<?php

/**
 * some assumptions to make:
 *
 * -- that this class will be invoked via the gacFactory class
 * -- that the gacFactory class will pre-validate the data template as being for the Ddb schema
 *
 */
class gacDdb extends gaaNamasteCore
{
    private $globalIndexes      = null;
    private $localIndexes       = null;
    protected $service;                                     // defines the end-point service


    /**
     * gacDdb constructor.
     *
     * the constructor for this class requires two input parameters:
     *
     * $_meta -- the meta data payload (has been vetted by the factory class)
     * $_guid -- an optional string containing a guid value -- if this is specified, then we're telling the class
     *           to instantiate the class with the designated record pre-loaded.
     *
     * We're going to initialize with some housekeeping chores - like loading up the configuration, initializing
     * a connection to the DDB resource via the resource manager, and then loading the template.
     *
     * if we passed a guid into the method, validate the guid
     *     if cache is enabled, check to see if the record is cached and, if so, load it
     *     if the $data property is still null, call the method to load the record
     *         note that the state/status of the class will be set here
     *
     * return control to the calling client
     *
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * @param array $_meta
     * @param string $_guid
     *
     * HISTORY:
     * ========
     * 06-21-17     mks     original coding
     *
     */
    public function __construct(array $_meta, string $_guid = '')
    {
        // set-up
        register_shutdown_function([$this, STRING_DESTRUCTOR]);
        $this->status = false;

        parent::__construct();

        // load config
        $this->config = gasConfig::$settings[CONFIG_DATABASE][CONFIG_DATABASE_DDB];
        if (empty($this->config)) {
            $this->logger->fatal(ERROR_CONFIG_RESOURCE_404 . CONFIG_DATABASE . COLON . CONFIG_DATABASE_DDB);
            $this->state = STATE_FRAMEWORK_FAIL;
            return;
        }

        // set the class properties based off the template settings for the data
        $this->templateName = STRING_CLASS_GAT . $_meta[META_TEMPLATE];
        if (!$this->loadTemplate()) {
            $this->logger->warn(ERROR_TEMPLATE_INSTANTIATE . $_meta[META_TEMPLATE]);
            $this->state = STATE_TEMPLATE_ERROR;
            return;
        }
        $this->class = $_meta[META_TEMPLATE];  // set the class to the name of the requested data class

        // get the http resource for connecting to DynamoDB instance
        if (gasResourceManager::$ddbAvailable and is_null($this->connection)) {
            $this->connection = gasResourceManager::fetchResource(RESOURCE_DDB);
            if (!is_object($this->connection)) {
                $this->logger->fatal(ERROR_RESOURCE_DDB_404);
                $this->setState(STATE_DB_ERROR);
                return;
            }
        }

        // store meta data and client identifier
        $this->client = STRING_UNDEFINED;       // todo:  why?
        if (!empty($_meta)) {
            $this->metaPayload = $_meta;
            if (isset($this->metaPayload[META_CLIENT])) {
                $this->client = $this->metaPayload[META_CLIENT];
            }
        }

        // store the event GUID
        if (isset($this->metaPayload[META_EVENT_GUID])) {
            $this->eventGUID = $this->metaPayload[META_EVENT_GUID];
        } else {
            $this->logger->warn(ERROR_EVENT_GUID_404);
        }

        // if a GUID/key was passed to the constructor, we need to fetch that record from the db
        // NOTE:  mBEDS code has connecting-to-remote-service (vault) code in this block
        $this->data = null;                                                     // reset the data container
        if (!empty($_guid) and validateGUID($_guid)) {                          // if we have a valid guid...
            if ($this->useCache and gasResourceManager::$cacheAvailable) {      // if cache is on and available
                $this->data = gasCache::get($_guid);                            // search cache for the key
                if (!is_null($this->data)) {
                    $this->data = json_decode(gzuncompress($this->data), true);
                }
            }
            if (is_null($this->data)) {
                $this->guidFetch($_guid);
            }
        } else {
            $this->state = STATE_SUCCESS;
            $this->status = true;
        }
    }


    protected function _createRecord($_data)
    {

    }

    protected function _fetchRecords($_dd, $_rd = null, $_co = true, $_skip = 0, $_limit = 0, $_sort = null)
    {

    }

    protected function _updateRecord($_data){

    }

    protected function _deleteRecord($_data)
    {

    }

    protected function _lockRecord()
    {

    }

    protected function _releaseLock()
    {

    }

    protected function _isLocked()
    {

    }


    /**
     * guidFetch() -- private method
     *
     * this method is (should only be) called from the class constructor and only then if the calling client passes
     * a guid into the constructor - which the framework interprets as a request to instantiate and populate with the
     * record designated by the guid - which is the primary key for the ddb table.
     *
     * The required input parameter is the guid for the record.  Validation (that this is a guid) happens in the
     * constructor or the calling client.
     *
     * First, we build the table name from the current environment and then build the query.  The query is just a
     * key-value-pair fetch but converts into something overly-complicated once we phrase it in ddb syntax.  Just
     * for logging and general readability, we sql-ize the ddb-query and store the string in the designated property.
     *
     * If the class is using timers, start the timer
     * Execute the query - which returns an iterator and not a data set
     * Log the timer results to the metrics table
     * parse the return data set and assign it to the $data property
     *
     * We exception-wrap the query so we'll return the error as to why the query failed and will log accordingly.
     *
     * Next, if cache is enabled for the current class, cache the item after converting the data set to a json
     * string.
     *
     * At all levels, set the state-status values accordingly - these are what should be evaluated by the calling
     * client on return from the method.
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * @param string $_guid
     *
     * HISTORY:
     * ========
     * 06-21-17     mks     original coding
     *
     */
    private function guidFetch(string $_guid)
    {
        if ($this->trace) $this->logger->trace(STRING_ENT_METH . __METHOD__);
        $this->status = false;
        $startTime = floatval(0);
        $tableName = gasConfig::$settings[CONFIG_ID][CONFIG_ID_ENV] . UDASH . $this->collectionName . $this->ext;
        $query = [
            DDB_STRING_CONSISTENT_READ => true,
            DDB_TABLE_NAME =>  $tableName,
            DDB_STRING_EXPR_ATTR_VALS => [
                ':q1' => [
                    $this->fieldTypes[$this->pKey . $this->ext] => $_guid
                ]
            ],
            DDB_STRING_KEY_COND_EXPR => "$this->pKey$this->ext = :q1"
        ];
        /** @noinspection SqlNoDataSourceInspection */
        $this->strQuery = 'DDB:SELECT * FROM ' . $tableName . ' WHERE id' . $this->ext . ' = "' . $_guid . '"';

        // todo - this was coded to see if it worked - next, build a query request array and pass to queryBuilder() and _fetchRecords()
        // exec the DDB query
        try {
            if ($this->useTimers) $startTime = gasStatic::doingTime();
            /** @var AWS\Result $result */
            /** @noinspection PhpUndefinedMethodInspection */
            $result = $this->connection->query($query);
            if ($this->useTimers) $this->logger->metrics($this->strQuery, gasStatic::doingTime($startTime));
            if ($result[DDB_STRING_COUNT] != 1) {
                $msg = sprintf(ERROR_DDB_RECORD_COUNT, count($result), 1);
                $this->eventMessages[] = $msg;
                $this->logger->error($msg);
                return;
            }
            // parse the return data set
            /** @var array $resultData */
            $resultData = $result[DDB_STRING_ITEMS];
            foreach ($resultData as $item) {
                $record = null;
                foreach ($item as $key => $value)
                    foreach ($value as $type => $column)
                        $record[$key] = $column;
                $this->data[] = $record;
            }
        } catch (\Aws\Exception\AwsException $e) {
            $this->eventMessages[] = $e->getMessage();
            $this->logger->error($e->getMessage());
            $this->state = STATE_DB_ERROR;
            return;
        }

        // cache the item if cache is enabled for the current class
        if ($this->useCache and !empty($this->data)) {
            $cacheData = json_encode($this->data);
            if (is_null(gasCache::add($this->getColumn($this->pKey), $cacheData))) {
                $msg = ERROR_CACHE_ADD_FAIL . $this->getColumn($this->pKey);
                $this->eventMessages[] = $msg;
                $this->logger->error($msg);
                $this->state = STATE_CACHE_ERROR;
                return;
            }
        }
        $this->event = DB_EVENT_FETCH;
        $this->status = true;
        $this->state = STATE_SUCCESS;
    }


    private function queryBuilder(array $_query)
    {
        if ($this->trace) $this->logger->trace(STRING_ENT_METH . __METHOD__);
        $this->status = false;
        $foundIndex = false;
        $attribute = '';

        if (!is_array($_query) or empty($_query)) {         // '[]' tests true for is_array
            $msg = ERROR_PARAM_404 . DDB_STRING_QUERY;
            $this->eventMessages[] = $msg;
            $this->logger->error($msg);
            $this->state = STATE_DATA_ERROR;
            return;
        }
        // deal with a single-key query
        if (count($_query) == 1) {
            // extract the key value pair
            foreach ($_query as $k1 => $v1) {                   // attribute level
                $attribute = $k1;
                foreach ($v1 as $k2 => $v2) {                   // operand level
                    foreach ($v2 as $k3 => $v3) {               // operator level
                        // check that the operand is '='
                        if ($k3 != OPERATOR_DDB_EQ) {
                            $this->eventMessages[] = ERROR_DDB_EXP_EQ_Q1;
                            $this->logger->data(ERROR_DDB_EXP_EQ_Q1);
                            $this->state = STATE_DATA_ERROR;
                            return;
                        }
                        if (count($v3) != 1) {
                            $this->eventMessages[] = ERROR_DDB_EXP_VAL_Q1;
                            $this->logger->data(ERROR_DDB_EXP_VAL_Q1);
                            $this->state = STATE_DATA_ERROR;
                            return;
                        }
                        $value = $v3[0];        // grab the search value
                    }
                }
            }
            // we have extracted the search key attribute and the search value...need to find it in one of
            // the three possible index declarations for the current table  (VALIDATE THE INDEX ATTRIBUTE)
            if (array_key_exists($attribute, $this->indexes) and $this->indexes[$attribute] == DDB_INDEX_HASH) {
                $foundIndex = 'base';
            } else {
                $ca = ['globalIndexes', 'localIndexes'];
                foreach ($ca as $index) {
                    if (is_array($this->$index)) {
                        foreach ($this->$index as $subIndex) {
                            if (array_key_exists($attribute, $subIndex) and $subIndex[$attribute] == DDB_INDEX_HASH) {
                                $foundIndex = true;
                                break;
                            }
                        }
                    }
                    if ($foundIndex) break;
                }
            }
//                if (is_array($this->globalIndexes)) {
//                    foreach ($this->globalIndexes as $gIndex) {
//                        if (array_key_exists($attribute, $gIndex)  and $gIndex[$attribute] == DDB_INDEX_HASH) {
//                            $foundIndex = true;
//                        }
//                    }
//                }
//                if (!$foundIndex and is_array($this->localIndexes)) {
//                    foreach ($this->localIndexes as $lIndex) {
//                        if (array_key_exists($attribute, $lIndex) and $lIndex[$attribute] == DDB_INDEX_HASH) {
//                            $foundIndex = true;
//                        }
//                    }
//                }
//            }
            if (!$foundIndex) {
                $msg = sprintf(ERROR_DDB_NO_HASH_IDX, $attribute);
                $this->eventMessages[] = $msg;
                $this->logger->data($msg);
                $this->state = STATE_DATA_ERROR;
                return;
            }
        } elseif (count($_query) == 1) {
            // todo: query uses the hash and the range

        } else {
            // todo -- malformed request

        }
    }


    /**
     * loadTemplate() -- private method
     *
     * this method is invoked by the constructor and serves to load the class template file, assimilating it into
     * the current instantiation.
     *
     * template loads are done on the schema-instantiation level, instead of the core, because of the changes in
     * the template file(s) across various schemas.
     *
     * the method will load the class template and set the class member variables controlled/referenced by the
     * template.
     *
     * successful loading of the template is determined by the return (boolean) value -- on error, a log message
     * will be generated so it's up to the developer to check logs on fail-returns to see why their template
     * file was not correctly assimilated.
     *
     * The template to be loaded is first derived in the constructor (post validation that the template file
     * exists) and is pulled from the member variable (also set in the constructor) within this method.
     *
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * @return bool
     *
     * HISTORY:
     * ========
     * 06-20-17     mks     original coding
     *
     */
    private function loadTemplate():bool
    {
        if ($this->trace) $this->logger->trace(STRING_ENT_METH . __METHOD__);

        try {
            $this->template = new $this->templateName();
        } catch (Exception $e) {
            $this->logger->warn($e->getMessage());
            $this->state = STATE_FRAMEWORK_FAIL;
            return (false);
        }

        if (!is_object($this->template)) {
            $this->logger->warn(ERROR_FILE_404 . $this->templateName);
            $this->setState(ERROR_FILE_404 . $this->templateName);
            return (false);
        }

        if ($this->template->schema != TEMPLATE_DB_DDB) {
            $this->logger->warn(ERROR_SCHEMA_MISMATCH . $this->template->schema . ERROR_STUB_EXPECTING . TEMPLATE_DB_DDB);
            $this->setState(ERROR_SCHEMA_MISMATCH . $this->templateName);
            return (false);
        }

        // transfer meta data info to current instantiation
        $this->service = $this->template->service;
        $this->schema = $this->template->schema;
        $this->collectionName = $this->template->collection;
        $this->ext = $this->template->extension;
        $this->useCache = $this->template->setCache;
        $this->useDeletes = $this->template->setDeletes;
        $this->useAuditing = $this->template->setAuditing;
        $this->useJournaling = $this->template->setJournaling;
        $this->allowUpdates = $this->template->setUpdates;
        $this->useDetailedHistory = $this->template->setHistory;
        $this->defaultStatus = $this->template->setDefaultStatus;
        $this->searchStatus = $this->template->setSearchStatus;
        $this->useLocking = $this->template->setLocking;
        $this->useTimers = ($this->template->setTimers and gasConfig::$settings[CONFIG_DATABASE][CONFIG_DATABASE_QUERY_TIMERS]);
        $this->pKey = $this->template->setPKey;
        $this->useToken = $this->template->setTokens;
        $this->cacheExpiry = $this->template->cacheTimer;

        if (isset($this->template->fields) and is_array($this->template->fields)) {
            foreach ($this->template->fields as $key => $value) {
                if ($key == DB_HISTORY) {
                    $this->fieldList[] = $key;
                    $this->fieldTypes[$key] = $value;
                } else {
                    $this->fieldList[] = ($key . $this->ext);
                    $this->fieldTypes[($key . $this->ext)] = $value;
                }
            }
        }

        if (isset($this->template->indexes) and is_array($this->template->indexes)) {
            foreach ($this->template->indexes as $key => $value) {
                $this->indexes[] = ($key . $this->ext);
            }
        }

        // todo:  validate the global index data
        if (isset($this->template->globalIndexes) and is_array($this->template->globalIndexes)) {
            foreach ($this->template->globalIndexes as $key ) {
                $this->globalIndexes[] = $key;
            }
        }

        // todo:  validate the local index data
        if (isset($this->template->localIndexes) and is_array($this->template->localIndexes)) {
            foreach ($this->template->localIndexes as $key) {
                $this->localIndexes[] = $key;
            }
        }

        if (!is_null($this->template->cacheMap)) {
            foreach ($this->template->cacheMap as $key => $value) {
                $this->cacheMap[($key . $this->ext)] = $value;
            }
        } else {
            $this->cacheMap = null;
        }

        if (!is_null($this->template->binFields)) {
            foreach ($this->template->binFields as $key) {
                $this->binaryFields[] = ($key . $this->ext);
            }
        }

        if ($this->template->selfDestruct) {
            unset($this->template);
        }
        return (true);
    }


    /**
     * __destruct() -- public function
     *
     * class destructor
     *
     * @author  mike@givingassistant.org
     * @version 1.0
     *
     * HISTORY:
     * ========
     * 06-20-17     mks     original coding
     *
     */
    public function __destruct()
    {
        // As of PHP 5.3.10 destructors are not run on shutdown caused by fatal errors.
        //
        // destructor is registered shut-down function in constructor -- so any recovery
        // efforts should go in this method.

        // there is no destructor method defined in the core abstraction class, hence
        // there is no call to that parent destructor in this class.
        parent::__destruct();
    }

}