<?php

declare(strict_types=1);

namespace App\Filament\Admin\Widgets;

use App\Models\ServerMetric;
use App\Services\Agent\AgentClient;
use Filament\Widgets\Widget;
use Illuminate\Support\Carbon;
use Illuminate\Support\Facades\Schema;

class ServerChartsWidget extends Widget
{
    private const HISTORY_INTERVAL_SECONDS = 10;

    protected string $view = 'filament.admin.widgets.server-charts';

    protected int|string|array $columnSpan = 'full';

    protected ?string $pollingInterval = '10s';

    public int $refreshKey = 0;

    public string $range = '5m';

    /**
     * @var array<string, mixed>
     */
    public array $diskSnapshot = [];

    public function mount(): void
    {
        $this->diskSnapshot = $this->fetchDiskSnapshot();
    }

    public function refreshData(): void
    {
        $this->refreshKey++;
        $data = $this->getData();

        $this->storeTenSecondMetrics(
            (float) ($data['load']['1min'] ?? 0),
            (float) ($data['cpu']['iowait'] ?? 0),
            (float) ($data['memory']['usage'] ?? 0),
            (float) ($data['memory']['swap_usage'] ?? 0),
            [],
        );

        $config = $this->rangeConfig($this->range);
        $label = now()->format($config['label_format']);
        $history = $this->getHistory(
            (float) ($data['load']['1min'] ?? 0),
            (float) ($data['cpu']['iowait'] ?? 0),
            (float) ($data['memory']['usage'] ?? 0),
            (float) ($data['memory']['swap_usage'] ?? 0),
            $data['disk']['partitions'] ?? [],
        );

        $this->dispatch('server-charts-updated', [
            'cpu' => $data['cpu']['usage'] ?? 0,
            'load' => $data['load']['1min'] ?? 0,
            'iowait' => $data['cpu']['iowait'] ?? 0,
            'memory' => $data['memory']['usage'] ?? 0,
            'swap' => $data['memory']['swap_usage'] ?? 0,
            'label' => $label,
            'history' => $history,
            'history_points' => $config['points'],
            'label_format' => $config['label_format'],
            'interval_seconds' => $config['interval_seconds'],
        ]);
    }

    public function getData(): array
    {
        try {
            $agent = new AgentClient;
            $overview = $agent->metricsOverview();
            $disk = $this->diskSnapshot;
            if (empty($disk)) {
                $disk = $this->fetchDiskSnapshot($agent);
                $this->diskSnapshot = $disk;
            }

            $cpu = $overview['cpu'] ?? [];
            $memory = $overview['memory'] ?? [];
            $swap = $memory['swap'] ?? [];

            $memUsage = $memory['usage_percent'] ?? $memory['usage'] ?? 0;
            if ($memUsage == 0 && ($memory['total'] ?? 0) > 0) {
                $memUsage = (($memory['used'] ?? 0) / $memory['total']) * 100;
            }

            $history = $this->getHistory(
                (float) ($overview['load']['1min'] ?? 0),
                (float) ($cpu['iowait'] ?? 0),
                (float) $memUsage,
                (float) ($swap['usage_percent'] ?? 0),
                $disk['partitions'] ?? [],
            );

            return [
                'cpu' => [
                    'usage' => round($cpu['usage'] ?? 0, 1),
                    'iowait' => round($cpu['iowait'] ?? 0, 1),
                    'cores' => $cpu['cores'] ?? 0,
                    'model' => $cpu['model'] ?? 'Unknown',
                ],
                'memory' => [
                    'usage' => round($memUsage, 1),
                    'used' => $memory['used'] ?? 0,
                    'total' => $memory['total'] ?? 0,
                    'free' => $memory['free'] ?? 0,
                    'cached' => $memory['cached'] ?? 0,
                    'swap_used' => $swap['used'] ?? 0,
                    'swap_total' => $swap['total'] ?? 0,
                    'swap_usage' => round((float) ($swap['usage_percent'] ?? 0), 1),
                ],
                'disk' => [
                    'partitions' => $disk['partitions'] ?? [],
                ],
                'load' => $overview['load'] ?? [],
                'uptime' => $overview['uptime']['human'] ?? 'N/A',
                'history' => $history,
                'source' => 'agent',
            ];
        } catch (\Exception $e) {
            $fallback = $this->getLocalMetrics();
            if ($fallback !== null) {
                if (empty($this->diskSnapshot)) {
                    $this->diskSnapshot = $fallback['disk'] ?? [];
                }
                $history = $this->getHistory(
                    (float) ($fallback['load']['1min'] ?? 0),
                    (float) ($fallback['cpu']['iowait'] ?? 0),
                    (float) ($fallback['memory']['usage'] ?? 0),
                    (float) ($fallback['memory']['swap_usage'] ?? 0),
                    $fallback['disk']['partitions'] ?? [],
                );

                return [
                    'cpu' => [
                        'usage' => round($fallback['cpu']['usage'] ?? 0, 1),
                        'iowait' => round($fallback['cpu']['iowait'] ?? 0, 1),
                        'cores' => $fallback['cpu']['cores'] ?? 0,
                        'model' => $fallback['cpu']['model'] ?? 'Local',
                    ],
                    'memory' => $fallback['memory'],
                    'disk' => $fallback['disk'],
                    'load' => $fallback['load'],
                    'uptime' => $fallback['uptime'] ?? 'N/A',
                    'history' => $history,
                    'source' => 'local',
                    'warning' => $e->getMessage(),
                ];
            }

            return [
                'error' => $e->getMessage(),
                'cpu' => ['usage' => 0, 'iowait' => 0, 'cores' => 0, 'model' => 'Error'],
                'memory' => ['usage' => 0, 'used' => 0, 'total' => 0, 'free' => 0, 'cached' => 0],
                'disk' => $this->diskSnapshot,
                'load' => [],
                'uptime' => 'N/A',
                'history' => $this->getHistory(0.0, 0.0, 0.0, 0.0, []),
                'source' => 'error',
            ];
        }
    }

    public function setRange(string $range): void
    {
        $this->range = $this->normalizeRange($range);

        $config = $this->rangeConfig($this->range);
        $history = $this->getHistory();
        $this->dispatch('server-charts-range-changed', [
            'history' => $history,
            'history_points' => $config['points'],
            'label_format' => $config['label_format'],
            'interval_seconds' => $config['interval_seconds'],
            'range' => $this->range,
        ]);
    }

    public function getHistory(
        float $load = 0.0,
        float $iowait = 0.0,
        float $memory = 0.0,
        float $swap = 0.0,
        array $diskPartitions = []
    ): array {
        if (! Schema::hasTable('server_metrics')) {
            $config = $this->rangeConfig($this->range);

            return $this->seedHistory(
                $config['points'],
                $config['label_format'],
                $config['interval_seconds'],
                $load,
                $iowait,
                $memory,
                $swap,
                $diskPartitions,
            );
        }

        $config = $this->rangeConfig($this->range);
        $since = now()->subMinutes($config['minutes']);

        $records = ServerMetric::query()
            ->where('resolution', $config['resolution'])
            ->where('captured_at', '>=', $since)
            ->orderBy('captured_at')
            ->get();

        if ($records->isEmpty()) {
            return $this->seedHistory(
                $config['points'],
                $config['label_format'],
                $config['interval_seconds'],
                $load,
                $iowait,
                $memory,
                $swap,
                $diskPartitions,
            );
        }

        $grouped = $records->groupBy(fn (ServerMetric $metric) => $metric->captured_at->format('Y-m-d H:i:s'));
        $diskLabels = $records
            ->where('metric', 'disk_gb')
            ->pluck('label')
            ->filter()
            ->unique()
            ->values()
            ->all();

        $labels = [];
        $loadSeries = [];
        $ioWaitSeries = [];
        $memorySeries = [];
        $swapSeries = [];
        $diskSeries = [];
        foreach ($diskLabels as $label) {
            $diskSeries[$label] = [];
        }

        foreach ($grouped as $timestamp => $rows) {
            $labels[] = Carbon::createFromFormat('Y-m-d H:i:s', $timestamp)->format($config['label_format']);
            $loadSeries[] = (float) ($rows->firstWhere('metric', 'load')->value ?? 0);
            $ioWaitSeries[] = (float) ($rows->firstWhere('metric', 'iowait')->value ?? 0);
            $memorySeries[] = (float) ($rows->firstWhere('metric', 'memory')->value ?? 0);
            $swapSeries[] = (float) ($rows->firstWhere('metric', 'swap')->value ?? 0);
            foreach ($diskLabels as $label) {
                $diskSeries[$label][] = (float) ($rows->firstWhere(fn (ServerMetric $metric) => $metric->metric === 'disk_gb' && $metric->label === $label)->value ?? 0);
            }
        }

        if (count($labels) < $config['points']) {
            $seed = $this->seedHistory(
                $config['points'],
                $config['label_format'],
                $config['interval_seconds'],
                $load,
                $iowait,
                $memory,
                $swap,
                $diskPartitions,
            );

            $missing = $config['points'] - count($labels);
            $labels = array_merge(array_slice($seed['labels'], 0, $missing), $labels);
            $loadSeries = array_merge(array_fill(0, $missing, null), $loadSeries);
            $ioWaitSeries = array_merge(array_fill(0, $missing, null), $ioWaitSeries);
            $memorySeries = array_merge(array_fill(0, $missing, null), $memorySeries);
            $swapSeries = array_merge(array_fill(0, $missing, null), $swapSeries);

            $seedDisk = $seed['disk'] ?? [];
            foreach ($diskSeries as $label => $series) {
                $prefix = array_fill(0, $missing, null);
                $diskSeries[$label] = array_merge($prefix, $series);
            }
        }

        if (count($labels) > $config['points']) {
            $labels = array_slice($labels, -$config['points']);
            $loadSeries = array_slice($loadSeries, -$config['points']);
            $ioWaitSeries = array_slice($ioWaitSeries, -$config['points']);
            $memorySeries = array_slice($memorySeries, -$config['points']);
            $swapSeries = array_slice($swapSeries, -$config['points']);
            foreach ($diskSeries as $label => $series) {
                $diskSeries[$label] = array_slice($series, -$config['points']);
            }
        }

        return [
            'labels' => $labels,
            'load' => $loadSeries,
            'iowait' => $ioWaitSeries,
            'memory' => $memorySeries,
            'swap' => $swapSeries,
            'disk' => $diskSeries,
        ];
    }

    private function rangeConfig(string $range): array
    {
        return match ($range) {
            '5m' => ['minutes' => 5, 'points' => 30, 'resolution' => '10s', 'label_format' => 'H:i:s', 'interval_seconds' => 10],
            '30m' => ['minutes' => 30, 'points' => 180, 'resolution' => '10s', 'label_format' => 'H:i:s', 'interval_seconds' => 10],
            'day' => ['minutes' => 1440, 'points' => 24, 'resolution' => '1h', 'label_format' => 'H:00', 'interval_seconds' => 3600],
            'week' => ['minutes' => 10080, 'points' => 28, 'resolution' => '6h', 'label_format' => 'M d H:00', 'interval_seconds' => 21600],
            'month' => ['minutes' => 43200, 'points' => 30, 'resolution' => '1d', 'label_format' => 'M d', 'interval_seconds' => 86400],
            default => ['minutes' => 30, 'points' => 180, 'resolution' => '10s', 'label_format' => 'H:i:s', 'interval_seconds' => 10],
        };
    }

    private function normalizeRange(string $range): string
    {
        return in_array($range, ['5m', '30m', 'day', 'week', 'month'], true) ? $range : '30m';
    }

    private function seedHistory(
        int $points,
        string $labelFormat,
        int $intervalSeconds,
        float $load,
        float $iowait,
        float $memory,
        float $swap,
        array $diskPartitions
    ): array {
        $labels = [];
        $loadSeries = [];
        $ioWaitSeries = [];
        $memorySeries = [];
        $swapSeries = [];
        $diskSeries = [];
        $diskSeeds = [];
        foreach ($diskPartitions as $partition) {
            $mount = $partition['mount'] ?? null;
            $usedGb = $this->bytesToGb((int) ($partition['used'] ?? 0));
            if ($mount !== null) {
                $diskSeeds[$mount] = $usedGb;
            }
        }
        foreach ($diskSeeds as $mount => $value) {
            $diskSeries[$mount] = [];
        }
        $now = now();

        for ($i = $points - 1; $i >= 0; $i--) {
            $labels[] = $now->copy()->subSeconds($i * $intervalSeconds)->format($labelFormat);
            $loadSeries[] = round($load, 3);
            $ioWaitSeries[] = round($iowait, 2);
            $memorySeries[] = round($memory, 1);
            $swapSeries[] = round($swap, 1);
            foreach ($diskSeeds as $mount => $value) {
                $diskSeries[$mount][] = round($value, 2);
            }
        }

        return [
            'labels' => $labels,
            'load' => $loadSeries,
            'iowait' => $ioWaitSeries,
            'memory' => $memorySeries,
            'swap' => $swapSeries,
            'disk' => $diskSeries,
        ];
    }

    private function storeTenSecondMetrics(float $load, float $iowait, float $memory, float $swap, array $partitions): void
    {
        if (! Schema::hasTable('server_metrics')) {
            return;
        }

        $capturedAt = now()->setSecond(intdiv(now()->second, self::HISTORY_INTERVAL_SECONDS) * self::HISTORY_INTERVAL_SECONDS);

        $this->storeMetric('load', '10s', $load, $capturedAt);
        $this->storeMetric('iowait', '10s', $iowait, $capturedAt);
        $this->storeMetric('memory', '10s', $memory, $capturedAt);
        $this->storeMetric('swap', '10s', $swap, $capturedAt);
        foreach ($partitions as $partition) {
            $mount = $partition['mount'] ?? null;
            if ($mount === null) {
                continue;
            }
            $used = (int) ($partition['used'] ?? 0);
            $this->storeMetric('disk_gb', '10s', $this->bytesToGb($used), $capturedAt, $mount);
        }

        $this->pruneResolution('10s', now()->subMinutes(30));
        $this->storeAggregateMetric('load', $load);
        $this->storeAggregateMetric('iowait', $iowait);
        $this->storeAggregateMetric('memory', $memory);
        $this->storeAggregateMetric('swap', $swap);
    }

    private function storeMetric(string $metric, string $resolution, float $value, Carbon $capturedAt, ?string $label = null): void
    {
        ServerMetric::updateOrCreate(
            [
                'metric' => $metric,
                'label' => $label,
                'resolution' => $resolution,
                'captured_at' => $capturedAt,
            ],
            [
                'value' => round($value, 3),
            ],
        );
    }

    private function storeAggregateMetric(string $metric, float $value): void
    {
        $now = now();
        $this->storeMetric($metric, '1h', $value, $this->bucketTimestamp($now, 3600));
        $this->storeMetric($metric, '6h', $value, $this->bucketTimestamp($now, 21600));
        $this->storeMetric($metric, '1d', $value, $this->bucketTimestamp($now, 86400));

        $this->pruneResolution('1h', $now->copy()->subHours(24));
        $this->pruneResolution('6h', $now->copy()->subDays(7));
        $this->pruneResolution('1d', $now->copy()->subDays(31));
    }

    private function bucketTimestamp(Carbon $now, int $bucketSeconds): Carbon
    {
        return $now->copy()->setTimestamp(intdiv($now->timestamp, $bucketSeconds) * $bucketSeconds);
    }

    private function pruneResolution(string $resolution, Carbon $before): void
    {
        ServerMetric::query()
            ->where('resolution', $resolution)
            ->where('captured_at', '<', $before)
            ->delete();
    }

    private function getLocalMetrics(): ?array
    {
        $load = sys_getloadavg();
        if (! is_array($load) || count($load) < 3) {
            return null;
        }

        $loadData = [
            '1min' => round((float) $load[0], 2),
            '5min' => round((float) $load[1], 2),
            '15min' => round((float) $load[2], 2),
        ];

        $cpuCores = 0;
        if (is_readable('/proc/cpuinfo')) {
            $lines = file('/proc/cpuinfo', FILE_IGNORE_NEW_LINES);
            foreach ($lines as $line) {
                if (str_starts_with($line, 'processor')) {
                    $cpuCores++;
                }
            }
        }
        $cpuCores = $cpuCores > 0 ? $cpuCores : 1;

        $memory = $this->readMeminfo();
        $disk = $this->readDiskUsage();

        return [
            'cpu' => [
                'usage' => 0,
                'iowait' => 0,
                'cores' => $cpuCores,
                'model' => 'Local',
            ],
            'memory' => $memory,
            'disk' => $disk,
            'load' => $loadData,
        ];
    }

    private function fetchDiskSnapshot(?AgentClient $agent = null): array
    {
        try {
            $client = $agent ?? new AgentClient;
            $disk = $client->metricsDisk()['data'] ?? [];
            if (! empty($disk)) {
                return $disk;
            }
        } catch (\Exception) {
            // Ignore and fall back to local disk stats below.
        }

        return $this->readDiskUsage();
    }

    private function readMeminfo(): array
    {
        $memInfo = [];
        if (is_readable('/proc/meminfo')) {
            $lines = file('/proc/meminfo', FILE_IGNORE_NEW_LINES);
            foreach ($lines as $line) {
                if (preg_match('/^(\w+):\s+(\d+)/', $line, $matches)) {
                    $memInfo[$matches[1]] = (int) $matches[2];
                }
            }
        }

        $totalKb = $memInfo['MemTotal'] ?? 0;
        $freeKb = $memInfo['MemFree'] ?? 0;
        $availableKb = $memInfo['MemAvailable'] ?? $freeKb;
        $buffersKb = $memInfo['Buffers'] ?? 0;
        $cachedKb = $memInfo['Cached'] ?? 0;
        $swapTotalKb = $memInfo['SwapTotal'] ?? 0;
        $swapFreeKb = $memInfo['SwapFree'] ?? 0;
        $swapUsedKb = max(0, $swapTotalKb - $swapFreeKb);

        $usedKb = max(0, $totalKb - $availableKb);

        return [
            'usage' => $totalKb > 0 ? round(($usedKb / $totalKb) * 100, 1) : 0,
            'used' => round($usedKb / 1024, 0),
            'total' => round($totalKb / 1024, 0),
            'free' => round($freeKb / 1024, 0),
            'cached' => round($cachedKb / 1024, 0),
            'swap_used' => round($swapUsedKb / 1024, 0),
            'swap_total' => round($swapTotalKb / 1024, 0),
            'swap_usage' => $swapTotalKb > 0 ? round(($swapUsedKb / $swapTotalKb) * 100, 1) : 0,
        ];
    }

    private function readDiskUsage(): array
    {
        $total = @disk_total_space('/') ?: 0;
        $free = @disk_free_space('/') ?: 0;
        $used = max(0, $total - $free);
        $usagePercent = $total > 0 ? round(($used / $total) * 100, 1) : 0;

        return [
            'partitions' => [
                [
                    'filesystem' => '/',
                    'mount' => '/',
                    'used' => $used,
                    'total' => $total,
                    'usage_percent' => $usagePercent,
                    'used_human' => $this->formatBytes($used),
                    'total_human' => $this->formatBytes($total),
                ],
            ],
        ];
    }

    private function formatBytes(int $bytes): string
    {
        $units = ['B', 'KB', 'MB', 'GB', 'TB'];
        $size = max(0, $bytes);
        $unit = 0;
        while ($size >= 1024 && $unit < count($units) - 1) {
            $size /= 1024;
            $unit++;
        }

        return round($size, 1).' '.$units[$unit];
    }

    private function bytesToGb(int $bytes): float
    {
        if ($bytes <= 0) {
            return 0.0;
        }

        return round($bytes / 1024 / 1024 / 1024, 2);
    }
}