Search Gear #16 – json Decoder Encoder

OK OK my test worked locally it seems but not via drone. No idea why – at this point I don’t much care long as they work for me. Now code changes to encode and decode tweets, efficiency be damned – lets just move on.

https://dev.twitter.com/docs/working-with-timelines

Tweets returned in reverse chronological order – so not optimal for writing to a file.

func (tw *twitter) collect(toGet string) (string, error) {

var searchResult []anaconda.Tweet
var err error
var file *os.File

v := url.Values{}
v.Set("count", "20")

fileName := strings.Join([]string{toGet, "-", strconv.Itoa(time.Now().Day()), ".json"}, "")

file, err = os.OpenFile(fileName, os.O_RDWR, 0666)
if err != nil {
    if file, err = os.Create(fileName); err != nil {
        err = errors.New(co.Lang("could neither open or create the file to save tweets to"))
    }
} else {
    /*  read the first tweet to get the ID then use v.Set to add this to the url query
        based on https://dev.twitter.com/docs/working-with-timelines
        max_id is to be set on subsequent tweet requests with the lowest id present
        Subtract 1 from the lowest Tweet ID returned from the previous request and use this for the value of max_id.
        It does not matter if this adjusted max_id is a valid Tweet ID, or if it corresponds with a Tweet posted by a different user -
        the value is just used to decide which Tweets to filter. When adjusted in this manner, it is possible to page through a
        timeline without receiving redundant Tweets
        Technically for my work it doesn't matter if some tweets go into an incorrect date file - it is not that iomportant and will be
        addressed at analysis time.
    */
    dec := json.NewDecoder(file)
    var tweet anaconda.Tweet
    var sinceID int64

    err := dec.Decode(&tweet)
    sinceID = tweet.Id

    for ; err != io.EOF; err = dec.Decode(&tweet) { //There must be a more efficient way of getting a tweet than this!
        if err != nil {
            err = errors.New(co.Lang(strings.Join([]string{"problem decoding tweet from json file", fileName}, " ")))
            break
        }
        if sinceID < tweet.Id {
            sinceID = tweet.Id
        }
    }
    v.Set("since_id", strconv.FormatInt(sinceID, 10))
}

if err == nil {
    anaconda.SetConsumerKey(tw.userKey)
    anaconda.SetConsumerSecret(tw.userSecret)
    api := anaconda.NewTwitterApi(tw.apiKey, tw.apiSecret)

    switch toGet[0] {
    case '@':
        v.Set("screen_name", toGet[1:len(toGet)])
        searchResult, err = api.GetUserTimeline(v) //Names Feed
    case '#':
        slice := toGet[1:len(toGet)]
        searchResult, err = api.GetSearch(slice, v) //Tag Feed
    default:
        searchResult, err = api.GetHomeTimeline(v) //Home Feed
    }
    if err != nil {
        err = errors.New(co.Lang("could not connect to twitter"))
    } else {
        file.Seek(0, 0)
        enc := json.NewEncoder(file)

        for i, tweet := range searchResult {
            if err := enc.Encode(&tweet); err != nil {
                err = errors.New(co.Lang(strings.Join([]string{"problem encoding tweet", strconv.Itoa(i), "to json file", fileName}, " ")))
            } else {
                file.Sync()
            }
        }
    }
}
file.Close()
return v.Get("since_id"), err

}

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