"""Plain-content document import/export. Layout, tracked changes and media are not preserved."""
from pathlib import Path
import subprocess,tempfile,zipfile,xml.etree.ElementTree as ET,re
from xml.sax.saxutils import escape
W='{http://schemas.openxmlformats.org/wordprocessingml/2006/main}'
def read(path):
    path=Path(path);ext=path.suffix.lower()
    if ext=='.txt':return path.read_text(encoding='utf-8-sig')
    if ext=='.rtf':return subprocess.check_output(['/usr/bin/textutil','-convert','txt','-stdout',str(path)]).decode('utf-8')
    if ext=='.docx':
        with zipfile.ZipFile(path) as z:
            if sum(i.file_size for i in z.infolist())>100_000_000:raise ValueError('Document expands beyond the 100 MB import limit.')
            root=ET.fromstring(z.read('word/document.xml'))
        return '\n'.join(''.join(n.text or '' if n.tag==W+'t' else '\t' if n.tag==W+'tab' else '\n' if n.tag in (W+'br',W+'cr') else '' for n in p.iter()) for p in root.iter(W+'p'))
    raise ValueError('Choose .txt, .rtf or .docx.')
def write(path,text):
    path=Path(path);ext=path.suffix.lower()
    if ext=='.txt':path.write_text(text,encoding='utf-8');return
    if ext=='.rtf':
        with tempfile.TemporaryDirectory() as d:
            src=Path(d)/'content.txt';src.write_text(text,encoding='utf-8')
            subprocess.run(['/usr/bin/textutil','-convert','rtf','-output',str(path),str(src)],check=True,capture_output=True)
        return
    if ext!='.docx':raise ValueError('Choose a .txt, .rtf or .docx filename.')
    body=''.join('<w:p><w:r><w:t xml:space="preserve">'+escape(line)+'</w:t></w:r></w:p>' for line in text.splitlines())
    with zipfile.ZipFile(path,'w',zipfile.ZIP_DEFLATED) as z:
        z.writestr('[Content_Types].xml','<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"><Default Extension="rels" ContentType="application/vnd.openxmlformats-package.relationships+xml"/><Default Extension="xml" ContentType="application/xml"/><Override PartName="/word/document.xml" ContentType="application/vnd.openxmlformats-officedocument.wordprocessingml.document.main+xml"/></Types>')
        z.writestr('_rels/.rels','<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>')
        z.writestr('word/document.xml','<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>'+body+'<w:sectPr/></w:body></w:document>')
def spans(text,limit=700):
    out=[]
    for m in re.finditer(r'\S[\s\S]*?(?=\r?\n[^\S\r\n]*\r?\n|\Z)',text):
        start,end=m.span()
        while end>start and text[end-1].isspace():end-=1
        while end-start>limit:
            part=text[start:start+limit]
            sentences=list(re.finditer(r'[.!?؟。！？]["”’]*?(?=\s)',part))
            sentence_cuts=[m.end() for m in sentences if m.end()>=limit//3]
            spaces=list(re.finditer(r'\s+',part))
            cut=sentence_cuts[-1] if sentence_cuts else spaces[-1].start() if spaces else limit
            if cut<limit//3:cut=limit
            stop=start+cut
            while stop>start and text[stop-1].isspace():stop-=1
            out.append((start,stop));start=stop
            while start<end and text[start].isspace():start+=1
        if start<end:out.append((start,end))
    return out

def assemble(text,locations,records):
    out=[];cursor=0
    for i,(a,b) in enumerate(locations):out.extend((text[cursor:a],records.get(str(i),{}).get('text',text[a:b])));cursor=b
    return ''.join(out)+text[cursor:]


def validate_spans(text,locations):
    """Validate saved coverage without resegmenting checkpoints from older releases."""
    cursor=0
    if not isinstance(locations,list):raise ValueError('Invalid saved passage layout.')
    for pair in locations:
        if not isinstance(pair,(list,tuple)) or len(pair)!=2:raise ValueError('Invalid saved passage offsets.')
        a,b=pair
        if type(a) is not int or type(b) is not int or not cursor<=a<b<=len(text) or text[cursor:a].strip():raise ValueError('Invalid saved passage coverage.')
        cursor=b
    if text[cursor:].strip():raise ValueError('Saved passage layout omits text.')
    return locations


def rewrite_allowance(text,locations,records,index,multiplier=2):
    """Carry unused 2x character allowance forward within the original paragraph.

    Unprocessed earlier chunks reserve their original text length. Whitespace
    between chunks stays in the assembled output and counts against the cap.
    No allowance crosses a blank-line paragraph separator.
    """
    first=index
    while first>0:
        gap=text[locations[first-1][1]:locations[first][0]]
        if re.search(r'\r?\n[^\S\r\n]*\r?\n',gap):break
        first-=1
    start=locations[first][0];end=locations[index][1]
    used=0
    for j in range(first,index):
        a,b=locations[j]
        used+=len(records.get(str(j),{}).get('text',text[a:b]))
        used+=locations[j+1][0]-b
    return max(0,int(multiplier*(end-start))-used)