"""Parse and normalize the field-assist model response.

Pure module: no FastAPI imports and no HTTPException.
"""

from __future__ import annotations

import re

from job_assist.prompt import LIST_FIELDS, SINGLE_LINE_FIELDS

MAX_SUGGESTION_CHARS = 6000

# Leading bullet/number markers the model may emit despite the prompt.
_BULLET = re.compile(r"^\s*(?:[-*•·]+|\d+[.)])\s+")


def parse_assist_response(data, field) -> str:
    """The suggestion string, normalized to the field's shape. Raises RuntimeError."""
    if not isinstance(data, dict):
        raise RuntimeError("assist response is not an object")
    suggestion = data.get("suggestion")
    if not isinstance(suggestion, str) or not suggestion.strip():
        raise RuntimeError("assist response has no suggestion")

    text = suggestion.replace("\r\n", "\n").replace("\r", "\n").strip()

    if field in SINGLE_LINE_FIELDS:
        text = " ".join(text.split())
    elif field in LIST_FIELDS:
        # The form splits these on newline (Jobs.jsx splitLines), so strip any
        # bullet markers and keep one item per line.
        lines = [_BULLET.sub("", line).strip() for line in text.split("\n")]
        text = "\n".join(line for line in lines if line)
        if not text:
            raise RuntimeError("assist response emptied after normalization")
    else:
        text = re.sub(r"\n{3,}", "\n\n", text)

    return text[:MAX_SUGGESTION_CHARS].strip()