"""Apply document commands to a docx using python-docx. No fallback: raises on error."""
import io
import logging
from typing import Any

from docx import Document

logger = logging.getLogger(__name__)


def apply_replace_text(doc: Document, search: str, replace: str) -> None:
    """Replace first occurrence of search with replace in all paragraphs."""
    if not search:
        raise ValueError("replaceText: search must be non-empty")
    for paragraph in doc.paragraphs:
        if search in paragraph.text:
            for run in paragraph.runs:
                if search in run.text:
                    run.text = run.text.replace(search, replace, 1)
                    return
            paragraph.text = paragraph.text.replace(search, replace, 1)
            return
    for table in doc.tables:
        for row in table.rows:
            for cell in row.cells:
                for paragraph in cell.paragraphs:
                    if search in paragraph.text:
                        for run in paragraph.runs:
                            if search in run.text:
                                run.text = run.text.replace(search, replace, 1)
                                return
                        paragraph.text = paragraph.text.replace(search, replace, 1)
                        return
    logger.warning("replaceText: search string not found: %s", repr(search[:50]))


def apply_insert_paragraph(
    doc: Document,
    text: str,
    position: str = "end",
) -> None:
    """Insert a paragraph. position: 'end' (default) or 'start'."""
    new_para = doc.add_paragraph(text)
    if position == "start" and len(doc.paragraphs) > 1:
        # Move the new paragraph to the start (python-docx adds at end)
        body = doc.element.body
        new_el = new_para._element
        body.remove(new_el)
        body.insert(0, new_el)
    elif position != "end" and position != "start":
        raise ValueError("insertParagraph: position must be 'start' or 'end'")


def load_docx(content: bytes) -> Document:
    """Load docx from bytes."""
    return Document(io.BytesIO(content))


def save_docx(doc: Document) -> bytes:
    """Save docx to bytes."""
    buf = io.BytesIO()
    doc.save(buf)
    buf.seek(0)
    return buf.read()


def apply_commands_docx(content: bytes, commands: list[dict[str, Any]]) -> bytes:
    """
    Apply a list of commands to docx content. Returns new content.
    Commands: { "type": "replaceText", "search": "...", "replace": "..." }
              { "type": "insertParagraph", "text": "...", "position": "end"|"start" }
    """
    doc = load_docx(content)
    for cmd in commands:
        ctype = cmd.get("type")
        if ctype == "replaceText":
            apply_replace_text(
                doc,
                search=str(cmd.get("search", "")),
                replace=str(cmd.get("replace", "")),
            )
        elif ctype == "insertParagraph":
            apply_insert_paragraph(
                doc,
                text=str(cmd.get("text", "")),
                position=str(cmd.get("position", "end")),
            )
        else:
            raise ValueError(f"Unknown command type: {ctype}")
    return save_docx(doc)