#  NanoVNASaver
#
#  A python program to view and export Touchstone data from a NanoVNA
#  Copyright (C) 2019, 2020  Rune B. Broberg
#  Copyright (C) 2020 NanoVNA-Saver Authors
#
#  This program is free software: you can redistribute it and/or modify
#  it under the terms of the GNU General Public License as published by
#  the Free Software Foundation, either version 3 of the License, or
#  (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program.  If not, see <https://www.gnu.org/licenses/>.
import logging
from math import log
from typing import Iterator, Tuple

logger = logging.getLogger(__name__)


class Sweep():
    def __init__(self, start: int = 3600000, end: int = 30000000,
                 points: int = 101, segments: int = 1,
                 logarithmic: bool = False):
        self.start = start
        self.end = end
        self.points = points
        self.segments = segments
        self.logarithmic = logarithmic
        self.span = self.end - self.start
        self.step = self.stepsize()
        self.check()

    def __repr__(self) -> str:
        return (
            f"Sweep({self.start}, {self.end}, {self.points}, {self.segments},"
            f" {self.logarithmic})")

    def __eq__(self, other) -> bool:
        return(self.start == other.start and
               self.end == other.end and
               self.points == other.points and
               self.segments == other.segments)

    def check(self):
        if not(self.segments > 0 and
               self.points > 0 and
               self.start > 0 and
               self.end > 0 and
               self.stepsize() >= 1):
            raise ValueError(f"Illegal sweep settings: {self}")

    def stepsize(self) -> int:
        return round(self.span / ((self.points -1) * self.segments))

    def _exp_factor(self, index: int) -> float:
        return 1 - log(self.segments + 1 - index) / log(self.segments + 1)

    def get_index_range(self, index: int) -> Tuple[int, int]:
        if not self.logarithmic:
            start = self.start + index * self.points * self.step
            end = start + (self.points - 1) * self.step
        else:
            start = round(self.start + self.span * self._exp_factor(index))
            end = round(self.start + self.span * self._exp_factor(index + 1))
        logger.debug("get_index_range(%s) -> (%s, %s)", index, start, end)
        return (start, end)


    def get_frequencies(self) -> Iterator[int]:
        if not self.logarithmic:
            for freq in range(self.start, self.end + 1, self.step):
                yield freq
            return
        for i in range(self.segments):
            start, stop = self.get_index_range(i)
            step = (stop - start) / self.points
            freq = start
            for _ in range(self.points):
                yield round(freq)
                freq += step