import os
import glob
import datetime

def last_of(us):
    return us[-1]


class Flick:
    def __init__(self, basename, save_dir=".", delay=10, stamp_sep='_', date_template="%Y-%m-%dT%H:%M:%S"):
        self.base = basename
        self.date_template = date_template
        self.date_sep = stamp_sep
        self.save_dir = save_dir
        self.delay = delay

        # Make a glob search expression with the date template.
        self.fields = {'Y':4,'m':2,'d':2,'H':2,'M':2,'S':2}
        self.glob_template = self.date_template
        for k in self.fields:
            self.glob_template = self.glob_template.replace("%"+k,'?'*self.fields[k])

    def __iter__(self):
        return self

    def make(self, save_dir, name, date, ext):
        # Current date with second precision (without micro-seconds).
        tag = date.isoformat().split(".")[0]
        flick = name + self.date_sep + tag + ext
        return os.path.join(save_dir, flick)

    def next(self):
        full = os.path.expanduser(self.base)
        head = os.path.basename(full)
        name,ext = os.path.splitext(head)

        pattern = name+self.date_sep+self.glob_template+ext
        existing = glob.glob(os.path.join(self.save_dir,pattern))

        date_now = datetime.datetime.now()
        #print(date_now)

        if existing:
            last = last_of(sorted(existing))
            root,ext = os.path.splitext(last)
            last_name = os.path.basename(root)
            # As we globbed the pattern, no need for complex regexp.
            last_tag = last_of(last_name.split(self.date_sep))
            last_date = datetime.datetime.strptime(last_tag, self.date_template)

            print("Last flick on:",last_date.isoformat())

            assert(last_date <= date_now)
            if date_now - last_date < datetime.timedelta(seconds=self.delay):
                return self.make(self.save_dir,name,last_date,ext)

        return self.make(self.save_dir,name,date_now,ext)


if __name__=="__main__":
    import sys

    f = Flick(sys.argv[1])
    print(f.next())