import atexit
import sys
import time

# TODO: make this a namedtuple? or one of those newfangles dataclasses.
options = dict(
    ascii=False,  # TODO
    color=True,
    flush=True,
    patient=True,  # TODO: better name?
)

active = []
allocated = 0

DEBUG = False


def get_terminal_size(file=sys.stderr):
    from os import get_terminal_size as os_gts

    cols, rows = 0, 0
    try:
        cols, rows = os_gts(file.fileno())
    except OSError:
        pass
    if cols <= 0 or rows <= 0:
        from shutil import get_terminal_size as shutil_gts

        # NOTE: this uses sys.stdout instead of our file!
        cols, rows = shutil_gts()
    return cols, rows


def extend72(s, mode=""):
    if "t" in mode or "d" in mode or "a" in mode:
        s = s[:-1]
    return ((s[0] + s[1:-1]) * 72)[:71] + s[-1]


@atexit.register  # in the absence of a try-except for KeyboardInterrupt...
def reset(*, file=sys.stderr):
    # TODO: flesh this out?
    # TODO: fancy backspace "\b" stuff to hide potentially unsupported escape sequences.
    s = "\0337\033[J\033[r\0338"
    if file is not None:
        print(end=s, file=file, flush=True)
    else:
        return s


def alloc(lines):
    # first, perform a reset of whatever scrolling region may already be set.
    # the cursor is (almost) always reset after performing a reset command,
    # so wrap the command in a cursor-save and cursor-restore.
    s = "\0337\033[r\0338"

    # now, do some magic to ensure there's enough empty lines for the progress bars
    # *without* forcing the screen to scroll if there already is.
    # TODO: clear these lines too? hmm, that would overwrite bars though, wouldn't it?
    s += "\n" * lines  # this part is simple enough; just print some newlines.
    s += "\0338"  # however, that resets the cursor's column, so restore its position.
    # the position might not be on the same row as the line of text it was on before,
    s += f"\033[{lines}B\033[{lines}A"  # so move it down (clamped) and back up again.
    # s += "\0337"  # that should be everything, so store the adjusted cursor for later.

    return s


class Prog80:
    # TODO: use different(-ly placed) delimiters when length < 72?
    styles = dict(
        # TODO: maybe use namedtuples for these?
        # TODO: maybe use a separate field for the "cursor" characters?
        #       this ought to eliminate the need for "d", "t" and "P" modes.
        bar=dict(A=" ", B="█▌", mode="r"),
        bar2=dict(A=" ▌", B="██", mode="dp"),  # TODO: what's the non-'p' version?
        bracketed=dict(A="[" + " " * 70 + "]", B="[" + "=" * 70 + "]", mode="P"),
        circumslider=dict(A="o", B="oô", mode="pr"),
        crossslider=dict(A="†", B="†‡", mode="pr"),
        dotslider=dict(A="-", B="-÷", mode="pr"),
        dotted=dict(A=".", B="!?", mode="r"),
        equally=dict(A=".", B="="),
        fractional=dict(
            A="·····¬·····¬·····¼·····¬·····¬·····½·····¬·····¬·····¾·····¬·····¬·····!",
            B="xƒ",
            mode="ir",
        ),
        longdotslider=dict(A="—", B="—÷", mode="pr"),
        meme=dict(  # slightly modified
            A="According to all known laws of aviation, there is no way a bee should be",
            B="able to fly. Its wings are too small to get its fat body off the ground.",
            mode="P",
        ),
        middledots=dict(A="•", B="◘"),
        money=dict(A="¢", B="$"),
        # pacman=dict(A="-", B="#"),
        # bracketedpacman=dict(A="[" + "-" * 70 + "]", B="[" + "#" * 70 + "]", mode="P"),
        pacman=dict(A="[" + "-" * 70 + "]", B="[" + "#" * 70 + "]", mode="P"),
        piping=dict(A="=", B="=|", mode="pr"),
        ruler=dict(A="90123456780", B="90123456780", mode="P"),
        slider=dict(A="_", B="_⌂", mode="pr"),
        smile=dict(A="☺", B="☻"),
        song=dict(
            A="        -        ♪        -        ♪        -        ♪        -        ♪",
            B="   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫   ♫",
        ),
        sticks=dict(A="/", B="\\|", mode="p"),
        virus=dict(A=".▀", B="  TECHNO  ▄", mode="ap"),  # »Don't touch the keyboard«
    )

    bands = [  # TODO: come up with a better name for this variable.
        ("*", -4.94065645841246544177e-324, lambda x: "Waiting"),
        ("*", 0.0, lambda x: "Running"),
        ("*", 1.3888888888888887e-08, lambda x: "TooSlow"),
        ("*", 0.00027776388888888886, lambda x: f"{x * 60 * 60:6.4f}/h"[1:]),
        ("*", 0.001666583333333333, lambda x: f"{x * 60 * 60:5.3f}/h"),
        ("s", 0.01666583333333333, lambda x: f"{x * 60:6.4f}/m"[1:]),
        ("m", 0.01666583333333333, lambda x: f"{x * 60:6.4f}/m"[1:]),
        ("s", 0.09995, lambda x: f"{x * 60:5.3f}/m"),
        ("s", 0.9999499999999999, lambda x: f"{x:6.4f}/s"[1:]),
        ("m", 0.16665833333333332, lambda x: f"{x * 60:5.3f}/m"),
        ("m", 1.666583333333333, lambda x: f"{x * 60:5.2f}/m"),
        ("s", 9.999499999999998, lambda x: f"{x:5.3f}/s"),
        ("s", 12.000833333333333, lambda x: f"{x:5.2f}/s"),
        ("m", 16.66583333333333, lambda x: f"{x * 60:5.1f}/m"),
        ("m", 166.6583333333333, lambda x: f"{x * 60:4.0f}./m"),
        ("*", 0.002777638888888889, lambda x: f"{x * 60 * 60:5.3f}/h"),
        ("*", 0.027776388888888885, lambda x: f"{x * 60 * 60:5.2f}/h"),
        ("*", 0.20001388888888888, lambda x: f"{x * 60 * 60:5.1f}/h"),
        ("h", 0.2777638888888888, lambda x: f"{x * 60 * 60:5.1f}/h"),
        ("h", 2.7776388888888883, lambda x: f"{x * 60 * 60:4.0f}./h"),
        ("*", 1.666583333333333, lambda x: f"{x * 60:5.2f}/m"),
        ("*", 12.000833333333333, lambda x: f"{x * 60:5.1f}/m"),
        ("*", 99.99499999999999, lambda x: f"{x:5.2f}/s"),
        ("*", 999.9499999999999, lambda x: f"{x:5.1f}/s"),
        ("*", 9999.499999999998, lambda x: f"{x:4.0f}./s"),
        ("*", 1.7976931348623157e308, lambda x: f"TooFast"),
    ]

    # TODO: default to sys.stderr as well!
    def __init__(
        self,
        it,
        length,
        *,
        printer=print,
        style=None,
        display="elapsed",
        preference="*",
    ):
        self.i = 0
        self.it = iter(it)
        self.length = length
        self.printer = printer
        self.depth = 0
        self.start, self.end = 0, 0
        self.cols, self.rows = 0, 0
        self.preference = preference
        self.previous_update = 0.0
        self._state = None
        self.state = "initialized"
        self.style = style if style in self.styles else "fractional"  # TODO: warning
        # self.style = style if style in self.styles else "slider"  # TODO: warning
        # self.style = style if style in self.styles else list(self.styles)[-1]
        self.display = display
        assert self.display in ("elapsed", "eta", "rate")

    @property
    def state(self):
        return self._state

    @state.setter
    def state(self, new_state):
        if self._state is not None and new_state == self._state:
            return  # just ignore this
        valid = {
            "initialized": {None},
            "prepared": {"initialized"},
            "began": {"prepared", "progressing"},
            "progressing": {"began"},
            "finished": {"began"},
        }
        assert new_state in valid, f"unknown state {new_state}"
        assert (
            self._state in valid[new_state]
        ), f"invalid state transition from {self._state} to {new_state}"
        self._state = new_state

    def __len__(self):
        return self.length

    @property
    def unfilled(self):
        return extend72(self.styles[self.style]["A"], self.styling)

    @property
    def filled(self):
        return extend72(self.styles[self.style]["B"], self.styling)

    @property
    def styling(self):
        return self.styles[self.style].get("mode", "")

    @property
    def full(self):
        return self.i * 72 // self.length if self.length > 0 else 72

    @property
    def needs_update(self):
        if self.length <= 0:
            return True
        w = 72 * 3 if "t" in self.styling else 72 * 2 if "d" in self.styling else 72
        return self.i * w // self.length != (self.i - 1) * w // self.length

    @property
    def elapsed(self):
        now = self.end if self.state == "finished" else time.time()
        return now - self.start

    @property
    def rate(self):
        assert self.state in (
            "began",
            "progressing",
            "finished",
        ), "invalid state for this"
        elapsed = self.elasped
        if elapsed == 0.0:
            return self.bands[-1][1]  # closest thing to infinity
        return self.i / elapsed

    @property
    def eta(self):
        raise NotImplementedError("TODO")

    @classmethod
    def format_rate(cls, rate, preference="*"):
        for pref, threshold, formater in cls.bands:
            if (pref == "*" or pref == preference) and rate <= threshold:
                return formater(rate) + " "
        return "????????"  # normally unreachable (unless perhaps rate is Inf or NaN?)

    @classmethod
    def format_time(cls, duration, preference="*"):
        o = "-" if duration < 0.0 else "+"
        duration = abs(duration)
        if duration < 60.0:
            o += f"{max(0.0, duration - 0.005):5.2f}s "
        elif duration < 3600.0:
            x = int(duration)
            o += f"{x // 60:2d}m{x % 60:02d}s "
        elif duration < 86400.0:
            x = int(duration)
            o += f"{x // 3600:2d}h{x // 60 % 60:02d}m "
        elif duration < 8640000.0:
            x = int(duration)
            o += f"{x // 86400:2d}d{x // 3600 % 24:02d}h "
        else:
            o += "TooLong"
        return o

    @property
    def blurb(self):  # only the first 8 characters that don't constitute the bar at all
        if self.display == "rate":
            return self.format_rate(self.rate, self.preference)
        elif self.display == "elapsed":
            return self.format_time(self.elapsed, self.preference)
        elif self.display == "eta":
            return self.format_time(-self.eta, self.preference)

    @property
    def bar(self):  # the full 80 characters available in any state
        if options["color"]:
            color1 = "\033[7m"
            color2 = "\033[m\033[1m"
            color_reset = "\033[m"
        else:
            color1 = ""
            color2 = ""
            color_reset = ""

        if self.state in ("began", "finished", "progressing"):
            s = self.blurb
            if options["color"] and "i" in self.styling:
                left = self.unfilled[: self.full]
                right = self.unfilled[self.full :]
                if self.state == "progressing" or "p" in self.styling:
                    s += color1 + left + color2 + right[0]
                    s += color_reset + right[1:]
                else:
                    s += color1 + left
                    s += color_reset + right

            else:
                filled = self.filled
                style = self.styles[self.style]
                progressing = self.state == "progressing" or "p" in self.styling
                t = (filled[-1], style["A"][-1], style["B"][-1])
                if "t" in self.styling and self.length > 0:
                    triple = self.i * 72 * 3 // self.length
                    filled = filled[:-1] + t[triple % 3]
                elif "d" in self.styling and self.length > 0:
                    double = self.i * 72 * 2 // self.length
                    filled = filled[:-1] + t[double % 2 + 1]
                elif "a" in self.styling and self.length > 0:
                    filled = filled[:-1] + t[self.full % 2 + 1]

                s += color2
                if progressing:
                    if "r" in self.styling:
                        s += filled[-self.full - 1 :]
                    elif "P" in self.styling:
                        s += filled[: self.full + 1]
                    else:
                        s += filled[: self.full] + filled[-1]
                    s += color_reset + self.unfilled[self.full + 1 :]
                else:
                    if "r" in self.styling and self.full > 0:
                        s += filled[-self.full :]
                    else:
                        s += filled[: self.full]
                    s += color_reset + self.unfilled[self.full :]
        elif self.state == "prepared":
            s = "Ready..." + " " * 72
        else:
            s = "watdafuk" + "?" * 72
        # assert len(s) == 80 + len(color2) + len(color_reset), (self.full, self.state, repr(s))
        return s

    @property
    def row(self):
        assert self.state in ("began", "progressing"), "invalid state for this"
        return self.rows - allocated + self.depth

    def __iter__(self):
        # TODO: check env-var override for disabling and colors!
        if self.length == 0:
            return self.it
        if self.i == 0:
            self.begin()
        for x in self.it:
            self.progress(False)
            yield x
            self.progress(True)
        self.progressing = False
        self.finish()

    # TODO: is there a case where i actually need this?
    #   def __next__(self):
    #       pass

    def prepare(self):
        self.state = "prepared"
        return self

    def begin(self):
        global allocated
        self.start = time.time()
        assert self not in active, "what"
        active.append(self)
        self.depth = len(active)

        (_cols, _rows) = get_terminal_size()
        # propagate terminal size to parents (and self) in case it has since changed:
        for pb in active:
            pb.cols, pb.rows = _cols, _rows

        # TODO: this should be handleable in most cases; hide the top bars for a while.
        # need at least 1 blank line for regular output (or just for the cursor to sit)
        # i guess just act as though only a subset of `active` are active for a while?
        assert self.rows - 1 > self.depth, "ran out of space for progress bars"

        s = alloc(self.depth)  # TODO: only do this as necessary? (based on allocated)

        # keep track of how many lines are available for progress bars.
        newly = len(active) - allocated if len(active) > allocated else 0
        # TODO: allow the user to allocate many at once.
        allocated += newly
        self.state = "began"

        s += "\0337"
        if 1:
            for pb in active:
                # TODO: respect 30 fps timers?
                s += f"\033[{pb.row};1H\033[K{pb.bar}"
        else:  # this isn't as flexible, but it works...?
            # FIXME: progress() is still broken!
            for pb in active:
                s += f"\n\033[K{pb.bar}"
        # prevent the user from accidentally printing over the progress bars.
        s += f"\033[1;{self.rows - allocated}r"
        s += "\0338"  # finally, return to the user's (properly adjusted) line and column.
        self.printer(end=s)
        # time.sleep(2); exit()

        if DEBUG:
            print(repr(s).replace("\\x1b", "\\033"))
            time.sleep(0.5)

    def progress(self, finishing=False):
        if finishing:
            self.i += 1
            self.state = "began"
        else:
            self.state = "progressing"

        if not options["patient"] or self.needs_update:
            now = time.time()
            if now >= self.previous_update + 0.03333333333333333:  # limit to 30 fps
                self.previous_update = now
                s = f"\0337\033[{self.row};1H\033[K{self.bar}\0338"
                self.printer(end=s)

    def finish(self):
        global allocated
        self.end = time.time()
        row = self.row  # we need this before we transition states
        assert self.depth == len(active) and active[-1] is self, "what"
        active.pop()
        self.state = "finished"
        s = ""
        if len(active) == 0:
            s += "\0337\033[J\033[r\0338"
            allocated = 0
        else:
            s += f"\0337\033[{row};1H\033[K\0338"
        self.printer(end=s)


def prog(it, *, file=sys.stderr, pref="*"):
    def printy(*args, **kwargs):
        # print(repr(kwargs.get("end", "?").replace("\\x1b", "\\033")))
        # time.sleep(2.5)
        print(*args, **kwargs, file=file, flush=options["flush"])
        # time.sleep(2.5)

    try:
        l = len(it)
    except TypeError:
        raise TypeError("prog(iterator) only works with iterators with a known length")
    return Prog80(it, l, printer=printy, preference=pref).prepare()