import re

import kutil
import klammer_base

# Emitted by @vspace.txt (sks/block/block.k), one marker per line of space.
# An @eval result consisting only of whitespace is trimmed away by the
# Klammermachine, so vertical space must travel as markers and become
# newlines here, after blank-line runs have been normalized.

def txt_nl_marker():
    return "__KTEXTNEWLINE__"

def txt_vspace_marker():
    return "__KTEXTVSPACE__"

# A space that survives to the output.  "~" used to serve, and could not:
# it is also a character a writer may want, and the substitution at the end
# of txt_justify_blocks turned EVERY tilde into a space -- so a literal
# tilde could not be written in the txt target at all (a "^~" resolves
# before the phases run, and by then is indistinguishable).  A marker of
# its own frees the character.  SYNC: the txt target's "~ ^0020^" transform
# in sks/target/target.k is the WRITER-facing convention (a tilde means a
# non-breaking space, as in LaTeX) and is deliberately unchanged.
def txt_nbsp_marker():
    return "__KTEXTNBSP__"

# The type-style markers, emitted by @b.txt, @i.txt, @u.txt and @ri.txt
# (sks/font/font.k) around their text.  Plain text has no bold, but a
# terminal does: the txt target STRIPS these in its last phase
# (txt_strip_styles) and the ansi target, which :includes txt, RESOLVES
# them to SGR escape sequences in its last phase (ansi_resolve_styles).
# So the two targets differ in nothing but that phase, and stripping the
# escape sequences from an ansi render gives the txt render byte for byte
# (sks/tst/ansi_test.sh pins it).  Every phase before the last measures
# them as ZERO width -- txt_visible_length below, which txt_wrap and the
# table layout use -- or a bold word would cost thirteen columns of line
# that the reader never sees.
#
# The OFF sequences are the specific resets (22 ends bold, 23 italic, 24
# underline), never "\033[0m": @b @i x @ y @ must leave y bold, and a
# blanket reset would cancel the outer style with the inner one.
TXT_STYLES = {
    "bold":      ("\033[1m", "\033[22m"),
    "italic":    ("\033[3m", "\033[23m"),
    "underline": ("\033[4m", "\033[24m"),
}

def txt_style_marker(style, on=True):
    if style not in TXT_STYLES:
        raise ValueError(f"unknown type style {style!r}; one of {sorted(TXT_STYLES)}")
    return f"__KTEXT{style.upper()}{'' if on else 'OFF'}__"

_STYLE_MARKER_RGX = re.compile(
    "|".join(re.escape(txt_style_marker(s, on))
             for s in TXT_STYLES for on in (True, False)))

def txt_strip_styles(text, K):
    return _STYLE_MARKER_RGX.sub("", text)

def ansi_resolve_styles(text, K):
    for style, (on, off) in TXT_STYLES.items():
        text = text.replace(txt_style_marker(style), on)
        text = text.replace(txt_style_marker(style, False), off)
    return text

def txt_visible_length(s):
    """How many columns s occupies once its markers resolve: a KTESC
    marker is one glyph, an nbsp marker one space, a style marker nothing.
    len() is the wrong measure for anything laid out (see txt_util)."""
    s = _STYLE_MARKER_RGX.sub("", s)
    return len(klammer_base.unescape_ktesc(s).replace(txt_nbsp_marker(), " "))

def txt_wrap(text, width, subsequent_indent=""):
    """textwrap.wrap(text, width, break_long_words=False) measured by
    VISIBLE width.  textwrap counts characters, so a marker inside a word
    -- a bold word carries a thirteen-character marker at each end -- made
    it break lines a dozen columns early.  Whitespace runs are kept as
    written (sentence spacing survives), a word longer than the measure
    stands on its own line, and no word is broken at a hyphen."""
    chunks = re.split(r"(\s+)", text.strip())
    lines, line, sep = [], "", ""
    for i in range(0, len(chunks), 2):
        word = chunks[i]
        if word:
            if line and (txt_visible_length(line) + len(sep)
                         + txt_visible_length(word) > width):
                lines.append(line)
                line = subsequent_indent + word
            else:
                line += sep + word
        sep = " " * len(chunks[i + 1]) if i + 1 < len(chunks) else ""
    if line:
        lines.append(line)
    return lines

# The tex line break, carried as a marker.
#
# @nl.tex used to emit "\\newline" directly, and that is destroyed the moment
# it passes through a GENERATOR.  A klammer whose @eval result still holds
# klammers is generator output, so the machine escapes its text before
# applying them -- which is what lets a writer put a "%" in generated data
# without knowing LaTeX.  A backslash meets the same rule and becomes
# "\\textbackslash{}".  So a row written
#
#     @offer_list  work done @nl@ (delivery date) | 10 ||  ...
#
# resolved @nl to "\\newline" while binding the rest argument, handed that to
# Python as ordinary text, and had it neutralised on the way back:
# "\\textbackslash{}newline" reached the .tex and printed as literal text.
#
# The marker has no backslash, so the escape pass has nothing to act on, and
# tex_resolve_markers puts the real command back at the very end.
#
# LETTERS AND DIGITS ONLY -- deliberately unlike the txt markers above.  The
# tex target escapes "_" to "\\_", so a "__KTEXT...__" marker would arrive as
# "\\_\\_KTEXT...\\_\\_" and never match.  Nothing in this marker is in tex's
# :escape list.
def tex_nl_marker():
    return "KTEXNEWLINEMARK"

# Declared as an :after_apply phase on BOTH tex and pdf.  ":includes" carries
# escapes, transforms and resolves from tex into pdf but NOT phases
# (target_registry.cpp), and pdf's own phase compiles the document, so this
# has to run before it -- hence the explicit entry in each rather than
# inheritance.
def tex_resolve_markers(text, K):
    return text.replace(tex_nl_marker(), "\\newline")

def txt_justify_blocks(text, K):
    delim = '__DIVIDE__'
    text = re.sub("\n\n+", delim, text)
    result = ""
    for par in text.split(delim):
        stripped = par.strip()
        n = stripped.count(txt_vspace_marker())
        if n and stripped == txt_vspace_marker() * n:
            # A paragraph of only @vspace markers: n blank lines in addition
            # to the normal paragraph separation.
            result += "\n" * n
            continue

        # A paragraph BEGINNING WITH WHITESPACE is verbatim: it is filled to
        # no width and keeps the line breaks it was written with.  The same
        # in-text rule the error messages use (justify() in mac/util.cpp),
        # and the one a klammer relies on to emit lines that must not
        # re-flow -- a @table's rows, a listing.
        #
        # The nbsp MARKER counts as that whitespace, and must: a klammer's
        # indent cannot be a real space, because Eval::eval TRIMS the result
        # katoms, so the leading spaces a klammer emits never reach this
        # pass at all.  The marker is the only space that survives, and it
        # becomes one at the end of this function.  (It was the character
        # "~" until 2026-08-27, which meant every tilde in the document
        # became a space and a literal tilde could not be written at all.)
        #
        # The emission below was INSIDE this "if" until 2026-08-26, so a
        # verbatim paragraph was not left alone, it was DELETED: the one
        # branch that had nothing to do also did not copy the text through.
        # An indented paragraph vanished from the output with no error.
        nbsp = txt_nbsp_marker()
        if par and par[0] != ' ' and not par.startswith(nbsp):
            label = re.match("(?:" + re.escape(nbsp) + r")*\[\d+\] ", par)
            par = "\n".join(txt_wrap(
                par, int(K.Target_txt_width),
                subsequent_indent=" " * len(label.group(0)) if label else ""))
        result += par + "\n\n"
    result = re.sub(" *" + txt_vspace_marker() + " *", "\n", result)
    result = re.sub(r"\n? *" + txt_nl_marker() + r" *\n?", "\n", result)
    result = result.replace(txt_nbsp_marker(), " ")
    return result

def txt_insert_captions(text, K):
    mark = kutil.caption_delimiter()
    caption_rgx = re.compile(f"{mark}(.*?){mark}(.*?){mark}", re.S)
    caption_number = 0
    width = int(K.Target_txt_width)
    indent = int(K.Target_txt_indent)
    indented_width = width - indent
    def replace(m):
        nonlocal caption_number
        name, text = m.groups()
        # An empty label means an unnumbered caption (":number false").  It
        # must NOT take a number from the sequence: a reader counting the
        # captions they can see would then find the next one a number
        # ahead.  The same is true of html and tex, where an unnumbered
        # caption emits no marker and so never reaches their counter.
        if name:
            caption_number += 1
            caption = f"{name} {caption_number} - {text}"
        else:
            caption = text
        # Visible widths throughout: a caption may carry style markers.
        if txt_visible_length(caption) > indented_width:
            caption = "\n".join(txt_wrap(
                caption, indented_width,
                subsequent_indent=txt_nbsp_marker()*indent))
        line_length = max([txt_visible_length(e) for e in caption.split("\n")])
        line = txt_nbsp_marker() * indent + "-" * line_length
        return caption + "\n" + line
    result = caption_rgx.sub(replace, text)
    return result

def txt_footnote_marker():
    return "KTEXTFOOTNOTE"

def txt_format_footnotes(text, K):
    footnote_number = 0
    footnotes = []
    def replace(m):
        nonlocal footnote_number, footnotes
        footnote_number += 1
        footnotes.append(m.group(1))
        return f"[{footnote_number}]"
    start_mark = "__" + txt_footnote_marker()
    end_mark = txt_footnote_marker() + "__"
    footnote_rgx = re.compile(rf"\s*{start_mark}\s+(.*?)\s+{end_mark}", re.S)
    result = footnote_rgx.sub(replace, text).rstrip() + "\n\n"
    if footnotes:
        rule_count = int(round(float(K.Target_txt_width) * 0.4))
        result += "-" * rule_count + "\n\n"
        # Calculate maximum width for right-justified numbers:
        width = len(f"[{len(footnotes)}]") 
        for n, footnote in enumerate(footnotes, 1):
            label = f"[{n}]"
            result += (txt_nbsp_marker() * (width - len(label))
                       + label + " " + footnote + "\n\n")
    return result

def html_footnote_marker():
    return "kt-footnote"

def html_format_footnotes(text, K=None):
    fnum = 0
    footnotes = []
    def replace(m):
        nonlocal fnum, footnotes
        fnum += 1
        footnotes.append(m.group(1))
        href = f'href ="#_footnote_{fnum}"'
        id = f'id="_footnote_src_{fnum}"'
        return f'<a {id} {href}><sup class="footnote_in_text">{fnum}</sup></a>'
    #return f'<a href="#_footnote_{fnum}" id="_footnote_src_{fnum}"><sup>{fnum}</sup></a>'
    start_mark = f"<{html_footnote_marker()}>"
    end_mark = f"</{html_footnote_marker()}>"
    footnote_rgx = re.compile(rf"\s*{start_mark}\s*(.*?)\s*{end_mark}", re.S)
    result = footnote_rgx.sub(replace, text).rstrip() + "\n\n"
    if footnotes:
        result += '<hr class="footnote_rule"/>\n'
        for n, footnote in enumerate(footnotes, 1):
            result += f'<a href="#_footnote_src_{n}" id="_footnote_{n}"><sup>{n} </sup></a>{footnote}<br/>\n'
        # Temporarily add room for footnotes to move to the top of the window for the test:
        result += '<div style="height: 100lh"></div>\n'
    return result