#!/usr/bin/python

"""
This program navigates between cities using the A* algorithm. It takes in a
".geo" file that models cities and roads as a graph. It is then able to recieve
requests from the user, planning the best route to take between any two cities
in its model.

It relies on an AStarGraph object, that you must write. The API is as given in
the assignment.
"""

__author__ = "Adam A. Smith"
__version__ = "2023.11.08"


from astargraph import AStarGraph
import decimal
import os

# load a file & make an AStarGraph from its lines
def make_astar_graph(filename):
    graph = AStarGraph()
    with open(filename, "r") as file:
        addCities = True
        for line in file:
            line = line.strip()
            if len(line) == 0: addCities = False

	    # 1st part: adding cities to the graph
            elif addCities:
                tokens = line.split("\t")
                graph.add_city(tokens[0], float(tokens[1]), float(tokens[2]))

	    # 2nd part: adding roads
            else:
                tokens = line.split("\t")
                graph.add_road(tokens[0], tokens[1], float(tokens[2]))
    return graph

def query_user(graph):
    print("Please enter your query:\n")
    while True:
        query = input("> ").strip()

        # do nothing on empty string
        if len(query) == 0: continue

	# quit on "!quit" or "!exit"
        elif query == "!quit" or query == "!exit": break

        # help menu
        elif query == "!help": print_help_menu()

	# find path(s)
        elif "-" in query:
            cities = query.split("-")
            cities = [city.strip() for city in cities]

	    # actual path finding
            for i in range(len(cities) - 1):
                try:
                    path = graph.find_path(cities[i], cities[i + 1])

		    # print on failure
                    if path is None:
                        print("I'm sorry. There's not a path from " + cities[i] + " to " + cities[i + 1] + ".")

		    # print on found path
                    else:
                        distance = round(graph.measure_path(path))
                        print("Path found: " + path[0], end="")
                        for j in range(1, len(path)):
                            print(" - " + path[j], end="")
                        print(" (" + str(distance) + " km)")

		# catch for bad cities
                except ValueError as ex:
                    print('I\'m sorry. Either "' + cities[i] + '" or "' + cities[i + 1] + '" is unknown to me.')
            print()

	# query 1 city--get info on it
        else:

	    # if valid, give its location & neighbors
            if graph.is_valid_city(query):
                location = graph.get_city_location(query)
                latitude = location[0]
                longitude = location[1]
                print(query + " is located at (", end="")

		# latitude
                if latitude > 0: print(str(round(latitude, 2)) + "° N, ", end="")
                elif latitude < 0: print(str(round(-latitude, 2)) + "° S, ", end="")
                else: print("0°, ", end="")

		# longitude
                if longitude > 0: print(str(round(longitude, 2)) + "° E). ", end="")
                elif longitude < 0: print(str(round(-longitude, 2)) + "° W). ", end="")
                else: print("0°). ", end="")

                # neighbors
                neighbors = graph.get_neighboring_cities(query)
                if len(neighbors) == 0: print("It is not connected to any other city.")
                else:
                    if len(neighbors) == 1: print("It has a road to " + neighbors[0] + ".")
                    elif len(neighbors) == 2: print("It has roads to " + neighbors[0] + " and " + neighbors[1] + ".")
                    else:
                        print("It has roads to ", end="")
                        for i in range(len(neighbors) - 1): print(neighbors[i] + ", ", end="")
                        print("and " + neighbors[-1] + ".")

	    # otherwise, error message
            else:
                print('I\'m sorry. There is no city "' + query + '".')
            print()
    print("Goodbye!")

# just prints a help menu
def print_help_menu():
    print("\t<city>\t\tprints info on a city")
    print("\t<city>-<city>\tcalculates a path")
    print("\t!help\t\tprints this help menu")
    print("\t!exit\t\texits the program")

if __name__ == "__main__":
    # test command-line args
    from sys import argv, exit, stderr

    # make sure we have a file
    if len(argv) != 2:
        print("Please enter a file name!", file=stderr)
        exit(1)

    # make the graph, and query on it
    try:
        graph = make_astar_graph(argv[1])
        print('File "' + argv[1] + '" has been loaded with ' + str(len(graph)) + ' cities.')
        query_user(graph)
    except FileNotFoundError:
        print('Couldn\'t open file "' +argv[1]+ '".', file=stderr)
        exit(1)