal()) {
            $data = $request->validate([
                'remark' => ['nullable', 'string', 'max:255'],
                'status' => ['nullable', 'integer', Rule::in([0, 1])],
            ]);
            if (array_key_exists('remark', $data)) {
                $channel->remark = $data['remark'];
            }
            if (array_key_exists('status', $data) && $data['status'] !== null) {
                $channel->status = (int) $data['status'];
            }
        } else {
            $data = $request->validate([
                'user_id' => ['nullable', 'integer', 'min:0'],
                'remark' => ['nullable', 'string', 'max:255'],
                'status' => ['nullable', 'integer', Rule::in([0, 1])],
            ]);
            if (array_key_exists('user_id', $data)) {
                $userId = (int) ($data['user_id'] ?? Channel::OFFICIAL_USER_ID);
                if ($userId > 0 && ! User::query()->whereKey($userId)->exists()) {
                    throw ValidationException::withMessages(['user_id' => '代理用户不存在']);
                }
                if ($userId !== (int) $channel->user_id && $userId > 0) {
                    $this->assertAgentChannelQuota($userId, $channel->id);
                }
                $channel->user_id = $userId;
            }
            if (array_key_exists('remark', $data)) {
                $channel->remark = $data['remark'];
            }
            if (array_key_exists('status', $data) && $data['status'] !== null) {
                $channel->status = (int) $data['status'];
            }
        }

        $channel->save();

        return response()->json([
            'code' => 0,
            'msg' => 'ok',
            'data' => ['links' => $channel->supportLinks()],
        ]);
    }

    public function destroy(Channel $channel, ChannelProjectService $projects)
    {
        abort_if($this->isAgentPortal(), 403);
        $this->authorizeChannel($channel);

        $channelId = $channel->channel_id;
        try {
            // Delete remotely first: a failed remote delete leaves the DB row available
            // for a safe retry instead of orphaning an unreachable static project.
            $projects->deleteWebTree($channelId);
            DB::transaction(static fn () => $channel->delete());
        } catch (\Throwable $e) {
            return response()->json([
                'code' => 1,
                'msg' => $e->getMessage() ?: '删除失败',
            ], 422);
        }

        return response()->json(['code' => 0, 'msg' => 'ok']);
    }

    private function assertAgentChannelQuota(int $userId, ?int $exceptChannelId = null): void
    {
        if ($userId <= 0) {
            return;
        }
        $q = Channel::query()->where('user_id', $userId);
        if ($exceptChannelId) {
            $q->where('id', '!=', $exceptChannelId);
        }
        $count = $q->count();
        $max = Channel::maxPerAgent();
        if ($count >= $max) {
            throw ValidationException::withMessages([
                'user_id' => "该代理最多只能拥有 {$max} 条渠道链接",
            ]);
        }
    }

    private function authorizeChannel(Channel $channel): void
    {
        if ($agent = $this->agent()) {
            abort_unless((int) $channel->user_id === (int) $agent->id, 403);
        }
    }

    private function compensateBuildUnlessChannelExists(
        ChannelProjectService $projects,
        string $channelId
    ): void {
        try {
            // A concurrent request may have won the unique channel_id insert. Its
            // project must not be removed by this request's compensation.
            if (Channel::query()->where('channel_id', $channelId)->exists()) {
                return;
            }
        } catch (\Throwable $e) {
            Log::warning('Skipped channel build compensation because DB state is unknown', [
                'channel_id' => $channelId,
                'error' => $e->getMessage(),
            ]);

            return;
        }

        try {
            $projects->deleteWebTree($channelId);
        } catch (\Throwable $e) {
            Log::error('Failed to compensate channel build', [
                'channel_id' => $channelId,
                'error' => $e->getMessage(),
            ]);
        }
    }
}