import os
import random
import re
import sys
import time
import glob
import constants
import trigger

class chooser(object):
    """Base class of a thing that chooses pages"""
    def get_page_list(self):
        now = time.time()
        valid_filename = re.compile("([^_]+)_(\d+)_([^\.]+)\.html")
        filenames = []
        pages = [ f for f in os.listdir(constants.pages_dir)
                  if os.path.isfile(os.path.join(constants.pages_dir, f))]
        for page in pages:
            result = re.match(valid_filename, page)
            if result != None:
                print(('chooser: candidate page: "%s"' % page))
                if (result.group(3) != "none"):
                    freshness_requirement = int(result.group(3))
                    last_modified = int(os.path.getmtime(
                        os.path.join(constants.pages_dir, page)))
                    age = (now - last_modified)
                    if (age > freshness_requirement):
                        print(('chooser: "%s" is too old.' % page))
                        continue
                filenames.append(page)
        return filenames

    def choose_next_page(self):
        pass

class weighted_random_chooser(chooser):
    """Chooser that does it via weighted RNG"""
    def __init__(self):
        self.last_choice = ""
        self.valid_filename = re.compile("([^_]+)_(\d+)_([^\.]+)\.html")
        self.pages = None
        self.count = 0

    def choose_next_page(self):
        if (self.pages == None or
            self.count % 100 == 0):
            self.pages = self.get_page_list()

        total_weight = 0
        weights = []
        for page in self.pages:
            result = re.match(self.valid_filename, page)
            if result != None:
                weight = int(result.group(2))
                weights.append(weight)
                total_weight += weight

        if (total_weight <= 0):
            raise error

        while True:
            pick = random.randrange(0, total_weight - 1)
            so_far = 0
            for x in range(0, len(weights)):
                so_far += weights[x]
                if (so_far > pick and
                    self.pages[x] != self.last_choice):
                    self.last_choice = self.pages[x]
                    self.count += 1
                    return self.pages[x]

class weighted_random_chooser_with_triggers(weighted_random_chooser):
    """Same as WRC but has trigger events"""
    def __init__(self, trigger_list):
        weighted_random_chooser.__init__(self)
        self.trigger_list = trigger_list
        self.page_queue = set(())

    def check_for_triggers(self):
        triggered = False
        for t in self.trigger_list:
            x = t.get_triggered_page_list()
            if x != None and len(x) > 0:
                for y in x:
                    self.page_queue.add(y)
                    triggered = True
        return triggered

    def choose_next_page(self):
        if (self.pages == None or
            self.count % 100 == 0):
            self.pages = self.get_page_list()

        triggered = self.check_for_triggers()

        # First try to satisfy from the page queue
        if (len(self.page_queue) > 0):
            print("Pulling page from queue")
            page = None
            priority = None
            for t in self.page_queue:
                if priority == None or t[1] > priority:
                    page = t[0]
                    priority = t[1]
            self.page_queue.remove((page, priority))
            return page, triggered

        # Fall back on weighted random choice.
        else:
            return weighted_random_chooser.choose_next_page(self), False

class rotating_chooser(chooser):
    """Chooser that does it in a rotation"""
    def __init__(self):
        self.valid_filename = re.compile("([^_]+)_(\d+)_([^\.]+)\.html")
        self.pages = None
        self.current = 0
        self.count = 0

    def choose_next_page(self):
        if (self.pages == None or
            self.count % 100 == 0):
            self.pages = self.get_page_list()

        if len(self.pages) == 0:
            raise error

        if (self.current >= len(self.pages)):
            self.current = 0

        page = self.pages[self.current]
        self.current += 1
        self.count += 1
        return page

#x = weighted_random_chooser_with_triggers(None)