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baseContentManagementContract.sol

pragma solidity ^0.4.24;

import "./sharedTypes.sol";
import "./catalogSmartContract.sol";


contract BaseContentManagementContract {

    // Enum that describe type of access which an user has
    enum AccessType {noneAccess, standardAccess, premiumAccess}
    
    // Struct that indentifies a user who was granted to consume current content
    struct GrantedUser {
        address userAddress;
        AccessType accessType;
        bool toBeConsumed;
        bool exists;
        bool [3] givenFeedbacks;        // Stores information about given feedback for each category
    }
    
    /* Variables to store feedbacks from users: each user has a unique position in each array. feedbacksSums stores sum of all given feedbacks
     * and feedbacksCount stores number of given feedbacks for each category (A user may or not rate a content for a category) */
    uint[3] feedbacksSums;      // contentAppreciation, priceFairness, availabilityTime
    uint8[3] feedbacksCount;    // Number of feedbacks given for each category

    address private catalogAddress;                     // Address of catalog to check if determined functions are called only by catalog
    SharedTypes.contentType private typeOfContent;      // Tpe of content which this contract contains
    
    bytes32 private contentTitle;                       // Title which identifies this contract in catalog
    uint private numberOfViews;                         // Number of viwes about content of this contract
    
    mapping (bytes32 => GrantedUser) allowedUsers;      // Map of users that are allowed to access this content

    
    
    constructor (SharedTypes.contentType _conType, bytes32 _conTitle, address _catalogAddr) public {
        typeOfContent   = _conType;
        numberOfViews   = 0;
        contentTitle    = _conTitle;
        catalogAddress  = _catalogAddr;
        
        feedbacksSums[0]    = 0;
        feedbacksSums[1]    = 0;
        feedbacksSums[2]    = 0;
        feedbacksCount[0]   = 0;
        feedbacksCount[1]   = 0;
        feedbacksCount[2]   = 0;
    }
    
    
    
    // *****           ***** //
    // ***** Modifiers ***** //
    
    modifier onlyCatalog () {
        require (msg.sender == catalogAddress);
        _;
    }
    
    modifier isAllowedUser (bytes32 _username, address _senderAddress) {
        bool exists= allowedUsers[_username].exists;
        bool correspondAddress= allowedUsers[_username].userAddress == _senderAddress;
        require (exists && correspondAddress);
        _;
    }
    
    modifier notToBeConsumedBy (bytes32 _username) {
        require (allowedUsers[_username].accessType == AccessType.noneAccess);
        _;
    }
    
    modifier toBeConsumedBy (bytes32 _username) {
        //require (allowedUsers[_username].toBeConsumed == true);
        require (allowedUsers[_username].accessType != AccessType.noneAccess);
        _;
    }
    
    modifier isCorrectRating (uint8 _val) {
        require ((_val <= 5) && (_val>0));
        _;
    }
    
    modifier isCorrectCategory (uint8 _category) {
        require ((_category<=3) && (_category>=1));
        _;
    }
    
    modifier notGivenFeedbackFor (uint8 _category, bytes32 _username) {
        require (allowedUsers[_username].givenFeedbacks[_category] == false);
        _;
    }
    
    
    
    // *****                                   ***** //
    // ***** Helper private/internal functions ***** //
    
    /* This function allows subContracts of this contract to retrieve content if and only if user
     * with addrs _userAddr is into "allowedUsers" map
     */
    function retrieveContent (bytes32 _username) internal isAllowedUser(_username, msg.sender) toBeConsumedBy (_username) {
        bool isStandard= allowedUsers[_username].accessType == AccessType.standardAccess;
        if (isStandard) {
            numberOfViews++;
            (CatalogSmartContract (catalogAddress)).notifyNewView (contentTitle, _username);
        }
    
        allowedUsers[_username].accessType      = AccessType.noneAccess;
        allowedUsers[_username].toBeConsumed    = false;
    }
    
    
    
    // *****                  ***** //
    // ***** Public functions ***** //
    
    // Function used by catalog to check that has the same address of catalogAddress local variable
    function getCatalogAddress () public view returns (address) {
        return catalogAddress;
    }
    
    function getViewsCount () public view returns (uint) {
        return numberOfViews;
    }
    
    function getTitle () public view returns (bytes32) {
        return contentTitle;
    }
    
    function getType () public view returns (SharedTypes.contentType) {
        return typeOfContent;
    }
    
    
    // This function allows (only to catalog) to grant access to a user with address _userAddr.
    function grantAccessToUser (bytes32 _username, address _userAddr, bool isPremium) public onlyCatalog () notToBeConsumedBy (_username) {
        if (allowedUsers[_username].exists == false) {
            allowedUsers[_username].exists              = true;
            allowedUsers[_username].userAddress         = _userAddr;
            allowedUsers[_username].givenFeedbacks[0]   = false;
            allowedUsers[_username].givenFeedbacks[1]   = false;
            allowedUsers[_username].givenFeedbacks[2]   = false;
        }
        
        if (isPremium)
            allowedUsers[_username].accessType= AccessType.premiumAccess;
        else
            allowedUsers[_username].accessType= AccessType.standardAccess;
        
        allowedUsers[_username].toBeConsumed = true;
    }
    
    
    // This function returns true if a user is allowed to view current content
    function isAllowed (bytes32 _username) public view returns (bool) {
        return allowedUsers[_username].accessType != AccessType.noneAccess;
    }
    
    
    
    // *****                    ***** //
    // ***** Feedback functions ***** //
    
    /* This function allows (only to allowed users) to leave a feedback of type 't' and value 'v' (1<=v<=5) for this content
     * _c:1 => first category,  _c:2 => second category,  _c:3 => third category */
    function leaveFeedback (bytes32 _username, uint8 _c, uint8 _v) public isAllowedUser(_username, msg.sender) isCorrectCategory(_c) isCorrectRating(_v) notGivenFeedbackFor(_c-1, _username) notToBeConsumedBy (_username) {
        uint8 c1= _c-1;
        
        feedbacksSums[c1]   += _v;
        feedbacksCount[c1]  +=1;
        allowedUsers[_username].givenFeedbacks[c1]= true;
    }
    
    
    
    function getFeedbacksAverages () public view returns (uint [3]) {
        uint[3] memory feeds;
        uint8 i=0;
        
        for (i=0; i<3; i++) {
            if (feedbacksCount[i] != 0)
                feeds[i] = feedbacksSums[i] / feedbacksCount[i];
            else 
                feeds[i] = 0;
        }
        
        return feeds;
    }
    
    
    function getFeedbacksCount () public view returns (uint [3]) {
        uint[3] memory feedsCount;
        uint i=0;
        
        for (i=0; i<3; i++) {
            feedsCount[i] = feedbacksCount[i];
        }
        
        return feedsCount;
    }
    
    
    
    // *****                     ***** //
    // ***** Abastract functions ***** //
    
    function consumeContent (bytes32 _username) public;
}




/* *************************************************************************************************************************************** */
/* *************************************************************************************************************************************** */
/* *************************************************************************************************************************************** */




contract SongManagementContract is BaseContentManagementContract {
    
    constructor (bytes32 _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.song, _title, _catAddr) public {
    }
    
    function consumeContent (bytes32 _username) public {
        retrieveContent (_username);
    }
}




/* ********************************************* */
/* ********************************************* */
/* ********************************************* */




contract VideoManagementContract is BaseContentManagementContract {
    constructor (bytes32 _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.video, _title, _catAddr) public {
    }
    
    function consumeContent (bytes32 _username) public {
        retrieveContent (_username);
    }
}




/* ********************************************* */
/* ********************************************* */
/* ********************************************* */




contract PhotoManagementContract is BaseContentManagementContract {
    constructor (bytes32 _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.photo, _title, _catAddr) public {
    }
    
    function consumeContent (bytes32 _username) public {
        retrieveContent (_username);
    }
}




/* ********************************************* */
/* ********************************************* */
/* ********************************************* */




contract DocumentManagementContract is BaseContentManagementContract {
    constructor (bytes32 _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.document, _title, _catAddr) public {
    }
    
    function consumeContent (bytes32 _username) public {
        retrieveContent (_username);
    }
}

catalogSmartContract.sol

pragma solidity ^0.4.24;

import "./sharedTypes.sol";
import "./ownable.sol";
import "./baseContentManagementContract.sol";


contract CatalogSmartContract is Ownable {
    
    // Event list
    event NewUser (bytes32 username, address userAddress);
    event ContentPublished (bytes32 username, bytes32 contentTitle, address contentAddress);
    event GrantedAccess (bytes32 username, address userAddress, bytes32 contentTitle, address contentAddress);
    event GrantedPremium (bytes32 username, address userAddress);
    event CatalogDied ();
    
    

    // Duration of premium account (in block height)
    uint constant PREMIUM_ACCOUNT_DURATION = 256; // ~240 blocks/hour
    
    // Cost of premium account
    uint constant PREMIUM_ACCOUNT_COST= 44000 szabo;    // ~ 20 €
    
    // Cost of each single content
    //uint constant CONTENT_COST= 6300 szabo;             // ~ 3 €
    
    // Payout for author for each content access (this value have to be minor than CONTENT_COST)
    uint constant PAYOUT_FOR_AUTHOR= 4200 szabo;        // ~ 2 €
    
    // Maximum number of views before sending payment
    uint constant MAX_VIEWS_LIMIT= 5;
    
    
    // Array of users which have are registered to service
    bytes32 [] usersArray;
    // Number of users
    uint usersCount;
    // Mapping which contains a User struct for each user that hav published or have requeested a content
    mapping (bytes32 => SharedTypes.User) usersMapping;
    // Mapping which link address to user: needed for functions like getContent
    mapping (address => bytes32) addr2User;
    
    // Mapping which contains an ExtendedContent struct for each content published on the platform (identified by a string)
    mapping (bytes32 => SharedTypes.ExtendedContent) contentsMapping;
    // Array containing addresses of contents published on the system (for loop functions)
    bytes32 [] contentsArray;
    // Number of contents (also index of next content in the array)
    uint contentsCount;
    
    
    constructor () public payable {
        contentsCount= 0;
        usersCount= 0;
    }
    
    
    
    // ************************************************************************************************************** //
    // ************************************************************************************************************** //
    // Modifiers
    
    // To check if the content "_contentTitle" is already published on catalog
    modifier alreadyPublishedM (bytes32 _contentTitle) {
        require (alreadyPublished(_contentTitle) == true);
        _;
    }
    
    // To check if the content "_contentTitle" is NOT already published on catalog
    modifier notPublished (bytes32 _contentTitle) {
        require (alreadyPublished(_contentTitle) == false);
        _;
    }
    
    // To check if no user with address "_address" was already registered
    modifier addressNotRegistered (address _address) {
        require (addr2User[_address] == "");      // Sembra funzionare
        _;
    }
    
    // To check if the user "_username" is NOT already registered on catalog
    modifier userDoesntExist (bytes32 _username) {
        require (userExists (_username) == false);
        _;
    }
    
    // To check if the user "_username" is already registered on catalog
    modifier userExistsM (bytes32 _username) {
        require (userExists(_username) == true);
        _;
    }
    
    // To check if the user "_username" has a premim account
    modifier isPremiumM (bytes32 _username) {
        require (isPremium(_username) == true);
        _;
    }
    
    // To check if "_msgValue" is equal to "_price"
    modifier equalTo (uint _msgValue, uint _price) {
        require (_msgValue == _price);
        _;
    }
    
    // To check if the user "_username" is already allowed to retreive content "_contentTitle". This function calls the "isAllowed" function on BaseContentManagementContract
    modifier userAllowed (bytes32 _username, bytes32 _contentTitle) {
        BaseContentManagementContract remoteContract= BaseContentManagementContract (contentsMapping[_contentTitle].contractAddress);
        require (remoteContract.isAllowed(_username) == true);
        _;
    }
    
    // To check corectness of category value.
    modifier isCorrectCategory (uint8 _category) {
        require ((_category<=3) && (_category>=1));
        _;
    }
    
    // To check corectness of category value. Admits also value 0 because is the value for "all categories"
    modifier isCorrectCategoryForGetRating (uint8 _category) {
        require ((_category<=3) && (_category>=0));
        _;
    }
    
    
    
    // ************************************************************************************************************** //
    // ************************************************************************************************************** //
    // Helper private functions
    
    // Function to check if a user exists or not in usersMapping
    function userExists (bytes32 _username) private view returns (bool){
       return (usersMapping[_username].exists == true);
    }

    // Function which returns wether a content is already published on the platform
    function alreadyPublished (bytes32 _conTitle) private view returns (bool) {
        return (contentsMapping[_conTitle].exists == true);
    }
    
    // Function to register a user to system ~ 125 k, ~95 k, ~95 k....
    function addUser (bytes32 _username, address _userAddr) userDoesntExist(_username) addressNotRegistered(_userAddr) userDoesntExist (_username) private {
        addr2User[_userAddr]= _username; // 20 k
        
        usersMapping[_username].userAddress= _userAddr;                         // 20 k
        usersMapping[_username].exists= true;                                   // 22 k
        
        // Following field have already correct values
        //usersMapping[_username].accType= SharedTypes.accountType.standard;
        //usersMapping[_username].expirationTime= 0;
        //usersMapping[_username].latestContent = 0x0;

        usersCount++;                                                           // 20 la prima volta, 5 poi
        usersArray.push (_username);                                            // 40 k
        
        emit NewUser (_username, _userAddr);                                    // 3 k
    }
    
    // Function to add new content with address 'contAddr' registered by user with address 'userAddr'
    function addContent (bytes32 _contentTitle, address _contentAddr, bytes32 _username, uint _price) notPublished(_contentTitle) private {
        contentsCount++;
        contentsArray.push (_contentTitle);
        
        contentsMapping[_contentTitle].exists           = true;
        contentsMapping[_contentTitle].author           = _username;
        contentsMapping[_contentTitle].contractAddress  = _contentAddr;
        contentsMapping[_contentTitle].contentPrice     = _price;
        
        usersMapping[_username].latestContent= _contentTitle;
    }
    
    // Return true if current premium account is valid
    function isPremiumValid (bytes32 _username, uint _currentBlockNumber) userExistsM(_username) private view returns (bool) {
        return (usersMapping[_username].expirationTime > _currentBlockNumber);
    }
    
    // Return the average value of feedbacks, given as parameter
    function feedbacksAverage (uint[3] feeds, uint[3] feedsCount) private pure returns (uint) {
        uint feedsSum=0;
        uint feedsCnt=0;
        uint i=0;
        
        for (i=0; i<3; i++) {
            if (feeds[i] != 0) {
                feedsSum += feeds[i];
                feedsCnt += feedsCount[i];
            }
        }
        
        if (feedsCnt != 0)
            return feedsSum / feedsCnt;
        else
            return 0;
    }
    
    // This function generalize getMostRated* operations
    function genericGetMostRated (bool _filterByAuthor, bytes32 _author, bool _filterByGenre, SharedTypes.contentType _type, uint8 _category)
                                private view isCorrectCategoryForGetRating(_category) returns (bytes32) {
        require (contentsCount > 0);
        
        uint i                  = 0;
        uint mostRatedIdx       = 0;
        uint mostRateValue      = 0;
        uint inspectedElements  = 0;
        
        for (i=0; i<contentsCount; i++) {
            BaseContentManagementContract _content  = BaseContentManagementContract (contentsMapping[contentsArray[i]].contractAddress);
            bytes32 currentAuthor                   = contentsMapping[contentsArray[i]].author;
            
            if (_filterByGenre && _content.getType() != _type)
                continue;
            if (_filterByAuthor && currentAuthor != _author)
                continue;
                
            uint[3] memory feeds        = (BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress)).getFeedbacksAverages();
            uint[3] memory feedsCount   = (BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress)).getFeedbacksCount();
            if (_category == 0) {
                // Calculating average and compare to temporary most rated
                // FIXME Add check on feedsCount > 0
                uint tmpRating  = feedbacksAverage (feeds, feedsCount);
                if (tmpRating > mostRateValue) {
                    mostRatedIdx    = i;
                    mostRateValue   = tmpRating;
                }
            }
            else {
                // FIXME Add check on feedsCount > 0
                if (feeds[_category-1] > mostRateValue) {
                    mostRatedIdx    = i;
                    mostRateValue   = feeds[_category-1];
                }
            }
            
            inspectedElements++;
        }
        
        // This instruction
        require (inspectedElements > 0);
        
        return contentsArray[mostRatedIdx];
    }
    
    
    
    // ************************************************************************************************************** //
    // ************************************************************************************************************** //
    // Public functions
    
    // Function which kills current contract. It is callable only from contract's owner
    // FIXME
    function killMe () public onlyOwner() {
        
        // First of all, it distrubutes payments amog authors
        uint i=0;
        uint sumViews= 0;
        for (i=0; i<usersCount; i++) {
            BaseContentManagementContract remoteContract= BaseContentManagementContract (usersMapping[usersArray[i]].userAddress);
            uint count= remoteContract.getViewsCount();
            
            if ((count % MAX_VIEWS_LIMIT) != 0) {
                address(remoteContract).transfer ((count % MAX_VIEWS_LIMIT) * PAYOUT_FOR_AUTHOR);
            }
            sumViews += count;
        }
        
        uint unit= address(this).balance / sumViews;
        
        // Second, equally distribute current balance to among authors
        for (i=0; i<usersCount; i++) {
            uint payment= unit * BaseContentManagementContract (usersMapping[usersArray[i]].userAddress).getViewsCount ();
            address (usersMapping[usersArray[i]].userAddress).transfer (payment);
        }
        
        emit CatalogDied ();
        
        selfdestruct (owner);
    }
    
    
    // Function that allows users to registrate themselves into service
    function registerMe (bytes32 _username) public userDoesntExist (_username) addressNotRegistered (msg.sender) {
        addUser (_username, msg.sender);
    }
    
    
    // Function to link a content with the system
    function publishContent (bytes32 _username, bytes32 _contentTitle, uint _price, address _contentAddr) notPublished (_contentTitle) public {
        if (!userExists(_username)) {
            // Registering new user
            addUser (_username, msg.sender);
        }
        
        // Checking wether content's catalogAddress and contentTitle are correct
        BaseContentManagementContract remoteContract= BaseContentManagementContract (_contentAddr);
        require (remoteContract.getCatalogAddress() == address (this));
        require (remoteContract.getTitle() == _contentTitle);
        
        addContent (_contentTitle, _contentAddr, _username, _price);
        
        emit ContentPublished (_username, _contentTitle, _contentAddr);
    }
    
    
    // Function to notify new view from another content manager
    // FIXME Update payment to author
    // FIXME Check correspondance between msg.sender and saved contentAddress
    function notifyNewView (bytes32 _contentTitle, bytes32 _username) alreadyPublishedM (_contentTitle) userExistsM (_username) userAllowed (_username, _contentTitle) public {
        bytes32 author= contentsMapping[_contentTitle].author;
        uint count= BaseContentManagementContract (msg.sender).getViewsCount ();
        feedbacksAverage
        
        if ((count % MAX_VIEWS_LIMIT) == 0) {
            address rcvAddr= usersMapping[author].userAddress;
            rcvAddr.transfer (MAX_VIEWS_LIMIT * PAYOUT_FOR_AUTHOR);
        }
    }
    
    
    // Function to get a content's address
    function getAddressOf (bytes32 _contentTitle) alreadyPublishedM (_contentTitle) public view returns (address) {
        return contentsMapping[_contentTitle].contractAddress;
    }
    
    
    
    // ************************************************************************************************************** //
    // ************************************************************************************************************** //
    // Required functions
    
    // Returns the number of views for each content
    function getStatistics () public view returns (uint [], bytes32 []) {
        uint [] memory stats= new uint[] (contentsCount);
        bytes32 [] memory strs= new bytes32[] (contentsCount);
        uint i= 0;
        bytes32 tmpCnt;
        
        for (i=0;i<contentsCount; i++) {
            tmpCnt= contentsArray[i];
            stats[i]= (BaseContentManagementContract (contentsMapping[tmpCnt].contractAddress)).getViewsCount();
            strs[i]= tmpCnt;
        }
        
        return (stats, strs);
    }
    
    
    // Returns the list of contents without the number of views
    function getContentList () public view returns (bytes32 []) {
        bytes32 [] memory conList= new bytes32[] (contentsCount);
        uint i=0;
        
        for (i=0; i<contentsCount; i++) {
            conList[i]= contentsArray[i];
        }
        
        return conList;
    }
    
    
    // Returns the list of x newest contents
    function getNewContentList (uint _n) public view returns (bytes32 []) {
        uint count=0;
        uint i=0;
        uint j=0;
        
        if (_n>contentsCount)
            count=contentsCount;
        else
            count=_n;
            
        bytes32 [] memory newest = new bytes32[] (count);
            
        while (count!=0) {
            j=i;
            i++;
            newest[j]= contentsArray[contentsCount-(i)];
            count--;
        }
        
        return newest;
    }
    
    
    
    // Returns the most recent content with genre x
    function getLatestByGenre (SharedTypes.contentType _ct) public view returns (bytes32) {
        uint i= contentsCount;
        bool found= false;
        bytes32 reqStr;
        
        if (contentsCount == 0) {
            return "";
        }
        
        while (i != 0 && !found ) {
            i--;
            if ((BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress)).getType() == _ct) {
                found = true;
                reqStr= (BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress)).getTitle();
            }
        }
        
        return reqStr;
    }
    
    
    
    // Returns the content with genre x, which has received the maximum number of views
    function getMostPopularByGenre (SharedTypes.contentType _ct) public view returns (bytes32) {
        bytes32 reqStr= "";
        uint maximum=0;
        uint i= contentsCount;
        
        if (contentsCount == 0) {
            return "";
        }
        
        while (i != 0) {
            i--;
            BaseContentManagementContract remoteContract= BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress);
            if (remoteContract.getType() == _ct) {
                if (remoteContract.getViewsCount() > maximum)
                    reqStr= remoteContract.getTitle();
            }
        }
        
        return reqStr;
    }
    
    
    
    // Returns the most recent content of the author x
    function getLatestByAuthor (bytes32 _author) userExistsM (_author) public view returns (bytes32) {
        bytes32 reqStr;
        bool found= false;
        uint i= contentsCount;
        
        if (contentsCount == 0) {
            return "";
        }
        
        while (i != 0 && !found) {
            i--;
            bytes32 author= contentsMapping[contentsArray[i]].author;
            if (author == _author) {
                found = true;
                reqStr= (BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress)).getTitle();
            }
        }
        
        return reqStr;
    }
    
    
    
    // FIXME Returns the content with most views of the author x
    function getMostPopularByAuthor (bytes32 _author) userExistsM (_author) public view returns (bytes32) {
        bytes32 reqStr= "";
        uint maximum=0;
        uint i= contentsCount;
        
        if (contentsCount == 0) {
            return "";
        }
        
        while (i != 0) {
            i--;
            BaseContentManagementContract remoteContract= BaseContentManagementContract(contentsMapping[contentsArray[i]].contractAddress);
            if (contentsMapping[contentsArray[i]].author == _author) {
                if (remoteContract.getViewsCount() > maximum)
                    reqStr= remoteContract.getTitle();
            }
        }
        
        return reqStr;
    }
    
    
    
    // Returns true if x holds a still valid premium account, false otherwise
    function isPremium (bytes32 _username)  userExistsM (_username) public view returns (bool) {
        return (usersMapping[_username].accType == SharedTypes.accountType.premium);
    }
    
    
    
    // Returns the content with highest rating for feedback category y (or highest average of all ratings if y is not specified)
    // TEST ME
    function getMostRated (uint8 _category) public view isCorrectCategoryForGetRating(_category) returns (bytes32) {
        return genericGetMostRated (false, 0, false, SharedTypes.contentType.song, _category);
    }
    
    
    
    /* Returns the content with highest rating for feedback gategory _category
     * (or highest average of all ratings if _category is not specified) with genre _genre */
    function getMostRatedByGenre (SharedTypes.contentType _genre, uint8 _category) public view returns (bytes32) {
        return genericGetMostRated (false, 0, true, _genre, _category);
    }
    
    
    
    /* Returns the content with highest rating for feedback category _category
     * (or highest average of all ratings it _category is not specified) with author _author */
     function getMostRatedByAuthor (bytes32 _author, uint8 _category) public view returns (bytes32) {
         return genericGetMostRated (true, _author, false, SharedTypes.contentType.song, _category);
     }
    
    
    // ************************************************************************************************************** //
    // ************************************************************************************************************** //
    
    // Pays for access to content x (NOT ACCESS TO CONTENT!)
    function getContent (bytes32 _contentTitle) userExistsM(addr2User[msg.sender]) alreadyPublishedM (_contentTitle)
                                                equalTo (msg.value, contentsMapping[_contentTitle].contentPrice) public payable {
        // ******* --> Check preconditions (enough value..) + handle payments <-- *******
        bytes32 senderUser= addr2User[msg.sender];
        (BaseContentManagementContract (contentsMapping[_contentTitle].contractAddress)).grantAccessToUser (senderUser, msg.sender, false);
        emit GrantedAccess (senderUser, msg.sender, _contentTitle, contentsMapping[_contentTitle].contractAddress);
    }
    
    
    
    // Requests access to content x without paying, premium accounts only
    function getContentPremium (bytes32 _contentTitle) isPremiumM (addr2User[msg.sender]) alreadyPublishedM (_contentTitle) public {
        bytes32 senderUser= addr2User[msg.sender];
        if (!isPremiumValid (senderUser, block.number)) {
            usersMapping[senderUser].accType= SharedTypes.accountType.standard;
            usersMapping[senderUser].expirationTime= 0;
            revert ();
        }
        
        (BaseContentManagementContract (contentsMapping[_contentTitle].contractAddress)).grantAccessToUser (senderUser, msg.sender, true);
        emit GrantedAccess (senderUser, msg.sender, _contentTitle, contentsMapping[_contentTitle].contractAddress);
    }
    
    
    
    // Pays for granting access for content x to the user u
    function giftContent (bytes32 _contentTitle, bytes32 _receivingUser)
    userExistsM(_receivingUser) alreadyPublishedM (_contentTitle) equalTo (msg.value, contentsMapping[_contentTitle].contentPrice) public payable {
        // ******* --> Check preconditions (enough value..) + handle payments <-- *******
        (BaseContentManagementContract (contentsMapping[_contentTitle].contractAddress)).grantAccessToUser (_receivingUser, usersMapping[_receivingUser].userAddress, false);
        
        emit GrantedAccess (_receivingUser, usersMapping[_receivingUser].userAddress, _contentTitle, contentsMapping[_contentTitle].contractAddress);
    }
    
    
    
    // Pays for granting a Premium Account to the user u
    function giftPremium (bytes32 _receivingUser)  userExistsM(_receivingUser) equalTo (msg.value, PREMIUM_ACCOUNT_COST) public payable {
        // ******* --> check preconditions + handle payments <-- *******
        usersMapping[_receivingUser].accType= SharedTypes.accountType.premium;
        usersMapping[_receivingUser].expirationTime= block.number + PREMIUM_ACCOUNT_DURATION;
        
        emit GrantedPremium (_receivingUser,  usersMapping[_receivingUser].userAddress);
    }
    
    
    
    // Starts a new premium subscription
    function buyPremium () userExistsM(addr2User[msg.sender]) equalTo (msg.value, PREMIUM_ACCOUNT_COST) public payable {
        // ******* --> check preconditions + handle payments <-- *******
        bytes32 senderUser= addr2User[msg.sender];
        usersMapping[senderUser].accType= SharedTypes.accountType.premium;
        usersMapping[senderUser].expirationTime= block.number + PREMIUM_ACCOUNT_DURATION;
        
        emit GrantedPremium (addr2User[msg.sender],  usersMapping[addr2User[msg.sender]].userAddress);
    }
}

contentManagementContracts.sol

pragma solidity ^0.4.24;

import "./baseContentManagementContract.sol";
import "./catalogSmartContract.sol";        // FIXME Remove me!!!!!

crowdfund.sol

pragma solidity ^0.4.24;

import "./mortal.sol";


contract Crowdfund {
    struct Funder {
        address addr;
        uint amount;
    }
    
    struct Project {
        bool created;
        bool opened;
        string name;
        address owner;
        mapping (uint => Funder) funders;
        uint fundersSize;
        uint amount;
        uint fundingGoal;
    }
    
    event ProjectCreated (string _name, uint _fundingGoal);
    event FundTransferred (address _backer, string _project, uint _amount, uint _remainingAmount);
    event fundingGoalReached (string project);
    
    
    address private owner;
    mapping (string => Project) private projects;
    
    
    modifier ProjectNotExists (string _name) {
        require (projects[_name].created == false);
        _;
    }
    
    modifier ProjectExists (string _name) {
        require (projects[_name].created == true);
        _;
    }
    
    
    
    constructor () public {
        owner= msg.sender;
    }
    
    
    
    function createProject (string _projectName, uint _amount) public ProjectNotExists (_projectName) {
        projects[_projectName]= Project (true, true, _projectName, msg.sender, 0, 0, _amount);
        emit ProjectCreated (_projectName, _amount);
    }
    
    
    
    function sendMoney (string _projectName, uint _sum) public ProjectExists (_projectName) {
        Project storage p= projects[_projectName];
        p.funders[p.fundersSize]= Funder (msg.sender, _sum);
        p.fundersSize++;
        p.amount += _sum; 
        uint remaining= p.fundingGoal - _sum;
        emit FundTransferred (msg.sender, _projectName, _sum, remaining);
        checkGoalReached (_projectName);
    }
    
    
    
    function checkGoalReached (string _projectName) private returns (bool) {
        Project storage p= projects[_projectName];
        if (p.fundingGoal <= p.amount) {
            emit fundingGoalReached (_projectName);
            p.opened= false;
            return true;
        }
        return false;
    }
    
    
    
    function getProject (string _projectName) public view returns (bool, address, uint, uint, uint, bool) {
        Project storage p= projects[_projectName];
        return (p.opened, p.owner, p.fundersSize, p.amount, p.fundingGoal, p.opened);
    }
}

ownable.sol

pragma solidity ^0.4.24;


contract Ownable {
    address owner;
    
    constructor () public {
        owner = msg.sender;
    }
    
    modifier onlyOwner () {
        require (msg.sender == owner);
        _;
    }
}

sharedTypes.sol

pragma solidity ^0.4.24;


// Library Containing types definitions
library SharedTypes {
    
    // Kind of content
    enum contentType {song, video, photo, document}
    
    // Kind of account
    enum accountType {standard, premium}
    
    /* Kind of feedback
     * contentAppreciation  : how much the customer enjoyed the content
     * priceFairness        : how fair the requested price is considered compared to the content
     * availabilityTime     : how fair the availability of content is considered compating to the price
     */
    enum feedbackType {contentAppreciation, priceFairness, availabilityTime}
    
    // Type for registered users, both authors or customers. This struct is stored in the catalog
    // Username is the identifier of content
    struct User {
        address userAddress;                    // Address of user (key value is the name)
        bool exists;                            // To check if an user exists in the system
        accountType accType;                    // Type of current account (default standard)
        uint expirationTime;                    // Expiration time (calculated in block.size). Valid only for premium account
        bytes32 latestContent;                  // Title of latest content published by current user
    }
    
    // Struct to hold reference of BaseContentManagementContracts with its author
    // Title of content (a bytes32) is the identifier of content
    struct ExtendedContent {
        uint contentPrice;                      // Price of conent, defined by the author
        bool exists;                            // To check if a content exists in the system
        address contractAddress;                // Contract's address associated to current content
        bytes32 author;                         // Name of owner of content

        // Others informations, about views and users which are granted to access to current content, are stored in BaseContentManagementContracts
    }
}