# Copyright (C) 2012  Codethink Limited
# 

import json
import logging
import re
import glob
import os
import time
import fnmatch

default_values = [
    ( u'create', u'never' ),
    ( u'destroy', u'never' ),
    ( u'interval', u'1m' ),
    ( u'stagger', False ),
    ( u'tarball', u'never' ),
    ( u'type', u'invalid_type' ),
]

valid_interval = re.compile(r"^([1-9][0-9]*)([mhd])?$")
interval_mults = {
    None: 1,
    'm': 60,
    'h': 60 * 60,
    'd': 60 * 60 * 24,
}
class LorryControllerConfig(object):
    '''This encapsulates the configuration for lorry-controller.'''

    def __init__(self, app, confpath):
        self.app = app
        self.confpath = confpath
        self.lorries = {}
        self.configs = {}
        self.duetimes = {}
        self.troves = []

    def parse_config(self):
        confpath = os.path.join(self.app.settings['work-area'], self.confpath)
        logging.info("Parsing configuration: %s" % confpath)
        try:
            with open(confpath, "r") as fh:
                self._raw_conf = json.load(fh)
        except Exception, e:
            logging.error("Unable to parse: %r" % e)
            raise
        logging.debug("Validating configuration semantics")
        self._validate__raw_conf()
        logging.info("Configuration loaded")

    def _validate__raw_conf(self):
        '''Validate the entire raw config.'''
        if type(self._raw_conf) != list:
            self._give_up("Configuration was not a list.")
        for entry in self._raw_conf:
            if type(entry) != dict:
                self._give_up("Configuration entry was not a dict.")
            if type(entry.get('type', None)) != unicode:
                self._give_up("Configuration entry lacked a suitable 'type' "
                             "field.")
            # Set the defaults
            for key, defval in default_values:
                entry[key] = entry.get(key, defval)
            # And validate the generic values
            self._validate__generics(entry)
            # Now validate the rest
            validator = getattr(self, '_validate_' + entry['type'], None)
            if validator is None:
                self._give_up("Configuration entry had unknown type: %s" %
                             entry['type'])
            validator(entry)

    def _validate__generics(self, entry):
        '''Validate the generic entries such as 'uuid'.'''
        if type(entry.get('uuid', None)) != unicode:
            self._give_up("UUID missing, cannot reconcile without it!")
        if entry['uuid'] in self.configs:
            self._give_up("UUID is not unique")
        self.configs[entry['uuid']] = entry
        for key, defval in default_values:
            if type(defval) != type(entry[key]):
                self._give_up("Invalid type for '%s': %r" % (key, entry[key]))
        self._validate__when(entry, 'create', ["always", "never"])
        self._validate__when(entry, 'destroy',
                             ["always", "never", "unchanged"])
        self._validate__when(entry, 'tarball', ["always", "never", "first"])
        entry['interval-parsed'] = self._parse_interval(entry['interval'])
        if 'ls-interval' in entry:
            entry['ls-interval-parsed'] = \
                self._parse_interval(entry['ls-interval'])

    def _validate__when(self, entry, key, valid_whens):
        if entry[key] not in valid_whens:
            self._give_up("Invalid value for %s: %s" % (key, entry[key]))

    def _parse_interval(self, interval):
        m = valid_interval.match(interval.lower())
        if m is None:
            self._give_up("Unable to parse '%s' as an interval" % interval)
        num, mult = m.groups()
        num = int(num)
        mult = interval_mults.get(mult, None)
        if mult is None:
            self._give_up("Somehow, '%s' managed to appear as a multiplier!" %
                         m.group(2))
        logging.debug("Converted interval %r to %r", interval, (num * mult))
        return num * mult

    def _validate_lorries(self, entry):
        '''Validate a 'lorries' stanza.'''
        if type(entry.get('globs', None)) != list:
            self._give_up("Lorries stanzas need lists for their 'globs'")
        if entry.get('prefix', None) is None:
            entry['prefix'] = u""
        if type(entry['prefix']) != unicode:
            self._give_up("Lorry prefixes should be strings.")
        my_lorries = set()
        git_base = os.path.join(self.app.settings['work-area'], 'git')
        for glob_entry in entry['globs']:
            if type(glob_entry) != unicode:
                self._give_up("Lorries globs should be strings")
            fullglob = os.path.join(git_base, glob_entry)
            my_lorries = my_lorries.union(set(glob.iglob(fullglob)))
        for lorry in my_lorries:
            if not lorry.startswith(git_base):
                self._give_up("Glob found %s which is outside the git base")

        logging.debug("Expanded globs in entry to %d lorry files" % 
                      len(my_lorries))
        logging.debug("Loading lorries into memory, please wait...")

        my_lorry_names = set()
        for lorry in my_lorries:
            try:
                with open(lorry, "r") as fh:
                    lorry_json = json.load(fh)
                for name, content in lorry_json.iteritems():
                    fullname = os.path.join(entry['prefix'], name)
                    if self.lorries.get(fullname, None) is not None:
                        self._give_up("Lorry repeated: %s" % fullname)
                    content['controller-uuid'] = entry['uuid']
                    if not content.has_key('source-HEAD'):
                        content['source-HEAD'] = 'refs/heads/master'
                    my_lorry_names.add(fullname)
                    self.lorries[fullname] = content
            except Exception, e:
                logging.warning("Unable to parse %s, because of %s. "
                                "Moving on" % (lorry, e))

        # Now calculate the 'next due' time for every lorry we just parsed
        starttime = time.time() - 1
        endtime = starttime + entry['interval-parsed']
        step = 0
        if entry['stagger']:
            step = (endtime - starttime) / (len(my_lorry_names) + 1)
        for lorry_name in my_lorry_names:
            self.duetimes[lorry_name] = starttime
            starttime += step

        logging.debug("Now loaded %d lorries" % len(self.lorries.keys()))

    def _validate_trove(self, entry):
        # Validate top levels
        if type(entry.get('trovehost', None)) != unicode:
            self._give_up("Trove host %r is not a string" %
                          entry.get('trovehost', None))
        if 'ls-interval-parsed' not in entry:
            self._give_up("No ls-interval specified for %s" %
                          entry['trovehost'])
        if type(entry.get('prefixmap', None)) != dict:
            self._give_up("Prefixmap not a dict for %s" %
                          entry['trovehost'])
        if type(entry.get('ignore', [])) != list:
            self._give_up("Ignore is not a list for %s" %
                          entry['trovehost'])
        # Validate prefixmap
        for local, remote in entry['prefixmap'].iteritems():
            if type(local) != unicode:
                self._give_up("Local part of prefixmap is not a string: %r" %
                              local)
            if type(remote) != unicode:
                self._give_up("Remote part of prefixmap is not a string: %r" %
                              remote)
        # Validate ignore
        for ign in entry.get('ignore', []):
            if type(ign) != unicode:
                self._give_up("Part of ignore list is not a string: %r" % ign)

        self.troves.append(entry)

    def update_trove(self, trove, state):
        logging.info("Processing trove %s (%s)" % (trove['trovehost'],
                                                   trove['uuid']))
        # 1. Ensure that if we need to 'ls' the trove, we do it
        now = time.time()
        listcmdargs = ["ssh", "-oStrictHostKeyChecking=no",
                       "-oBatchMode=yes", "git@" + trove['trovehost'], "ls",
                       "--verbose"]
        state['next-vls'] = state.get('next-vls', now - 1)
        if state['next-vls'] < now:
            exit, out, err = self.app.maybe_runcmd(listcmdargs, dry=True)
            if exit == 0:
                repo_info = {}
                for entry in [x for x in out.split("\n") if x != ""]:
                    while entry.find("  ") > -1:
                        entry = entry.replace("  ", " ")
                    elems = entry.split(" ")
                    this_repo = {
                        "perm": elems[0],
                        "name": elems[1],
                        "head": elems[2],
                        "desc": " ".join(elems[3:]),
                        }
                    repo_info[elems[1]] = this_repo
                state['last-ls-output'] = repo_info
                logging.info("ls interval %d" % trove['ls-interval-parsed'])
                logging.info("next-vls was %s" % time.asctime(time.gmtime(state['next-vls'])))
                while state['next-vls'] < now:
                    state['next-vls'] += trove['ls-interval-parsed']
                logging.info("next-vls now %s" % time.asctime(time.gmtime(state['next-vls'])))
            else:
                # Pass through unchanged
                state['last-ls-output'] = state.get('last-ls-output', {})

        def ignored(reponame):
            for pattern in trove['ignore']:
                if fnmatch.fnmatch(reponame, pattern):
                    return True
            return False

        # 2. For every entry in last-ls-output, construct a lorry if we want it
        lorries_made = set()
        for remotereponame, info in state['last-ls-output'].iteritems():
            localreponame = None
            for local, remote in trove['prefixmap'].iteritems():
                if remotereponame.startswith(remote+"/"):
                    localreponame = "%s/%s" % (local,
                                               remotereponame[len(remote)+1:])
            if ((not ignored(remotereponame)) and (localreponame is not None)):
                # Construct a lorry for this one.
                lorry = {
                    "type": "git",
                    "url": "ssh://git@%s/%s.git" % (trove['trovehost'],
                                                        remotereponame),
                    "controller-uuid": trove['uuid'],
                    "source-HEAD": info["head"],
                    "refspecs": [ "+refs/heads/*:refs/heads/*",
                                  "+refs/tags/*:refs/tags/*" ]
                    }
                if localreponame in self.lorries:
                    logging.warn("Skipping %s (%s from %s) because we already "
                                 "have something for that." % (
                            localreponame, remotereponame, trove['trovehost']))
                else:
                    self.lorries[localreponame] = lorry
                    lorries_made.add(localreponame)

        # 3. Now schedule all those lorries in case they're new
        starttime = time.time() - 1
        endtime = starttime + trove['interval-parsed']
        step = 0
        if trove['stagger']:
            step = (endtime - starttime) / (len(lorries_made)+1)
        for lorry_name in lorries_made:
            self.duetimes[lorry_name] = starttime
            starttime += step

        logging.debug("Generated %d lorries from that trove" %
                      len(lorries_made))

    def update_troves(self, statemgr):
        # Now that we have a state manager we can look at the trove data.
        for trove in self.troves:
            self.app.html.set_processing(trove['uuid'])
            trove_state = statemgr.get_trove(trove['uuid'])
            self.update_trove(trove, trove_state)

    def _give_up(self, *args, **kwargs):
        logging.error(*args, **kwargs)
        raise SystemExit(5)