#We can't be sure which location is the best

def scrapeTideForecast(self,locations,bestguess=None):

#Lets try a one-shot with what we believe is the best location first - avoids hammering the API

establishedLocation = None

if bestguess:

logger.debug("Attempting oneshot lookup against {}".format(bestguess))

page = requests.post("http://www.tide-forecast.com/locations/catch",data={'query':bestguess})

if page.status_code == 200:

establishedLocation = bestguess

if page.status_code != 200:

logger.debug("Oneshot failed, removing {} from locations".format(bestguess))

locations.remove(bestguess)

for location in locations:

page = requests.post("http://www.tide-forecast.com/locations/catch",data={'query':location})

if page.status_code == 200:

logger.debug("Lookup for {} succeeded!".format(location))

establishedLocation = location

break

else:

logger.debug("Lookup for {} failed".format(location))

if page.status_code != 200:

#Loop completed without finding anything valuable

raise Exception("Couldn't find a viable location")

root = html.document_fromstring(page.text)

scripts = root.xpath("//script[@src]")

locname = None

for script in scripts:

if establishedLocation.lower() in script.get('src').lower():

for part in script.get('src').split("/"):

if establishedLocation.lower() in part.lower():

locname = part.split(".")[0]

if not locname:

logger.error("Could not find location {}".format(establishedLocation))

return

data = []

logger.debug("Fetching javascript data for {}".format(locname))

page = requests.get("http://www.tide-forecast.com/tides/{}.js".format(locname))

if page.status_code != 200:

logger.error(page.text)

logger.error('locname = {}'.format(locname))

for line in page.text.split():

cleanline = line.strip('[').strip(',').strip(']')

elements = cleanline.split(",")

if len(elements) == 4:

ydelta = time.localtime(int(elements[2])+int(elements[1]))

ld = {'x' : int(elements[0]),

'y' : int(elements[1]),

'epoch' : int(elements[2]),

'height' : float(elements[3]),

'date' : time.strftime("%d-%m-%Y", ydelta),

'time' : time.strftime("%H:%M", ydelta),

'utc' : int(elements[2])+int(elements[1]),

}

data.append(ld)

return data,establishedLocation

def getTidesForDate(self,dataset,datestr):

day = []

for d in dataset:

if d['date'] == datestr:

day.append(d)

return day

def getTides(self,wholedataset,datestr):

dataset = self.getTidesForDate(wholedataset,datestr)

tides = []

state = 'unknown'

for i in range(1,len(dataset)):

if state == 'unknown':

if dataset[i]['height'] < dataset[i-1]['height']:

state = 'dropping'

else:

state = 'rising'

#Rather than looking for the lowest value we look for when the tide turns

#Possibly need to introduce some countback in case data sets are the same ie slack water

if state == 'dropping':

if dataset[i]['height'] > dataset[i-1]['height']:

#logger.debug("{} {:.1f}m - Low tide".format(dataset[i-1]['time'],dataset[i-1]['height']))

heightPretty = "{:.1f}m".format(dataset[i-1]['height'])

tides.append({'time':dataset[i-1]['time'], 'height':dataset[i-1]['height'], 'type':'Low', 'heightPretty':heightPretty, 'utc':dataset[i-1]['utc']})

state = 'rising'

if state == 'rising':

if dataset[i]['height'] < dataset[i-1]['height']:

#logger.debug("{} {:.1f}m - High tide".format(dataset[i-1]['time'],dataset[i-1]['height']))

heightPretty = "{:.1f}m".format(dataset[i-1]['height'])

tides.append({'time':dataset[i-1]['time'], 'height':dataset[i-1]['height'], 'type':'High', 'heightPretty':heightPretty, 'utc':dataset[i-1]['utc']})

state = 'dropping'

if dataset[i]['height'] == dataset[i-1]['height']:

logger.info("Two adjacent tides with height {}m".format(dataset[i]['height']))