"""
Grid extension for qrm
---
Copyright (C) 2019-2020 Abigail Gold, 0x5c

This file is part of discord-qrm2 and is released under the terms of the GNU
General Public License, version 2.
"""

import math

import discord.ext.commands as commands

import common as cmn


class GridCog(commands.Cog):
    def __init__(self, bot: commands.Bot):
        self.bot = bot

    @commands.command(name="grid", category=cmn.cat.maps)
    async def _grid_sq_lookup(self, ctx: commands.Context, lat: str, lon: str):
        '''Calculates the grid square for latitude and longitude coordinates,
with negative being latitude South and longitude West.'''
        with ctx.typing():
            grid = "**"
            latf = float(lat) + 90
            lonf = float(lon) + 180
            if 0 <= latf <= 180 and 0 <= lonf <= 360:
                grid += chr(ord('A') + int(lonf / 20))
                grid += chr(ord('A') + int(latf / 10))
                grid += chr(ord('0') + int((lonf % 20)/2))
                grid += chr(ord('0') + int((latf % 10)/1))
                grid += chr(ord('a') + int((lonf - (int(lonf/2)*2)) / (5/60)))
                grid += chr(ord('a') + int((latf - (int(latf/1)*1)) / (2.5/60)))
                grid += "**"
                embed = cmn.embed_factory(ctx)
                embed.title = f'Maidenhead Grid Locator for {float(lat):.6f}, {float(lon):.6f}'
                embed.description = grid
                embed.colour = cmn.colours.good
            else:
                embed = cmn.embed_factory(ctx)
                embed.title = f'Error generating grid square for {lat}, {lon}.'
                embed.description = ("Coordinates out of range.\n"
                                     "The valid ranges are:\n"
                                     "- Latitude: `-90` to `+90`\n"
                                     "- Longitude: `-180` to `+180`")
                embed.colour = cmn.colours.bad
        await ctx.send(embed=embed)

    @commands.command(name="ungrid", aliases=['loc'], category=cmn.cat.maps)
    async def _location_lookup(self, ctx: commands.Context, grid: str, grid2: str = None):
        '''Calculates the latitude and longitude for the center of a grid square.
If two grid squares are given, the distance and azimuth between them is calculated.'''
        with ctx.typing():
            if grid2 is None or grid2 == '':
                try:
                    grid = grid.upper()
                    loc = get_coords(grid)

                    embed = cmn.embed_factory(ctx)
                    embed.title = f'Latitude and Longitude for {grid}'
                    embed.colour = cmn.colours.good

                    if len(grid) >= 6:
                        embed.description = f'**{loc[0]:.5f}, {loc[1]:.5f}**'
                        embed.url = f'https://www.openstreetmap.org/#map=13/{loc[0]:.5f}/{loc[1]:.5f}'
                    else:
                        embed.description = f'**{loc[0]:.1f}, {loc[1]:.1f}**'
                        embed.url = f'https://www.openstreetmap.org/#map=10/{loc[0]:.1f}/{loc[1]:.1f}'
                except Exception as e:
                    embed = cmn.embed_factory(ctx)
                    embed.title = f'Error generating latitude and longitude for grid {grid}.'
                    embed.description = str(e)
                    embed.colour = cmn.colours.bad
            else:
                radius = 6371
                try:
                    grid = grid.upper()
                    grid2 = grid2.upper()
                    loc = get_coords(grid)
                    loc2 = get_coords(grid2)
                    # Haversine formula
                    d_lat = math.radians(loc2[0] - loc[0])
                    d_lon = math.radians(loc2[1] - loc[1])
                    a = (math.sin(d_lat/2) ** 2
                         + math.cos(math.radians(loc[0]))
                         * math.cos(math.radians(loc2[0]))
                         * math.sin(d_lon/2) ** 2)
                    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1-a))
                    d = radius * c
                    d_mi = 0.6213712 * d

                    # Bearing
                    y_dist = math.sin(math.radians(loc2[1]-loc[1])) * math.cos(math.radians(loc2[0]))
                    x_dist = (math.cos(math.radians(loc[0]))
                              * math.sin(math.radians(loc2[0]))
                              - math.sin(math.radians(loc[0]))
                              * math.cos(math.radians(loc2[0]))
                              * math.cos(math.radians(loc2[1] - loc[1])))
                    bearing = (math.degrees(math.atan2(y_dist, x_dist)) + 360) % 360

                    embed = cmn.embed_factory(ctx)
                    embed.title = f'Great Circle Distance and Bearing from {grid} to {grid2}'
                    embed.description = f'**Distance:** {d:.1f} km ({d_mi:.1f} mi)\n**Bearing:** {bearing:.1f}°'
                    embed.colour = cmn.colours.good
                except Exception as e:
                    embed = cmn.embed_factory(ctx)
                    embed.title = f'Error generating great circle distance and bearing from {grid} and {grid2}.'
                    embed.description = str(e)
                    embed.colour = cmn.colours.bad
        await ctx.send(embed=embed)


def get_coords(grid: str):
    if len(grid) < 3:
        raise ValueError('The grid locator must be at least 4 characters long.')

    if not grid[0:2].isalpha() or not grid[2:4].isdigit():
        if len(grid) <= 4:
            raise ValueError('The grid locator must be of the form AA##.')
        if len(grid) >= 6 and not grid[5:7].isalpha():
            raise ValueError('The grid locator must be of the form AA##AA.')

    lon = ((ord(grid[0]) - ord('A')) * 20) - 180
    lat = ((ord(grid[1]) - ord('A')) * 10) - 90
    lon += ((ord(grid[2]) - ord('0')) * 2)
    lat += ((ord(grid[3]) - ord('0')) * 1)

    if len(grid) >= 6:
        # have subsquares
        lon += ((ord(grid[4])) - ord('A')) * (5/60)
        lat += ((ord(grid[5])) - ord('A')) * (2.5/60)
        # move to center of subsquare
        lon += (2.5/60)
        lat += (1.25/60)
        return (lat, lon)
    # move to center of square
    lon += 1
    lat += 0.5
    return (lat, lon)


def setup(bot: commands.Bot):
    bot.add_cog(GridCog(bot))