#!/usr/bin/env python

############################################################################
# Control class for beermon
#
# $Id: Control.py,v 1.4 2008/01/29 11:27:20 darius Exp $
#
# Depends on: Python 2.3 (I think)
#
############################################################################
#
# Copyright (C) 2007 Daniel O'Connor. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
#
############################################################################

import threading, ConfigParser, time

class ThreadDied(Exception):
    """Raised when the monitor thread has died for some reason"""
    pass

class Control():
    """This class is responsible for controlling the temperature of
the fermenter by switching the heater & cooler."""
    staleDataTime = 30
    
    def __init__(self, _log, m, conf):
        """m is a MonitorDev object, _log is a logging object, conf is a ConfigParser object"""
        global log
        log = _log

        self.m = m

        self.targetTemp = conf.getfloat('control', 'targetTemp')
        self.hysteresis = conf.getfloat('control', 'hysteresis')
        self.pollInterval = conf.getfloat('control', 'pollInterval')

        log.debug("target temperature - %3.2f" % (self.targetTemp))
        log.debug("hysteresis - %3.2f" % (self.hysteresis))
        log.debug("pollInterval - %d" % (self.pollInterval))

        # We sleep on this, using time.sleep() doesn't work well in a
        # threaded environment (eg ctrl-c will be blocked until the
        # timeout expires.)
        self.cv = threading.Condition()
        self.cv.acquire()
        
    def doit(self):
        """Runs forever controlling the temperature until something breaks or interrupted"""
        log.debug("=== Starting ===")
        log.debug("Fermenter	Fridge	Ambient	State	New State")
        
        while True:
            # Check if the monitor thread has died
            if (not self.m.isAlive()):
                raise ThreadDied, "Monitor thread has died"

            # Check for stale data
            if (self.m.lastUpdate[self.m.fermenterId] + self.staleDataTime < time.time()):
                log.debug("Stale data")
                self.cv.wait(self.pollInterval)
                self.m.setState('idle')
                continue

            # Work out what state we should go into
            nextState = "-"
            # Temperature diff, -ve => too cold, +ve => too warm
            diff = self.m.temps[self.m.fermenterId] - self.targetTemp
            if (self.m.currState == 'idle'):
                # If we're idle then only heat or cool if the temperate difference is out of the
                # hysteresis band
                if (abs(diff) > self.hysteresis):
                    if (diff < 0 and self.m.minHeatOffTime + self.m.lastHeatOff < time.time()):
                        nextState = 'heat'
                    elif (diff > 0 and self.m.minHeatOffTime + self.m.lastHeatOff < time.time()):
                        nextState = 'cool'
            elif (self.m.currState == 'cool'):
                # Work out if we should go idle (based on min on time & overshoot)
                if (diff + self.m.minCoolOvershoot < 0 and self.m.minCoolOnTime + self.m.lastCoolOn < time.time()):
                    nextState = 'idle'
            elif (self.m.currState == 'heat'):
                # Ditto
                if (diff - self.m.minHeatOvershoot > 0 and self.m.minHeatOnTime + self.m.lastHeatOn < time.time()):
                    nextState = 'idle'
            else:
                # Not possible..
                raise KeyError

            log.debug("%3.2f   	%3.2f	%3.2f	%s	%s" %
                      (self.m.temps[self.m.fermenterId],
                       self.m.temps[self.m.fridgeId], self.m.temps[self.m.ambientId],
                       self.m.currState, nextState))

            if (nextState != "-"):
                self.m.setState(nextState)

            self.cv.wait(self.pollInterval)