<?php
/**
 * FuzeWorks Async Library
 *
 * The FuzeWorks PHP FrameWork
 *
 * Copyright (C) 2013-2020 TechFuze
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * @author    TechFuze
 * @copyright Copyright (c) 2013 - 2020, TechFuze. (http://techfuze.net)
 * @license   https://opensource.org/licenses/MIT MIT License
 *
 * @link  http://techfuze.net/fuzeworks
 * @since Version 1.0.0
 *
 * @version Version 1.0.0
 */

namespace FuzeWorks\Async\TaskStorage;
use FuzeWorks\Async\Events\TaskModifyEvent;
use FuzeWorks\Async\Task;
use FuzeWorks\Async\TasksException;
use FuzeWorks\Async\TaskStorage;
use FuzeWorks\Events;
use FuzeWorks\Logger;
use Redis;
use RedisException;

class RedisTaskStorage implements TaskStorage
{

    /**
     * @var Redis
     */
    protected $conn;

    protected $indexSet = 'async_index';
    protected $unfinishedSet = 'async_index_unfinished';
    protected $key_prefix = 'async_task_';

    /**
     * @inheritDoc
     */
    public function __construct(array $parameters)
    {
        // Attempt to connect to Redis
        try {
            $this->conn = new Redis();

            // Afterwards connect to server
            $socketType = $parameters['socket_type'];
            if ($socketType == 'unix')
                $success = $this->conn->connect($parameters['socket']);
            elseif ($socketType == 'tcp')
                $success = $this->conn->connect($parameters['host'], $parameters['port'], $parameters['timeout']);
            else
                $success = false;

            // If unsuccessful, return false
            if (!$success)
                throw new TasksException("Could not construct RedisTaskStorage. Failed to connect.");

            // Otherwise attempt authentication, if needed
            if (isset($parameters['password']) && !$this->conn->auth($parameters['password']))
                throw new TasksException("Could not construct RedisTaskStorage. Authentication failure.");

            // And select the DB index
            $this->conn->select($parameters['db_index']);
        } catch (RedisException $e) {
            throw new TasksException("Could not construct RedisTaskStorage. RedisException thrown: '" . $e->getMessage() . "'");
        }
    }

    /**
     * @inheritDoc
     * @throws TasksException
     */
    public function addTask(Task $task): bool
    {
        // Check if the task doesn't exist yet
        $taskId = $task->getId();

        // Query the index
        $isMember = $this->conn->sIsMember($this->indexSet, $taskId);
        if ($isMember)
            throw new TasksException("Could not add Task to TaskStorage. Task '$taskId' already exists.");

        // Serialize the task and save it
        $taskData = serialize($task);

        // Register the task
        $this->conn->sAdd($this->indexSet, $taskId);
        if ($task->getStatus() !== Task::COMPLETED && $task->getStatus() !== Task::CANCELLED)
            $this->conn->sAdd($this->unfinishedSet, $taskId);

        // And create a hash for it
        if ($this->conn->hSet($this->key_prefix . $taskId, 'data', $taskData) === FALSE)
            return false;

        return true;
    }

    /**
     * @inheritDoc
     */
    public function readTasks(bool $noIncludeDone = false): array
    {
        // First fetch an array of all tasks in the set
        if ($noIncludeDone)
            $taskList = $this->conn->sMembers($this->unfinishedSet);
        else
            $taskList = $this->conn->sMembers($this->indexSet);

        // Go over each taskId and fetch the specific task
        $tasks = [];
        foreach ($taskList as $taskId)
            $tasks[] = unserialize($this->conn->hGet($this->key_prefix . $taskId, 'data'));

        return $tasks;
    }

    /**
     * @inheritDoc
     */
    public function getTaskById(string $identifier): Task
    {
        // Query the index
        $isMember = $this->conn->sIsMember($this->indexSet, $identifier);
        if (!$isMember)
            throw new TasksException("Could not get task by ID. Task not found.");

        // Fetch the task
        /** @var Task $task */
        $task = unserialize($this->conn->hGet($this->key_prefix . $identifier, 'data'));

        // Return the task
        return $task;
    }

    /**
     * @inheritDoc
     */
    public function modifyTask(Task $task): bool
    {
        // First get the task ID
        $taskId = $task->getId();

        // Check if it exists
        $isMember = $this->conn->sIsMember($this->indexSet, $taskId);
        if (!$isMember)
            throw new TasksException("Could not modify task. Task '$taskId' does not exists.");

        // Fire the TaskModifyEvent
        /** @var TaskModifyEvent $event */
        $event = Events::fireEvent(new TaskModifyEvent(), $task);
        if ($event->isCancelled())
        {
            Logger::log("Did not modify task. Cancelled by taskModifyEvent.");
            return false;
        }

        // And write the data
        $taskData = serialize($event->getTask());
        if ($this->conn->hSet($this->key_prefix . $taskId, 'data', $taskData) === FALSE)
            return false;

        // Modify the unfinished set
        if ($this->conn->sIsMember($this->unfinishedSet, $taskId) && ($task->getStatus() === Task::COMPLETED || $task->getStatus() === Task::CANCELLED ))
            $this->conn->sRem($this->unfinishedSet, $taskId);
        elseif (!$this->conn->sIsMember($this->unfinishedSet, $taskId) && $task->getStatus() !== Task::COMPLETED && $task->getStatus() !== Task::CANCELLED)
            $this->conn->sAdd($this->unfinishedSet, $taskId);

        return true;
    }

    /**
     * @inheritDoc
     * @throws TasksException
     */
    public function deleteTask(Task $task): bool
    {
        // First get the task ID
        $taskId = $task->getId();

        // Check if it exists
        $isMember = $this->conn->sIsMember($this->indexSet, $taskId);
        if (!$isMember)
            throw new TasksException("Could not delete task. Task '$taskId' does not exists.");

        // Delete the task from the index
        $this->conn->sRem($this->indexSet, $taskId);

        // And remove the task from the unfinishedSet
        if ($this->conn->sIsMember($this->unfinishedSet, $taskId))
            $this->conn->sRem($this->unfinishedSet, $taskId);

        // Delete the task itself
        if ($this->conn->del($this->key_prefix . $taskId) > 0)
            return true;

        return false;
    }

    /**
     * @inheritDoc
     */
    public function writeTaskOutput(Task $task, string $output, string $errors, int $statusCode): bool
    {
        // First get the task ID
        $taskId = $task->getId();

        // Check if the task exists
        $isMember = $this->conn->sIsMember($this->indexSet, $taskId);
        if (!$isMember)
            throw new TasksException("Could not write task output. Task '$taskId' not found.");

        // Prepare the data
        $contents = ['taskId' => $taskId, 'output' => $output, 'errors' => $errors, 'statusCode' => $statusCode];

        // Determine the attempt number
        $attempt = $this->conn->hIncrBy($this->key_prefix . $taskId, 'taskOutputAttempts', 1);

        // Then write this output
        if ($this->conn->hSet($this->key_prefix . $taskId, 'output' . $attempt, serialize($contents)) === FALSE)
            return false;

        return true;
    }

    /**
     * @inheritDoc
     */
    public function writePostOutput(Task $task, string $output, string $errors, int $statusCode): bool
    {
        // First get the task ID
        $taskId = $task->getId();

        // Check if the task exists
        $isMember = $this->conn->sIsMember($this->indexSet, $taskId);
        if (!$isMember)
            throw new TasksException("Could not write post output. Task '$taskId' not found.");

        // Prepare the data
        $contents = ['taskId' => $taskId, 'output' => $output, 'errors' => $errors, 'statusCode' => $statusCode];

        // Determine the attempt number
        $attempt = $this->conn->hIncrBy($this->key_prefix . $taskId, 'taskPostAttempts', 1);

        // Then write this output
        if ($this->conn->hSet($this->key_prefix . $taskId, 'postOutput' . $attempt, serialize($contents)) === FALSE)
            return false;

        return true;
    }

    /**
     * @inheritDoc
     */
    public function readTaskOutput(Task $task, int $attempt = 0): ?array
    {
        // First get the task ID
        $taskId = $task->getId();

        // If a nothing in particular is requested, fetch the latest and select that as the attempt
        if ($attempt === 0)
            $attempt = $this->conn->hGet($this->key_prefix . $taskId, 'taskOutputAttempts');

        // If -1 is requested, fetch all
        if ($attempt === -1)
        {
            // Get amount of attempts
            $totalAttempts = $this->conn->hGet($this->key_prefix . $taskId, 'taskOutputAttempts');
            $output = [];
            for ($i=1;$i<=$totalAttempts;$i++)
            {
                // Check if this output exists
                if (!$this->conn->hExists($this->key_prefix . $taskId, 'output' . $i))
                    $output[] = null;

                // Load and convert the data
                $data = $this->conn->hGet($this->key_prefix . $taskId, 'output' . $i);
                $data = unserialize($data);

                $output[] = ['output' => $data['output'], 'errors' => $data['errors'], 'statusCode' => $data['statusCode']];
            }

            if (!empty($output))
                return $output;
        }
        // If a specific one is requested, fetch that one
        else
        {
            // Check if this output exists
            if (!$this->conn->hExists($this->key_prefix . $taskId, 'output' . $attempt))
                return null;

            // Load and convert the data
            $data = $this->conn->hGet($this->key_prefix . $taskId, 'output' . $attempt);
            $data = unserialize($data);

            return ['output' => $data['output'], 'errors' => $data['errors'], 'statusCode' => $data['statusCode']];
        }

        return null;
    }

    /**
     * @inheritDoc
     */
    public function readPostOutput(Task $task, int $attempt = 0): ?array
    {
        // First get the task ID
        $taskId = $task->getId();

        // If a nothing in particular is requested, fetch the latest and select that as the attempt
        if ($attempt === 0)
            $attempt = $this->conn->hGet($this->key_prefix . $taskId, 'taskPostAttempts');

        // If -1 is requested, fetch all
        if ($attempt === -1)
        {
            // Get amount of attempts
            $totalAttempts = $this->conn->hGet($this->key_prefix . $taskId, 'taskPostAttempts');
            $output = [];
            for ($i=1;$i<=$totalAttempts;$i++)
            {
                // Check if this output exists
                if (!$this->conn->hExists($this->key_prefix . $taskId, 'postOutput' . $i))
                    $output[] = null;

                // Load and convert the data
                $data = $this->conn->hGet($this->key_prefix . $taskId, 'postOutput' . $i);
                $data = unserialize($data);

                $output[] = ['output' => $data['output'], 'errors' => $data['errors'], 'statusCode' => $data['statusCode']];
            }

            if (!empty($output))
                return $output;
        }
        // If a specific one is requested, fetch that one
        else
        {
            // Check if this output exists
            if (!$this->conn->hExists($this->key_prefix . $taskId, 'postOutput' . $attempt))
                return null;

            // Load and convert the data
            $data = $this->conn->hGet($this->key_prefix . $taskId, 'postOutput' . $attempt);
            $data = unserialize($data);

            return ['output' => $data['output'], 'errors' => $data['errors'], 'statusCode' => $data['statusCode']];
        }

        return null;
    }

    /**
     * @inheritDoc
     */
    public function reset(): bool
    {
        // Clear the current db
        return $this->conn->flushDB();
    }
}