sequenceDiagram
  actor User
  participant UserInterface
  participant Database

  User->>+UserInterface: createPost(content, image)
  UserInterface->>Database: post(username, content, image)

  alt Success
    Database-->>UserInterface: Success.
    UserInterface-->>User: Post created successfully.
  else Failure
    Database-->>UserInterface: <ERR_CODE>
    UserInterface-->>User: <ERR_CODE, errorMessage>
  end

sequenceDiagram
    actor User
    User->>+UserInterface: likeUnlikePost(post_id)
    UserInterface->>+ Database: likeUnlikePost(username, post_id)
    alt Success
        alt Post is liked
            Database-->>UserInterface: <OK, post_unlikes>
            UserInterface-->> User: updatePostLikes(post_id, updated_likes)
        else Post is not liked
            Database-->>UserInterface: <OK, post_likes>
            UserInterface-->> User: updatePostLikes(post_id, updated_likes)
        end
    else Failure
        Database-->>UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end

sequenceDiagram
    actor User
    User->>+UserInterface: bookmarkUnbookmarkPost(post_id)
    UserInterface->>+ Database: bookmarkUnbookmarkPost(username, post_id)
    alt Success
         alt Post is bookmarked
            Database-->>UserInterface: <OK, post_unbookmark>
            UserInterface-->> User: updatePostBookmarks(post_id, updated_bookmarks)
        else Post is not bookmarked
            Database-->>UserInterface: <OK, post_bookmark>
            UserInterface-->> User: updatePostBookmark(post_id, updated_bookmarks)
        end
    else Failure
        Database-->>UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end

sequenceDiagram
    actor User
    User->>+UserInterface: viewPost(post_id)
    UserInterface->>+ Database: viewPost(post_id)
    alt Success
       Database-->>UserInterface: <OK, post, comments>
       UserInterface-->> User: displayPost(post)
       UserInterface-->> User: displayComments(comments)     
    else Failure
        Database-->>UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end

sequenceDiagram
    actor U as User
    U->>+UserInterface: comment(post_id, message)
    UserInterface->>+ Database: saveComment(username, post_id, message)
    alt Success
       Database-->>UserInterface: <OK, comments>
       UserInterface-->> U: displayComments(comments)     
    else Error
        Database-->>UserInterface: <ERR_CODE, comments>
        UserInterface-->> U: displayCommentsWithErr(ERR_CODE, comments)
    end

sequenceDiagram
    actor User
    User->>+FeedController: viewFollowingFeed(username)
    FeedController->>+Database: getFollowingFeed(username)
    Database-->>FeedController: followingFeed
    alt Success
        FeedController-->>User: displayFollowingFeed(followingFeed)
    else Error
        FeedController-->>User: displayErrorMessage("Error retrieving following feed")
    end

sequenceDiagram
    actor User
    User->>+Search: search(query, filters)
    Search->>Wikidata API: search(query)
    Search->>Database: search(query)
    alt Success
        Database-->>Search: <OK, results>
        alt results.tag is post
            Search-->>User : post
        else results.tag is username
            Search-->>User : username
        end
    else Fail
        Database-->>Search: <ERR_CODE, results>
        Search-->>User : ERR_CODE
    end
    alt Success
        Wikidata API-->>Search: <OK, results>
        alt results.tag is team
            Search-->>User : team.id
            Search-->>User : team.logo
            Search-->>User : team.name
            Search-->>User : team.coach
            Search-->>User : team.conference
        else results.tag is player
            Search-->>User : player.id
            Search-->>User : player.name
            Search-->>User : player.picture
            Search-->>User : player.height
            Search-->>User : player.dateOfBirth
        end
    else
        Wikidata API-->>Search: <ERR_CODE, results>
        Search-->>User: ERR_CODE
    end

sequenceDiagram
    actor U as User
    U->>+UserInterface: getOtherProfile(username)
    UserInterface->>Database: getUsername(username)
    Database-->> UserInterface: username
    UserInterface->>Database: getProfilePicture(username)
    Database-->> UserInterface: profilePicture
    UserInterface->>Database: getBio(userID)
    Database-->> UserInterface: bio
    UserInterface->>Database: getFollowerCount(username)
    Database-->> UserInterface: followerCount
    UserInterface->>Database: getFollowedCount(username)
    Database-->> UserInterface: followedCount
    UserInterface->>Database: getPosts(username)
    Database-->> UserInterface: posts
    UserInterface-->>U: displayOtherProfile(profileInformation)

sequenceDiagram
    actor User
    User->>+UserInterface: followUser(username)
    UserInterface->>+ Database: followUser(username)
    alt Success
       Database-->>UserInterface: <OK, follower_count>
       UserInterface-->> User: updateFollowers(username, updated_follower_count)
    else Failure
        Database-->>UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end

    sequenceDiagram
    actor U as User
    
    U->>+Profile: getProfile(userID)
    Profile->>Database: getUsername(userID)
    Database-->> Profile: username
    Profile->>Database: getEmailAddress(userID)
    Database-->> Profile: emailAddress
    Profile->>Database: getProfilePicture(userID)
    Database-->> Profile: profilePicture
    Profile->>Database: getBio(userID)
    Database-->> Profile: bio
    UserInterface->>Database: getFollowerCount(username)
    Database-->> UserInterface: followerCount
    UserInterface->>Database: getFollowedCount(username)
    Database-->> UserInterface: followedCount
    UserInterface->>Database: getFollowers(username)
    Database-->> UserInterface: followerCount
    UserInterface->>Database: getFollowedUsers(username)
    Database-->> UserInterface: followedUsers
    UserInterface->>Database: getPosts(username)
    Database-->> UserInterface: posts
    Profile-->>U: displayProfile(profileInformation)

    sequenceDiagram
    actor U as User

    U->>+Profile: changeEmailAddress(userID, newEmailAddress)
    alt email address is valid
       Profile->>Database: setEmailAddress(userID, newEmailAddress)
       alt success
          Database-->>Profile: <OK>
          Profile-->>U: <OK, successMessage>
       else
          Database-->>Profile: <ERR_CODE>
          Profile-->>U: <ERR_CODE, errorMessage>
       end
    else
       Profile-->>U: <ERR_CODE, invalidMessage>
    end

    U->>+Profile: changeProfilePicture(userID, newProfilePicture)
    alt profile picture is valid
       Profile->>Database: setProfilePicture(userID, newProfilePicture)
       alt success
          Database-->>Profile: <OK>
          Profile-->>U: <OK, successMessage>
       else
          Database-->>Profile: <ERR_CODE>
          Profile-->>U: <ERR_CODE, errorMessage>
       end
    else
       Profile-->>U: <ERR_CODE, invalidMessage>
    end

    U->>+Profile: changeBio(userID, newBio)
    alt bio is valid
       Profile->>Database: setBio(userID, newBio)
       alt success
          Database-->>Profile: <OK>
          Profile-->>U: <OK, successMessage>
       else
          Database-->>Profile: <ERR_CODE>
          Profile-->>U: <ERR_CODE, errorMessage>
       end
    else
       Profile-->>U: <ERR_CODE, invalidMessage>
    end

    U->>+Profile: changePassword(userID, newPassword)
    alt password is valid
       Profile->>Database: setPassword(userID, newPassword)
       alt success
          Database-->>Profile: <OK>
          Profile-->>U: <OK, successMessage>
       else
          Database-->>Profile: <ERR_CODE>
          Profile-->>U: <ERR_CODE, errorMessage>
       end
    else
       Profile-->>U: <ERR_CODE, invalidMessage>
    end

sequenceDiagram
    actor User
    User->>+ UserInterface: viewTeamPage(team_name)
    UserInterface->>+ SearchComponent: searchTeam(team_id)
    SearchComponent->>+ Wikidata API: requestTeam(query)
    alt Success
       Wikidata API-->> SearchComponent: <OK, response>
       SearchComponent-->> UserInterface: <OK, data>
       UserInterface-->> User: displayTeamPage(team_data)
    else Failure
        Wikidata API-->> SearchComponent: <ERR_CODE, None>
        SearchComponent-->> UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end

sequenceDiagram
    actor User
    User->>+ UserInterface: viewPlayerPage(player_name)
    UserInterface->>+ SearchComponent: searchPlayer(player_id)
    SearchComponent->>+ Wikidata API: requestPlayer(query)
    alt Success
       Wikidata API-->> SearchComponent: <OK, response>
       SearchComponent-->> UserInterface: <OK, data>
       UserInterface-->> User: displayPlayerPage(player_data)
    else Failure
        Wikidata API-->> SearchComponent: <ERR_CODE, None>
        SearchComponent-->> UserInterface: <ERR_CODE>
        UserInterface-->> User: displayErrorMessage(ERR_CODE, errorMessage)
    end