#!/usr/bin/env python

from datetime import timedelta

from aman.sys.aco.Colony import Colony
from aman.sys.aco.Constraints import SpacingConstraints
from aman.types.Inbound import Inbound

class CostFunction:
    def __init__(self, colony : Colony):
        self.Spacings = SpacingConstraints()
        self.Colony = colony

        # initialize the tracker which inbound arrives at which runway
        self.RunwayInbounds = {}
        for runway in self.Colony.Configuration.PreceedingInbounds:
            self.RunwayInbounds[runway] = self.Colony.Configuration.PreceedingInbounds[runway]
        for runway in self.Colony.Configuration.RunwayConstraints.ActiveArrivalRunways:
            if not runway in self.RunwayInbounds:
                self.RunwayInbounds[runway] = None

        return

    def validateWtc(inbound : Inbound):
        wtc = inbound.Report.aircraft.wtc.upper()
        if 'L' == wtc or 'M' == wtc or 'H' == None or 'J' == None:
            return wtc
        else:
            return None

    def calculateEta(self, runway : str, inbound : Inbound):
        if None == self.RunwayInbounds[runway]:
            return inbound.EstimatedArrivalTime

        preceedingInbound = self.RunwayInbounds[runway]

        # get the WTC constrained ETA
        wtcPre = CostFunction.validateWtc(preceedingInbound)
        wtcThis = CostFunction.validateWtc(inbound)
        if None == wtcPre or None == wtcThis:
            spacing = 3
        else:
            spacing = self.Spacings[wtcPre][wtcThis]
        delay = timedelta(seconds = round(spacing / inbound.PerformanceData.speedApproach + 0.5))
        wtcETA = self.RunwayInbounds[runway].EstimatedArrivalTime + delay

        # get the staggered time spacing
        dependentRunway = self.Colony.Configuration.RunwayConstraints.findDependentRunway(runway)
        if None != dependentRunway and None != self.RunwayInbounds[dependentRunway.Runway.name]:
            if preceedingInbound.EstimatedArrivalTime < self.RunwayInbounds[dependentRunway.Runway.name].EstimatedArrivalTime:
                delay = timedelta(seconds = round(3 / inbound.PerformanceData.speedApproach + 0.5))
                staggeredETA = self.RunwayInbounds[dependentRunway.Runway.name].EstimatedArrivalTime + delay
            else:
                staggeredETA = wtcETA
        else:
            staggeredETA = wtcETA

        # get the runway time spacing
        spacing = self.Colony.Configuration.RunwayConstraints.findRunway(runway).Spacing
        delay = timedelta(seconds = round(spacing / inbound.PerformanceData.speedApproach + 0.5))
        runwayETA = self.RunwayInbounds[runway].EstimatedArrivalTime + delay

        # get the biggest ETA to define the maximum but ensure that we are not earlier than the ITA
        # TODO model the TTG-concept depending on the distance to the IAF
        candidate = max(max(wtcETA, staggeredETA), runwayETA)
        if candidate < inbound.InitialArrivalTime:
            return inbound.InitialArrivalTime
        else:
            return candidate

    def selectArrivalRunway(self, inbound : Inbound):
        availableRunways = []
        for runway in self.Colony.Configuration.RunwayConstraints.ActiveArrivalRunways:
            availableRunways.append(runway)

        #if 1 < len(availableRunways):
            # TODO filter based on type
            # TODO filter based on airline
            # ensure that at least one runway is available

        # fallback to check if we have available runways
        if 0 == len(availableRunways):
            return self.Colony.Configuration.RunwayConstraints.ActiveArrivalRunways[0]

        # start with the beginning
        selectedRunway = self.Colony.Configuration.RunwayConstraints.findRunway(availableRunways[0])
        eta = self.calculateEta(availableRunways[0], inbound)

        # get the runway with the earliest ETA
        for runway in availableRunways:
            candidate = self.calculateEta(runway, inbound)
            if eta > candidate:
                selectedRunway = self.Colony.Configuration.RunwayConstraints.findRunway(runway)
                eta = candidate

        return selectedRunway