diff --git a/.env b/.env
index 66106a0..a1b285e 100644
--- a/.env
+++ b/.env
@@ -7,3 +7,7 @@ APP_SECRET=akwhdaeuifzuieshuikjfjk
 ###> application ###
 REQUIRED_API_KEY=74857389798572903480209489024
 ###< application ###
+
+HOME_ASSISTANT_URL=https://ha.strolap.com
+HOME_ASSISTANT_TOKEN=
+HOME_ASSISTANT_VERIFY_SSL=true
diff --git a/config/secrets/dev/dev.HOME_ASSISTANT_TOKEN.ad10d3.php b/config/secrets/dev/dev.HOME_ASSISTANT_TOKEN.ad10d3.php
new file mode 100644
index 0000000..af67e7a
--- /dev/null
+++ b/config/secrets/dev/dev.HOME_ASSISTANT_TOKEN.ad10d3.php
@@ -0,0 +1,3 @@
+<?php // dev.HOME_ASSISTANT_TOKEN.ad10d3 on Sat, 15 Mar 2025 08:32:34 +0000
+
+return "\x85\xCB\xCD4\xAC\x23\xEF\x87\x08\x7F\x14q\x93Kq\xB3Q\xDF\x27\xD3\xF1B5\x7C\x7CO\xADz\x86\x9EK\x1B\xE5b1\xEA\x26\xA9\x5Bk\xBC\xE0y\xE4V\xA1q\x8D\xC1\x1F\xA4\x98f\xBF\xCF\x29\x3C2\xEE.\xCAE\xFD1\xAD\xA3\xAE\xC5\x94\xD1\xA8\x9C\x0F\xFDy\xC5K\x9A\x8D\xAC\xA9\xF1_\xBA4\x87\x98\x8An\x84\x8A\x23\xCF\x89or\xBF\x09\xBC\x8En\x7F\x04\xEB\x25\x01l\x9Fc\x09\x03\xA25\x3E\x3AVVL2r\x89ifh\xE0N\x40\xCA\xFB\x20A\xCDtCVl\xDF\x01\x3E\x0FP\x5Er\xC3\x27\x82\xE6_\xBE\xE1bi\x20k\xDA\x09J\xF7\x91rKs\x98\xC2\x7B\x3Ac\xD9\xB6z\x2FHw\x84\xA1\x3B\x3FA\xDB\x83_cB\xFF\x94M\xC8\x86\xEE\x05\xA7U\xA1\x8A\x9A\x81\xB3\x85\xF6\xFBG\xC4\x0B\x8D\xA9\x98\x82\xC4\xB5\xA6\x95\xFE\x5D\xBE\x98EQ\xA9\xC3\xE8\xBB\xDD7\x133\x5C\x40\xD5\xC1\x5D\x3B";
diff --git a/config/secrets/dev/dev.list.php b/config/secrets/dev/dev.list.php
index 7a0cb24..7e67bb1 100644
--- a/config/secrets/dev/dev.list.php
+++ b/config/secrets/dev/dev.list.php
@@ -3,4 +3,5 @@
 return [
     'ABSENCE_API_ID' => null,
     'ABSENCE_API_KEY' => null,
+    'HOME_ASSISTANT_TOKEN' => null,
 ];
diff --git a/src/Commands/ShowEntityStateHistoryCommand.php b/src/Commands/ShowEntityStateHistoryCommand.php
new file mode 100644
index 0000000..402d3f7
--- /dev/null
+++ b/src/Commands/ShowEntityStateHistoryCommand.php
@@ -0,0 +1,57 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Commands;
+
+use App\HomeAssistant\HomeAssistantClient;
+use DateTimeImmutable;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+#[AsCommand(
+    name: 'app:show-entity-state-history',
+    description: 'Shows the state history for a Home Assistant entity',
+)]
+final class ShowEntityStateHistoryCommand extends Command
+{
+    public function __construct(
+        private readonly HomeAssistantClient $client,
+    ) {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this->addArgument('entity-id', InputArgument::REQUIRED, 'The entity ID to show history for');
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $io = new SymfonyStyle($input, $output);
+        $entityId = $input->getArgument('entity-id');
+
+        $history = $this->client->getEntityStateHistory($entityId, new DateTimeImmutable('-10 days'), new DateTimeImmutable('+10 days'));
+
+        if (empty($history)) {
+            $io->error('No history found for entity ' . $entityId);
+            return Command::FAILURE;
+        }
+
+        $io->title('State History for ' . $entityId);
+
+        foreach ($history[0] as $state) {
+            $io->writeln(sprintf(
+                '%s: %s',
+                $state['last_changed'],
+                $state['state']
+            ));
+        }
+
+        return Command::SUCCESS;
+    }
+}
diff --git a/src/Core/Services/Home/HomeEntityInterface.php b/src/Core/Services/Home/HomeEntityInterface.php
new file mode 100644
index 0000000..0f2873f
--- /dev/null
+++ b/src/Core/Services/Home/HomeEntityInterface.php
@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core\Services\Home;
+
+use DateTimeImmutable;
+
+interface HomeEntityInterface
+{
+    public function getId(): string;
+
+    public function getState(): mixed;
+
+    public function getName(): string;
+
+    public function getType(): HomeEntityType;
+
+    public function getLastChanged(): DateTimeImmutable;
+
+    public function getLastUpdated(): DateTimeImmutable;
+} 
\ No newline at end of file
diff --git a/src/Core/Services/Home/HomeEntityType.php b/src/Core/Services/Home/HomeEntityType.php
new file mode 100644
index 0000000..420850f
--- /dev/null
+++ b/src/Core/Services/Home/HomeEntityType.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core\Services\Home;
+
+enum HomeEntityType
+{
+    case LIGHT;
+    case SWITCH;
+    case SENSOR;
+    case BINARY_SENSOR;
+    case CLIMATE;
+    case MEDIA_PLAYER;
+    case SCENE;
+    case SCRIPT;
+    case AUTOMATION;
+    case CAMERA;
+    case COVER;
+    case FAN;
+    case LOCK;
+    case VACUUM;
+    case WEATHER;
+    case ZONE;
+} 
\ No newline at end of file
diff --git a/src/Core/Services/Home/HomeServiceInterface.php b/src/Core/Services/Home/HomeServiceInterface.php
new file mode 100644
index 0000000..fd3e67d
--- /dev/null
+++ b/src/Core/Services/Home/HomeServiceInterface.php
@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core\Services\Home;
+
+interface HomeServiceInterface
+{
+    public function findEntity(string $entityId): HomeEntityInterface;
+
+    public function findAllEntities(): array;
+
+    public function callService(string $service, array $data = []): array;
+} 
\ No newline at end of file
diff --git a/src/HomeAssistant/EntityState.php b/src/HomeAssistant/EntityState.php
new file mode 100644
index 0000000..080b656
--- /dev/null
+++ b/src/HomeAssistant/EntityState.php
@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\HomeAssistant;
+
+use function explode;
+use function in_array;
+
+final readonly class EntityState
+{
+    public function __construct(
+        public string $entityId,
+        public string $state,
+        public array $attributes,
+        public string $lastChanged,
+        public string $lastUpdated,
+        public array|string|null $context = null,
+    ) {
+    }
+
+    public static function fromArray(array $data): self
+    {
+        return new self(
+            $data['entity_id'],
+            $data['state'],
+            $data['attributes'] ?? [],
+            $data['last_changed'] ?? '',
+            $data['last_updated'] ?? '',
+            $data['context'] ?? null,
+        );
+    }
+
+    public function isOn(): bool
+    {
+        return in_array($this->state, ['on', 'home', 'open', 'unlocked', 'active'], true);
+    }
+
+    public function isOff(): bool
+    {
+        return in_array($this->state, ['off', 'away', 'closed', 'locked', 'inactive'], true);
+    }
+
+    public function getDomain(): string
+    {
+        $parts = explode('.', $this->entityId, 2);
+
+        return $parts[0];
+    }
+
+    public function getName(): string
+    {
+        return $this->attributes['friendly_name'] ?? $this->entityId;
+    }
+}
diff --git a/src/HomeAssistant/HomeAssistantClient.php b/src/HomeAssistant/HomeAssistantClient.php
new file mode 100644
index 0000000..145f23d
--- /dev/null
+++ b/src/HomeAssistant/HomeAssistantClient.php
@@ -0,0 +1,107 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\HomeAssistant;
+
+use DateTimeInterface;
+use function explode;
+
+use Symfony\Component\DependencyInjection\Attribute\Autowire;
+use Symfony\Contracts\HttpClient\HttpClientInterface;
+use Symfony\Contracts\HttpClient\ResponseInterface;
+
+final readonly class HomeAssistantClient
+{
+    public function __construct(
+        private HttpClientInterface $httpClient,
+        #[Autowire('%env(HOME_ASSISTANT_URL)%')]
+        private string $baseUrl,
+        #[Autowire('%env(HOME_ASSISTANT_TOKEN)%')]
+        private string $token,
+        #[Autowire('%env(HOME_ASSISTANT_VERIFY_SSL)%')]
+        private bool $verifySSL,
+    ) {
+    }
+
+    public function getStates(): array
+    {
+        return $this->request('GET', '/api/states');
+    }
+
+    public function getServices(): array
+    {
+        return $this->request('GET', '/api/services');
+    }
+
+    public function getEntityState(string $entityId): array
+    {
+        return $this->request('GET', "/api/states/{$entityId}");
+    }
+
+    public function getEntityStateHistory(string $entityId, DateTimeInterface $startDate, DateTimeInterface $endDate): array
+    {
+        $queryParams = http_build_query([
+            'end_time' => $endDate->format('Y-m-d\TH:i:s\Z'),
+            'filter_entity_id' => $entityId,
+        ]);
+
+        return $this->request('GET', "/api/history/period/{$startDate->format('Y-m-d\TH:i:s\Z')}?{$queryParams}");
+    }
+
+    public function callService(string $domain, string $service, array $data = []): array
+    {
+        return $this->request('POST', "/api/services/{$domain}/{$service}", $data);
+    }
+
+    public function turnOn(string $entityId): array
+    {
+        $domain = explode('.', $entityId)[0];
+
+        return $this->callService($domain, 'turn_on', ['entity_id' => $entityId]);
+    }
+
+    public function turnOff(string $entityId): array
+    {
+        $domain = explode('.', $entityId)[0];
+
+        return $this->callService($domain, 'turn_off', ['entity_id' => $entityId]);
+    }
+
+    private function request(string $method, string $endpoint, array $data = []): array
+    {
+        $options = [
+            'headers' => [
+                'Authorization' => "Bearer {$this->token}",
+                'Content-Type' => 'application/json',
+            ],
+            'verify_peer' => $this->verifySSL,
+            'verify_host' => $this->verifySSL,
+        ];
+
+        if (!empty($data)) {
+            $options['json'] = $data;
+        }
+
+        $response = $this->httpClient->request(
+            $method,
+            $this->baseUrl.$endpoint,
+            $options,
+        );
+
+        return $this->handleResponse($response);
+    }
+
+    private function handleResponse(ResponseInterface $response): array
+    {
+        $statusCode = $response->getStatusCode();
+
+        if ($statusCode >= 200 && $statusCode < 300) {
+            return $response->toArray();
+        }
+
+        $content = $response->getContent(false);
+
+        throw new HomeAssistantException($content, $statusCode);
+    }
+}
diff --git a/src/HomeAssistant/HomeAssistantEntity.php b/src/HomeAssistant/HomeAssistantEntity.php
new file mode 100644
index 0000000..10858b2
--- /dev/null
+++ b/src/HomeAssistant/HomeAssistantEntity.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\HomeAssistant;
+
+use App\Core\Services\Home\HomeEntityInterface;
+use App\Core\Services\Home\HomeEntityType;
+use DateTimeImmutable;
+
+final readonly class HomeAssistantEntity implements HomeEntityInterface
+{
+    public function __construct(
+        private EntityState $entityState,
+    ) {
+    }
+
+    public function getId(): string
+    {
+        return $this->entityState->entityId;
+    }
+
+    public function getState(): mixed
+    {
+        return $this->entityState->state;
+    }
+
+    public function getName(): string
+    {
+        return $this->entityState->getName();
+    }
+
+    public function getType(): HomeEntityType
+    {
+        $domain = $this->entityState->getDomain();
+
+        return match ($domain) {
+            'light' => HomeEntityType::LIGHT,
+            'switch' => HomeEntityType::SWITCH,
+            'sensor' => HomeEntityType::SENSOR,
+            'binary_sensor' => HomeEntityType::BINARY_SENSOR,
+            'climate' => HomeEntityType::CLIMATE,
+            'media_player' => HomeEntityType::MEDIA_PLAYER,
+            'scene' => HomeEntityType::SCENE,
+            'script' => HomeEntityType::SCRIPT,
+            'automation' => HomeEntityType::AUTOMATION,
+            'camera' => HomeEntityType::CAMERA,
+            'cover' => HomeEntityType::COVER,
+            'fan' => HomeEntityType::FAN,
+            'lock' => HomeEntityType::LOCK,
+            'vacuum' => HomeEntityType::VACUUM,
+            'weather' => HomeEntityType::WEATHER,
+            'zone' => HomeEntityType::ZONE,
+            default => throw new HomeAssistantException("Unknown entity type: {$domain}")
+        };
+    }
+
+    public function getLastChanged(): DateTimeImmutable
+    {
+        return new DateTimeImmutable($this->entityState->lastChanged);
+    }
+
+    public function getLastUpdated(): DateTimeImmutable
+    {
+        return new DateTimeImmutable($this->entityState->lastUpdated);
+    }
+}
diff --git a/src/HomeAssistant/HomeAssistantException.php b/src/HomeAssistant/HomeAssistantException.php
new file mode 100644
index 0000000..48b8889
--- /dev/null
+++ b/src/HomeAssistant/HomeAssistantException.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\HomeAssistant;
+
+use RuntimeException;
+
+final class HomeAssistantException extends RuntimeException
+{
+}
diff --git a/src/HomeAssistant/HomeAssistantHomeService.php b/src/HomeAssistant/HomeAssistantHomeService.php
new file mode 100644
index 0000000..13998ae
--- /dev/null
+++ b/src/HomeAssistant/HomeAssistantHomeService.php
@@ -0,0 +1,121 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Services\HomeAssistant;
+
+use App\Core\Services\Home\HomeEntityInterface;
+use App\Core\Services\Home\HomeEntityType;
+use App\Core\Services\Home\HomeServiceInterface;
+
+use function array_filter;
+use function array_keys;
+use function array_map;
+use function explode;
+use function str_contains;
+
+final readonly class HomeAssistantHomeService implements HomeServiceInterface
+{
+    public function __construct(
+        private HomeAssistantClient $client,
+    ) {
+    }
+
+    public function findEntity(string $entityId): HomeEntityInterface
+    {
+        $entityState = $this->getEntityState($entityId);
+
+        return new HomeAssistantEntity($entityState);
+    }
+
+    public function findAllEntities(): array
+    {
+        $states = $this->getAllEntityStates();
+
+        if (empty($states)) {
+            throw new HomeAssistantException('No entities found');
+        }
+
+        $entities = [];
+        foreach ($states as $state) {
+            $type = HomeEntityType::tryFrom($state->getDomain());
+
+            if ($type === null) {
+                continue;
+            }
+
+            $entities[] = new HomeAssistantEntity($state);
+        }
+
+        return array_filter($entities, fn (HomeEntityInterface $entity) => $entity->getType() === HomeEntityType::LIGHT);
+    }
+
+    public function callService(string $service, array $data = []): array
+    {
+        // Extract domain and service name from the service string
+        if (str_contains($service, '.')) {
+            [$domain, $serviceName] = explode('.', $service, 2);
+
+            return $this->client->callService($domain, $serviceName, $data);
+        }
+
+        throw new HomeAssistantException("Invalid service format. Expected 'domain.service'");
+    }
+
+    /**
+     * @return EntityState[]
+     */
+    public function getAllEntityStates(): array
+    {
+        $states = $this->client->getStates();
+
+        return array_map(
+            static fn (array $state): EntityState => EntityState::fromArray($state),
+            $states,
+        );
+    }
+
+    public function getEntityState(string $entityId): EntityState
+    {
+        $state = $this->client->getEntityState($entityId);
+
+        return EntityState::fromArray($state);
+    }
+
+    /**
+     * @return EntityState[]
+     */
+    public function getEntitiesByDomain(string $domain): array
+    {
+        $allStates = $this->getAllEntityStates();
+
+        return array_filter(
+            $allStates,
+            static fn (EntityState $state): bool => $state->getDomain() === $domain,
+        );
+    }
+
+    public function turnOn(string $entityId): EntityState
+    {
+        $this->client->turnOn($entityId);
+
+        return $this->getEntityState($entityId);
+    }
+
+    public function turnOff(string $entityId): EntityState
+    {
+        $this->client->turnOff($entityId);
+
+        return $this->getEntityState($entityId);
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getAvailableDomains(): array
+    {
+        $services = $this->client->getServices();
+
+        return array_keys($services);
+    }
+}
diff --git a/src/Service/CalendarExportService.php b/src/Service/CalendarExportService.php
index 96a1cea..a924ff8 100644
--- a/src/Service/CalendarExportService.php
+++ b/src/Service/CalendarExportService.php
@@ -2,17 +2,25 @@
 
 namespace App\Service;
 
-use App\Model\Absence;
-use DateTime;
+use App\HomeAssistant\HomeAssistantClient;
+use DateTimeImmutable;
 use DateTimeInterface;
 use DateTimeZone;
+use RuntimeException;
 
 final class CalendarExportService
 {
-    private const DUSSELDORF_ADDRESS = 'CHECK24 \nHeinricht-Heine-Allee 53\n40213 Düsseldorf\nDeutschland';
-    private const KAMEN_ADDRESS = 'Privat \nHeidkamp 21\n59174 Kamen\nDeutschland';
-    private const COMPANY_NAME = 'CHECK24';
-    private const TIMEZONE = 'Europe/Berlin';
+    private const string DUSSELDORF_ADDRESS = 'CHECK24 \nHeinricht-Heine-Allee 53\n40213 Düsseldorf\nDeutschland';
+    private const string KAMEN_ADDRESS = 'Privat \nHeidkamp 21\n59174 Kamen\nDeutschland';
+    private const string COMPANY_NAME = 'CHECK24';
+    private const string TIMEZONE = 'Europe/Berlin';
+    private const string PERSON_ENTITY = 'person.tim';
+    private const string OFFICE_STATE = 'CHECK24';
+
+    public function __construct(
+        private readonly HomeAssistantClient $homeAssistantClient
+    ) {
+    }
 
     public function generateIcsContent(array $days, array $absences): string
     {
@@ -30,11 +38,18 @@ final class CalendarExportService
                 continue;
             }
 
-            $eventStart = clone $day['date'];
-            $eventStart->setTime(9, 0, 0);
+            $dayDate = clone $day['date'];
+            $startAndEndTimes = $this->getWorkTimesFromHomeAssistant($dayDate);
             
-            $eventEnd = clone $day['date'];
-            $eventEnd->setTime(17, 30, 0);
+            if ($startAndEndTimes === null) {
+                $eventStart = clone $day['date'];
+                $eventStart->setTime(9, 0, 0);
+                
+                $eventEnd = clone $day['date'];
+                $eventEnd->setTime(17, 30, 0);
+            } else {
+                [$eventStart, $eventEnd] = $startAndEndTimes;
+            }
             
             $isHomeOffice = $day['isFtk'] ?? false;
             $location = $isHomeOffice ? self::KAMEN_ADDRESS : self::DUSSELDORF_ADDRESS;
@@ -46,7 +61,7 @@ final class CalendarExportService
             
             $icsContent[] = 'BEGIN:VEVENT';
             $icsContent[] = 'UID:' . $this->generateUid($eventStart);
-            $icsContent[] = 'DTSTAMP:' . $this->formatDateTime(new DateTime('now', new DateTimeZone(self::TIMEZONE)));
+            $icsContent[] = 'DTSTAMP:' . $this->formatDateTime(new DateTimeImmutable('now', new DateTimeZone(self::TIMEZONE)));
             $icsContent[] = 'DTSTART;TZID=' . self::TIMEZONE . ':' . $this->formatDateTimeLocal($eventStart);
             $icsContent[] = 'DTEND;TZID=' . self::TIMEZONE . ':' . $this->formatDateTimeLocal($eventEnd);
             $icsContent[] = 'SUMMARY:' . $name;
@@ -59,16 +74,67 @@ final class CalendarExportService
         return implode("\r\n", $icsContent);
     }
 
+    private function getWorkTimesFromHomeAssistant(DateTimeInterface $date): ?array
+    {
+        $startOfDay = DateTimeImmutable::createFromInterface($date)->setTime(0, 0, 0);
+        $typicalEndOfDay = DateTimeImmutable::createFromInterface($date)->setTime(17, 30, 0);
+        
+        try {
+            $stateHistory = $this->homeAssistantClient->getEntityStateHistory(
+                self::PERSON_ENTITY,
+                $startOfDay, 
+                $typicalEndOfDay
+            );
+            
+            if (empty($stateHistory) || empty($stateHistory[0])) {
+                return null;
+            }
+            
+            $startTime = null;
+            $endTime = null;
+            $states = $stateHistory[0];
+            
+            foreach ($states as $i => $state) {
+                if ($state['state'] === self::OFFICE_STATE) {
+                    $startTime = new DateTimeImmutable($state['last_changed']);
+                    
+                    for ($j = $i + 1; $j < count($states); $j++) {
+                        if ($states[$j]['state'] !== self::OFFICE_STATE) {
+                            $endTime = new DateTimeImmutable($states[$j]['last_changed']);
+                            break;
+                        }
+                    }
+                    
+                    if ($startTime !== null && $endTime === null) {
+                        $endTime = clone $startTime;
+                        $endTime = $endTime->modify('+9 hours');
+                    }
+                    
+                    break;
+                }
+            }
+            
+            if ($startTime === null || $endTime === null) {
+                return null;
+            }
+
+            $startTime = $startTime->setTimezone(new DateTimeZone('Europe/Berlin'));
+            $endTime = $endTime->setTimezone(new DateTimeZone('Europe/Berlin'));
+            
+            return [$startTime, $endTime];
+        } catch (RuntimeException) {
+            return null;
+        }
+    }
+
     private function isWeekend(array $day): bool
     {
         return $day['weekday'] >= 6;
     }
 
-    private function formatDateTime(DateTimeInterface $dateTime): string
+    private function formatDateTime(DateTimeImmutable $dateTime): string
     {
-        $utcDateTime = clone $dateTime;
-        $utcDateTime->setTimezone(new DateTimeZone('UTC'));
-        return $utcDateTime->format('Ymd\THis\Z');
+        return $dateTime->setTimezone(new DateTimeZone('UTC'))->format('Ymd\THis\Z');
     }
 
     private function formatDateTimeLocal(DateTimeInterface $dateTime): string
@@ -104,4 +170,4 @@ final class CalendarExportService
             'END:VTIMEZONE',
         ]);
     }
-} 
\ No newline at end of file
+}
\ No newline at end of file