"""Parse service — PDF (pdfplumber), DOCX (python-docx), plain text fallback."""
import io


def parse_file(filename, data):
    """Parse file bytes → {status, elements, element_count}."""
    ext = filename.rsplit(".", 1)[-1].lower() if "." in filename else ""
    try:
        if ext == "pdf":
            return _parse_pdf(data)
        elif ext == "docx":
            return _parse_docx(data)
        elif ext == "doc":
            return _parse_docx(data)  # python-docx handles most .doc
        else:
            return _parse_text(data)
    except Exception as e:
        return {"status": "error", "error": str(e), "element_count": 0}


def _parse_pdf(data):
    """Parse PDF with pdfplumber — preserves table structure (unlike PyPDF2)."""
    import pdfplumber
    elements = []
    with pdfplumber.open(io.BytesIO(data)) as pdf:
        for page in pdf.pages:
            # Tables first — preserves column structure critical for specs
            tables = page.extract_tables()
            for table in tables:
                if table:
                    rows = []
                    for row in table:
                        if row:
                            cells = [str(cell or "").strip() for cell in row]
                            if any(cells):
                                rows.append(cells)
                    if rows:
                        elements.append({"type": "table", "rows": rows})
            # Remaining text as paragraphs
            text = page.extract_text()
            if text:
                for line in text.split("\n"):
                    line = line.strip()
                    if line:
                        elements.append({"type": "paragraph", "text": line, "style": ""})
    return {"status": "parsed", "element_count": len(elements), "elements": elements}


def _parse_docx(data):
    import docx
    doc = docx.Document(io.BytesIO(data))
    elements = []

    for block in doc.element.body:
        tag = block.tag.split("}")[-1] if "}" in block.tag else block.tag
        if tag == "p":
            text = _extract_paragraph_text(block)
            if text:
                elements.append({"type": "paragraph", "text": text, "style": ""})
        elif tag == "tbl":
            rows = []
            for tr in block.findall(".//{http://schemas.openxmlformats.org/wordprocessingml/2006/main}tr"):
                cells = []
                for tc in tr.findall(".//{http://schemas.openxmlformats.org/wordprocessingml/2006/main}tc"):
                    cell_text = "".join(t.text or "" for t in tc.findall(".//{http://schemas.openxmlformats.org/wordprocessingml/2006/main}t"))
                    cells.append(cell_text.strip())
                if cells:
                    rows.append(cells)
            if rows:
                elements.append({"type": "table", "rows": rows})

    return {"status": "parsed", "element_count": len(elements), "elements": elements}


def _extract_paragraph_text(p_elem):
    texts = []
    for t in p_elem.findall(".//{http://schemas.openxmlformats.org/wordprocessingml/2006/main}t"):
        if t.text:
            texts.append(t.text)
    return "".join(texts).strip()


def _parse_text(data):
    text = data.decode("utf-8", errors="ignore")[:5000]
    lines = [l.strip() for l in text.split("\n") if l.strip()]
    return {"status": "parsed", "element_count": len(lines),
            "elements": [{"type": "paragraph", "text": l, "style": ""} for l in lines]}