"""Residual-question dedup: group pending cells by the KNOWLEDGE needed, not per cell.

- INVALID_NCM  -> one work item per product fingerprint (same product in N databases collapses)
- CEST/EX_TIPI -> one work item per (doubt, NCM): all databases sharing that NCM collapse
- PRODUCT_ROLE -> tenant-specific by contract: one work item per (company, group)
- Everything else (origin, ST retention, company profile, duplicate key) never becomes
  an AI work item.
"""
from dataclasses import dataclass, field

_INVALID_NCM, _ROLE = "ncm", "product_role"


@dataclass
class WorkItem:
    task_type: str
    dedup_key: str
    question_refs: list = field(default_factory=list)
    cells_covered: int = 0
    payload: dict = field(default_factory=dict)
    kb_product_id: int | None = None


def build_work_items(questions, product_fingerprints=None) -> list[WorkItem]:
    """`product_fingerprints` maps "{DATABASE}:{erp_code}" -> KB fingerprint (from the seed pass)."""
    product_fingerprints = product_fingerprints or {}
    items: dict = {}

    def _get(task_type, dedup_key, ref, cells):
        item = items.get(dedup_key)
        if item is None:
            item = WorkItem(task_type=task_type, dedup_key=dedup_key)
            items[dedup_key] = item
        item.question_refs.append(ref)
        item.cells_covered += cells
        return item

    for question in questions:
        key = question.get("KEY")
        scope = question.get("SCOPE")
        cells = int(question.get("CELLS") or question.get("PRODUCTS_AFFECTED") or 0)
        ref = question.get("QUESTION_ID") or f"{question.get('DATABASE')}:{scope}:{question.get('NCM') or question.get('GROUP')}:{key}"
        if key in ("cest", "ex_tipi") and scope == "NCM":
            ncm = str(question.get("NCM") or "").strip()
            if ncm:
                item = _get(key.upper(), f"{key}:{ncm}", ref, cells)
                item.payload.setdefault("ncm", ncm)
                item.payload["description"] = question.get("EXAMPLES", "").split(";")[0].strip() if question.get("EXAMPLES") else ""
        elif key == _INVALID_NCM and scope == "PRODUCT":
            database = question.get("DATABASE", "")
            erp_code = str(question.get("DATABASE_CODE") or "").strip()
            fingerprint = product_fingerprints.get(f"{database}:{erp_code}")
            dedup = f"invalid_ncm:{fingerprint}" if fingerprint else f"invalid_ncm:{database}:{erp_code}"
            item = _get("INVALID_NCM", dedup, ref, cells)
            item.payload.setdefault("erp_code", erp_code)
            item.payload["description"] = question.get("EXAMPLES", "").split(";")[0].strip() if question.get("EXAMPLES") else ""
        elif key == _ROLE and scope == "GROUP":
            company = question.get("COMPANY", "")
            group = str(question.get("GROUP") or "").strip()
            if group:
                item = _get("PRODUCT_ROLE", f"product_role:{company}:{group}", ref, cells)
                item.payload.setdefault("company_key", company)
                item.payload["group"] = group
    return list(items.values())