"""Compare the two EpcPropertyData source paths for one real cert, to
separate MAPPER fidelity from CALCULATOR correctness.

For a cert captured under
``backend/epc_api/json_samples/real_life_examples/<schema>/uprn_<uprn>/``
this:
  1. builds `EpcPropertyData` from the gov-EPC API json (`epc.json`), and
  2. builds `EpcPropertyData` from the Elmhurst summary PDF
     (`elmhurst_summary.pdf`) via `parse_site_notes_pdf`,
then deep-diffs the two and runs BOTH through `Sap10Calculator`. Where the
two objects match, any SAP gap is the calculator; where they differ, it's
input mapping / data entry. If `elmhurst_worksheet.pdf` is present its
printed SAP rating (258) is shown as the ground truth.

USAGE
-----
    PYTHONPATH=/workspaces/model python scripts/compare_epc_paths.py <uprn>

Part of the `validate-cert-sap-accuracy` workflow — see that skill.
"""

from __future__ import annotations

import dataclasses
import json
import re
import sys
from pathlib import Path
from typing import Any, Optional
from unittest.mock import patch

import httpx

from backend.documents_parser.parser import parse_site_notes_pdf
from datatypes.epc.domain.epc_property_data import EpcPropertyData
from datatypes.epc.domain.mapper import EpcPropertyDataMapper
from domain.sap10_calculator.calculator import Sap10Calculator

_ROOT = Path("backend/epc_api/json_samples/real_life_examples")


def _find_sample_dir(uprn: str) -> Path:
    matches = list(_ROOT.glob(f"*/uprn_{uprn}"))
    if not matches:
        raise SystemExit(
            f"no sample dir for UPRN {uprn} under {_ROOT} — capture it first "
            f"with scripts/fetch_real_life_epc_sample.py {uprn}"
        )
    return matches[0]


def _gov_api_epc(epc_json: Path) -> EpcPropertyData:
    data = json.loads(epc_json.read_text())

    def _mock(*_a: object, **_k: object) -> httpx.Response:
        return httpx.Response(
            200, json={"data": data}, request=httpx.Request("GET", "x")
        )

    # Route the raw payload through the real mapper (httpx mocked, no network).
    with patch("httpx.get", side_effect=_mock):
        from infrastructure.epc_client.epc_client_service import EpcClientService

        return EpcClientService(auth_token="t").get_by_certificate_number("x")


def _elmhurst_printed_sap(worksheet_pdf: Path) -> Optional[int]:
    if not worksheet_pdf.exists():
        return None
    import fitz  # pymupdf

    text = "\n".join(p.get_text() for p in fitz.open(str(worksheet_pdf)))
    for line in text.splitlines():
        if "SAP rating" in line and "(258)" in line:
            # value sits immediately before the "(258)" line ref
            match = re.search(r"(\d+)\s*\(258\)", line)
            if match:
                return int(match.group(1))
    return None


def _deep_diff(a: Any, b: Any, prefix: str, out: list[str]) -> None:
    if dataclasses.is_dataclass(a) and dataclasses.is_dataclass(b):
        for f in dataclasses.fields(a):
            _deep_diff(getattr(a, f.name), getattr(b, f.name), f"{prefix}.{f.name}", out)
    elif isinstance(a, list) and isinstance(b, list):
        if len(a) != len(b):
            out.append(f"  {prefix}: LEN {len(a)} vs {len(b)}")
        for i, (x, y) in enumerate(zip(a, b)):
            _deep_diff(x, y, f"{prefix}[{i}]", out)
    elif a != b:
        out.append(f"  {prefix}: API={a!r}  ELM={b!r}")


def compare(uprn: str) -> None:
    sample = _find_sample_dir(uprn)
    print(f"=== {sample} ===")
    gov = _gov_api_epc(sample / "epc.json")

    summary = sample / "elmhurst_summary.pdf"
    elm: Optional[EpcPropertyData] = None
    if summary.exists():
        elm = parse_site_notes_pdf(str(summary))
    else:
        print("  (no elmhurst_summary.pdf yet — gov-API side only)")

    rg = Sap10Calculator().calculate(gov)
    print("\nOUR ENGINE:")
    print(
        f"  gov-API inputs      → SAP {rg.sap_score} ({rg.sap_score_continuous:.2f})"
        f"  HW {rg.hot_water_kwh_per_yr:.0f} kWh  cost £{rg.total_fuel_cost_gbp:.2f}"
    )
    if elm is not None:
        re_ = Sap10Calculator().calculate(elm)
        print(
            f"  Elmhurst-PDF inputs → SAP {re_.sap_score} ({re_.sap_score_continuous:.2f})"
            f"  HW {re_.hot_water_kwh_per_yr:.0f} kWh  cost £{re_.total_fuel_cost_gbp:.2f}"
        )
        printed = _elmhurst_printed_sap(sample / "elmhurst_worksheet.pdf")
        if printed is not None:
            print(f"  Elmhurst's OWN engine (worksheet 258): {printed}")
        diffs: list[str] = []
        _deep_diff(gov, elm, "epc", diffs)
        print(f"\nFIELD DIFFS gov-API vs Elmhurst ({len(diffs)}):")
        print("\n".join(diffs) if diffs else "  (none — paths identical)")


def main() -> None:
    if len(sys.argv) != 2:
        raise SystemExit(__doc__)
    compare(sys.argv[1])


if __name__ == "__main__":
    main()