(C) Download File from Dropbox (Streaming)

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Downloads a file from Dropbox, streaming it directly to a file in the filesystem.

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#include <C_CkRest.h>
#include <C_CkJsonObject.h>
#include <C_CkStream.h>
#include <C_CkDateTime.h>
#include <C_CkDtObj.h>

void ChilkatSample(void)
    {
    HCkRest rest;
    BOOL success;
    HCkJsonObject json;
    HCkStream fileStream;
    int expectedStatus;
    const char *responseStr;
    const char *apiResult;
    HCkJsonObject jsonResult;
    int size;
    const char *rev;
    const char *clientModified;
    HCkDateTime ckdt;
    BOOL bLocalTime;
    HCkDtObj dt;

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

    // A Dropbox access token should have been previously obtained.
    // Dropbox access tokens do not expire.
    // See Dropbox Access Token.

    rest = CkRest_Create();

    // Connect to Dropbox
    success = CkRest_Connect(rest,"content.dropboxapi.com",443,TRUE,TRUE);
    if (success != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        return;
    }

    // Add request headers.
    CkRest_AddHeader(rest,"Authorization","Bearer DROPBOX_ACCESS_TOKEN");

    // The download "parameters" are contained in JSON passed in an HTTP request header.
    // This is the JSON indicating the file to be downloaded:
    // { 
    //    "path": "/Homework/lit/hamlet.xml",
    // }

    json = CkJsonObject_Create();
    CkJsonObject_AppendString(json,"path","/Homework/lit/hamlet.xml");
    CkRest_AddHeader(rest,"Dropbox-API-Arg",CkJsonObject_emit(json));

    // Setup a file stream for the download
    fileStream = CkStream_Create();
    CkStream_putSinkFile(fileStream,"qa_output/hamletFromDropbox.xml");

    // Indicate that the call to FullRequestNoBody should send the response body
    // to fileStream if the response status code is 200.
    // If a non-success response status code is received, then nothing
    // is streamed to the output file and the error response is returned by FullRequestNoBody.
    expectedStatus = 200;
    CkRest_SetResponseBodyStream(rest,expectedStatus,TRUE,fileStream);

    responseStr = CkRest_fullRequestNoBody(rest,"POST","/2/files/download");
    if (CkRest_getLastMethodSuccess(rest) != TRUE) {
        printf("%s\n",CkRest_lastErrorText(rest));
        CkRest_Dispose(rest);
        CkJsonObject_Dispose(json);
        CkStream_Dispose(fileStream);
        return;
    }

    // When successful, Dropbox responds with a 200 response code.
    if (CkRest_getResponseStatusCode(rest) != 200) {
        // Examine the request/response to see what happened.
        printf("response status code = %d\n",CkRest_getResponseStatusCode(rest));
        printf("response status text = %s\n",CkRest_responseStatusText(rest));
        printf("response header: %s\n",CkRest_responseHeader(rest));
        printf("response body (if any): %s\n",responseStr);
        printf("---\n");
        printf("LastRequestStartLine: %s\n",CkRest_lastRequestStartLine(rest));
        printf("LastRequestHeader: %s\n",CkRest_lastRequestHeader(rest));
        CkRest_Dispose(rest);
        CkJsonObject_Dispose(json);
        CkStream_Dispose(fileStream);
        return;
    }

    // Information about the downloaded file is also available as JSON in a response header.
    // The "dropbox-api-result" response header contains the information.  For example:
    apiResult = CkRest_responseHdrByName(rest,"dropbox-api-result");
    printf("%s\n",apiResult);

    // In this case, the pretty-formatted dropbox-api-result JSON looks like this:
    // { 
    //   "name": "hamlet.xml",
    //   "path_lower": "/homework/lit/hamlet.xml",
    //   "path_display": "/Homework/lit/hamlet.xml",
    //   "id": "id:74FkdeNuyKAAAAAAAAAAAQ",
    //   "client_modified": "2016-06-02T23:19:00Z",
    //   "server_modified": "2016-06-02T23:19:00Z",
    //   "rev": "9482db15f",
    //   "size": 279658
    // }

    // Load the JSON, pretty-print it, and demonstrate how to get some values...
    jsonResult = CkJsonObject_Create();
    CkJsonObject_putEmitCompact(jsonResult,FALSE);
    CkJsonObject_Load(jsonResult,apiResult);
    // Show the JSON pretty-printed...
    printf("%s\n",CkJsonObject_emit(jsonResult));

    // Sample code to get data from the JSON response:
    size = CkJsonObject_IntOf(jsonResult,"size");
    printf("size = %d\n",size);

    rev = CkJsonObject_stringOf(jsonResult,"rev");
    printf("rev = %s\n",rev);

    clientModified = CkJsonObject_stringOf(jsonResult,"client_modified");
    ckdt = CkDateTime_Create();
    CkDateTime_SetFromTimestamp(ckdt,clientModified);
    bLocalTime = TRUE;
    dt = CkDateTime_GetDtObj(ckdt,bLocalTime);
    printf("%d/%d/%d %d:%d\n",CkDtObj_getDay(dt),CkDtObj_getMonth(dt),CkDtObj_getYear(dt),CkDtObj_getHour(dt),CkDtObj_getMinute(dt));
    CkDtObj_Dispose(dt);


    CkRest_Dispose(rest);
    CkJsonObject_Dispose(json);
    CkStream_Dispose(fileStream);
    CkJsonObject_Dispose(jsonResult);
    CkDateTime_Dispose(ckdt);

    }