"""Tests for flow.core.template."""

import os

import pytest

from flow.core.errors import ConfigError
from flow.core.template import substitute_template


class TestSubstituteTemplate:
    def test_replaces_double_braces(self):
        assert substitute_template("nvim-{{os}}", {"os": "linux"}) == "nvim-linux"

    def test_env_dot_notation(self, monkeypatch):
        monkeypatch.setenv("USER", "tomas")
        result = substitute_template("{{ env.USER }}", {"env": dict(os.environ)})
        assert result == "tomas"

    def test_nested_dict_lookup(self):
        ctx = {"platform": {"arch": "arm64"}}
        assert substitute_template("{{ platform.arch }}", ctx) == "arm64"

    def test_unknown_variable_raises(self):
        with pytest.raises(ConfigError, match=r"\{\{ unknown \}\}"):
            substitute_template("{{ unknown }}", {})

    def test_nested_unresolved_raises(self):
        with pytest.raises(ConfigError, match=r"\{\{ platform.missing \}\}"):
            substitute_template("{{ platform.missing }}", {"platform": {"arch": "arm64"}})

    def test_unresolved_env_raises(self, monkeypatch):
        monkeypatch.delenv("SOME_NEVER_SET_VAR", raising=False)
        with pytest.raises(ConfigError):
            substitute_template("{{ env.SOME_NEVER_SET_VAR }}", {"env": {}})

    def test_non_string_passthrough(self):
        assert substitute_template(42, {}) == 42

    def test_whitespace_in_braces(self):
        assert substitute_template("{{  os  }}", {"os": "linux"}) == "linux"