#!/usr/bin/python
#
# Urwid utility functions
#    Copyright (C) 2004-2011  Ian Ward
#
#    This library is free software; you can redistribute it and/or
#    modify it under the terms of the GNU Lesser General Public
#    License as published by the Free Software Foundation; either
#    version 2.1 of the License, or (at your option) any later version.
#
#    This library 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
#    Lesser General Public License for more details.
#
#    You should have received a copy of the GNU Lesser General Public
#    License along with this library; if not, write to the Free Software
#    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# Urwid web site: https://urwid.org/


from __future__ import annotations

import codecs
import typing
import warnings

from urwid import escape

if typing.TYPE_CHECKING:
    from typing_extensions import Self

str_util = escape.str_util

# bring str_util functions into our namespace
calc_text_pos = str_util.calc_text_pos
calc_width = str_util.calc_width
is_wide_char = str_util.is_wide_char
move_next_char = str_util.move_next_char
move_prev_char = str_util.move_prev_char
within_double_byte = str_util.within_double_byte


def detect_encoding() -> str:
    # Try to determine if using a supported double-byte encoding
    import locale

    no_set_locale = locale.getpreferredencoding(False)

    if no_set_locale != "ascii":
        # ascii is fallback locale in case of detect failed

        return no_set_locale

    # Use actual `getpreferredencoding` with public API only
    old_loc = locale.setlocale(locale.LC_CTYPE)  # == getlocale, but not mangle data
    try:
        try:
            locale.setlocale(locale.LC_CTYPE, "")
        except locale.Error:
            pass
        # internally call private `_get_locale_encoding`
        return locale.getpreferredencoding(False)
    finally:
        try:
            locale.setlocale(locale.LC_CTYPE, old_loc)
        except locale.Error:
            pass


if 'detected_encoding' not in locals():
    detected_encoding = detect_encoding()
else:
    assert 0, "It worked!"

_target_encoding = 'ascii'
_use_dec_special = True


def set_encoding( encoding ):
    """
    Set the byte encoding to assume when processing strings and the
    encoding to use when converting unicode strings.
    """
    encoding = encoding.lower()

    global _target_encoding, _use_dec_special

    if encoding in ( 'utf-8', 'utf8', 'utf' ):
        str_util.set_byte_encoding("utf8")

        _use_dec_special = False
    elif encoding in ( 'euc-jp' # JISX 0208 only
            , 'euc-kr', 'euc-cn', 'euc-tw' # CNS 11643 plain 1 only
            , 'gb2312', 'gbk', 'big5', 'cn-gb', 'uhc'
            # these shouldn't happen, should they?
            , 'eucjp', 'euckr', 'euccn', 'euctw', 'cncb' ):
        str_util.set_byte_encoding("wide")

        _use_dec_special = True
    else:
        str_util.set_byte_encoding("narrow")
        _use_dec_special = True

    # if encoding is valid for conversion from unicode, remember it
    _target_encoding = 'ascii'
    try:
        if encoding:
            "".encode(encoding)
            _target_encoding = encoding
    except LookupError: pass


def get_encoding_mode():
    """
    Get the mode Urwid is using when processing text strings.
    Returns 'narrow' for 8-bit encodings, 'wide' for CJK encodings
    or 'utf8' for UTF-8 encodings.
    """
    return str_util.get_byte_encoding()


def apply_target_encoding(s: str | bytes):
    """
    Return (encoded byte string, character set rle).
    """
    if _use_dec_special and isinstance(s, str):
        # first convert drawing characters
        s = s.translate(escape.DEC_SPECIAL_CHARMAP)

    if isinstance(s, str):
        s = s.replace(escape.SI+escape.SO, "") # remove redundant shifts
        s = codecs.encode(s, _target_encoding, 'replace')

    assert isinstance(s, bytes)
    SO = escape.SO.encode('ascii')
    SI = escape.SI.encode('ascii')

    sis = s.split(SO)

    assert isinstance(sis[0], bytes)

    sis0 = sis[0].replace(SI, b'')
    sout = []
    cout = []
    if sis0:
        sout.append( sis0 )
        cout.append( (None,len(sis0)) )

    if len(sis)==1:
        return sis0, cout

    for sn in sis[1:]:
        assert isinstance(sn, bytes)
        assert isinstance(SI, bytes)
        sl = sn.split(SI, 1)
        if len(sl) == 1:
            sin = sl[0]
            assert isinstance(sin, bytes)
            sout.append(sin)
            rle_append_modify(cout, (escape.DEC_TAG, len(sin)))
            continue
        sin, son = sl
        son = son.replace(SI, b'')
        if sin:
            sout.append(sin)
            rle_append_modify(cout, (escape.DEC_TAG, len(sin)))
        if son:
            sout.append(son)
            rle_append_modify(cout, (None, len(son)))

    outstr = b''.join(sout)
    return outstr, cout


######################################################################
# Try to set the encoding using the one detected by the locale module
set_encoding( detected_encoding )
######################################################################


def supports_unicode():
    """
    Return True if python is able to convert non-ascii unicode strings
    to the current encoding.
    """
    return _target_encoding and _target_encoding != 'ascii'


def calc_trim_text( text, start_offs: int, end_offs: int, start_col: int, end_col: int):
    """
    Calculate the result of trimming text.
    start_offs -- offset into text to treat as screen column 0
    end_offs -- offset into text to treat as the end of the line
    start_col -- screen column to trim at the left
    end_col -- screen column to trim at the right

    Returns (start, end, pad_left, pad_right), where:
    start -- resulting start offset
    end -- resulting end offset
    pad_left -- 0 for no pad or 1 for one space to be added
    pad_right -- 0 for no pad or 1 for one space to be added
    """
    spos = start_offs
    pad_left = pad_right = 0
    if start_col > 0:
        spos, sc = calc_text_pos( text, spos, end_offs, start_col )
        if sc < start_col:
            pad_left = 1
            spos, sc = calc_text_pos( text, start_offs,
                end_offs, start_col+1 )
    run = end_col - start_col - pad_left
    pos, sc = calc_text_pos( text, spos, end_offs, run )
    if sc < run:
        pad_right = 1
    return ( spos, pos, pad_left, pad_right )


def trim_text_attr_cs(text, attr, cs, start_col: int, end_col: int):
    """
    Return ( trimmed text, trimmed attr, trimmed cs ).
    """
    spos, epos, pad_left, pad_right = calc_trim_text(text, 0, len(text), start_col, end_col )
    attrtr = rle_subseg( attr, spos, epos )
    cstr = rle_subseg( cs, spos, epos )
    if pad_left:
        al = rle_get_at( attr, spos-1 )
        rle_prepend_modify( attrtr, (al, 1) )
        rle_prepend_modify( cstr, (None, 1) )
    if pad_right:
        al = rle_get_at( attr, epos )
        rle_append_modify( attrtr, (al, 1) )
        rle_append_modify( cstr, (None, 1) )

    return (b''.rjust(pad_left) + text[spos:epos] +
        b''.rjust(pad_right), attrtr, cstr)


def rle_get_at(rle, pos: int):
    """
    Return the attribute at offset pos.
    """
    x = 0
    if pos < 0:
        return None
    for a, run in rle:
        if x+run > pos:
            return a
        x += run
    return None


def rle_subseg(rle, start: int, end: int):
    """Return a sub segment of an rle list."""
    l = []
    x = 0
    for a, run in rle:
        if start:
            if start >= run:
                start -= run
                x += run
                continue
            x += start
            run -= start
            start = 0
        if x >= end:
            break
        if x+run > end:
            run = end-x
        x += run
        l.append( (a, run) )
    return l


def rle_len(rle) -> int:
    """
    Return the number of characters covered by a run length
    encoded attribute list.
    """

    run = 0
    for v in rle:
        assert isinstance(v, tuple), repr(rle)
        a, r = v
        run += r
    return run


def rle_prepend_modify(rle, a_r) -> None:
    """
    Append (a, r) (unpacked from *a_r*) to BEGINNING of rle.
    Merge with first run when possible

    MODIFIES rle parameter contents. Returns None.
    """
    a, r = a_r
    if not rle:
        rle[:] = [(a, r)]
    else:
        al, run = rle[0]
        if a == al:
            rle[0] = (a,run+r)
        else:
            rle[0:0] = [(a, r)]


def rle_append_modify(rle, a_r):
    """
    Append (a, r) (unpacked from *a_r*) to the rle list rle.
    Merge with last run when possible.

    MODIFIES rle parameter contents. Returns None.
    """
    a, r = a_r
    if not rle or rle[-1][0] != a:
        rle.append( (a,r) )
        return
    la,lr = rle[-1]
    rle[-1] = (a, lr+r)


def rle_join_modify( rle, rle2 ):
    """
    Append attribute list rle2 to rle.
    Merge last run of rle with first run of rle2 when possible.

    MODIFIES attr parameter contents. Returns None.
    """
    if not rle2:
        return
    rle_append_modify(rle, rle2[0])
    rle += rle2[1:]


def rle_product( rle1, rle2 ):
    """
    Merge the runs of rle1 and rle2 like this:
    eg.
    rle1 = [ ("a", 10), ("b", 5) ]
    rle2 = [ ("Q", 5), ("P", 10) ]
    rle_product: [ (("a","Q"), 5), (("a","P"), 5), (("b","P"), 5) ]

    rle1 and rle2 are assumed to cover the same total run.
    """
    i1 = i2 = 1 # rle1, rle2 indexes
    if not rle1 or not rle2: return []
    a1, r1 = rle1[0]
    a2, r2 = rle2[0]

    l = []
    while r1 and r2:
        r = min(r1, r2)
        rle_append_modify( l, ((a1,a2),r) )
        r1 -= r
        if r1 == 0 and i1< len(rle1):
            a1, r1 = rle1[i1]
            i1 += 1
        r2 -= r
        if r2 == 0 and i2< len(rle2):
            a2, r2 = rle2[i2]
            i2 += 1
    return l


def rle_factor( rle ):
    """
    Inverse of rle_product.
    """
    rle1 = []
    rle2 = []
    for (a1, a2), r in rle:
        rle_append_modify( rle1, (a1, r) )
        rle_append_modify( rle2, (a2, r) )
    return rle1, rle2


class TagMarkupException(Exception): pass


def decompose_tagmarkup(tm):
    """Return (text string, attribute list) for tagmarkup passed."""

    tl, al = _tagmarkup_recurse(tm, None)
    # join as unicode or bytes based on type of first element
    if tl:
        text = tl[0][:0].join(tl)
    else:
        text = ""

    if al and al[-1][0] is None:
        del al[-1]

    return text, al


def _tagmarkup_recurse(tm, attr):
    """Return (text list, attribute list) for tagmarkup passed.

    tm -- tagmarkup
    attr -- current attribute or None"""

    if isinstance(tm, list):
        # for lists recurse to process each subelement
        rtl = []
        ral = []
        for element in tm:
            tl, al = _tagmarkup_recurse(element, attr)
            if ral:
                # merge attributes when possible
                last_attr, last_run = ral[-1]
                top_attr, top_run = al[0]
                if last_attr == top_attr:
                    ral[-1] = (top_attr, last_run + top_run)
                    del al[0]
            rtl += tl
            ral += al
        return rtl, ral

    if isinstance(tm, tuple):
        # tuples mark a new attribute boundary
        if len(tm) != 2:
            raise TagMarkupException(f"Tuples must be in the form (attribute, tagmarkup): {tm!r}")

        attr, element = tm
        return _tagmarkup_recurse( element, attr )

    if not isinstance(tm, (str, bytes)):
        raise TagMarkupException(f"Invalid markup element: {tm!r}")

    # text
    return [tm], [(attr, len(tm))]


def is_mouse_event(ev: tuple[str, int, int, int] | typing.Any) -> bool:
    return isinstance(ev, tuple) and len(ev) == 4 and "mouse" in ev[0]


def is_mouse_press(ev: str) -> bool:
    return "press" in ev


class MetaSuper(type):
    """adding .__super"""
    def __init__(cls, name: str, bases, d):
        super().__init__(name, bases, d)
        if hasattr(cls, f"_{name}__super"):
            raise AttributeError("Class has same name as one of its super classes")

        @property
        def _super(self):
            warnings.warn(
                f"`{name}.__super` was a deprecated feature for old python versions."
                f"Please use `super()` call instead.",
                DeprecationWarning,
                stacklevel=3,
            )
            return super(cls, self)
        setattr(cls, f"_{name}__super", _super)


def int_scale(val: int, val_range: int, out_range: int):
    """
    Scale val in the range [0, val_range-1] to an integer in the range
    [0, out_range-1].  This implementation uses the "round-half-up" rounding
    method.

    >>> "%x" % int_scale(0x7, 0x10, 0x10000)
    '7777'
    >>> "%x" % int_scale(0x5f, 0x100, 0x10)
    '6'
    >>> int_scale(2, 6, 101)
    40
    >>> int_scale(1, 3, 4)
    2
    """
    num = int(val * (out_range-1) * 2 + (val_range-1))
    dem = ((val_range-1) * 2)
    # if num % dem == 0 then we are exactly half-way and have rounded up.
    return num // dem


class StoppingContext:
    """Context manager that calls ``stop`` on a given object on exit.  Used to
    make the ``start`` method on `MainLoop` and `BaseScreen` optionally act as
    context managers.
    """
    def __init__(self, wrapped):
        self._wrapped = wrapped

    def __enter__(self) -> Self:
        return self

    def __exit__(self, *exc_info):
        self._wrapped.stop()