from typing import List

from src.domain.entities.merchant import Merchant, MerchantListItem
from src.domain.interfaces.merchant_repository import MerchantRepositoryInterface
from src.core.exceptions import NotFoundException


def _compute_pending_docs(item: MerchantListItem) -> List[str]:
    """
    Mirrors MerchantController::getHelperTxt() from the Laravel codebase.

    Stage 1: If ALL 3 critical docs are missing → show the missing ones.
    Stage 2: If at least one doc exists → sequential checklist:
             Module → Signed Agreement → Offers → Maker Checker → Bank Details → Status
    """
    any_doc_exists = item.has_pan_card or item.has_equifax or item.has_gst_reg

    if not any_doc_exists:
        pending = []
        if not item.has_pan_card:
            pending.append("Pan Card")
        if not item.has_equifax:
            pending.append("Bureau Report")
        if not item.has_gst_reg:
            pending.append("Business Reg")
        return pending

    # At least one document uploaded — check workflow steps in order
    if not item.has_module:
        return ["Module"]
    if not item.is_agreement_signed:
        return ["Signed Agreement"]
    if not item.has_active_offer:
        return ["Offers"]
    if item.has_inactive_offer:
        return ["Maker Checker"]
    if not item.has_bank:
        return ["Bank Details"]
    if item.status == "inactive":
        return ["Status"]

    return []


def _resolve_display_status(item: MerchantListItem) -> str:
    """
    Mirrors the status display logic from resources/views/admin/merchant/index.blade.php line 174.

    Conditions (in order):
      1. status not set              → "--"
      2. receive_application is null → "Deactivated"
      3. status='active', pre_status=0 → "Active for disbursements"
      4. status='active', pre_status=1 → "Active for login/training"
      5. otherwise                   → raw status value
    """
    if item.status is None:
        return "--"
    if item.receive_application is None:
        return "Deactivated"
    if item.status == "active" and item.pre_status == 0:
        return "Active for disbursements"
    if item.status == "active" and item.pre_status == 1:
        return "Active for login/training"
    return item.status


class GetMerchantsUseCase:
    """Returns slim merchant list with resolved display status (for frontend list view)."""

    def __init__(self, merchant_repo: MerchantRepositoryInterface):
        self.merchant_repo = merchant_repo

    def execute(self) -> List[MerchantListItem]:
        items = self.merchant_repo.get_list()
        for item in items:
            pending = _compute_pending_docs(item)   # compute before status is mutated
            item.status = _resolve_display_status(item)
            item._pending_docs = pending            # attach for schema serialization
        return items


class GetMerchantByIdUseCase:
    """Returns a single merchant by ID."""

    def __init__(self, merchant_repo: MerchantRepositoryInterface):
        self.merchant_repo = merchant_repo

    def execute(self, merchant_id: int) -> Merchant:
        merchant = self.merchant_repo.get_by_id(merchant_id)
        if not merchant:
            raise NotFoundException(f"Merchant {merchant_id} not found")
        return merchant