"""Grouping service — match classified documents into contract groups."""
import re
from db import documents as db_docs
from db import contracts as db_contracts
from db import supplements as db_supplements


def normalize_number(num):
    """Normalize contract number for matching: uppercase, only letters/digits."""
    if not num:
        return ""
    return re.sub(r"[^A-Z0-9А-Я]", "", num.upper())


def group_documents(batch_id):
    """Group classified documents by contract. Returns list of groups."""
    docs = db_docs.list_by_batch(batch_id)
    classified = [d for d in docs if d.get("classify_status") == "classified"]

    # Separate contracts and supplements
    contracts_list = []
    supplements_list = []

    for d in classified:
        if d.get("doc_type") == "contract":
            contracts_list.append(d)
        else:
            supplements_list.append(d)

    groups = []

    # Each contract becomes a group
    for c in contracts_list:
        group = {
            "contract_number": c.get("own_number") or c.get("filename", ""),
            "counterparty": c.get("counterparty") or "",
            "documents": [c],
        }
        # Find supplements matching this contract
        c_norm = normalize_number(c.get("own_number"))
        for s in supplements_list:
            parent = normalize_number(s.get("parent_number") or "")
            own = normalize_number(s.get("own_number") or "")
            if parent == c_norm or own == c_norm:
                if s not in group["documents"]:
                    group["documents"].append(s)

        # Sort by date
        group["documents"].sort(key=lambda x: x.get("doc_date") or "")

        # Remove matched supplements from the pool
        for s in group["documents"]:
            if s in supplements_list:
                supplements_list.remove(s)

        groups.append(group)

    # Unmatched documents → "unresolved" group
    unmatched = [s for s in supplements_list if s.get("doc_type") != "contract"]
    unmatched += [d for d in classified if d.get("classify_status") != "classified"]

    if unmatched or len(contracts_list) == 0:
        # Put unmatched into a separate group
        if unmatched:
            groups.append({
                "contract_number": "__unresolved__",
                "counterparty": "",
                "documents": unmatched,
            })

    return {"ok": True, "groups": groups, "total_docs": len(classified)}


def apply_groups(batch_id, groups_data):
    """Apply confirmed groups: create contracts + supplements."""
    created = 0
    for g in groups_data:
        contract_number = g.get("contract_number", "")
        if contract_number == "__unresolved__":
            continue
        counterparty = g.get("counterparty", "")
        docs = g.get("documents", [])

        # Create contract
        c = db_contracts.insert(contract_number, counterparty)
        contract_id = c["id"]

        # Create supplements in order
        for i, d in enumerate(docs):
            doc_id = d.get("id")
            supp_type = "initial" if i == 0 else "additional"
            db_supplements.insert(contract_id, doc_id, supp_type)
            created += 1

    return {"ok": True, "created": created}