<?php
/**
 * Created by PhpStorm.
 * User: crose
 * Date: 3/13/17
 * Time: 9:29 PM
 */

namespace qfq;

use qfq;

require_once(__DIR__ . '/../store/Session.php');
require_once(__DIR__ . '/../Constants.php');
require_once(__DIR__ . '/../database/Database.php');
require_once(__DIR__ . '/../../qfq/store/Client.php');
require_once(__DIR__ . '/../exceptions/UserFormException.php');

/**
 * Class Dirty
 * Process Record locking in mode DIRTY_MODE_ADVISORY, DIRTY_MODE_EXCLUSIVE or DIRTY_MODE_NONE.
 * Two entry points: process() and checkDirtyAndRelease().
 * Check doc/diagram/*.png for detailed workflow.
 *
 * @package qfq
 */
class Dirty {

    /**
     * @var Database instantiated class
     */
    protected $db = null;

    /**
     * @var array
     */
    protected $client = array();

    /**
     * @var Session
     */
    private $session = null;

    /**
     * Init class
     */
    public function __construct($phpUnit = false) {

        $this->session = Session::getInstance($phpUnit);
        $this->client = Client::getParam();
        if (!isset($this->client[DIRTY_RECORD_HASH_MD5])) {
            $this->client[DIRTY_RECORD_HASH_MD5] = '';
        }
        $this->db = new Database();
    }

    /**
     * Handle any lock requests submitted via api/dirty.php.
     *
     * @return array|int
     * @throws CodeException
     * @throws DbException
     * @throws UserFormException
     */
    public function process() {
        $tableVars = array();

        $sipClass = new Sip();

        $sipVars = $sipClass->getVarsFromSip($this->client[SIP_SIP]);

        if (empty($sipVars[SIP_FORM])) {
            throw new CodeException("Missing 'form' in SIP. There might be something broken.", ERROR_DIRTY_MISSING_FORM_IN_SIP);
        }

        $recordId = empty($sipVars[SIP_RECORD_ID]) ? 0 : $sipVars[SIP_RECORD_ID];
        if ($recordId == 0) {
            // For r=0 (new) , 'dirty' will always succeed.
            return [API_STATUS => 'success', API_MESSAGE => ''];
        } else {
            $tableVars = $this->db->sql("SELECT tableName, dirtyMode, recordLockTimeoutSeconds FROM Form AS f WHERE f.name=?", ROW_EXPECT_1, [$sipVars[SIP_FORM]], "Form not found: '" . $sipVars[SIP_FORM] . "'");
        }

        switch ($this->client[API_LOCK_ACTION]) {
            case API_LOCK_ACTION_LOCK:
            case API_LOCK_ACTION_EXTEND:
                $answer = $this->acquireDirty($recordId, $tableVars, $this->client[DIRTY_RECORD_HASH_MD5]);
                break;
            case API_LOCK_ACTION_RELEASE:
                $answer = $this->checkDirtyAndRelease(FORM_SAVE, $tableVars[F_RECORD_LOCK_TIMEOUT_SECONDS], $tableVars[F_DIRTY_MODE], $tableVars[F_TABLE_NAME], $recordId);
                break;
            default;
                throw new CodeException("Unknown action: " . $this->client[API_LOCK_ACTION], ERROR_DIRTY_UNKNOWN_ACTION);
        }

        return $answer;
    }

    /**
     * Tries to get a 'DirtyRecord'. Returns an array (becomes JSON) about success or failure.
     *
     * @param int    $recordId
     * @param array  $tableVars
     * @param string $recordHashMd5
     * @return array
     * @throws \qfq\CodeException
     */
    private function acquireDirty($recordId, array $tableVars, $recordHashMd5) {

        $tableName = $tableVars[F_TABLE_NAME];
        $formDirtyMode = $tableVars[F_DIRTY_MODE];
        $rcMd5 = '';

        // Check for changed record. Compute $rcMd5
        $flagModified = $this->isRecordModified($tableName, $recordId, $recordHashMd5, $rcMd5);
        if (($recordHashMd5 != '') && $flagModified) {
            return [API_STATUS => API_ANSWER_STATUS_CONFLICT, API_MESSAGE => 'The record has been modified in the meantime. Please reload the form, edit and save again.'];
        }

        $feUser = $this->session->get(SESSION_FE_USER);

        // Look for already existing dirty record.
        $recordDirty = $this->getRecordDirty($tableName, $recordId);

        // Check if the record is timed out - owner doesn't matter.
        if (count($recordDirty) != 0 && $recordDirty[DIRTY_EXPIRE] < date('Y-m-d H:i:s')) {
            $this->deleteDirtyRecord($recordDirty[COLUMN_ID]);
            $recordDirty = array();
        }

        if (count($recordDirty) == 0) {
            if ($formDirtyMode == DIRTY_MODE_NONE) {
                $answer = [API_STATUS => 'success', API_MESSAGE => ''];
            } else {
                // No dirty record found.
                $answer = $this->writeDirty($this->client[SIP_SIP], $recordId, $tableVars, $feUser, $rcMd5);
            }
        } else {
            $answer = $this->conflict($recordDirty, $formDirtyMode);
        }

        return $answer;
    }

    /**
     * Load (if exist) a DirtyRecord (lock).
     *
     * @param string $tableName
     * @param int    $recordId
     * @return array   DirtyRecord or empty array.
     * @throws CodeException
     * @throws DbException
     */
    private function getRecordDirty($tableName, $recordId) {

        $recordDirty = $this->db->sql("SELECT * FROM Dirty AS d WHERE d.tableName LIKE ? AND recordId=? ",
            ROW_EXPECT_0_1, [$tableName, $recordId]);

        return $recordDirty;
    }

    /**
     *
     * @param array  $recordDirty
     * @param string $currentFormDirtyMode
     * @return array
     */
    private function conflict(array $recordDirty, $currentFormDirtyMode) {
        $status = API_ANSWER_STATUS_CONFLICT;
        $at = "at " . $recordDirty[COLUMN_CREATED] . " from " . $recordDirty[DIRTY_REMOTE_ADDRESS];

        // Compare modified timestamp
        if ($this->isRecordModified($recordDirty[DIRTY_TABLE_NAME], $recordDirty[DIRTY_RECORD_ID], $recordDirty[DIRTY_RECORD_HASH_MD5], $dummy)) {
            return [API_STATUS => API_ANSWER_STATUS_CONFLICT, API_MESSAGE => 'The record has been modified in the meantime. Please reload the form, edit and save again.'];
        }

        if ($this->client[CLIENT_COOKIE_QFQ] == $recordDirty[DIRTY_QFQ_USER_SESSION_COOKIE]) {
            $msg = "The record has already been locked by you (maybe in another browser tab) $at!";
            $status = ($recordDirty[F_DIRTY_MODE] == DIRTY_MODE_EXCLUSIVE) ? API_ANSWER_STATUS_CONFLICT : API_ANSWER_STATUS_CONFLICT_ALLOW_FORCE;

        } else {

            if (empty($recordDirty[DIRTY_FE_USER])) {
                $msgUser = "another user";
            } else {
                $msgUser = "user '$recordDirty[DIRTY_FE_USER]'";
            }

            $msg = "The record has already been locked by $msgUser at $at.";

            // Mandatory lock on Record or current Form?
            if ($recordDirty[F_DIRTY_MODE] == DIRTY_MODE_EXCLUSIVE || $currentFormDirtyMode == DIRTY_MODE_EXCLUSIVE) {
                $status = API_ANSWER_STATUS_CONFLICT;
            } else {
                $status = API_ANSWER_STATUS_CONFLICT_ALLOW_FORCE;
            }
        }

        return [API_STATUS => $status, API_MESSAGE => $msg];
    }

    /**
     * Write a 'Dirty'-Record.
     *
     * @param string $s SIP given by URL GET
     * @param int    $recordId extracted from SIP
     * @param array  $tableVars columns: F_TABLE_NAME, F_DIRTY_MODE, F_RECORD_LOCK_TIMEOUT_SECONDS
     * @param string $feUser
     * @param string $recordHashMd5
     * @return array
     * @throws \qfq\CodeException
     * @throws \qfq\DbException
     */
    private function writeDirty($s, $recordId, array $tableVars, $feUser, $recordHashMd5) {

        $tableName = $tableVars[F_TABLE_NAME];
        $formDirtyMode = $tableVars[F_DIRTY_MODE];

        $record = $this->db->sql("SELECT * FROM $tableName WHERE id=?", ROW_EXPECT_1, [$recordId], "Record to lock not found.");

        $expire = date('Y-m-d H:i:s', strtotime("+" . $tableVars[F_RECORD_LOCK_TIMEOUT_SECONDS] . " seconds"));
        // Write 'dirty' record
        $this->db->sql("INSERT INTO Dirty (`sip`, `tableName`, `recordId`, `expire`, `recordHashMd5`, `feUser`, `qfqUserSessionCookie`, `dirtyMode`, `remoteAddress`, `created`) " .
            "VALUES ( ?,?,?,?,?,?,?,?,?,? )", ROW_REGULAR,
            [$s, $tableName, $recordId, $expire, $recordHashMd5, $feUser, $this->client[CLIENT_COOKIE_QFQ], $formDirtyMode,
                $this->client[CLIENT_REMOTE_ADDRESS], date('YmdHis')]);

        return [API_STATUS => API_ANSWER_STATUS_SUCCESS, API_MESSAGE => '',
            API_LOCK_TIMEOUT => $tableVars[F_RECORD_LOCK_TIMEOUT_SECONDS]];

    }

    /**
     * Get MD5 from tableName/recordId and compare with $recordHashMd5.
     *
     * @param string $tableName
     * @param int    $recordId
     * @param string $recordHashMd5 - timestamp e.g. '2017-07-27 14:06:56'
     * @return bool true if $recordHashMd5 is different from current record md5 hash.
     * @throws CodeException
     * @throws DbException
     */
    private function isRecordModified($tableName, $recordId, $recordHashMd5, &$rcMd5) {

        if($recordHashMd5 =='') {
            return false; // If there is no recordHashMd5, the check is not possible. Always return 'not modified' (=ok)
        }

        $record = $this->db->sql("SELECT * FROM $tableName WHERE id=?", ROW_EXPECT_1, [$recordId], "Record to lock not found.");

        $rcMd5 = OnArray::getMd5($record);

        return ($recordHashMd5 != $rcMd5);
    }

    /**
     * Check if a lock exist for the current table, recordId and session.
     *
     * @param string $tableName
     * @param int    $recordId
     * @param array  $recordDirty - return dirty record if one exist.
     * @param string $msg - return preformatted message in case of conflict
     * @return int LOCK_NOT_FOUND | LOCK_FOUND_OWNER | LOCK_FOUND_CONFLICT,
     */
    public function getCheckDirty($tableName, $recordId, array &$recordDirty, &$msg) {

        $msg = '';

        if ($recordId == 0) {
            return LOCK_NOT_FOUND; // New records never have a recordDirty nor a conflict.
        }

        $recordDirty = $this->getRecordDirty($tableName, $recordId);

        if (empty($recordDirty)) {
            return LOCK_NOT_FOUND;
        }

        if ($recordDirty[DIRTY_QFQ_USER_SESSION_COOKIE] == $this->client[CLIENT_COOKIE_QFQ]) {
            $msgUser = "you";
        } else {
            $msgUser = (empty($recordDirty[DIRTY_FE_USER])) ? "another user" : "user '$recordDirty[DIRTY_FE_USER]'";
        }
        $msgAt = "at " . $recordDirty[COLUMN_CREATED] . " from " . $recordDirty[DIRTY_REMOTE_ADDRESS];
        $msg = "The record has been locked by $msgUser $msgAt";

        // Is the dirtyRecord mine?
        if ($recordDirty[DIRTY_QFQ_USER_SESSION_COOKIE] == $this->client[CLIENT_COOKIE_QFQ]) {
            return LOCK_FOUND_OWNER;
        } else {
            return LOCK_FOUND_CONFLICT;
        }
    }

    /**
     * Release a dirtyRecord. This is only possible if the current user owns the dirtyRecord.
     * In case of not owner, throws an exception and the save should break.
     *
     * @param string $formMode FORM_DELETE, FORM_SAVE
     * @param int    $lockTimeout
     * @param string $dirtyMode DIRTY_MODE_EXCLUSIVE, DIRTY_MODE_ADVISORY, DIRTY_MODE_NONE
     * @param string $tableName
     * @param int    $recordId
     * @return array
     * @throws \qfq\CodeException
     * @throws \qfq\UserFormException
     */
    public function checkDirtyAndRelease($formMode, $lockTimeout, $dirtyMode, $tableName, $recordId, $flagCheckModifiedFirst = false) {

        $rcRecordDirty = array();
        $rcMsg = '';

        $answer = [API_STATUS => API_ANSWER_STATUS_SUCCESS, API_MESSAGE => ''];

        if ($recordId == 0) {
            return $answer; // New records never have a recordDirty nor a conflict.
        }

        // Check if the record has changed in the meantime.
        if ($flagCheckModifiedFirst && $this->isRecordModified($tableName, $recordId, $this->client[DIRTY_RECORD_HASH_MD5], $dummy)) {
            throw new UserFormException ('The record has been modified in the meantime. Please reload the form, edit and save again.', ERROR_DIRTY_RECORD_MODIFIED);
//            return [API_STATUS => API_ANSWER_STATUS_CONFLICT, API_MESSAGE => 'The record has been modified in the meantime. Please reload the form, edit and save again.'];
        }

        $lockStatus = $this->getCheckDirty($tableName, $recordId, $rcRecordDirty, $rcMsg);

        if (empty($rcRecordDirty)) {
            if ($dirtyMode == DIRTY_MODE_NONE) {
                return $answer; // only situation where it's ok that there is no dirtyRecord.
            }
            if ($formMode == FORM_DELETE) {
                return $answer;
            }

            // This is pessimistic, but secure.
            throw new UserFormException("Missing record lock: please reload the form, edit and save again.", ERROR_DIRTY_MISSING_LOCK);
        }

        if ($formMode == FORM_DELETE) {
            // Check if the record is timed out
            if ($lockTimeout > 0 && $rcRecordDirty[DIRTY_EXPIRE] < date('Y-m-d H:i:s')) {
                $this->deleteDirtyRecord($rcRecordDirty[COLUMN_ID]);

                return $answer;
            }

            $answer = [API_STATUS => API_ANSWER_STATUS_CONFLICT, API_MESSAGE => $rcMsg];
            return $answer;
        }

        // Is the dirtyRecord mine?
        if ($lockStatus == LOCK_FOUND_OWNER) {
            // Check if the record has changed in the meantime.
            if ($this->isRecordModified($tableName, $recordId, $rcRecordDirty[DIRTY_RECORD_HASH_MD5], $dummy)) {
                return [API_STATUS => API_ANSWER_STATUS_CONFLICT, API_MESSAGE => 'The record has been modified in the meantime. Please reload the form, edit and save again.'];
            }

            // Clear the lock
            $this->deleteDirtyRecord($rcRecordDirty[COLUMN_ID]);
            return $answer;
        }

        //----------------------------------------
        // From here: there is a foreign lock!

        // Check if overwrite is allowed
        if ($dirtyMode == DIRTY_MODE_ADVISORY && $rcRecordDirty[F_DIRTY_MODE] == DIRTY_MODE_ADVISORY) {
            return $answer;
        }

        // Check if the record is timed out
        if ($lockTimeout > 0 && $rcRecordDirty[DIRTY_EXPIRE] < date('Y-m-d H:i:s')) {
            $this->deleteDirtyRecord($rcRecordDirty[COLUMN_ID]);
            return $answer;
        }

        throw new UserFormException($rcMsg, ERROR_DIRTY_ALREADY_LOCKED);
    }

    /**
     * Delete the dirtyRecord with $recordDirtyId. Throw an exception if the record has not been deleted.
     *
     * @param int $recordDirtyId
     * @throws CodeException
     * @throws DbException
     */
    private function deleteDirtyRecord($recordDirtyId) {

        $cnt = $this->db->sql('DELETE FROM Dirty WHERE id=? LIMIT 1', ROW_REGULAR, [$recordDirtyId]);
        if ($cnt != 1) {
            throw new CodeException("Failed to delete dirty record id=" . $recordDirtyId, ERROR_DIRTY_DELETE_RECORD);
        }
    }
}