// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0

package confmap

import (
	"errors"
	"fmt"
	"math"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	yaml "sigs.k8s.io/yaml/goyaml.v3"
)

func TestToStringMapFlatten(t *testing.T) {
	conf := NewFromStringMap(map[string]any{"key::embedded": int64(123)})
	assert.Equal(t, map[string]any{"key": map[string]any{"embedded": int64(123)}}, conf.ToStringMap())
}

func TestToStringMap(t *testing.T) {
	tests := []struct {
		name      string
		fileName  string
		stringMap map[string]any
	}{
		{
			name:     "Sample Collector configuration",
			fileName: filepath.Join("testdata", "config.yaml"),
			stringMap: map[string]any{
				"receivers": map[string]any{
					"nop":            nil,
					"nop/myreceiver": nil,
				},

				"processors": map[string]any{
					"nop":             nil,
					"nop/myprocessor": nil,
				},

				"exporters": map[string]any{
					"nop":            nil,
					"nop/myexporter": nil,
				},

				"extensions": map[string]any{
					"nop":             nil,
					"nop/myextension": nil,
				},

				"service": map[string]any{
					"extensions": []any{"nop"},
					"pipelines": map[string]any{
						"traces": map[string]any{
							"receivers":  []any{"nop"},
							"processors": []any{"nop"},
							"exporters":  []any{"nop"},
						},
					},
				},
			},
		},
		{
			name:     "Sample types",
			fileName: filepath.Join("testdata", "basic_types.yaml"),
			stringMap: map[string]any{
				"typed.options": map[string]any{
					"floating.point.example": 3.14,
					"integer.example":        1234,
					"bool.example":           false,
					"string.example":         "this is a string",
					"nil.example":            nil,
				},
			},
		},
		{
			name:     "Embedded keys",
			fileName: filepath.Join("testdata", "embedded_keys.yaml"),
			stringMap: map[string]any{
				"typed": map[string]any{"options": map[string]any{
					"floating": map[string]any{"point": map[string]any{"example": 3.14}},
					"integer":  map[string]any{"example": 1234},
					"bool":     map[string]any{"example": false},
					"string":   map[string]any{"example": "this is a string"},
					"nil":      map[string]any{"example": nil},
				}},
			},
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			assert.Equal(t, test.stringMap, newConfFromFile(t, test.fileName))
		})
	}
}

type testConfigAny struct {
	AnyField any `mapstructure:"any_field"`
}

func TestNilToAnyField(t *testing.T) {
	stringMap := map[string]any{
		"any_field": nil,
	}
	conf := NewFromStringMap(stringMap)
	cfg := &testConfigAny{}
	require.NoError(t, conf.Unmarshal(cfg))
	assert.Nil(t, cfg.AnyField)
}

func TestExpandNilStructPointersHookFunc(t *testing.T) {
	stringMap := map[string]any{
		"boolean": nil,
		"struct":  nil,
		"map_struct": map[string]any{
			"struct": nil,
		},
	}
	conf := NewFromStringMap(stringMap)
	cfg := &testConfig{}
	assert.Nil(t, cfg.Struct)
	require.NoError(t, conf.Unmarshal(cfg))
	assert.Nil(t, cfg.Boolean)
	// assert.False(t, *cfg.Boolean)
	assert.Nil(t, cfg.Struct)
	assert.NotNil(t, cfg.MapStruct)
	assert.Equal(t, &myStruct{}, cfg.MapStruct["struct"])
}

func TestExpandNilStructPointersHookFuncDefaultNotNilConfigNil(t *testing.T) {
	stringMap := map[string]any{
		"boolean": nil,
		"struct":  nil,
		"map_struct": map[string]any{
			"struct": nil,
		},
	}
	conf := NewFromStringMap(stringMap)
	varBool := true
	s1 := &myStruct{Name: "s1"}
	s2 := &myStruct{Name: "s2"}
	cfg := &testConfig{
		Boolean:   &varBool,
		Struct:    s1,
		MapStruct: map[string]*myStruct{"struct": s2},
	}
	require.NoError(t, conf.Unmarshal(cfg))
	assert.NotNil(t, cfg.Boolean)
	assert.True(t, *cfg.Boolean)
	assert.NotNil(t, cfg.Struct)
	assert.Equal(t, s1, cfg.Struct)
	assert.NotNil(t, cfg.MapStruct)
	assert.Equal(t, &myStruct{}, cfg.MapStruct["struct"])
}

func TestUnmarshalWithIgnoreUnused(t *testing.T) {
	stringMap := map[string]any{
		"boolean": true,
		"string":  "this is a string",
	}
	conf := NewFromStringMap(stringMap)
	require.Error(t, conf.Unmarshal(&testIDConfig{}))
	assert.NoError(t, conf.Unmarshal(&testIDConfig{}, WithIgnoreUnused()))
}

type testConfig struct {
	Boolean   *bool                `mapstructure:"boolean"`
	Struct    *myStruct            `mapstructure:"struct"`
	MapStruct map[string]*myStruct `mapstructure:"map_struct"`
}

func (t testConfig) Marshal(conf *Conf) error {
	if t.Boolean != nil && !*t.Boolean {
		return errors.New("unable to marshal")
	}
	if err := conf.Marshal(t); err != nil {
		return err
	}
	return conf.Merge(NewFromStringMap(map[string]any{
		"additional": "field",
	}))
}

type myStruct struct {
	Name string
}

type TestID string

func (tID *TestID) UnmarshalText(text []byte) error {
	*tID = TestID(strings.TrimSuffix(string(text), "_"))
	if *tID == "error" {
		return errors.New("parsing error")
	}
	return nil
}

func (tID TestID) MarshalText() (text []byte, err error) {
	out := string(tID)
	if !strings.HasSuffix(out, "_") {
		out += "_"
	}
	return []byte(out), nil
}

type testIDConfig struct {
	Boolean bool              `mapstructure:"bool"`
	Map     map[TestID]string `mapstructure:"map"`
}

func TestMapKeyStringToMapKeyTextUnmarshalerHookFunc(t *testing.T) {
	stringMap := map[string]any{
		"bool": true,
		"map": map[string]any{
			"string": "this is a string",
		},
	}
	conf := NewFromStringMap(stringMap)

	cfg := &testIDConfig{}
	require.NoError(t, conf.Unmarshal(cfg))
	assert.True(t, cfg.Boolean)
	assert.Equal(t, map[TestID]string{"string": "this is a string"}, cfg.Map)
}

type uint32Config struct {
	Value uint32 `mapstructure:"value"`
}

func TestUint32UnmarshalerSuccess(t *testing.T) {
	tests := []struct {
		name      string
		testValue uint32
	}{
		{
			name:      "Test convert 0 to uint",
			testValue: 0,
		},
		{
			name:      "Test positive uint conversion",
			testValue: 1000,
		},
		{
			name:      "Test largest uint64 conversion",
			testValue: math.MaxUint32,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			stringMap := map[string]any{
				"value": int(tt.testValue),
			}
			conf := NewFromStringMap(stringMap)
			cfg := &uint32Config{}
			err := conf.Unmarshal(cfg)

			require.NoError(t, err)
			assert.Equal(t, cfg.Value, tt.testValue)
		})
	}
}

func TestUint32UnmarshalerFailure(t *testing.T) {
	testValue := -1000
	stringMap := map[string]any{
		"value": testValue,
	}
	conf := NewFromStringMap(stringMap)
	cfg := &uint32Config{}
	err := conf.Unmarshal(cfg)

	assert.ErrorContains(t, err, fmt.Sprintf("decoding failed due to the following error(s):\n\ncannot parse 'value', %d overflows uint", testValue))
}

type uint64Config struct {
	Value uint64 `mapstructure:"value"`
}

func TestUint64Unmarshaler(t *testing.T) {
	// Equivalent to -1000, but converted to uint64
	value := uint64(1000)
	testValue := ^(value - 1)

	stringMap := map[string]any{
		"value": testValue,
	}

	conf := NewFromStringMap(stringMap)
	cfg := &uint64Config{}
	err := conf.Unmarshal(cfg)

	require.NoError(t, err)
	assert.Equal(t, cfg.Value, testValue)
}

func TestUint64UnmarshalerFailure(t *testing.T) {
	testValue := -1000
	stringMap := map[string]any{
		"value": testValue,
	}
	conf := NewFromStringMap(stringMap)
	cfg := &uint64Config{}
	err := conf.Unmarshal(cfg)

	assert.ErrorContains(t, err, fmt.Sprintf("decoding failed due to the following error(s):\n\ncannot parse 'value', %d overflows uint", testValue))
}

func TestMapKeyStringToMapKeyTextUnmarshalerHookFuncDuplicateID(t *testing.T) {
	stringMap := map[string]any{
		"bool": true,
		"map": map[string]any{
			"string":  "this is a string",
			"string_": "this is another string",
		},
	}
	conf := NewFromStringMap(stringMap)

	cfg := &testIDConfig{}
	assert.Error(t, conf.Unmarshal(cfg))
}

func TestMapKeyStringToMapKeyTextUnmarshalerHookFuncErrorUnmarshal(t *testing.T) {
	stringMap := map[string]any{
		"bool": true,
		"map": map[string]any{
			"error": "this is a string",
		},
	}
	conf := NewFromStringMap(stringMap)

	cfg := &testIDConfig{}
	assert.Error(t, conf.Unmarshal(cfg))
}

func TestMarshal(t *testing.T) {
	conf := New()
	cfg := &testIDConfig{
		Boolean: true,
		Map: map[TestID]string{
			"string": "this is a string",
		},
	}
	require.NoError(t, conf.Marshal(cfg))
	assert.Equal(t, true, conf.Get("bool"))
	assert.Equal(t, map[string]any{"string_": "this is a string"}, conf.Get("map"))
}

func TestMarshalDuplicateID(t *testing.T) {
	conf := New()
	cfg := &testIDConfig{
		Boolean: true,
		Map: map[TestID]string{
			"string":  "this is a string",
			"string_": "this is another string",
		},
	}
	assert.Error(t, conf.Marshal(cfg))
}

func TestMarshalError(t *testing.T) {
	conf := New()
	assert.Error(t, conf.Marshal(nil))
}

func TestMarshaler(t *testing.T) {
	conf := New()
	cfg := &testConfig{
		Struct: &myStruct{
			Name: "StructName",
		},
	}
	require.NoError(t, conf.Marshal(cfg))
	assert.Equal(t, "field", conf.Get("additional"))

	conf = New()
	type NestedMarshaler struct {
		TestConfig *testConfig
	}
	nmCfg := &NestedMarshaler{
		TestConfig: cfg,
	}
	require.NoError(t, conf.Marshal(nmCfg))
	sub, err := conf.Sub("testconfig")
	require.NoError(t, err)
	assert.True(t, sub.IsSet("additional"))
	assert.Equal(t, "field", sub.Get("additional"))
	varBool := false
	nmCfg.TestConfig.Boolean = &varBool
	assert.Error(t, conf.Marshal(nmCfg))
}

// newConfFromFile creates a new Conf by reading the given file.
func newConfFromFile(tb testing.TB, fileName string) map[string]any {
	content, err := os.ReadFile(filepath.Clean(fileName))
	require.NoErrorf(tb, err, "unable to read the file %v", fileName)

	var data map[string]any
	require.NoError(tb, yaml.Unmarshal(content, &data), "unable to parse yaml")

	return NewFromStringMap(data).ToStringMap()
}

type testConfig2 struct {
	Next            *nextConfig `mapstructure:"next"`
	Another         string      `mapstructure:"another"`
	EmbeddedConfig  `mapstructure:",squash"`
	EmbeddedConfig2 `mapstructure:",squash"`
}

type testConfigWithoutUnmarshaler struct {
	Next            *nextConfig `mapstructure:"next"`
	Another         string      `mapstructure:"another"`
	EmbeddedConfig  `mapstructure:",squash"`
	EmbeddedConfig2 `mapstructure:",squash"`
}

type testConfigWithEmbeddedError struct {
	Next                    *nextConfig `mapstructure:"next"`
	Another                 string      `mapstructure:"another"`
	EmbeddedConfigWithError `mapstructure:",squash"`
}

type testConfigWithMarshalError struct {
	Next                           *nextConfig `mapstructure:"next"`
	Another                        string      `mapstructure:"another"`
	EmbeddedConfigWithMarshalError `mapstructure:",squash"`
}

func (tc *testConfigWithEmbeddedError) Unmarshal(component *Conf) error {
	if err := component.Unmarshal(tc, WithIgnoreUnused()); err != nil {
		return err
	}
	return nil
}

type EmbeddedConfig struct {
	Some string `mapstructure:"some"`
}

func (ec *EmbeddedConfig) Unmarshal(component *Conf) error {
	if err := component.Unmarshal(ec, WithIgnoreUnused()); err != nil {
		return err
	}
	ec.Some += " is also called"
	return nil
}

type EmbeddedConfig2 struct {
	Some2 string `mapstructure:"some_2"`
}

func (ec *EmbeddedConfig2) Unmarshal(component *Conf) error {
	if err := component.Unmarshal(ec, WithIgnoreUnused()); err != nil {
		return err
	}
	ec.Some2 += " also called2"
	return nil
}

type EmbeddedConfigWithError struct{}

func (ecwe *EmbeddedConfigWithError) Unmarshal(_ *Conf) error {
	return errors.New("embedded error")
}

type EmbeddedConfigWithMarshalError struct{}

func (ecwe EmbeddedConfigWithMarshalError) Marshal(_ *Conf) error {
	return errors.New("marshaling error")
}

func (ecwe EmbeddedConfigWithMarshalError) Unmarshal(_ *Conf) error {
	return nil
}

func (tc *testConfig2) Unmarshal(component *Conf) error {
	if err := component.Unmarshal(tc); err != nil {
		return err
	}
	tc.Another += " is only called directly"
	return nil
}

type nextConfig struct {
	String  string `mapstructure:"string"`
	private string
}

func (nc *nextConfig) Unmarshal(component *Conf) error {
	if err := component.Unmarshal(nc); err != nil {
		return err
	}
	nc.String += " is called"
	return nil
}

func TestUnmarshaler(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
		"some":    "make sure this",
		"some_2":  "this better be",
	})

	tc := &testConfig2{}
	require.NoError(t, cfgMap.Unmarshal(tc))
	assert.Equal(t, "make sure this is only called directly", tc.Another)
	assert.Equal(t, "make sure this is called", tc.Next.String)
	assert.Equal(t, "make sure this is also called", tc.Some)
	assert.Equal(t, "this better be also called2", tc.Some2)
}

func TestEmbeddedUnmarshaler(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
		"some":    "make sure this",
		"some_2":  "this better be",
	})

	tc := &testConfigWithoutUnmarshaler{}
	require.NoError(t, cfgMap.Unmarshal(tc))
	assert.Equal(t, "make sure this", tc.Another)
	assert.Equal(t, "make sure this is called", tc.Next.String)
	assert.Equal(t, "make sure this is also called", tc.Some)
	assert.Equal(t, "this better be also called2", tc.Some2)
}

func TestEmbeddedUnmarshalerError(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
		"some":    "make sure this",
	})

	tc := &testConfigWithEmbeddedError{}
	assert.EqualError(t, cfgMap.Unmarshal(tc), "embedded error")
}

func TestEmbeddedMarshalerError(t *testing.T) {
	t.Skip("This test fails because the main struct calls the embedded struct Unmarshal method, and doesn't execute the embedded struct hook.")
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
	})

	tc := &testConfigWithMarshalError{}
	assert.EqualError(t, cfgMap.Unmarshal(tc), "error running encode hook: marshaling error")
}

type B struct {
	String string `mapstructure:"string"`
}

func (b *B) Unmarshal(conf *Conf) error {
	return conf.Unmarshal(b)
}

type A struct {
	B `mapstructure:",squash"`
}

func (a *A) Unmarshal(conf *Conf) error {
	return conf.Unmarshal(a)
}

func TestUnmarshalerEmbeddedNilMap(t *testing.T) {
	cfg := A{}
	nilConf := NewFromStringMap(nil)
	require.NoError(t, nilConf.Unmarshal(&cfg))
}

func TestUnmarshalerKeepAlreadyInitialized(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
	})

	tc := &testConfig2{Next: &nextConfig{
		private: "keep already configured members",
	}}
	require.NoError(t, cfgMap.Unmarshal(tc))
	assert.Equal(t, "make sure this is only called directly", tc.Another)
	assert.Equal(t, "make sure this is called", tc.Next.String)
	assert.Equal(t, "keep already configured members", tc.Next.private)
}

func TestDirectUnmarshaler(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"next": map[string]any{
			"string": "make sure this",
		},
		"another": "make sure this",
	})

	tc := &testConfig2{Next: &nextConfig{
		private: "keep already configured members",
	}}
	require.NoError(t, tc.Unmarshal(cfgMap))
	assert.Equal(t, "make sure this is only called directly is only called directly", tc.Another)
	assert.Equal(t, "make sure this is called", tc.Next.String)
	assert.Equal(t, "keep already configured members", tc.Next.private)
}

type testErrConfig struct {
	Err errConfig `mapstructure:"err"`
}

type errConfig struct {
	Foo string `mapstructure:"foo"`
}

func (tc *errConfig) Unmarshal(*Conf) error {
	return errors.New("never works")
}

func TestUnmarshalerErr(t *testing.T) {
	cfgMap := NewFromStringMap(map[string]any{
		"err": map[string]any{
			"foo": "will not unmarshal due to error",
		},
	})

	tc := &testErrConfig{}
	require.EqualError(t, cfgMap.Unmarshal(tc), "decoding failed due to the following error(s):\n\nerror decoding 'err': never works")
	assert.Empty(t, tc.Err.Foo)
}

func TestZeroSliceHookFunc(t *testing.T) {
	type structWithSlices struct {
		Strings []string `mapstructure:"strings"`
	}

	tests := []struct {
		name     string
		cfg      map[string]any
		provided any
		expected any
	}{
		{
			name: "overridden by slice",
			cfg: map[string]any{
				"strings": []string{"111"},
			},
			provided: &structWithSlices{
				Strings: []string{"xxx", "yyyy", "zzzz"},
			},
			expected: &structWithSlices{
				Strings: []string{"111"},
			},
		},
		{
			name: "overridden by a bigger slice",
			cfg: map[string]any{
				"strings": []string{"111", "222", "333"},
			},
			provided: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
			expected: &structWithSlices{
				Strings: []string{"111", "222", "333"},
			},
		},
		{
			name: "overridden by an empty slice",
			cfg: map[string]any{
				"strings": []string{},
			},
			provided: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
			expected: &structWithSlices{
				Strings: []string{},
			},
		},
		{
			name: "not overridden by nil",
			cfg: map[string]any{
				"strings": nil,
			},
			provided: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
			expected: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
		},
		{
			name: "not overridden by missing value",
			cfg:  map[string]any{},
			provided: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
			expected: &structWithSlices{
				Strings: []string{"xxx", "yyyy"},
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			cfg := NewFromStringMap(tt.cfg)

			err := cfg.Unmarshal(tt.provided)
			if assert.NoError(t, err) {
				assert.Equal(t, tt.expected, tt.provided)
			}
		})
	}
}

// Tests for issue that happened in https://github.com/open-telemetry/opentelemetry-collector/issues/12661.
func TestStructValuesReplaced(t *testing.T) {
	type S struct {
		A string `mapstructure:"A,omitempty"`
		B string `mapstructure:"B,omitempty"`
	}

	type structWithSlices struct {
		Structs []S `mapstructure:"structs"`
	}

	slicesStruct := structWithSlices{
		Structs: []S{
			{A: "A"},
		},
	}

	bCfg := map[string]any{
		"structs": []any{
			map[string]any{
				"B": "B",
			},
		},
	}
	bConf := NewFromStringMap(bCfg)
	err := bConf.Unmarshal(&slicesStruct)
	require.NoError(t, err)

	assert.Equal(t, []S{{B: "B"}}, slicesStruct.Structs)
}

func TestNilValuesUnchanged(t *testing.T) {
	type structWithSlices struct {
		Strings []string `mapstructure:"strings"`
	}

	slicesStruct := &structWithSlices{}

	nilCfg := map[string]any{
		"strings": []any(nil),
	}
	nilConf := NewFromStringMap(nilCfg)
	err := nilConf.Unmarshal(slicesStruct)
	require.NoError(t, err)

	confFromStruct := New()
	err = confFromStruct.Marshal(slicesStruct)
	require.NoError(t, err)

	require.Equal(t, nilCfg, nilConf.ToStringMap())
	require.Equal(t, confFromStruct.ToStringMap(), nilConf.ToStringMap())
}

func TestEmptySliceUnchanged(t *testing.T) {
	type structWithSlices struct {
		Strings []string `mapstructure:"strings"`
	}

	slicesStruct := &structWithSlices{}

	nilCfg := map[string]any{
		"strings": []any{},
	}
	nilConf := NewFromStringMap(nilCfg)
	err := nilConf.Unmarshal(slicesStruct)
	require.NoError(t, err)

	confFromStruct := New()
	err = confFromStruct.Marshal(slicesStruct)
	require.NoError(t, err)

	require.Equal(t, nilCfg, nilConf.ToStringMap())
	require.Equal(t, nilConf.ToStringMap(), confFromStruct.ToStringMap())
}

type c struct {
	Modifiers []string `mapstructure:"modifiers"`
}

func (c *c) Unmarshal(conf *Conf) error {
	if err := conf.Unmarshal(c); err != nil {
		return err
	}
	c.Modifiers = append(c.Modifiers, "c.Unmarshal")
	return nil
}

type b struct {
	Modifiers []string `mapstructure:"modifiers"`
	C         c        `mapstructure:"c"`
}

func (b *b) Unmarshal(conf *Conf) error {
	if err := conf.Unmarshal(b); err != nil {
		return err
	}
	b.Modifiers = append(b.Modifiers, "B.Unmarshal")
	b.C.Modifiers = append(b.C.Modifiers, "B.Unmarshal")
	return nil
}

type a struct {
	Modifiers []string `mapstructure:"modifiers"`
	B         b        `mapstructure:"b"`
}

func (a *a) Unmarshal(conf *Conf) error {
	if err := conf.Unmarshal(a); err != nil {
		return err
	}
	a.Modifiers = append(a.Modifiers, "A.Unmarshal")
	a.B.Modifiers = append(a.B.Modifiers, "A.Unmarshal")
	a.B.C.Modifiers = append(a.B.C.Modifiers, "A.Unmarshal")
	return nil
}

type wrapper struct {
	A a `mapstructure:"a"`
}

// Test that calling the Unmarshal method on configuration structs is done from the inside out.
func TestNestedUnmarshalerImplementations(t *testing.T) {
	conf := NewFromStringMap(map[string]any{"a": map[string]any{
		"modifiers": []string{"conf.Unmarshal"},
		"b": map[string]any{
			"modifiers": []string{"conf.Unmarshal"},
			"c": map[string]any{
				"modifiers": []string{"conf.Unmarshal"},
			},
		},
	}})

	// Use a wrapper struct until we deprecate component.UnmarshalConfig
	w := &wrapper{}
	require.NoError(t, conf.Unmarshal(w))

	a := w.A
	assert.Equal(t, []string{"conf.Unmarshal", "A.Unmarshal"}, a.Modifiers)
	assert.Equal(t, []string{"conf.Unmarshal", "B.Unmarshal", "A.Unmarshal"}, a.B.Modifiers)
	assert.Equal(t, []string{"conf.Unmarshal", "c.Unmarshal", "B.Unmarshal", "A.Unmarshal"}, a.B.C.Modifiers)
}

// Test that unmarshaling the same conf twice works.
func TestUnmarshalDouble(t *testing.T) {
	conf := NewFromStringMap(map[string]any{
		"str": "test",
	})

	type Struct struct {
		Str string `mapstructure:"str"`
	}
	s := &Struct{}
	require.NoError(t, conf.Unmarshal(s))
	assert.Equal(t, "test", s.Str)

	type Struct2 struct {
		Str string `mapstructure:"str"`
	}
	s2 := &Struct2{}
	require.NoError(t, conf.Unmarshal(s2))
	assert.Equal(t, "test", s2.Str)
}

type embeddedStructWithUnmarshal struct {
	Foo     string `mapstructure:"foo"`
	success string
}

func (e *embeddedStructWithUnmarshal) Unmarshal(c *Conf) error {
	if err := c.Unmarshal(e, WithIgnoreUnused()); err != nil {
		return err
	}
	e.success = "success"
	return nil
}

type configWithUnmarshalFromEmbeddedStruct struct {
	embeddedStructWithUnmarshal
}

type topLevel struct {
	Cfg *configWithUnmarshalFromEmbeddedStruct `mapstructure:"toplevel"`
}

// Test that Unmarshal is called on the embedded struct on the struct.
func TestUnmarshalThroughEmbeddedStruct(t *testing.T) {
	c := NewFromStringMap(map[string]any{
		"toplevel": map[string]any{
			"foo": "bar",
		},
	})
	cfg := &topLevel{}
	err := c.Unmarshal(cfg)
	require.NoError(t, err)
	require.Equal(t, "success", cfg.Cfg.success)
	require.Equal(t, "bar", cfg.Cfg.Foo)
}

type configWithOwnUnmarshalAndEmbeddedSquashedStruct struct {
	embeddedStructWithUnmarshal `mapstructure:",squash"`
}

type topLevelSquashedEmbedded struct {
	Cfg *configWithOwnUnmarshalAndEmbeddedSquashedStruct `mapstructure:"toplevel"`
}

// Test that the Unmarshal method is called on the squashed, embedded struct.
func TestUnmarshalOwnThroughEmbeddedSquashedStruct(t *testing.T) {
	c := NewFromStringMap(map[string]any{
		"toplevel": map[string]any{
			"foo": "bar",
		},
	})
	cfg := &topLevelSquashedEmbedded{}
	err := c.Unmarshal(cfg)
	require.NoError(t, err)
	require.Equal(t, "success", cfg.Cfg.success)
	require.Equal(t, "bar", cfg.Cfg.Foo)
}

type recursive struct {
	Foo string `mapstructure:"foo"`
}

func (r *recursive) Unmarshal(conf *Conf) error {
	newR := &recursive{}
	if err := conf.Unmarshal(newR); err != nil {
		return err
	}
	*r = *newR
	return nil
}

// Tests that a struct can unmarshal itself by creating a new copy of itself, unmarshaling itself, and setting its value.
func TestRecursiveUnmarshaling(t *testing.T) {
	conf := NewFromStringMap(map[string]any{
		"foo": "something",
	})
	r := &recursive{}
	require.NoError(t, conf.Unmarshal(r))
	require.Equal(t, "something", r.Foo)
}

func TestExpandedValue(t *testing.T) {
	cm := NewFromStringMap(map[string]any{
		"key": expandedValue{
			Value:    0xdeadbeef,
			Original: "original",
		},
	})
	assert.Equal(t, 0xdeadbeef, cm.Get("key"))
	assert.Equal(t, map[string]any{"key": 0xdeadbeef}, cm.ToStringMap())

	type ConfigStr struct {
		Key string `mapstructure:"key"`
	}

	cfgStr := ConfigStr{}
	require.NoError(t, cm.Unmarshal(&cfgStr))
	assert.Equal(t, "original", cfgStr.Key)

	type ConfigInt struct {
		Key int `mapstructure:"key"`
	}
	cfgInt := ConfigInt{}
	require.NoError(t, cm.Unmarshal(&cfgInt))
	assert.Equal(t, 0xdeadbeef, cfgInt.Key)

	type ConfigBool struct {
		Key bool `mapstructure:"key"`
	}
	cfgBool := ConfigBool{}
	assert.Error(t, cm.Unmarshal(&cfgBool))
}

func TestSubExpandedValue(t *testing.T) {
	cm := NewFromStringMap(map[string]any{
		"key": map[string]any{
			"subkey": expandedValue{
				Value:    map[string]any{"subsubkey": "value"},
				Original: "subsubkey: value",
			},
		},
	})

	assert.Equal(t, map[string]any{"subkey": map[string]any{"subsubkey": "value"}}, cm.Get("key"))
	assert.Equal(t, map[string]any{"key": map[string]any{"subkey": map[string]any{"subsubkey": "value"}}}, cm.ToStringMap())
	assert.Equal(t, map[string]any{"subsubkey": "value"}, cm.Get("key::subkey"))

	sub, err := cm.Sub("key::subkey")
	require.NoError(t, err)
	assert.Equal(t, map[string]any{"subsubkey": "value"}, sub.ToStringMap())

	// This should return value, but currently `Get` does not support keys within expanded values.
	assert.Nil(t, cm.Get("key::subkey::subsubkey"))
}

func TestStringyTypes(t *testing.T) {
	tests := []struct {
		valueOfType any
		isStringy   bool
	}{
		{
			valueOfType: "string",
			isStringy:   true,
		},
		{
			valueOfType: 1,
			isStringy:   false,
		},
		{
			valueOfType: map[string]any{},
			isStringy:   false,
		},
		{
			valueOfType: []any{},
			isStringy:   false,
		},
		{
			valueOfType: map[string]string{},
			isStringy:   true,
		},
		{
			valueOfType: []string{},
			isStringy:   true,
		},
		{
			valueOfType: map[string][]string{},
			isStringy:   true,
		},
		{
			valueOfType: map[string]map[string]string{},
			isStringy:   true,
		},
		{
			valueOfType: []map[string]any{},
			isStringy:   false,
		},
		{
			valueOfType: []map[string]string{},
			isStringy:   true,
		},
	}

	for _, tt := range tests {
		// Create a reflect.Type from the value
		to := reflect.TypeOf(tt.valueOfType)
		assert.Equal(t, tt.isStringy, isStringyStructure(to))
	}
}

func TestConfDelete(t *testing.T) {
	tests := []struct {
		path      string
		stringMap map[string]any
	}{
		{
			path:      "key",
			stringMap: map[string]any{"key": "value"},
		},
		{
			path: "map::expanded",
			stringMap: map[string]any{"map": map[string]any{
				"expanded": expandedValue{
					Value:    0o1234,
					Original: "01234",
				},
			}},
		},
	}

	for _, test := range tests {
		t.Run(test.path, func(t *testing.T) {
			cm := NewFromStringMap(test.stringMap)

			assert.True(t, cm.IsSet(test.path))
			assert.True(t, cm.Delete(test.path))
			assert.Nil(t, cm.Get(test.path))
			assert.False(t, cm.IsSet(test.path))

			assert.False(t, cm.Delete(test.path))
			assert.Nil(t, cm.Get(test.path))
			assert.False(t, cm.IsSet(test.path))
		})
	}
}

type structWithConfigOpaqueMap struct {
	Headers map[string]string `mapstructure:"headers"`
}

func TestMapMerge(t *testing.T) {
	tests := []struct {
		name     string
		initial  map[string]string
		added    map[string]string
		expected map[string]string
	}{
		{
			name:     "both nil",
			initial:  nil,
			added:    nil,
			expected: nil,
		},
		{
			name:     "nil map",
			initial:  map[string]string{},
			added:    nil,
			expected: map[string]string{},
		},
		{
			name: "initialized",
			initial: map[string]string{
				"foo": "bar",
			},
			added: nil,
			expected: map[string]string{
				"foo": "bar",
			},
		},
		{
			name: "both",
			initial: map[string]string{
				"foo": "bar",
			},
			added: map[string]string{
				"foobar": "bar",
			},
			expected: map[string]string{
				"foo":    "bar",
				"foobar": "bar",
			},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			s := structWithConfigOpaqueMap{
				Headers: test.initial,
			}
			c := NewFromStringMap(map[string]any{
				"headers": test.added,
			})
			require.NoError(t, c.Unmarshal(&s))
			assert.Equal(t, test.expected, s.Headers)
		})
	}
}

func TestConfIsNil(t *testing.T) {
	const subKey = "foo"
	testCases := []struct {
		name         string
		input        map[string]any
		expectIsNil  bool
		subExpectNil bool
		subExpectErr string
	}{
		{
			name:         "nil input",
			input:        nil,
			expectIsNil:  true,
			subExpectNil: true,
		},
		{
			name:         "empty map",
			input:        map[string]any{},
			expectIsNil:  false,
			subExpectNil: true,
		},
		{
			name:         "nil subkey",
			input:        map[string]any{subKey: nil},
			expectIsNil:  false,
			subExpectNil: true,
		},
		{
			name:         "empty subkey",
			input:        map[string]any{subKey: map[string]any{}},
			expectIsNil:  false,
			subExpectNil: false,
		},
		{
			name:         "non-empty map",
			input:        map[string]any{subKey: map[string]any{"bar": 42}},
			expectIsNil:  false,
			subExpectNil: false,
		},
		{
			name:         "non-map subkey",
			input:        map[string]any{subKey: 123},
			expectIsNil:  false,
			subExpectErr: "unexpected sub-config value kind",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			conf := NewFromStringMap(tc.input)
			if tc.expectIsNil {
				assert.Empty(t, conf.AllKeys())
				assert.Equal(t, map[string]any(nil), conf.ToStringMap())
			} else {
				assert.NotEqual(t, map[string]any(nil), conf.ToStringMap())
			}

			sub, err := conf.Sub(subKey)
			if tc.subExpectErr != "" {
				assert.ErrorContains(t, err, tc.subExpectErr)
			} else {
				assert.NoError(t, err)
				if tc.subExpectNil {
					assert.Empty(t, sub.AllKeys())
					assert.Equal(t, map[string]any(nil), sub.ToStringMap())
				} else {
					assert.NotEqual(t, map[string]any(nil), sub.ToStringMap())
				}
			}
		})
	}
}

func TestConfmapNilMerge(t *testing.T) {
	tests := []struct {
		name     string
		left     map[string]any
		right    map[string]any
		expected map[string]any
	}{
		{
			name:     "both nil",
			left:     nil,
			right:    nil,
			expected: nil,
		},
		{
			name:     "left nil",
			left:     nil,
			right:    map[string]any{"key": "value"},
			expected: map[string]any{"key": "value"},
		},
		{
			name:     "right nil",
			left:     map[string]any{"key": "value"},
			right:    nil,
			expected: map[string]any{"key": "value"},
		},
		{
			name:     "both non-nil",
			left:     map[string]any{"key1": "value1"},
			right:    map[string]any{"key2": "value2"},
			expected: map[string]any{"key1": "value1", "key2": "value2"},
		},
		{
			name:     "left empty, right non-empty",
			left:     map[string]any{},
			right:    map[string]any{"key": "value"},
			expected: map[string]any{"key": "value"},
		},
		{
			name:     "left non-empty, right empty",
			left:     map[string]any{"key": "value"},
			right:    map[string]any{},
			expected: map[string]any{"key": "value"},
		},
		{
			name:     "left nil, right empty",
			left:     nil,
			right:    map[string]any{},
			expected: map[string]any{},
		},
		{
			name:     "left empty, right nil",
			left:     map[string]any{},
			right:    nil,
			expected: map[string]any{},
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			leftConf := NewFromStringMap(test.left)
			assert.Equal(t, test.left, leftConf.ToStringMap())
			rightConf := NewFromStringMap(test.right)
			assert.Equal(t, test.right, rightConf.ToStringMap())

			err := leftConf.Merge(rightConf)
			require.NoError(t, err)

			assert.Equal(t, test.expected, leftConf.ToStringMap())
		})

		t.Run(test.name+"merge append", func(t *testing.T) {
			leftConf := NewFromStringMap(test.left)
			assert.Equal(t, test.left, leftConf.ToStringMap())
			rightConf := NewFromStringMap(test.right)
			assert.Equal(t, test.right, rightConf.ToStringMap())

			err := leftConf.mergeAppend(rightConf)
			require.NoError(t, err)

			assert.Equal(t, test.expected, leftConf.ToStringMap())
		})
	}
}