#!/usr/bin/env python

import math
import sys

from datetime import datetime, timedelta

from aman.config.AirportSequencing import AirportSequencing
from aman.formats.SctEseFormat import SctEseFormat
from aman.sys.WeatherModel import WeatherModel
from aman.types.ArrivalData import ArrivalData
from aman.types.ArrivalRoute import ArrivalRoute
from aman.types.ArrivalWaypoint import ArrivalWaypoint
from aman.types.Runway import Runway
from aman.types.Inbound import Inbound
from aman.types.Waypoint import Waypoint

class Node:
    def findArrivalRoute(iaf : str, runway : Runway, navData : SctEseFormat):
        for arrivalRunway in navData.ArrivalRoutes:
            if arrivalRunway == runway.Name:
                stars = navData.ArrivalRoutes[arrivalRunway]
                for star in stars:
                    if 0 != len(star.Route) and iaf == star.Iaf.Name:
                        return star
        return None

    def arrivalEstimation(self, runway : Runway, star : ArrivalRoute, weather : WeatherModel):
        # calculate remaining trackmiles
        trackmiles = self.PredictedDistanceToIAF
        start = star.Route[0]
        turnIndices = [ -1, -1 ]
        constraints = []
        for i in range(0, len(star.Route)):
            # identified the base turn
            if True == star.Route[i].BaseTurn:
                turnIndices[0] = i
            # identified the final turn
            elif -1 != turnIndices[0] and True == star.Route[i].FinalTurn:
                turnIndices[1] = i
            # skip waypoints until the final turn point is found
            elif -1 != turnIndices[0] and -1 == turnIndices[1]:
                continue

            trackmiles += start.haversine(star.Route[i])

            # check if a new constraint is defined
            altitude = -1
            speed = -1
            if None != star.Route[i].Altitude:
                altitude = star.Route[i].Altitude
            if None != star.Route[i].Speed:
                speed = star.Route[i].Speed
            if -1 != altitude or -1 != speed:
                constraints.append([ trackmiles, altitude, speed ])

            start = star.Route[i]

        # add the remaining distance from the last waypoint to the runway threshold
        trackmiles += start.haversine(runway.Start)

        if turnIndices[0] > turnIndices[1] or (-1 == turnIndices[1] and -1 != turnIndices[0]):
            sys.stderr.write('Invalid constraint definition found for ' + star.Name)
            sys.exit(-1)

        # calculate descend profile
        currentHeading = Waypoint(latitude = self.Inbound.Report.position.latitude, longitude = self.Inbound.Report.position.longitude).bearing(star.Route[0])
        currentIAS = self.Inbound.PerformanceData.ias(self.Inbound.Report.dynamics.altitude, trackmiles)
        currentPosition = [ self.Inbound.Report.dynamics.altitude, self.Inbound.Report.dynamics.groundSpeed ]
        distanceToWaypoint = self.PredictedDistanceToIAF
        flightTimeSeconds = 0
        nextWaypointIndex = 0
        flownDistance = 0.0
        arrivalRoute = [ ArrivalWaypoint(waypoint = star.Route[0], trackmiles = distanceToWaypoint) ]

        while True:
            # check if a constraint cleanup is needed and if a speed-update is needed
            if 0 != len(constraints) and flownDistance >= constraints[0][0]:
                if -1 != constraints[0][2]:
                    currentIAS = min(constraints[0][2], self.Inbound.PerformanceData.ias(self.Inbound.Report.dynamics.altitude, trackmiles - flownDistance))
                    currentPosition[1] = min(weather.calculateGS(currentPosition[0], currentIAS, currentHeading), currentPosition[1])
                constraints.pop(0)

            # search next altitude constraint
            altitudeDistance = 0
            nextAltitude = 0
            for constraint in constraints:
                if -1 != constraint[1]:
                    altitudeDistance = constraint[0]
                    nextAltitude = constraint[1]
                    break

            # check if update of altitude and speed is needed on 3° glide
            if currentPosition[0] > nextAltitude and ((currentPosition[0] - nextAltitude) / 1000 * 3) > (altitudeDistance - flownDistance):
                oldGroundspeed = currentPosition[1]
                descendRate = (currentPosition[1] / 60) / 3 * 1000 / 6
                newAltitude = currentPosition[0] - descendRate
                if 0 > newAltitude:
                    newAltitude = 0

                currentPosition = [ newAltitude, min(weather.calculateGS(newAltitude, currentIAS, currentHeading), currentPosition[1]) ]
                distance = (currentPosition[1] + oldGroundspeed) / 2 / 60 / 6
            else:
                distance = currentPosition[1] / 60 / 6

            # update the statistics
            distanceToWaypoint -= distance
            flownDistance += distance
            newIAS = min(currentIAS, self.Inbound.PerformanceData.ias(currentPosition[0], trackmiles - flownDistance))
            if newIAS < currentIAS:
                currentPosition[1] = min(weather.calculateGS(currentPosition[0], newIAS, currentHeading), currentPosition[1])
                currentIAS = newIAS

            flightTimeSeconds += 10
            if flownDistance >= trackmiles:
                break

            # check if we follow a new waypoint pair
            if 0 >= distanceToWaypoint:
                lastWaypointIndex = nextWaypointIndex
                nextWaypointIndex += 1

                arrivalRoute[-1].FlightTime = timedelta(seconds = flightTimeSeconds)
                arrivalRoute[-1].ETA = self.Inbound.ReportTime + arrivalRoute[-1].FlightTime
                arrivalRoute[-1].PTA = arrivalRoute[-1].ETA
                arrivalRoute[-1].Altitude = currentPosition[0]
                arrivalRoute[-1].IndicatedAirspeed = currentIAS
                arrivalRoute[-1].GroundSpeed = currentPosition[1]

                # check if a skip from base to final turn waypoints is needed
                if -1 != turnIndices[0] and nextWaypointIndex > turnIndices[0] and nextWaypointIndex < turnIndices[1]:
                    nextWaypointIndex = turnIndices[1]

                # update the statistics
                if nextWaypointIndex < len(star.Route):
                    distanceToWaypoint = star.Route[lastWaypointIndex].haversine(star.Route[nextWaypointIndex])
                    currentHeading = star.Route[lastWaypointIndex].bearing(star.Route[nextWaypointIndex])
                    currentPosition[1] = min(weather.calculateGS(currentPosition[0], currentIAS, currentHeading), currentPosition[1])

                    arrivalRoute.append(ArrivalWaypoint(waypoint = star.Route[nextWaypointIndex], trackmiles = arrivalRoute[-1].Trackmiles + distanceToWaypoint))

        return timedelta(seconds = flightTimeSeconds), trackmiles, arrivalRoute

    def __init__(self, inbound : Inbound, referenceTime : datetime, weatherModel : WeatherModel,
                 navData : SctEseFormat, sequencingConfig : AirportSequencing):
        self.PredictedDistanceToIAF = inbound.Report.distanceToIAF
        self.PredictedCoordinate = [ inbound.CurrentPosition.latitude, inbound.CurrentPosition.longitude ]
        self.ArrivalCandidates = {}
        self.Inbound = inbound

        if None == referenceTime or None == sequencingConfig:
            return

        # predict the distance to IAF
        timePrediction = (referenceTime - inbound.ReportTime).total_seconds()
        if 0 != timePrediction and 0 != len(sequencingConfig.ActiveArrivalRunways):
            # calculate current motion information
            course = weatherModel.estimateCourse(inbound.Report.dynamics.altitude, inbound.Report.dynamics.groundSpeed, inbound.Report.dynamics.heading)
            tempWaypoint = Waypoint(longitude = inbound.CurrentPosition.longitude, latitude = inbound.CurrentPosition.latitude)
            gs = inbound.Report.dynamics.groundSpeed * 0.514444 # ground speed in m/s
            distance = gs * timePrediction
            self.PredictedCoordinate = tempWaypoint.project(course, distance)

            # calculate the bearing between the current position and the IAF
            star = Node.findArrivalRoute(inbound.Report.initialApproachFix, sequencingConfig.ActiveArrivalRunways[0].Runway, navData)

            # calculate the distance based on the flown distance and update the predicted distance
            self.PredictedDistanceToIAF = Waypoint(longitude = self.PredictedCoordinate[1], latitude = self.PredictedCoordinate[0]).haversine(star.Route[0])
            if 0.0 > self.PredictedDistanceToIAF:
                self.PredictedDistanceToIAF = 0.0

        # calculate the timings for the different arrival runways
        for identifier in sequencingConfig.ActiveArrivalRunways:
            star = Node.findArrivalRoute(self.Inbound.Report.initialApproachFix, identifier.Runway, navData)

            if None != star:
                flightTime, trackmiles, arrivalRoute = self.arrivalEstimation(identifier.Runway, star, weatherModel)

                # calculate average speed gain
                avgSpeed = trackmiles / (flightTime.total_seconds() / 3600.0)
                avgSpeedIncrease = avgSpeed * 1.10
                avgSpeedDecrease = avgSpeed * 0.80
                decreasedSpeedFlighttime = (trackmiles / avgSpeedDecrease) * 3600.0 # given in seconds

                # calculate shortcut gain and add 15 miles for final and base turn
                currentPosition = Waypoint(latitude = self.PredictedCoordinate[0], longitude = self.PredictedCoordinate[1])
                shortcutDistance = currentPosition.haversine(identifier.Runway.Start) + 15.0
                shortcutFlighttime = (shortcutDistance / avgSpeedIncrease) * 3600.0
                if shortcutFlighttime > flightTime.total_seconds():
                    shortcutFlighttime = flightTime.total_seconds()

                # the best TTG is the shortest path with the fastest speed
                ttg = timedelta(seconds = flightTime.total_seconds() - shortcutFlighttime)
                # the best TTL is the longest path with the slowest speed
                ttl = timedelta(seconds = decreasedSpeedFlighttime - flightTime.total_seconds())
                ita = self.Inbound.ReportTime + flightTime
                earliest = ita - ttg
                latest = ita + ttl

                self.ArrivalCandidates[identifier.Runway.Name] = ArrivalData(ttg = ttg, star = star, ita = ita, earliest = earliest,
                                                                             ttl = ttl, latest = latest, route = arrivalRoute,
                                                                             trackmiles = trackmiles)

                if None == self.Inbound.InitialArrivalTime:
                    self.Inbound.InitialArrivalTime = self.ArrivalCandidates[identifier.Runway.Name].InitialArrivalTime