"""Upload duplicate protection — the historical double-count bug.

Re-uploading a file with the same name used to overwrite it on disk but insert a SECOND
session_files row pointing at the same path, so processing parsed and summed the file
twice. Same content under a different name was equally unguarded."""
from __future__ import annotations

import os
import tempfile

from fastapi.testclient import TestClient

from app.api.main import app
from app.db import models
from app.db.database import SessionLocal, init_db
from tests.test_excel_export import make_amazon_xlsx

_TMP = tempfile.mkdtemp(prefix="ar_dedup_test_")


def _upload(c, sid: int, path: str, as_name: str | None = None):
    with open(path, "rb") as fh:
        return c.post(f"/api/sessions/{sid}/files",
                      files={"files": (as_name or os.path.basename(path), fh)})


def _file_rows(sid: int) -> list[models.SessionFile]:
    db = SessionLocal()
    try:
        return db.query(models.SessionFile).filter_by(session_id=sid).all()
    finally:
        db.close()


def test_same_filename_reupload_updates_row_not_duplicates():
    init_db()
    a = os.path.join(_TMP, "USA jan.xlsx")
    make_amazon_xlsx(a, order_rows=6)
    with TestClient(app) as c:
        sid = c.post("/api/sessions", json={"name": "dedup-name", "month_end_date": "2027-01-31",
                                            "allow_duplicate": True}).json()["id"]
        first = _upload(c, sid, a).json()
        assert len(first["files"]) == 1 and first["skipped"] == []
        first_id = first["files"][0]["id"]

        # Different bytes, same filename -> the existing row is replaced, never doubled.
        b = os.path.join(_TMP, "USA jan v2.xlsx")
        make_amazon_xlsx(b, order_rows=9)
        second = _upload(c, sid, b, as_name="USA jan.xlsx").json()
        assert len(second["files"]) == 1 and second["skipped"] == []
        assert second["files"][0]["id"] == first_id            # updated in place

        rows = _file_rows(sid)
        assert len(rows) == 1
        assert rows[0].sha256 == second["files"][0]["sha256"]


def test_identical_bytes_same_name_is_skipped():
    init_db()
    a = os.path.join(_TMP, "USA feb.xlsx")
    make_amazon_xlsx(a, order_rows=6)
    with TestClient(app) as c:
        sid = c.post("/api/sessions", json={"name": "dedup-same", "month_end_date": "2027-02-28",
                                            "allow_duplicate": True}).json()["id"]
        assert _upload(c, sid, a).status_code == 200
        again = _upload(c, sid, a).json()
        assert again["files"] == []
        assert len(again["skipped"]) == 1
        assert "unchanged" in again["skipped"][0]["reason"]
        assert len(_file_rows(sid)) == 1


def test_identical_content_under_new_name_is_skipped():
    init_db()
    a = os.path.join(_TMP, "USA mar.xlsx")
    make_amazon_xlsx(a, order_rows=6)
    with TestClient(app) as c:
        sid = c.post("/api/sessions", json={"name": "dedup-bytes", "month_end_date": "2027-03-31",
                                            "allow_duplicate": True}).json()["id"]
        assert _upload(c, sid, a).status_code == 200
        renamed = _upload(c, sid, a, as_name="USA mar COPY.xlsx").json()
        assert renamed["files"] == []
        assert "already uploaded as" in renamed["skipped"][0]["reason"]
        assert len(_file_rows(sid)) == 1


def test_double_upload_no_longer_doubles_the_totals():
    """End to end: upload, process, re-upload the SAME file, re-process — totals unchanged."""
    init_db()
    a = os.path.join(_TMP, "USA apr.xlsx")
    make_amazon_xlsx(a, order_rows=8)
    with TestClient(app) as c:
        sid = c.post("/api/sessions", json={"name": "dedup-e2e", "month_end_date": "2027-04-30",
                                            "allow_duplicate": True}).json()["id"]
        assert _upload(c, sid, a).status_code == 200
        assert c.post(f"/api/sessions/{sid}/process").status_code == 200
        assert c.get(f"/api/sessions/{sid}/status").json()["status"] == "processed"
        before = c.get(f"/api/sessions/{sid}/summary").json()["closing_receivable_usd"]

        assert _upload(c, sid, a).status_code == 200           # skipped as unchanged
        assert c.post(f"/api/sessions/{sid}/process").status_code == 200
        assert c.get(f"/api/sessions/{sid}/status").json()["status"] == "processed"
        after = c.get(f"/api/sessions/{sid}/summary").json()["closing_receivable_usd"]
        assert after == before