// Package yaml implements YAML support for the Go language.

//

// Source code and other details for the project are available at GitHub:

//

//   https://github.com/go-yaml/yaml

//

package yaml

import (

	"errors"

	"fmt"

	"io"

	"reflect"

	"strings"

	"sync"

)

// MapSlice encodes and decodes as a YAML map.

// The order of keys is preserved when encoding and decoding.

type MapSlice []MapItem

// MapItem is an item in a MapSlice.

type MapItem struct {

	Key, Value interface{}

}

// The Unmarshaler interface may be implemented by types to customize their

// behavior when being unmarshaled from a YAML document. The UnmarshalYAML

// method receives a function that may be called to unmarshal the original

// YAML value into a field or variable. It is safe to call the unmarshal

// function parameter more than once if necessary.

type Unmarshaler interface {

	UnmarshalYAML(unmarshal func(interface{}) error) error

}

// The Marshaler interface may be implemented by types to customize their

// behavior when being marshaled into a YAML document. The returned value

// is marshaled in place of the original value implementing Marshaler.

//

// If an error is returned by MarshalYAML, the marshaling procedure stops

// and returns with the provided error.

type Marshaler interface {

	MarshalYAML() (interface{}, error)

}

// Unmarshal decodes the first document found within the in byte slice

// and assigns decoded values into the out value.

//

// Maps and pointers (to a struct, string, int, etc) are accepted as out

// values. If an internal pointer within a struct is not initialized,

// the yaml package will initialize it if necessary for unmarshalling

// the provided data. The out parameter must not be nil.

//

// The type of the decoded values should be compatible with the respective

// values in out. If one or more values cannot be decoded due to a type

// mismatches, decoding continues partially until the end of the YAML

// content, and a *yaml.TypeError is returned with details for all

// missed values.

//

// Struct fields are only unmarshalled if they are exported (have an

// upper case first letter), and are unmarshalled using the field name

// lowercased as the default key. Custom keys may be defined via the

// "yaml" name in the field tag: the content preceding the first comma

// is used as the key, and the following comma-separated options are

// used to tweak the marshalling process (see Marshal).

// Conflicting names result in a runtime error.

//

// For example:

//

//     type T struct {

//         F int `yaml:"a,omitempty"`

//         B int

//     }

//     var t T

//     yaml.Unmarshal([]byte("a: 1\nb: 2"), &t)

//

// See the documentation of Marshal for the format of tags and a list of

// supported tag options.

//

func Unmarshal(in []byte, out interface{}) (err error) {

	return unmarshal(in, out, false)

}

// UnmarshalStrict is like Unmarshal except that any fields that are found

// in the data that do not have corresponding struct members, or mapping

// keys that are duplicates, will result in

// an error.

func UnmarshalStrict(in []byte, out interface{}) (err error) {

	return unmarshal(in, out, true)

}

// A Decoder reads and decodes YAML values from an input stream.

type Decoder struct {

	strict bool

	parser *parser

}

// NewDecoder returns a new decoder that reads from r.

//

// The decoder introduces its own buffering and may read

// data from r beyond the YAML values requested.

func NewDecoder(r io.Reader) *Decoder {

	return &Decoder{

		parser: newParserFromReader(r),

	}

}

// SetStrict sets whether strict decoding behaviour is enabled when

// decoding items in the data (see UnmarshalStrict). By default, decoding is not strict.

func (dec *Decoder) SetStrict(strict bool) {

	dec.strict = strict

}

// Decode reads the next YAML-encoded value from its input

// and stores it in the value pointed to by v.

//

// See the documentation for Unmarshal for details about the

// conversion of YAML into a Go value.

func (dec *Decoder) Decode(v interface{}) (err error) {

	d := newDecoder(dec.strict)

	defer handleErr(&err)

	node := dec.parser.parse()

	if node == nil {

		return io.EOF

	}

	out := reflect.ValueOf(v)

	if out.Kind() == reflect.Ptr && !out.IsNil() {

		out = out.Elem()

	}

	d.unmarshal(node, out)

	if len(d.terrors) > 0 {

		return &TypeError{d.terrors}

	}

	return nil

}

func unmarshal(in []byte, out interface{}, strict bool) (err error) {

	defer handleErr(&err)

	d := newDecoder(strict)

	p := newParser(in)

	defer p.destroy()

	node := p.parse()

	if node != nil {

		v := reflect.ValueOf(out)

		if v.Kind() == reflect.Ptr && !v.IsNil() {

			v = v.Elem()

		}

		d.unmarshal(node, v)

	}

	if len(d.terrors) > 0 {

		return &TypeError{d.terrors}

	}

	return nil

}

// Marshal serializes the value provided into a YAML document. The structure

// of the generated document will reflect the structure of the value itself.

// Maps and pointers (to struct, string, int, etc) are accepted as the in value.

//

// Struct fields are only marshalled if they are exported (have an upper case

// first letter), and are marshalled using the field name lowercased as the

// default key. Custom keys may be defined via the "yaml" name in the field

// tag: the content preceding the first comma is used as the key, and the

// following comma-separated options are used to tweak the marshalling process.

// Conflicting names result in a runtime error.

//

// The field tag format accepted is:

//

//     `(...) yaml:"[<key>][,<flag1>[,<flag2>]]" (...)`

//

// The following flags are currently supported:

//

//     omitempty    Only include the field if it's not set to the zero

//                  value for the type or to empty slices or maps.

//                  Zero valued structs will be omitted if all their public

//                  fields are zero, unless they implement an IsZero

//                  method (see the IsZeroer interface type), in which

//                  case the field will be included if that method returns true.

//

//     flow         Marshal using a flow style (useful for structs,

//                  sequences and maps).

//

//     inline       Inline the field, which must be a struct or a map,

//                  causing all of its fields or keys to be processed as if

//                  they were part of the outer struct. For maps, keys must

//                  not conflict with the yaml keys of other struct fields.

//

// In addition, if the key is "-", the field is ignored.

//

// For example:

//

//     type T struct {

//         F int `yaml:"a,omitempty"`

//         B int

//     }

//     yaml.Marshal(&T{B: 2}) // Returns "b: 2\n"

//     yaml.Marshal(&T{F: 1}} // Returns "a: 1\nb: 0\n"

//

func Marshal(in interface{}) (out []byte, err error) {

	defer handleErr(&err)

	e := newEncoder()

	defer e.destroy()

	e.marshalDoc("", reflect.ValueOf(in))

	e.finish()

	out = e.out

	return

}

// An Encoder writes YAML values to an output stream.

type Encoder struct {

	encoder *encoder

}

// NewEncoder returns a new encoder that writes to w.

// The Encoder should be closed after use to flush all data

// to w.

func NewEncoder(w io.Writer) *Encoder {

	return &Encoder{

		encoder: newEncoderWithWriter(w),

	}

}

// Encode writes the YAML encoding of v to the stream.

// If multiple items are encoded to the stream, the

// second and subsequent document will be preceded

// with a "---" document separator, but the first will not.

//

// See the documentation for Marshal for details about the conversion of Go

// values to YAML.

func (e *Encoder) Encode(v interface{}) (err error) {

	defer handleErr(&err)

	e.encoder.marshalDoc("", reflect.ValueOf(v))

	return nil

}

// Close closes the encoder by writing any remaining data.

// It does not write a stream terminating string "...".

func (e *Encoder) Close() (err error) {

	defer handleErr(&err)

	e.encoder.finish()

	return nil

}

func handleErr(err *error) {

	if v := recover(); v != nil {

		if e, ok := v.(yamlError); ok {

			*err = e.err

		} else {

			panic(v)

		}

	}

}

type yamlError struct {

	err error

}

func fail(err error) {

	panic(yamlError{err})

}

func failf(format string, args ...interface{}) {

	panic(yamlError{fmt.Errorf("yaml: "+format, args...)})

}

// A TypeError is returned by Unmarshal when one or more fields in

// the YAML document cannot be properly decoded into the requested

// types. When this error is returned, the value is still

// unmarshaled partially.

type TypeError struct {

	Errors []string

}

func (e *TypeError) Error() string {

	return fmt.Sprintf("yaml: unmarshal errors:\n  %s", strings.Join(e.Errors, "\n  "))

}

// --------------------------------------------------------------------------

// Maintain a mapping of keys to structure field indexes

// The code in this section was copied from mgo/bson.

// structInfo holds details for the serialization of fields of

// a given struct.

type structInfo struct {

	FieldsMap  map[string]fieldInfo

	FieldsList []fieldInfo

	// InlineMap is the number of the field in the struct that

	// contains an ,inline map, or -1 if there's none.

	InlineMap int

}

type fieldInfo struct {

	Key       string

	Num       int

	OmitEmpty bool

	Flow      bool

	// Id holds the unique field identifier, so we can cheaply

	// check for field duplicates without maintaining an extra map.

	Id int

	// Inline holds the field index if the field is part of an inlined struct.

	Inline []int

}

var structMap = make(map[reflect.Type]*structInfo)

var fieldMapMutex sync.RWMutex

func getStructInfo(st reflect.Type) (*structInfo, error) {

	fieldMapMutex.RLock()

	sinfo, found := structMap[st]

	fieldMapMutex.RUnlock()

	if found {

		return sinfo, nil

	}

	n := st.NumField()

	fieldsMap := make(map[string]fieldInfo)

	fieldsList := make([]fieldInfo, 0, n)

	inlineMap := -1

	for i := 0; i != n; i++ {

		field := st.Field(i)

		if field.PkgPath != "" && !field.Anonymous {

			continue // Private field

		}

		info := fieldInfo{Num: i}

		tag := field.Tag.Get("yaml")

		if tag == "" && strings.Index(string(field.Tag), ":") < 0 {

			tag = string(field.Tag)

		}

		if tag == "-" {

			continue

		}

		inline := false

		fields := strings.Split(tag, ",")

		if len(fields) > 1 {

			for _, flag := range fields[1:] {

				switch flag {

				case "omitempty":

					info.OmitEmpty = true

				case "flow":

					info.Flow = true

				case "inline":

					inline = true

				default:

					return nil, errors.New(fmt.Sprintf("Unsupported flag %q in tag %q of type %s", flag, tag, st))

				}

			}

			tag = fields[0]

		}

		if inline {

			switch field.Type.Kind() {

			case reflect.Map:

				if inlineMap >= 0 {

					return nil, errors.New("Multiple ,inline maps in struct " + st.String())

				}

				if field.Type.Key() != reflect.TypeOf("") {

					return nil, errors.New("Option ,inline needs a map with string keys in struct " + st.String())

				}

				inlineMap = info.Num

			case reflect.Struct:

				sinfo, err := getStructInfo(field.Type)

				if err != nil {

					return nil, err

				}

				for _, finfo := range sinfo.FieldsList {

					if _, found := fieldsMap[finfo.Key]; found {

						msg := "Duplicated key '" + finfo.Key + "' in struct " + st.String()

						return nil, errors.New(msg)

					}

					if finfo.Inline == nil {

						finfo.Inline = []int{i, finfo.Num}

					} else {

						finfo.Inline = append([]int{i}, finfo.Inline...)

					}

					finfo.Id = len(fieldsList)

					fieldsMap[finfo.Key] = finfo

					fieldsList = append(fieldsList, finfo)

				}

			default:

				//return nil, errors.New("Option ,inline needs a struct value or map field")

				return nil, errors.New("Option ,inline needs a struct value field")

			}

			continue

		}

		if tag != "" {

			info.Key = tag

		} else {

			info.Key = strings.ToLower(field.Name)

		}

		if _, found = fieldsMap[info.Key]; found {

			msg := "Duplicated key '" + info.Key + "' in struct " + st.String()

			return nil, errors.New(msg)

		}

		info.Id = len(fieldsList)

		fieldsList = append(fieldsList, info)

		fieldsMap[info.Key] = info

	}

	sinfo = &structInfo{

		FieldsMap:  fieldsMap,

		FieldsList: fieldsList,

		InlineMap:  inlineMap,

	}

	fieldMapMutex.Lock()

	structMap[st] = sinfo

	fieldMapMutex.Unlock()

	return sinfo, nil

}

// IsZeroer is used to check whether an object is zero to

// determine whether it should be omitted when marshaling

// with the omitempty flag. One notable implementation

// is time.Time.

type IsZeroer interface {

	IsZero() bool

}

func isZero(v reflect.Value) bool {

	kind := v.Kind()

	if z, ok := v.Interface().(IsZeroer); ok {

		if (kind == reflect.Ptr || kind == reflect.Interface) && v.IsNil() {

			return true

		}

		return z.IsZero()

	}

	switch kind {

	case reflect.String:

		return len(v.String()) == 0

	case reflect.Interface, reflect.Ptr:

		return v.IsNil()

	case reflect.Slice:

		return v.Len() == 0

	case reflect.Map:

		return v.Len() == 0

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:

		return v.Int() == 0

	case reflect.Float32, reflect.Float64:

		return v.Float() == 0

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:

		return v.Uint() == 0

	case reflect.Bool:

		return !v.Bool()

	case reflect.Struct:

		vt := v.Type()

		for i := v.NumField() - 1; i >= 0; i-- {

			if vt.Field(i).PkgPath != "" {

				continue // Private field

			}

			if !isZero(v.Field(i)) {

				return false

			}

		}

		return true

	}

	return false

}