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baseContentManagementContract.sol

pragma solidity ^0.4.24;

import "./sharedTypes.sol";


contract BaseContentManagementContract {
    address private authorAddress;                      // Address of contract's author
    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
    
    string private contentTitle;                        // Title which identifies this contract in catalog
    string private content;                             // Content of resource
    uint private numberOfViews;                         // Number of viwes about content of this contract
    
    mapping (address => bool) allowedUsers;             // Map of users that are allowed to access this content

    
    
    constructor (SharedTypes.contentType _conType, string _conTitle, string _cnt, address _catAddr) public {
        typeOfContent = _conType;
        authorAddress= msg.sender;
        numberOfViews= 0;
        contentTitle= _conTitle;
        content= _cnt;
        catalogAddress= _catAddr;
    }
    
    
    
    // *****           ***** //
    // ***** Modifiers ***** //
    
    modifier onlyCatalog () {
        require (msg.sender == catalogAddress);
        _;
    }
    
    modifier onlyAllowedUsers (address _userAddr) {
        require (allowedUsers[_userAddr] == true);
        _;
    }
    
    
    
    // *****                                   ***** //
    // ***** Helper private/internal functions ***** //
    
    
    
    // *****                  ***** //
    // ***** 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 (string) {
        return contentTitle;
    }
    
    // This function allows (only to catalog) to grant access to a user with address _userAddr
    function grantAccessToUser (address _userAddr) public onlyCatalog () {
        allowedUsers[_userAddr]= true;
    }
    
    /* This function allows subContracts of this contract to retreive content if and only if user
     * with addrs _userAddr is into "allowedUsers" map
     */
    function retreiveContent (address _userAddr) internal onlyAllowedUsers(_userAddr) returns (string) {
        allowedUsers[_userAddr]= false;
        numberOfViews++;
        return content;
    }
    
    
    
    // *****                     ***** //
    // ***** Abastract functions ***** //
    
    function consumeContent (address _userAddr) public returns (string);
}

catalogSmartContract.sol

pragma solidity ^0.4.24;
pragma experimental ABIEncoderV2;

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


contract CatalogSmartContract is Ownable {
    
    // True if 'selfdestruct' function wasn't called --> is this necessary?
    bool active= false;
    
    
    // Mapping which contains a User struct for each user that hav published or have requeested a content
    mapping (address => SharedTypes.User) usersMapping;
    // Array containing addresses of users registered to system (for loop functions)
    address [] usersArray;
    // Number of user (also index of next user in the array)
    uint usersCount;
    
    // Mapping which contains an ExtendedContent struct for each content published on the platform (identified by a string)
    mapping (string => SharedTypes.ExtendedContent) contentsMapping;
    // Array containing addresses of contents published on the system (for loop functions)
    string [] contentsArray;
    // Number of contents (also index of next content in the array)
    uint contentsCount;
    
    
    constructor () public {
        active= true;
        usersCount=0;
        contentsCount= 0;
    }
    
    
    
    // *****           ***** //
    // ***** Modifiers ***** //
    
    modifier isActive () {
        require (active == true);
        _;
    }
    
    modifier notPublished (string _contentTitle) {
        require (alreadyPublished(_contentTitle) == false);
        _;
    }
    
    
    
    // *****                          ***** //
    // ***** Helper private functions ***** //
    
    // Function to check if a user exists or not in usersMapping
    function userExists (address _addr) private view returns (bool){
       return (usersMapping[_addr].exists == true);
    }

    // Function which returns wether a content is already published on the platform
    function alreadyPublished (string conTitle) private view returns (bool) {
        return (contentsMapping[conTitle].exists == true);
    }
    
    // Function to register an user to system
    function addUser (address _addr) private {
        usersCount++;
        usersArray.push (_addr);
        
        usersMapping[_addr].accType= SharedTypes.accountType.standard;
        usersMapping[_addr].exists= true;
        usersMapping[_addr].expirationTime= 0;
        usersMapping[_addr].latestContent = "";
    }
    
    // Function to add new content with address 'contAddr' registered by user with address 'userAddr'
    function addContent (string _conTitle, address _contAddr, address _userAddr, SharedTypes.contentType _ct) private {
        contentsCount++;
        contentsArray.push (_conTitle);
        
        contentsMapping[_conTitle].exists= true;
        contentsMapping[_conTitle].owner= _userAddr;
        contentsMapping[_conTitle].contractAddress= _contAddr;
        contentsMapping[_conTitle].cType= _ct;
    }
    
    
    
    // *****                  ***** //
    // ***** Public functions ***** //
   
    function killMe () public onlyOwner() {
        active= false;
        selfdestruct (owner);
    }
    
    
    // Function to link a content with the system
    function publishContent (string _contentTitle, address _contentAddr, SharedTypes.contentType _ct) public {
        if (!userExists(msg.sender)) {
            // Registering new user
            addUser (msg.sender);
        }
        addContent (_contentTitle, _contentAddr, msg.sender, _ct);
    }
    
    // Returns the number of views for each content
    function getStatistics () public returns (uint [], string []) {
        uint [] storage stats= new uint[] (contentsCount);
        
        stats.push (10);
        
        return (stats, contentsArray);
    }
    
    
    // Returns the list of contents without the number of views
    function getContentList () public view returns (string []) {
        string [] storage conList;
        // TODO
        return conList;
    }
    
    
/*    // Returns the list of x newest contents
    function getNewContentList (uint n) public view returns (...) {
    }
    
    
    
    // Returns the most recent content with genre x
    function getLatestByGenre (...) public view returns (...) {
    }
    
    
    
    // Returns the content with genre x, which has received the maximum number of views
    function getMostPopularByGenre (...) public view returns (...) {
    }
    
    
    
    // Returns the most recent content of the author x
    function getLatestByAuthor (...) public view returns (...) {
    }
    
    
    
    // Returns the content with most views of the author x
    function getMostPopularByAuthor (...) public view returns (...) {
    }
    
    
    
    // Returns true if x holds a still valid premium account, false otherwise
    function isPremium (...)  public view returns (...) {
    }
    
    
    /* ********************************************* */
    /* ********************************************* */
    /* ********************************************* */
    
    
    // Pays for access to content x
    /*function getContent (...) public {
    }
    
    
    
    // Requests access to content x without paying, premium accounts only
    function getContentPremium (...) public {
    }
    
    
    
    // Pays for granting access to content x to the user u
    function giftContent (..., ...) public {
    }
    
    
    
    // Pays for granting a Premium Account to the user u
    function giftPremium (...) public {
    }
    
    
    
    // Starts a new premium subscription
    function buyPremium () public {
    }
*/
}

contentManagementContracts.sol

pragma solidity ^0.4.24;

import "./baseContentManagementContract.sol";


contract SongManagementContract is BaseContentManagementContract {
    
    constructor (string _cnt, string _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.song, _title, _cnt, _catAddr) public {
    }
    
    function consumeContent (address _userAddr) public returns (string) {
        return retreiveContent (_userAddr);
    }
}



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



contract VideoManagementContract is BaseContentManagementContract {
    constructor (string _cnt, string _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.video, _title, _cnt, _catAddr) public {
    }
    
    function consumeContent (address _userAddr) public returns (string) {
        return retreiveContent (_userAddr);
    }
}



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



contract PhotoManagementContract is BaseContentManagementContract {
    constructor (string _cnt, string _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.photo, _title, _cnt, _catAddr) public {
    }
    
    function consumeContent (address _userAddr) public returns (string) {
        return retreiveContent (_userAddr);
    }
}



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



contract DocumentManagementContract is BaseContentManagementContract {
    constructor (string _cnt, string _title, address _catAddr)
            BaseContentManagementContract(SharedTypes.contentType.document, _title, _cnt, _catAddr) public {
    }
    
    function consumeContent (address _userAddr) public returns (string) {
        return retreiveContent (_userAddr);
    }
}

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);
    }
}

mortal.sol

pragma solidity ^0.4.24;


contract Mortal {
    address owner;
    
    constructor () public {
        owner= msg.sender;
    }
    
    function kill () public {
        if (msg.sender == owner)
            selfdestruct (owner);
    }
}

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 SharedTypes {
    
    // Kind of content
    enum contentType {song, video, photo, document}
    
    // Kind of account
    enum accountType {standard, premium}
    
    // Type for registered users, both authors or customers. This struct is stored in the catalog
    struct User {
        bool exists;            // To check if an user exists in the system
        accountType accType;    // Type of current account (default standard)
        uint expirationTime;    // Expiration time. Valid only for premium account
        string latestContent;   // Title of latest content published by current user
    }
    
    // Struct to hold togheter BasContentManagementContracts and list of users which payed to view these contents
    // Title of content (a string) is the identifier of content
    struct ExtendedContent {
        bool exists;                            // To check if a content exists in the system
        address contractAddress;                // Contract's address associated to current content
        address owner;                          // Address of owner of content
        contentType cType;                       // Type of current content

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