"""Tests for flow.core.yaml."""

from pathlib import Path

import pytest

from flow.core.errors import ConfigError
from flow.core.yaml import (
    list_yaml_files,
    load_yaml_documents,
    load_yaml_file,
    load_yaml_source,
    load_yaml_sources,
    merge_yaml_values,
)


class TestLoadYamlFile:
    def test_loads_mapping(self, tmp_path):
        f = tmp_path / "a.yaml"
        f.write_text("key: value\n")
        assert load_yaml_file(f) == {"key": "value"}

    def test_empty_file_returns_empty_dict(self, tmp_path):
        f = tmp_path / "empty.yaml"
        f.write_text("")
        assert load_yaml_file(f) == {}

    def test_non_mapping_raises(self, tmp_path):
        f = tmp_path / "list.yaml"
        f.write_text("- one\n- two\n")
        with pytest.raises(ConfigError, match="mapping at root"):
            load_yaml_file(f)

    def test_invalid_yaml_raises(self, tmp_path):
        f = tmp_path / "bad.yaml"
        f.write_text(":\n  :\n    [invalid")
        with pytest.raises(ConfigError, match="Invalid YAML"):
            load_yaml_file(f)


class TestMergeYamlValues:
    def test_dict_merge(self):
        base = {"a": 1, "b": {"x": 10}}
        overlay = {"b": {"y": 20}, "c": 3}
        result = merge_yaml_values(base, overlay)
        assert result == {"a": 1, "b": {"x": 10, "y": 20}, "c": 3}

    def test_list_concat(self):
        assert merge_yaml_values([1, 2], [3, 4]) == [1, 2, 3, 4]

    def test_scalar_override(self):
        assert merge_yaml_values("old", "new") == "new"

    def test_overlay_wins_type_mismatch(self):
        assert merge_yaml_values({"a": 1}, "scalar") == "scalar"


class TestListYamlFiles:
    def test_lists_sorted(self, tmp_path):
        (tmp_path / "b.yaml").write_text("b: 1\n")
        (tmp_path / "a.yml").write_text("a: 1\n")
        (tmp_path / "c.txt").write_text("ignored")
        files = list_yaml_files(tmp_path)
        assert [f.name for f in files] == ["a.yml", "b.yaml"]

    def test_missing_dir_returns_empty(self, tmp_path):
        assert list_yaml_files(tmp_path / "nope") == []


class TestLoadYamlSource:
    def test_file(self, tmp_path):
        f = tmp_path / "config.yaml"
        f.write_text("key: val\n")
        assert load_yaml_source(f) == {"key": "val"}

    def test_directory_merges(self, tmp_path):
        (tmp_path / "01.yaml").write_text("a: 1\n")
        (tmp_path / "02.yaml").write_text("b: 2\n")
        result = load_yaml_source(tmp_path)
        assert result == {"a": 1, "b": 2}

    def test_missing_returns_empty(self, tmp_path):
        assert load_yaml_source(tmp_path / "gone") == {}


class TestLoadYamlDocuments:
    def test_single_file(self, tmp_path):
        f = tmp_path / "doc.yaml"
        f.write_text("x: 1\n")
        docs = load_yaml_documents(f)
        assert docs == [{"x": 1}]

    def test_directory(self, tmp_path):
        (tmp_path / "a.yaml").write_text("a: 1\n")
        (tmp_path / "b.yaml").write_text("b: 2\n")
        docs = load_yaml_documents(tmp_path)
        assert docs == [{"a": 1}, {"b": 2}]

    def test_missing_returns_empty(self, tmp_path):
        assert load_yaml_documents(tmp_path / "gone") == []


class TestLoadYamlSources:
    def test_merges_multiple_paths(self, tmp_path):
        d1 = tmp_path / "d1"
        d2 = tmp_path / "d2"
        d1.mkdir()
        d2.mkdir()
        (d1 / "a.yaml").write_text("a: 1\n")
        (d2 / "b.yaml").write_text("b: 2\n")
        result = load_yaml_sources(d1, d2)
        assert result == {"a": 1, "b": 2}