"""Tests for token_usage passthrough in the webapp report builder."""
from __future__ import annotations

import json
from pathlib import Path

from webapp.services.report_builder import build_report


def _write_minimal_run(run_dir: Path, token_usage: dict | None) -> None:
    run_dir.mkdir(parents=True, exist_ok=True)
    (run_dir / "scores.csv").write_text(
        "sample_id,faithfulness\ns1,0.9\n", encoding="utf-8"
    )
    (run_dir / "summary.md").write_text("summary", encoding="utf-8")
    metadata = {"run_id": run_dir.name}
    if token_usage is not None:
        metadata["token_usage"] = token_usage
    (run_dir / "metadata.json").write_text(json.dumps(metadata), encoding="utf-8")


def test_build_report_passes_through_token_usage(tmp_path: Path) -> None:
    run_dir = tmp_path / "run"
    _write_minimal_run(
        run_dir,
        token_usage={"gpt-5": {"input_tokens": 100, "output_tokens": 50, "calls": 2}},
    )

    report = build_report(run_dir, ["faithfulness"])

    assert report.token_usage == {
        "gpt-5": {"input_tokens": 100, "output_tokens": 50, "calls": 2}
    }


def test_build_report_defaults_token_usage_to_empty_dict(tmp_path: Path) -> None:
    run_dir = tmp_path / "run"
    _write_minimal_run(run_dir, token_usage=None)

    report = build_report(run_dir, ["faithfulness"])

    assert report.token_usage == {}


def test_build_report_early_return_branch_still_surfaces_token_usage(tmp_path: Path) -> None:
    """metrics=[] forces the early-return branch; token_usage must still surface."""
    run_dir = tmp_path / "run"
    _write_minimal_run(
        run_dir,
        token_usage={"gpt-5": {"input_tokens": 5, "output_tokens": 5, "calls": 1}},
    )

    report = build_report(run_dir, [])

    assert report.token_usage == {"gpt-5": {"input_tokens": 5, "output_tokens": 5, "calls": 1}}