"""
Top-level invoice processing pipeline.

Flow: validation → routing → matching → final result.

No business logic lives here. Each step delegates entirely to its own module:
  - Validation  : Invoice Validation Functions/orchestrator.py
  - Routing     : match_router.py
  - 2-way match : two_way_match.py
  - 3-way match : three_way_match.py (layers on top of 2-way result)
  - Contract    : contract_match.py

Caller responsibilities (not enforced here):
  - Acquire the advisory lock before calling (SDD §3.1).
  - Pre-fetch po, po_lines, gr_rows from the database.
  - Construct matching_invoice (InvoiceHeader) and matching_inv_lines.
  - Construct contract_invoice (ContractInvoiceHeader) when contract match is possible.
  - Handle prior-match supersession in the database after this call returns (SDD §3.5).
"""

from __future__ import annotations

import importlib.util
import json
import os
from typing import Any, Optional

# ============================================================
# Load validation orchestrator by path
# (the directory name contains spaces, so importlib is required)
# ============================================================

_HERE = os.path.dirname(os.path.abspath(__file__))
_VALIDATION_DIR = os.path.normpath(os.path.join(_HERE, "..", "Invoice Validation Functions"))


def _load_module_by_path(filepath: str, module_name: str):
    spec = importlib.util.spec_from_file_location(module_name, filepath)
    mod = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(mod)
    return mod


_val_orch = _load_module_by_path(
    os.path.join(_VALIDATION_DIR, "orchestrator.py"),
    "_validation_orchestrator",
)
_run_validation_pipeline = _val_orch.run_invoice_validation_pipeline


# ============================================================
# Matching layer imports
# ============================================================

from match_router import (
    MatchPreconditionError,
    RouteDecision,
    RoutingDocument,
    RoutingExtractedFields,
    route_invoice,
)
from two_way_match import (
    InvoiceHeader,
    InvoiceLine,
    MatchExceptionRecord,
    POHeader,
    POLine,
    run_two_way_match_core,
)
from three_way_match import GRLineItem, run_three_way_match
from contract_match import (
    ContractInvoiceHeader,
    ContractMatchResult,
    run_contract_match_core,
)


# ============================================================
# Config loader
# ============================================================

def _load_matching_configs(path: Optional[str] = None) -> dict:
    if path is None:
        path = os.path.join(_HERE, "matching_configs.json")
    with open(path, encoding="utf-8") as fh:
        return json.load(fh)


# ============================================================
# Internal helpers
# ============================================================

def _stub_missing_contract_invoice(inv_lines: list[InvoiceLine]) -> ContractMatchResult:
    """Returned when contract route is selected but contract_invoice was not provided."""
    res = ContractMatchResult(
        match_type="contract",
        overall_status="exception",
        match_zone="red",
        documents_status="pending_approval",
        lines_total=len(inv_lines),
        lines_matched=0,
        lines_in_exception=len(inv_lines),
    )
    res.header_exceptions.append(
        MatchExceptionRecord(
            exception_type="cannot_match_missing_contract_invoice",
            exception_detail={"reason": "contract_invoice_not_provided_to_pipeline"},
        )
    )
    return res


def _collect_match_flags(match_result: Any) -> tuple[list, list, list]:
    """Extract risk_flags, advisory_flags, skipped_steps from a match result."""
    if match_result is None:
        return [], [], []
    return (
        list(getattr(match_result, "risk_flags", None) or []),
        list(getattr(match_result, "advisory_flags", None) or []),
        list(getattr(match_result, "skipped_steps", None) or []),
    )


def _compute_final_status(validation_risk_flags: list, match_result: Any) -> str:
    """
    Derive a single final status from both validation and match outcomes.
    Any validation risk flag is treated as an exception regardless of match result.
    """
    if validation_risk_flags:
        return "exception"
    if match_result is None:
        return "exception"
    return getattr(match_result, "overall_status", "exception")


# ============================================================
# Top-level pipeline
# ============================================================

def run_invoice_pipeline(
    *,
    # --- Validation inputs ---
    document,
    extracted_fields,
    vendors,
    vendor_bank_accounts,
    vendor_tax_ids,
    entity,
    line_items,
    purchase_orders,
    contracts,
    tax_master_rows,
    currency_seed_map,
    platform_configs: Optional[dict] = None,
    route_contexts=None,
    actor_id=None,
    # --- Matching inputs ---
    matching_invoice: InvoiceHeader,
    matching_inv_lines: list[InvoiceLine],
    contract_invoice: Optional[ContractInvoiceHeader] = None,
    po: Optional[POHeader] = None,
    po_lines: Optional[list[POLine]] = None,
    gr_rows: Optional[list[GRLineItem]] = None,
    matching_configs: Optional[dict] = None,
) -> dict[str, Any]:
    """
    Run the full invoice processing pipeline and return a single combined result.

    Parameters
    ----------
    document              : Invoice document object (.id, .tenant_id, .entity_id,
                            .status, .doc_type required for routing).
    extracted_fields      : VLM-extracted fields (.po_number_canonical used for routing).
    vendors               : Vendor records for vendor validation.
    vendor_bank_accounts  : Vendor bank account records.
    vendor_tax_ids        : Vendor tax-ID records.
    entity                : Routing entity (.country_code, .vat_id, .region_code).
    line_items            : Invoice line-item records (for validation).
    purchase_orders       : Purchase-order records (for payment-terms validation).
    contracts             : Contract records (for payment-terms validation and contract match).
    tax_master_rows       : Tax-master records.
    currency_seed_map     : Dict mapping ISO currency code → minor-unit row.
    platform_configs      : Validation config dict; loaded from platform_configs.json if None.
    route_contexts        : Route-context strings forwarded to Vendor Validation.
    actor_id              : Actor identifier forwarded to Vendor Validation for audit.
    matching_invoice      : InvoiceHeader for 2-way / 3-way matching.
    matching_inv_lines    : Invoice lines for all match types.
    contract_invoice      : ContractInvoiceHeader for contract matching (optional).
    po                    : Pre-fetched POHeader; None if no PO number on the invoice.
    po_lines              : Pre-fetched PO lines; None if no PO.
    gr_rows               : Pre-fetched GR rows; None or [] triggers 2-way instead of 3-way.
    matching_configs      : Matching config dict; loaded from matching_configs.json if None.

    Returns
    -------
    dict with keys:
      validation_result  — raw dict from the validation pipeline
      route              — 'two_way' | 'three_way' | 'contract' | 'credit_note' |
                           'stub' | 'precondition_error'
      match_result       — TwoWayMatchResult | ContractMatchResult | None
      risk_flags         — combined validation + matching risk flags, in execution order
      advisory_flags     — combined, in execution order
      skipped_steps      — combined, in execution order
      ops_alerts         — operational alerts from the validation layer
      resolved_vendor_id — from vendor validation
      final_status       — 'matched' | 'partial_match' | 'exception'
    """

    # ------------------------------------------------------------------
    # Step 1 — Validation
    # ------------------------------------------------------------------
    validation_result = _run_validation_pipeline(
        document=document,
        extracted_fields=extracted_fields,
        vendors=vendors,
        vendor_bank_accounts=vendor_bank_accounts,
        vendor_tax_ids=vendor_tax_ids,
        entity=entity,
        line_items=line_items,
        purchase_orders=purchase_orders,
        contracts=contracts,
        tax_master_rows=tax_master_rows,
        currency_seed_map=currency_seed_map,
        platform_configs=platform_configs,
        route_contexts=route_contexts,
        actor_id=actor_id,
    )

    resolved_vendor_id = validation_result.get("resolved_vendor_id")
    risk_flags: list    = list(validation_result.get("risk_flags")     or [])
    advisory_flags: list = list(validation_result.get("advisory_flags") or [])
    skipped_steps: list  = list(validation_result.get("skipped_steps")  or [])

    # ------------------------------------------------------------------
    # Step 2 — Routing
    # ------------------------------------------------------------------
    if matching_configs is None:
        matching_configs = _load_matching_configs()

    routing_doc = RoutingDocument(
        id=getattr(document, "id", None),
        tenant_id=getattr(document, "tenant_id", None),
        entity_id=getattr(document, "entity_id", None),
        status=getattr(document, "status", "validated"),
        doc_type=getattr(document, "doc_type", "invoice"),
    )
    routing_ef = RoutingExtractedFields(
        po_number_canonical=getattr(extracted_fields, "po_number_canonical", None),
        resolved_vendor_id=resolved_vendor_id,
    )

    try:
        decision: RouteDecision = route_invoice(
            document=routing_doc,
            ef=routing_ef,
            inv_lines=matching_inv_lines,
            po=po,
            po_lines=po_lines,
            gr_rows=gr_rows,
        )
    except MatchPreconditionError as exc:
        return {
            "validation_result": validation_result,
            "route": "precondition_error",
            "match_result": None,
            "risk_flags": risk_flags,
            "advisory_flags": advisory_flags,
            "skipped_steps": skipped_steps,
            "ops_alerts": list(validation_result.get("ops_alerts") or []),
            "resolved_vendor_id": resolved_vendor_id,
            "final_status": "exception",
            "error": str(exc),
        }

    route = decision.route

    # ------------------------------------------------------------------
    # Step 3 — Matching
    # ------------------------------------------------------------------
    match_result: Any = None

    if route == "stub":
        match_result = decision.stub_result

    elif route == "two_way":
        match_result = run_two_way_match_core(
            matching_invoice,
            matching_inv_lines,
            decision.po,
            decision.po_lines or [],
            matching_configs=matching_configs,
        )

    elif route == "three_way":
        two_way_result = run_two_way_match_core(
            matching_invoice,
            matching_inv_lines,
            decision.po,
            decision.po_lines or [],
            matching_configs=matching_configs,
        )
        match_result = run_three_way_match(
            two_way_result,
            matching_invoice,
            matching_inv_lines,
            decision.po_lines or [],
            decision.gr_rows or [],
            matching_configs=matching_configs,
        )

    elif route == "contract":
        if contract_invoice is None:
            match_result = _stub_missing_contract_invoice(matching_inv_lines)
        else:
            match_result = run_contract_match_core(
                contract_invoice,
                matching_inv_lines,
                list(contracts),
                matching_configs=matching_configs,
            )

    # ------------------------------------------------------------------
    # Step 4 — Combine flags and return
    # ------------------------------------------------------------------
    m_risk, m_advisory, m_skipped = _collect_match_flags(match_result)
    risk_flags.extend(m_risk)
    advisory_flags.extend(m_advisory)
    skipped_steps.extend(m_skipped)

    return {
        "validation_result": validation_result,
        "route": route,
        "match_result": match_result,
        "risk_flags": risk_flags,
        "advisory_flags": advisory_flags,
        "skipped_steps": skipped_steps,
        "ops_alerts": list(validation_result.get("ops_alerts") or []),
        "resolved_vendor_id": resolved_vendor_id,
        "final_status": _compute_final_status(
            validation_result.get("risk_flags") or [], match_result
        ),
    }