"""Tests for field extraction module."""

import pytest
from cmdparse.extractors import (
    extract_fields,
    get_nested_value,
    extract_array_index,
    flatten_dict
)


class TestGetNestedValue:
    def test_simple_dict_access(self):
        data = {'name': 'John', 'age': 30}
        assert get_nested_value(data, 'name') == 'John'
        assert get_nested_value(data, 'age') == 30

    def test_nested_dict_access(self):
        data = {'user': {'address': {'city': 'NYC'}}}
        assert get_nested_value(data, 'user.address.city') == 'NYC'

    def test_list_index_access(self):
        data = {'items': ['a', 'b', 'c']}
        assert get_nested_value(data, 'items.0') == 'a'
        assert get_nested_value(data, 'items.1') == 'b'

    def test_missing_key_returns_none(self):
        data = {'name': 'John'}
        assert get_nested_value(data, 'age') is None

    def test_none_data_returns_none(self):
        assert get_nested_value(None, 'name') is None


class TestExtractArrayIndex:
    def test_with_array_index(self):
        base, index, rest = extract_array_index('items[0].name')
        assert base == 'items'
        assert index == 0
        assert rest == 'name'

    def test_without_array_index(self):
        base, index, rest = extract_array_index('name')
        assert base == 'name'
        assert index is None
        assert rest is None


class TestExtractFields:
    def test_extract_single_field(self):
        data = [{'name': 'John', 'age': 30, 'city': 'NYC'}]
        result = extract_fields(data, ['name'])
        assert result == [{'name': 'John'}]

    def test_extract_multiple_fields(self):
        data = [{'name': 'John', 'age': 30, 'city': 'NYC'}]
        result = extract_fields(data, ['name', 'city'])
        assert result == [{'name': 'John', 'city': 'NYC'}]

    def test_extract_nested_fields(self):
        data = [{'user': {'name': 'John', 'age': 30}}]
        result = extract_fields(data, ['user.name'])
        assert result == [{'user.name': 'John'}]

    def test_extract_from_multiple_rows(self):
        data = [
            {'name': 'John', 'age': 30},
            {'name': 'Jane', 'age': 25}
        ]
        result = extract_fields(data, ['name'])
        assert result == [{'name': 'John'}, {'name': 'Jane'}]

    def test_empty_fields_returns_original(self):
        data = [{'name': 'John', 'age': 30}]
        result = extract_fields(data, [])
        assert result == data

    def test_empty_data_returns_empty(self):
        result = extract_fields([], ['name'])
        assert result == []


class TestFlattenDict:
    def test_flatten_simple_dict(self):
        d = {'name': 'John', 'age': 30}
        result = flatten_dict(d)
        assert result == {'name': 'John', 'age': 30}

    def test_flatten_nested_dict(self):
        d = {'user': {'name': 'John', 'address': {'city': 'NYC'}}}
        result = flatten_dict(d)
        assert 'user.name' in result
        assert 'user.address.city' in result
        assert result['user.name'] == 'John'
        assert result['user.address.city'] == 'NYC'