(C) Facebook Download all Photos to Local Files

Demonstrates how to download all of one's Facebook photos to a local filesystem directory. This sample code keeps a local cache to avoid re-downloading the same photos twice. The program can be run again after a time, and it will download only photos that haven't yet been downloaded.

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#include <C_CkCache.h>
#include <C_CkOAuth2.h>
#include <C_CkRest.h>
#include <C_CkJsonObject.h>
#include <C_CkStringArray.h>
#include <C_CkStringBuilder.h>
#include <C_CkHttp.h>
#include <C_CkByteData.h>
#include <C_CkFileAccess.h>

void ChilkatSample(void)
    {
    HCkCache fbCache;
    HCkOAuth2 oauth2;
    HCkRest rest;
    BOOL success;
    const char *responseJson;
    HCkJsonObject photoJson;
    HCkStringArray saPhotoUrls;
    HCkStringBuilder sbPhotoIdPath;
    HCkJsonObject json;
    int i;
    const char *photoId;
    const char *imageUrl;
    const char *afterCursor;
    int numItems;
    const char *photoJsonStr;
    HCkJsonObject imgUrlJson;
    HCkHttp http;
    int numUrls;
    HCkJsonObject urlJson;
    HCkByteData imageBytes;
    HCkFileAccess fac;
    HCkStringBuilder sbImageUrl;
    const char *extension;
    HCkStringBuilder sbLocalFilePath;

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // This example will use a local disk cache to avoid re-fetching the same
    // photo id after it's been fetched once.
    fbCache = CkCache_Create();
    // The cache will use 1 level of 256 sub-directories.
    CkCache_putLevel(fbCache,1);
    // Use a directory path that makes sense on your operating system..
    CkCache_AddRoot(fbCache,"C:/fbCache");

    // This example assumes a previously obtained an access token
    oauth2 = CkOAuth2_Create();
    CkOAuth2_putAccessToken(oauth2,"FACEBOOK-ACCESS-TOKEN");

    rest = CkRest_Create();

    // Connect to Facebook.
    success = CkRest_Connect(rest,"graph.facebook.com",443,TRUE,TRUE);
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkCache_Dispose(fbCache);
        CkOAuth2_Dispose(oauth2);
        CkRest_Dispose(rest);
        return;
    }

    // Provide the authentication credentials (i.e. the access key)
    CkRest_SetAuthOAuth2(rest,oauth2);

    // There are two choices:  
    // We can choose to download the photos the person is tagged in or has uploaded
    // by setting type to "tagged" or "uploaded".
    CkRest_AddQueryParam(rest,"type","uploaded");

    // To download all photos, we begin with an outer loop that iterates over
    // the list of photo nodes in pages.  Each page returned contains a list of 
    // photo node ids.  Each photo node id must be retrieved to get the download URL(s)
    // of the actual image.

    // I don't know the max limit for the number of records that can be downloaded at once.
    CkRest_AddQueryParam(rest,"limit","100");

    // Get the 1st page of photos ids.
    // See https://developers.facebook.com/docs/graph-api/reference/user/photos/ for more information.
    responseJson = CkRest_fullRequestNoBody(rest,"GET","/v2.7/me/photos");
    if (CkRest_getLastMethodSuccess(rest) != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkCache_Dispose(fbCache);
        CkOAuth2_Dispose(oauth2);
        CkRest_Dispose(rest);
        return;
    }

    photoJson = CkJsonObject_Create();
    saPhotoUrls = CkStringArray_Create();
    sbPhotoIdPath = CkStringBuilder_Create();

    json = CkJsonObject_Create();
    CkJsonObject_putEmitCompact(json,FALSE);
    CkJsonObject_Load(json,responseJson);

    // Get the "after" cursor.
    afterCursor = CkJsonObject_stringOf(json,"paging.cursors.after");
    while (CkJsonObject_getLastMethodSuccess(json) == TRUE) {

        printf("-------------------\n");
        printf("afterCursor = %s\n",afterCursor);

        // For each photo id in this page...
        i = 0;
        numItems = CkJsonObject_SizeOfArray(json,"data");
        while (i < numItems) {
            CkJsonObject_putI(json,i);
            photoId = CkJsonObject_stringOf(json,"data[i].id");
            printf("photoId = %s\n",photoId);

            // We need to fetch the JSON for this photo.  Check to see if it's in the local disk cache,
            // and if not, then get it from Facebook.
            photoJsonStr = CkCache_fetchText(fbCache,photoId);
            if (CkCache_getLastMethodSuccess(fbCache) == FALSE) {
                // It's not locally available, so get it from Facebook..
                CkStringBuilder_Clear(sbPhotoIdPath);
                CkStringBuilder_Append(sbPhotoIdPath,"/v2.7/");
                CkStringBuilder_Append(sbPhotoIdPath,photoId);

                CkRest_ClearAllQueryParams(rest);
                CkRest_AddQueryParam(rest,"fields","id,album,images");

                printf("Fetching photo node from Facebook...\n");

                // This REST request will continue using the existing connection.
                // If the connection was closed, it will automatically reconnect to send the request.
                photoJsonStr = CkRest_fullRequestNoBody(rest,"GET",CkStringBuilder_getAsString(sbPhotoIdPath));
                if (CkRest_getLastMethodSuccess(rest) != TRUE) {
                    printf("%s\n",CkRest_lastErrorText(rest));
                    CkCache_Dispose(fbCache);
                    CkOAuth2_Dispose(oauth2);
                    CkRest_Dispose(rest);
                    CkJsonObject_Dispose(photoJson);
                    CkStringArray_Dispose(saPhotoUrls);
                    CkStringBuilder_Dispose(sbPhotoIdPath);
                    CkJsonObject_Dispose(json);
                    return;
                }

                // Add the photo JSON to the local cache.
                CkCache_SaveTextNoExpire(fbCache,photoId,"",photoJsonStr);
            }

            // Parse the photo JSON and add the main photo download URL to saPhotoUrls
            // There may be multiple URLs in the images array, but the 1st one is the largest and main photo URL.
            // The others are smaller sizes of the same photo.
            CkJsonObject_Load(photoJson,photoJsonStr);
            imageUrl = CkJsonObject_stringOf(photoJson,"images[0].source");
            if (CkJsonObject_getLastMethodSuccess(photoJson) == TRUE) {

                // Actually, we'll add a small JSON document that contains both the image ID and the URL.
                imgUrlJson = CkJsonObject_Create();
                CkJsonObject_AppendString(imgUrlJson,"id",photoId);
                CkJsonObject_AppendString(imgUrlJson,"url",imageUrl);
                CkStringArray_Append(saPhotoUrls,CkJsonObject_emit(imgUrlJson));
                printf("imageUrl = %s\n",imageUrl);
            }

            i = i + 1;
        }

        // Prepare for getting the next page of photos ids.
        // We can continue using the same REST object.
        // If already connected, we'll continue using the existing connection.
        // Otherwise, a new connection will automatically be made if needed.
        CkRest_ClearAllQueryParams(rest);
        CkRest_AddQueryParam(rest,"type","uploaded");
        CkRest_AddQueryParam(rest,"limit","20");
        CkRest_AddQueryParam(rest,"after",afterCursor);

        // Get the next page of photo ids.
        responseJson = CkRest_fullRequestNoBody(rest,"GET","/v2.7/me/photos");
        if (CkRest_getLastMethodSuccess(rest) != TRUE) {
            printf("%s\n",CkRest_lastErrorText(rest));
            CkCache_Dispose(fbCache);
            CkOAuth2_Dispose(oauth2);
            CkRest_Dispose(rest);
            CkJsonObject_Dispose(photoJson);
            CkStringArray_Dispose(saPhotoUrls);
            CkStringBuilder_Dispose(sbPhotoIdPath);
            CkJsonObject_Dispose(json);
            CkJsonObject_Dispose(imgUrlJson);
            return;
        }

        CkJsonObject_Load(json,responseJson);
        afterCursor = CkJsonObject_stringOf(json,"paging.cursors.after");
    }

    printf("No more pages of photos.\n");

    // Now iterate over the photo URLs and download each to a file.
    // We can use Chilkat HTTP.  No Facebook authorization (access token) is required to download
    // the photo once the URL is known.  
    http = CkHttp_Create();

    // We'll cache the image data so that if run again, we don't re-download the same image again.
    numUrls = CkStringArray_getCount(saPhotoUrls);
    i = 0;
    urlJson = CkJsonObject_Create();
    imageBytes = CkByteData_Create();
    fac = CkFileAccess_Create();

    while (i < numUrls) {
        CkJsonObject_Load(urlJson,CkStringArray_getString(saPhotoUrls,i));
        photoId = CkJsonObject_stringOf(urlJson,"id");
        imageUrl = CkJsonObject_stringOf(urlJson,"url");

        // Check the local cache for the image data.
        // Only download and save if not already cached.
        success = CkCache_FetchFromCache(fbCache,imageUrl,imageBytes);
        if (CkCache_getLastMethodSuccess(fbCache) == FALSE) {
            //  This photo needs to be downloaded.

            sbImageUrl = CkStringBuilder_Create();
            CkStringBuilder_Append(sbImageUrl,imageUrl);

            // Let's form a filename..
            extension = ".jpg";
            if (CkStringBuilder_Contains(sbImageUrl,".gif",FALSE) == TRUE) {
                extension = ".gif";
            }

            if (CkStringBuilder_Contains(sbImageUrl,".png",FALSE) == TRUE) {
                extension = ".png";
            }

            if (CkStringBuilder_Contains(sbImageUrl,".tiff",FALSE) == TRUE) {
                extension = ".tiff";
            }

            if (CkStringBuilder_Contains(sbImageUrl,".bmp",FALSE) == TRUE) {
                extension = ".bmp";
            }

            sbLocalFilePath = CkStringBuilder_Create();
            CkStringBuilder_Append(sbLocalFilePath,"C:/Photos/facebook/uploaded/");
            CkStringBuilder_Append(sbLocalFilePath,photoId);
            CkStringBuilder_Append(sbLocalFilePath,extension);

            success = CkHttp_QuickGet(http,imageUrl,imageBytes);
            if (CkHttp_getLastMethodSuccess(http) != TRUE) {
                printf("%s\n",CkHttp_lastErrorText(http));
                CkCache_Dispose(fbCache);
                CkOAuth2_Dispose(oauth2);
                CkRest_Dispose(rest);
                CkJsonObject_Dispose(photoJson);
                CkStringArray_Dispose(saPhotoUrls);
                CkStringBuilder_Dispose(sbPhotoIdPath);
                CkJsonObject_Dispose(json);
                CkJsonObject_Dispose(imgUrlJson);
                CkHttp_Dispose(http);
                CkJsonObject_Dispose(urlJson);
                CkByteData_Dispose(imageBytes);
                CkFileAccess_Dispose(fac);
                CkStringBuilder_Dispose(sbImageUrl);
                CkStringBuilder_Dispose(sbLocalFilePath);
                return;
            }

            // We've downloaded the photo image bytes into memory.
            // Save it to the cache AND save it to the output file.
            CkCache_SaveToCacheNoExpire(fbCache,imageUrl,"",imageBytes);
            CkFileAccess_WriteEntireFile(fac,CkStringBuilder_getAsString(sbLocalFilePath),imageBytes);

            printf("Downloaded to %s\n",CkStringBuilder_getAsString(sbLocalFilePath));
        }

        i = i + 1;
    }

    printf("Finished downloading all Facebook photos!\n");


    CkCache_Dispose(fbCache);
    CkOAuth2_Dispose(oauth2);
    CkRest_Dispose(rest);
    CkJsonObject_Dispose(photoJson);
    CkStringArray_Dispose(saPhotoUrls);
    CkStringBuilder_Dispose(sbPhotoIdPath);
    CkJsonObject_Dispose(json);
    CkJsonObject_Dispose(imgUrlJson);
    CkHttp_Dispose(http);
    CkJsonObject_Dispose(urlJson);
    CkByteData_Dispose(imageBytes);
    CkFileAccess_Dispose(fac);
    CkStringBuilder_Dispose(sbImageUrl);
    CkStringBuilder_Dispose(sbLocalFilePath);

    }