# The MIT License (MIT)
# Copyright (c) 2019 by the xcube development team and contributors
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
# of the Software, and to permit persons to whom the Software is furnished to do
# so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import fractions
import math
from typing import Tuple, List, Optional, Union

import click

from xcube.util.constants import EARTH_EQUATORIAL_PERIMETER

_DEFAULT_MIN_LEVEL = 0
_DEFAULT_MAX_TILE = 2500
_DEFAULT_RES_DELTA = "2.5%"
_DEFAULT_SORT_BY = "R_D"
_DEFAULT_NUM_RESULTS = 10
_DEFAULT_LAT_COVERAGE = fractions.Fraction(180, 1)

_SORT_BY_KEYS_0 = ['R_D', 'R_NOM', 'R_DEN', 'R', 'H', 'H0', 'L']
_SORT_BY_KEYS_P = ["+" + k for k in _SORT_BY_KEYS_0]
_SORT_BY_KEYS_M = ["-" + k for k in _SORT_BY_KEYS_0]
_SORT_BY_KEYS = _SORT_BY_KEYS_0 + _SORT_BY_KEYS_P + _SORT_BY_KEYS_M


def find_close_resolutions(target_res: float,
                           delta_res: float,
                           coverage: Union[int, fractions.Fraction],
                           max_height_0: int = _DEFAULT_MAX_TILE,
                           min_level: int = _DEFAULT_MIN_LEVEL,
                           int_inv_res: bool = False,
                           sort_by: str = _DEFAULT_SORT_BY) -> List[Tuple]:
    if target_res <= 0.0:
        raise ValueError('illegal target_res')
    if delta_res < 0.0 or delta_res >= target_res:
        raise ValueError('illegal delta_res')
    if min_level < 0.0:
        raise ValueError('illegal min_level')
    header = ("R_D (%)", "R_NOM", "R_DEN", "R (deg)", "R (m)", "H", "H0", "L")
    reverse_sort = False
    if sort_by.startswith("+") or sort_by.startswith("-"):
        reverse_sort = sort_by[0] == "-"
        sort_by = sort_by[1:]
    if sort_by == "R_D":
        def sort_key(item):
            return abs(item[0])
    elif sort_by == "R_NOM":
        def sort_key(item):
            return item[1]
    elif sort_by == "R_DEN":
        def sort_key(item):
            return item[2]
    elif sort_by == "R":
        def sort_key(item):
            return item[3]
    elif sort_by == "H":
        def sort_key(item):
            return item[5]
    elif sort_by == "H0":
        def sort_key(item):
            return item[6]
    elif sort_by == "L":
        def sort_key(item):
            return item[7]
    else:
        raise ValueError(f'illegal sort key: {sort_by}')
    # Compute h_min, h_max, the range of possible integer heights
    h_min = int(math.floor(coverage / (target_res + delta_res)))
    h_max = int(math.ceil(coverage / (target_res - delta_res)))
    # Collect resolutions all possible integer heights
    data = []
    for height in range(h_min, h_max + 1):
        res = coverage / fractions.Fraction(height, 1)
        # We may only want resolutions whose inverse is integer, e.g. 1/12 degree
        if not int_inv_res or res.numerator == 1:
            res_d = float(res)
            delta = res_d - target_res
            # Only if we are within delta_res
            if abs(delta) <= delta_res:
                # Only if res * height = coverage
                if res * height == coverage:
                    height_0, level = factor_out_two(height)
                    # Only if tile size falls below max and level exceeds min
                    if height_0 <= max_height_0 and level >= min_level:
                        delta_p = _round(100 * delta / target_res, 1000)
                        res_m = _round(degrees_to_meters(res_d), 100)
                        data.append((delta_p, res.numerator, res.denominator, res_d, res_m, height, height_0, level))
    data = sorted(data, key=sort_key, reverse=reverse_sort)
    # noinspection PyTypeChecker
    return [header] + data


def get_levels(height: int,
               coverage: Union[int, fractions.Fraction],
               level_min: int = None) -> List[Tuple]:
    res = coverage / fractions.Fraction(height)
    height_0, level = factor_out_two(height)
    data = []
    f = 1
    res_0 = res * (2 ** level)
    for i in range(0, max(level, level_min or level) + 1):
        height_i = height_0 * f
        res_i = res_0 / f
        res_i_d = float(res_i)
        res_i_m = _round(degrees_to_meters(res_i_d), 100)
        data.append((i, height_i, res_i, res_i_d, res_i_m))
        f *= 2
    header = ("L", "H", "R", "R (deg)", "R (m)")
    # noinspection PyTypeChecker
    return [header] + data


def get_adjusted_box(x1: float, y1: float, x2: float, y2: float, res: float) \
        -> Tuple[float, float, float, float]:
    # TODO: clamp values
    adj_x1 = res * math.floor(x1 / res)
    adj_y1 = res * math.floor(y1 / res)
    adj_x2 = res * math.ceil(x2 / res)
    adj_y2 = res * math.ceil(y2 / res)
    if adj_x2 - res >= x2:
        adj_x2 -= res
    if adj_y2 - res >= y2:
        adj_y2 -= res
    return adj_x1, adj_y1, adj_x2, adj_y2


def meters_to_degrees(res):
    return (360.0 * res) / EARTH_EQUATORIAL_PERIMETER


def degrees_to_meters(res):
    return (res / 360.0) * EARTH_EQUATORIAL_PERIMETER


def _round(x: float, n: int) -> float:
    return round(n * x) / n


def factor_out_two(x: int) -> Tuple[int, int]:
    if x < 0:
        raise ValueError("x must not be negative")
    if x == 0:
        return 0, 0
    e = 0
    while x % 2 == 0:
        x >>= 1
        e += 1
    return x, e


@click.command(name="res")
@click.argument('target_res', metavar='TARGET_RES')
@click.option('--delta_res', '-D', metavar='DELTA_RES', default=_DEFAULT_RES_DELTA,
              help=f'Maximum resolution delta. Defaults to {_DEFAULT_RES_DELTA}.')
@click.option('--coverage', '--cov', metavar="COVERAGE", default=str(_DEFAULT_LAT_COVERAGE),
              help=f'The vertical coverage in degrees. Defaults to {_DEFAULT_LAT_COVERAGE} degrees.')
@click.option('--tile_max', metavar='TILE_MAX', default=_DEFAULT_MAX_TILE, type=int,
              help=f'Maximum tile size. Defaults to {_DEFAULT_MAX_TILE}.')
@click.option('--level_min', '-l', metavar='LEVEL_MIN', default=_DEFAULT_MIN_LEVEL, type=int,
              help=f'Minimum resolution level. Defaults to {_DEFAULT_MIN_LEVEL}.')
@click.option('--int_inv_res', metavar='INT_INV_RES', is_flag=True,
              help=f'Find only resolutions whose inverse are integers.')
@click.option('--sort_by', metavar='SORT_BY',
              type=click.Choice(_SORT_BY_KEYS), default=_DEFAULT_SORT_BY,
              help='Sort output by column name.')
@click.option('--num_results', '-N', metavar='NUM_RESULTS',
              type=int, default=_DEFAULT_NUM_RESULTS,
              help=f'Maximum number of results to list. Defaults to {_DEFAULT_NUM_RESULTS}')
@click.option('--sep', metavar='SEP', default='\t',
              help='Column separator for the output. Defaults to TAB.')
def list_resolutions(target_res: str,
                     delta_res: str,
                     coverage: str,
                     tile_max: int,
                     level_min: int,
                     int_inv_res: bool,
                     sort_by: str,
                     num_results: int,
                     sep: str):
    """
    List resolutions close to a target resolution.

    Lists possible resolutions of a fixed Earth grid that are close to a given target
    resolution TARGET_RES within a maximum allowed deviation DELTA_RES.

    Both TARGET_RES and DELTA_RES can be suffixed by a "m" to indicate meter units.
    DELTA_RES can also be suffixed by a "%" to indicate deviation from TARGET_RES in percent.

    If LEVEL_MIN is provided and greater zero, only resolutions are listed whose
    HEIGHT is larger than TILE * 2 ^ LEVEL_MIN.
    """
    if target_res.endswith("m"):
        target_res = meters_to_degrees(float(target_res[0: -1]))
    else:
        target_res = float(target_res)

    if delta_res.endswith("m"):
        delta_res = meters_to_degrees(float(delta_res[0: -1]))
    elif delta_res.endswith("%"):
        delta_res = float(delta_res[0: -1]) * target_res / 100
    else:
        delta_res = float(delta_res)

    coverage = _fetch_coverage_from_option(coverage)

    sep = '\t' if sep.upper() == "TAB" else sep

    results = find_close_resolutions(target_res,
                                     delta_res,
                                     coverage,
                                     max_height_0=tile_max,
                                     min_level=level_min,
                                     int_inv_res=int_inv_res,
                                     sort_by=sort_by)

    click.echo()
    if len(results) <= num_results:
        for result in results:
            click.echo(sep.join(map(str, result)))
    else:
        for result in results[0: num_results]:
            click.echo(sep.join(map(str, result)))
        click.echo(f"{len(results) - num_results} more...")


@click.command(name="levels")
@click.option('--res', '-R', metavar="RES",
              help='Resolution in degrees. Can also be a rational number of form RES_NOM/RES_DEN.')
@click.option('--height', '-h', metavar="HEIGHT", type=int,
              help='Height in grid cells.')
@click.option('--coverage', '--cov', metavar="COVERAGE", default=str(_DEFAULT_LAT_COVERAGE),
              help=f'The vertical coverage in degrees. Defaults to {_DEFAULT_LAT_COVERAGE} degrees.')
@click.option('--level_min', '-l', metavar="LEVEL_MIN", type=int,
              help="List at least up to this level.")
@click.option('--sep', metavar='SEP', default='\t',
              help='Column separator for the output. Defaults to TAB.')
def list_levels(res: str, height: int, coverage: str, level_min: Optional[int], sep: str):
    """
    List levels for a resolution or a tile size.

    Lists the given number of LEVELS for given resolution RES or given height in grid cells HEIGHT.
    which can both be used to define a fixed Earth grid.
    """
    height, coverage = _fetch_height_and_coverage_from_options(res, height, coverage)

    sep = '\t' if sep.upper() == "TAB" else sep

    rows = get_levels(height, coverage, level_min)

    click.echo()
    for row in rows:
        click.echo(sep.join(map(str, row)))


@click.command(name="abox", context_settings={"ignore_unknown_options": True})
@click.argument('geom', metavar="GEOM")
@click.option('--res', '-R', metavar="RES",
              help='The parent grid\'s resolution in degrees. Can also be a rational number of form A/B.')
@click.option('--height', '-h', metavar="HEIGHT", type=int,
              help='The parent grid\'s height in grid cells.')
@click.option('--coverage', '--cov', metavar="COVERAGE", default=str(_DEFAULT_LAT_COVERAGE),
              help=f'The parent grid\'s coverage in degrees. Defaults to {_DEFAULT_LAT_COVERAGE} degrees.')
@click.option('--tile_factor', metavar="TILE_FACTOR", type=int,
              help='A tile factor to compute tile sizes from height at level zero: TILE = TILE_FACTOR * HEIGHT_0.'
                   'Usually TILE_FACTOR = 2^N. If not given, TILE = 1.')
def adjust_box(geom: str, res: Optional[str], height: Optional[int], coverage: str, tile_factor: Optional[int]):
    """
    Adjust a bounding box to a fixed Earth grid.

    Adjusts a bounding box given by GEOM  to a fixed Earth grid by the
    inverse resolution INV_RES in degrees^-1 units, which must be an integer number.

    GEOM is a bounding box given as x1,y1,x2,y2 in decimal degrees.
    (Geometry WKT and GeoJSON support may be added later.)
    """
    try:
        x1, y1, x2, y2 = [float(c) for c in geom.split(",")]
    except (ValueError, TypeError) as e:
        raise click.ClickException(f"Invalid GEOM: {geom}") from e

    height, coverage = _fetch_height_and_coverage_from_options(res, height, coverage)

    height_0, level = factor_out_two(height)

    res = coverage / fractions.Fraction(height, 1)
    res_0 = res * 2 ** level

    if tile_factor is not None:
        tile_size = tile_factor * height_0
    else:
        tile_size = 1
    graticule_dist = res_0 * tile_size

    # Adjust along tile boundaries
    adj_x1, adj_y1, adj_x2, adj_y2 = get_adjusted_box(x1, y1, x2, y2, float(graticule_dist))

    reg_width = round((adj_x2 - adj_x1) / float(res))
    reg_height = round((adj_y2 - adj_y1) / float(res))

    orig_coords = (f'(({x1} {y1},'
                   f' {x2} {y1},'
                   f' {x2} {y2},'
                   f' {x1} {y2},'
                   f' {x1} {y1}))')
    adj_coords = (f'(({adj_x1} {adj_y1},'
                  f' {adj_x2} {adj_y1},'
                  f' {adj_x2} {adj_y2},'
                  f' {adj_x1} {adj_y2},'
                  f' {adj_x1} {adj_y1}))')

    click.echo()
    click.echo(f'Orig. box coord. = {x1},{y1},{x2},{y2}')
    click.echo(f'Adj. box coord.  = {adj_x1},{adj_y1},{adj_x2},{adj_y2}')
    click.echo(f'Orig. box WKT    = POLYGON {orig_coords}')
    click.echo(f'Adj. box WKT     = POLYGON {adj_coords}')
    click.echo(f'Combined WKT     = MULTIPOLYGON ({orig_coords}, {adj_coords})')
    click.echo(f'Box grid size    = {reg_width} x {reg_height} cells')
    click.echo(f'Graticule dist.  = {graticule_dist} degrees')
    click.echo(f'Tile size        = {tile_size} cells')
    click.echo(f'Granularity      = {height_0} cells')
    click.echo(f'Level            = {level}')
    click.echo(f'Res. at level 0  = {res_0} degrees')
    click.echo(f'Resolution       = {res} degrees')
    click.echo(f'                 = {_round(degrees_to_meters(res), 100)} meters')


def _fetch_height_and_coverage_from_options(res_str: Optional[str],
                                            height: Optional[int],
                                            coverage_str: str) -> Tuple[int, fractions.Fraction]:
    coverage = _fetch_coverage_from_option(coverage_str)
    if res_str is not None:
        if height is not None:
            raise click.ClickException(f"Either RES or HEIGHT must be given, not both")
        try:
            res = fractions.Fraction(res_str)
        except ValueError as e:
            raise click.ClickException(f"Invalid RES: {res_str}") from e
        if res <= 0:
            raise click.ClickException(f"Invalid RES: {res_str}")
        height = coverage / res
        if height.denominator != 1:
            raise click.ClickException(f"Invalid RES: {res_str}, {coverage_str}/RES must be an integer number.")
        height = height.numerator
    elif height is None:
        raise click.ClickException(f"Either RES or HEIGHT must be given.")
    return height, coverage


def _fetch_coverage_from_option(coverage_str: str) -> fractions.Fraction:
    try:
        coverage = fractions.Fraction(coverage_str)
    except ValueError as e:
        raise click.ClickException(f"Invalid COVERAGE: {coverage_str}") from e
    if coverage <= 0:
        raise click.ClickException(f"Invalid COVERAGE: {coverage_str}")

    return coverage


@click.group()
def grid():
    """
    Find spatial xcube dataset resolutions and adjust bounding boxes.

    We find suitable resolutions with respect to a possibly regional fixed Earth grid and adjust regional spatial
    bounding boxes to that grid. We also try to select the resolutions such
    that they are taken from a certain level of a multi-resolution pyramid whose
    level resolutions increase by a factor of two.

    The graticule at a given resolution level L within the grid is given by

    \b
        RES(L) = COVERAGE * HEIGHT(L)
        HEIGHT(L) = HEIGHT_0 * 2 ^ L
        LON(L, I) = LON_MIN + I * HEIGHT_0 * RES(L)
        LAT(L, J) = LAT_MIN + J * HEIGHT_0 * RES(L)

    With

    \b
        RES:      Grid resolution in degrees.
        HEIGHT:   Number of vertical grid cells for given level
        HEIGHT_0: Number of vertical grid cells at lowest resolution level.

    Let WIDTH and HEIGHT be the number of horizontal and vertical grid cells
    of a global grid at a certain LEVEL with WIDTH * RES = 360 and HEIGHT * RES = 180, then
    we also force HEIGHT = TILE * 2 ^ LEVEL.
   """


grid.add_command(list_resolutions)
grid.add_command(list_levels)
grid.add_command(adjust_box)
