#!/usr/bin/python
"""Daemon that performs mergebot operations and manages the associated work.
"""

import sys
import socket
import select
import os
import time
import trac
import base64

from threading import Thread

from mergebot.BranchActor import BranchActor
from mergebot.RebranchActor import RebranchActor
from mergebot.CheckMergeActor import CheckMergeActor
from mergebot.MergeActor import MergeActor

from mergebot.daemonize import daemonize


class Task(object):
    """Represents a task in the queue with its dependencies.
    """
    task_id = 0
    task_name_to_actor = {
        'merge': MergeActor,
        'branch': BranchActor,
        'rebranch': RebranchActor,
        'checkmerge': CheckMergeActor,
    }
    def __init__(self, master, ticket, action, component, version, summary,
                 requestor):
        self.id = Task.task_id = Task.task_id + 1
        self.master = master
        self.action = action.lower()
        if action not in Task.task_name_to_actor.keys():
            raise Exception('Invalid task type %s' % action)
        self.ticket = ticket
        self.component = component
        self.version = version
        self.summary = summary
        self.requestor = requestor
        self.blocked_by = []
        self._queued = False
        self._running = False
        self._completed = False

    def find_blockers(self, tasks):
        """Adds existing tasks that block this task to this task's blocked_by
        list.
        """
        for task in tasks:
            # Tasks for different components are completely independent
            if task.component == self.component:
                is_blocked = False
                # if self.version is a ticket ID, then any action other than
                # 'checkmerge' on the parent ticket blocks this action
                if self.version.startswith('#'):
                    parent_ticket = int(self.version.lstrip('#'))
                    if task.ticket == parent_ticket and task.action != 'checkmerge':
                        is_blocked = True
                # Any action other than checkmerge on a child ticket of ours blocks us
                if task.version.startswith('#'):
                    parent_ticket = int(task.version.lstrip('#'))
                    if self.ticket == parent_ticket and task.action != 'checkmerge':
                        is_blocked = True
                # If (re)branching, then blocked by other tickets that are merging _to_ self.version
                if self.action == 'branch' or self.action == 'rebranch':
                    if task.action == 'merge' and task.version == self.version:
                        is_blocked = True
                # A merge operation targeting our version blocks us
                if task.action == 'merge' and task.version == self.version:
                    is_blocked = True
                # If there is another queued operation for this same ticket,
                # that task blocks this one
                if self.ticket == task.ticket:
                    is_blocked = True

                if is_blocked:
                    self.blocked_by.append(task)
        return len(self.blocked_by)

    def other_task_completed(self, task):
        """Remove the given task from this task's blocked_by list.
        """
        if task in self.blocked_by:
            self.blocked_by.remove(task)
        return len(self.blocked_by)

    def queued(self):
        """Mark this task ask queued to run.
        """
        self._queued = True

    def started(self):
        """Mark this task as running/started.
        """
        self._running = True

    def completed(self):
        """Mark this task as completed/zombie.
        """
        self._completed = True

    def get_state(self):
        """Return a single-character indicator of this task's current state.

        Tasks are:
            Pending if they are ready to run.
            Waiting if they are blocked by another task.
            Running if they are currently being done.
            Queued if they have been sent to a worker but not yet begun.
            Zombie if they have been completed.
        """
        if self._completed:
            state = 'Z'#ombie
        elif self._running:
            state = 'R'#unning
        elif self._queued:
            state = 'Q'#ueued
        elif self.blocked_by:
            state = 'W'#aiting
        else:
            state = 'P'#ending
        return state

    def execute(self):
        """Performs the actions for this task.
        """
        work_dir = os.path.join(self.master.work_dir, 'worker-%s' % self.id)
        actor = Task.task_name_to_actor[self.action](work_dir,
            self.master.repo_url, self.master.repo_dir, self.ticket,
            self.component, self.version, self.summary, self.requestor)
        self.results, self.result_comment, self.success = actor.execute()
        
    def __str__(self):
        summary = base64.b64encode(self.summary)
        return ','.join([str(e) for e in (self.id, self.get_state(),
            self.ticket, self.action, self.component, self.version,
            self.requestor, summary)])


class Worker(object):
    """Thread to do the work for an operation; has a work area it is
    responsible for.
    """
    def __init__(self, num, work_dir):
        self.number = num
        self.work_dir = work_dir
        self.task = None
        self.inbox_read, self.inbox_write = os.pipe()
        self.notifier_read, self.notifier_write = os.pipe()
        self.thread = Thread(target=self.work)
        self.thread.setDaemon(True)
        self.thread.start()

    def queue(self, task):
        task.queued()
        self.task = task
        os.write(self.inbox_write, 'q')

    def _dequeue(self):
        os.read(self.inbox_read, 1)

    def _completed(self):
        self.task.completed()
        os.write(self.notifier_write, 'd')

    def ack_complete(self):
        os.read(self.notifier_read, 1)
        return self.task

    def notifier(self):
        return self.notifier_read

    def work(self):
        while True:
            # get a task -- blocking read on pipe?
            self._dequeue()
            # do the task
            log_filename = os.path.join(self.work_dir, 'worker.%s' % self.number)
            open(log_filename, 'a').write(str(self.task) + ' started %s\n' % time.time())
            self.task.started()
            self.task.execute()
            open(log_filename, 'a').write(str(self.task) + ' completed %s\n' % time.time())
            # notify master of completion -- write to pipe?
            self._completed()


class Mergebot(object):
    # Maybe I should just pass this the trac environment dir and have it create
    # an environment, then pull config info from that.
    def __init__(self, trac_dir):
        self.trac_dir = os.path.abspath(trac_dir)
        self.trac_env = trac.env.open_environment(self.trac_dir)
        config = self.trac_env.config
        self.listen_on = (config.get('mergebot', 'listen.ip'),
                          config.getint('mergebot', 'listen.port'))
        self.work_dir = config.get('mergebot', 'work_dir')
        if not os.path.isabs(self.work_dir):
            self.work_dir = os.path.join(self.trac_dir, self.work_dir)
        self.repo_url = config.get('mergebot', 'repository_url')
        repo_dir = config.get('trac', 'repository_dir')
        if not os.path.isabs(repo_dir):
            repo_dir = os.path.join(self.trac_dir, repo_dir)
        self.repo_dir = repo_dir

        self.listening = None
        self.worker_count = config.getint('mergebot', 'worker_count')
        self.task_list = []

    def run(self):
        """Run forever, handling requests.
        """
        self.listening = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.listening.bind(self.listen_on)
        self.listening.listen(10)
        open_sockets = []
        workers = [Worker(i, work_dir=self.work_dir) for i in range(self.worker_count)]
        active = []
        try:
            while True:
                fds = [self.listening] + open_sockets + [w.notifier() for w in
                                                         active]
                readable, _writeable, _other = select.select(fds, [], [])
                for s in readable:
                    if s is self.listening:
                        new_socket, _address = self.listening.accept()
                        open_sockets.append(new_socket)
                    elif s in open_sockets:
                        data = s.recv(4096)
                        for line in data.rstrip('\n').split('\n'):
                            if line == '':
                                open_sockets.remove(s)
                                s.close()
                            elif line[:4].upper() == 'QUIT':
                                open_sockets.remove(s)
                                s.close()
                            else:
                                response = self.handle_command(line)
                                if response:
                                    s.send(response)
                                # I think we're going to want to make this a
                                # single-shot deal
                                #s.close()
                                #open_sockets.remove(s)
                    else:
                        # Must be an active worker telling us it is done
                        worker = [w for w in active if w.notifier() == s][0]
                        task = worker.ack_complete()
                        active.remove(worker)
                        workers.insert(0, worker)
                        # On failure, cancel all tasks that depend on this one.
                        if not task.success:
                            self._remove_dependant_tasks(task)
                        self._remove_task(task)
                        self._update_ticket(task)
                # TODO: need to handle connections that the other end
                # terminates?

                # Assign a task to a worker
                available_workers = list(workers)
                pending = [t for t in self.task_list if t.get_state() == 'P']
                for w, t in zip(available_workers, pending):
                    w.queue(t)
                    workers.remove(w)
                    active.append(w)

        except KeyboardInterrupt:
            print 'Exiting due to keyboard interrupt.'
        except Exception, e:
            print 'Exiting due to: ', e
            raise
        self.listening.close()

    def handle_command(self, command):
        """Takes input from clients, and calls the appropriate sub-command.
        """
        parts = command.strip().split()
        if not parts:
            return '\n'
        command = parts[0].upper()
        args = parts[1:]

        response = 'unrecognized command "%s"' % command
        if command == 'LIST':
            response = self.command_list()
        elif command == 'ADD':
            response = self.command_add(args)
        elif command == 'CANCEL':
            response = self.command_cancel(args)
        # etc...
        return response + '\n'

    def command_list(self):
        """Returns a listing of all active tasks.
        """
        listing = []
        for task in self.task_list:
            listing.append(str(task))
        return '\n'.join(listing) + '\nOK'

    def command_add(self, args):
        # create a new task object and add it to the pool
        try:
            ticket, action, component, version, requestor = args
        except ValueError:
            return 'Error: wrong number of args: add <ticket> <action> ' \
                '<component> <version> <requestor>\nGot: %r' % args
        try:
            ticket = int(ticket.strip('#'))
        except ValueError:
            return 'Error: invalid ticket number "%s"' % ticket

        trac_ticket = trac.ticket.Ticket(self.trac_env, ticket)        
        summary = trac_ticket['summary']
        new_task = Task(self, ticket, action, component, version, summary,
                        requestor)
        new_task.find_blockers(self.task_list)
        self.task_list.append(new_task)
        # and trigger the worker threads if needed
        return 'OK'

    def command_cancel(self, args):
        try:
            tasknum = int(args[0])
        except ValueError:
            return 'Error'
        except IndexError:
            return 'Error'
        found = [t for t in self.task_list if t.id == tasknum]
        if len(found) != 1:
            return 'Error: Not found'
        dead = found[0]
        dead_state = dead.get_state()
        if dead_state not in ['W', 'P']:
            return 'Error: Cannot kill task (state %s)' % dead_state
        self._remove_dependant_tasks(dead)
        self._remove_task(dead)
        return 'OK'

    def _remove_task(self, dead):
        """Removes the given task from the queue.
        Removes task as a dependency from any other tasks in the queue.
        Assumes the task is in the task_list.
        """
        try:
            self.task_list.remove(dead)
        except ValueError:
            self.trac_env.log.error("Task %s not in task_list when asked to remove" % dead)
        for t in self.task_list:
            if dead in t.blocked_by:
                t.blocked_by.remove(dead)

    def _remove_dependant_tasks(self, task):
        for t in self.task_list:
            if task in t.blocked_by:
                self._remove_dependant_tasks(t)
                self._remove_task(t)

    def _update_ticket(self, task):
        ticket = trac.ticket.Ticket(self.trac_env, task.ticket)        
        if task.results or task.result_comment:
            for key, value in task.results.items():
                ticket[key] = value
            try:
                ticket.save_changes('mergebot', task.result_comment)
            except:
                time.sleep(1) # attempt to avoid "pysqlite2.dbapi2.IntegrityError: columns ticket, time, field are not unique"
                ticket.save_changes('mergebot', task.result_comment)


def main(args):
    foreground = False
    if args[0] == '-f':
        foreground = True
        args = args[1:]
    trac_dir = args[0]
    if not foreground:
        daemonize()
    bot = Mergebot(trac_dir)
    bot.run()

def run():
    main(sys.argv[1:])

if __name__ == '__main__':
    run()