package toml

import (

	"bytes"

	"errors"

	"fmt"

	"io"

	"reflect"

	"strconv"

	"strings"

	"time"

)

const tagKeyMultiline = "multiline"

type tomlOpts struct {

	name      string

	comment   string

	commented bool

	multiline bool

	include   bool

	omitempty bool

}

type encOpts struct {

	quoteMapKeys            bool

	arraysOneElementPerLine bool

}

var encOptsDefaults = encOpts{

	quoteMapKeys: false,

}

var timeType = reflect.TypeOf(time.Time{})

var marshalerType = reflect.TypeOf(new(Marshaler)).Elem()

// Check if the given marshall type maps to a Tree primitive

func isPrimitive(mtype reflect.Type) bool {

	switch mtype.Kind() {

	case reflect.Ptr:

		return isPrimitive(mtype.Elem())

	case reflect.Bool:

		return true

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

		return true

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

		return true

	case reflect.Float32, reflect.Float64:

		return true

	case reflect.String:

		return true

	case reflect.Struct:

		return mtype == timeType || isCustomMarshaler(mtype)

	default:

		return false

	}

}

// Check if the given marshall type maps to a Tree slice

func isTreeSlice(mtype reflect.Type) bool {

	switch mtype.Kind() {

	case reflect.Slice:

		return !isOtherSlice(mtype)

	default:

		return false

	}

}

// Check if the given marshall type maps to a non-Tree slice

func isOtherSlice(mtype reflect.Type) bool {

	switch mtype.Kind() {

	case reflect.Ptr:

		return isOtherSlice(mtype.Elem())

	case reflect.Slice:

		return isPrimitive(mtype.Elem()) || isOtherSlice(mtype.Elem())

	default:

		return false

	}

}

// Check if the given marshall type maps to a Tree

func isTree(mtype reflect.Type) bool {

	switch mtype.Kind() {

	case reflect.Map:

		return true

	case reflect.Struct:

		return !isPrimitive(mtype)

	default:

		return false

	}

}

func isCustomMarshaler(mtype reflect.Type) bool {

	return mtype.Implements(marshalerType)

}

func callCustomMarshaler(mval reflect.Value) ([]byte, error) {

	return mval.Interface().(Marshaler).MarshalTOML()

}

// Marshaler is the interface implemented by types that

// can marshal themselves into valid TOML.

type Marshaler interface {

	MarshalTOML() ([]byte, error)

}

/*

Marshal returns the TOML encoding of v.  Behavior is similar to the Go json

encoder, except that there is no concept of a Marshaler interface or MarshalTOML

function for sub-structs, and currently only definite types can be marshaled

(i.e. no `interface{}`).

The following struct annotations are supported:

  toml:"Field"      Overrides the field's name to output.

  omitempty         When set, empty values and groups are not emitted.

  comment:"comment" Emits a # comment on the same line. This supports new lines.

  commented:"true"  Emits the value as commented.

Note that pointers are automatically assigned the "omitempty" option, as TOML

explicitly does not handle null values (saying instead the label should be

dropped).

Tree structural types and corresponding marshal types:

  *Tree                            (*)struct, (*)map[string]interface{}

  []*Tree                          (*)[](*)struct, (*)[](*)map[string]interface{}

  []interface{} (as interface{})   (*)[]primitive, (*)[]([]interface{})

  interface{}                      (*)primitive

Tree primitive types and corresponding marshal types:

  uint64     uint, uint8-uint64, pointers to same

  int64      int, int8-uint64, pointers to same

  float64    float32, float64, pointers to same

  string     string, pointers to same

  bool       bool, pointers to same

  time.Time  time.Time{}, pointers to same

*/

func Marshal(v interface{}) ([]byte, error) {

	return NewEncoder(nil).marshal(v)

}

// Encoder writes TOML values to an output stream.

type Encoder struct {

	w io.Writer

	encOpts

}

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

func NewEncoder(w io.Writer) *Encoder {

	return &Encoder{

		w:       w,

		encOpts: encOptsDefaults,

	}

}

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

//

// See the documentation for Marshal for details.

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

	b, err := e.marshal(v)

	if err != nil {

		return err

	}

	if _, err := e.w.Write(b); err != nil {

		return err

	}

	return nil

}

// QuoteMapKeys sets up the encoder to encode

// maps with string type keys with quoted TOML keys.

//

// This relieves the character limitations on map keys.

func (e *Encoder) QuoteMapKeys(v bool) *Encoder {

	e.quoteMapKeys = v

	return e

}

// ArraysWithOneElementPerLine sets up the encoder to encode arrays

// with more than one element on multiple lines instead of one.

//

// For example:

//

//   A = [1,2,3]

//

// Becomes

//

//   A = [

//     1,

//     2,

//     3,

//   ]

func (e *Encoder) ArraysWithOneElementPerLine(v bool) *Encoder {

	e.arraysOneElementPerLine = v

	return e

}

func (e *Encoder) marshal(v interface{}) ([]byte, error) {

	mtype := reflect.TypeOf(v)

	if mtype.Kind() != reflect.Struct {

		return []byte{}, errors.New("Only a struct can be marshaled to TOML")

	}

	sval := reflect.ValueOf(v)

	if isCustomMarshaler(mtype) {

		return callCustomMarshaler(sval)

	}

	t, err := e.valueToTree(mtype, sval)

	if err != nil {

		return []byte{}, err

	}

	var buf bytes.Buffer

	_, err = t.writeTo(&buf, "", "", 0, e.arraysOneElementPerLine)

	return buf.Bytes(), err

}

// Convert given marshal struct or map value to toml tree

func (e *Encoder) valueToTree(mtype reflect.Type, mval reflect.Value) (*Tree, error) {

	if mtype.Kind() == reflect.Ptr {

		return e.valueToTree(mtype.Elem(), mval.Elem())

	}

	tval := newTree()

	switch mtype.Kind() {

	case reflect.Struct:

		for i := 0; i < mtype.NumField(); i++ {

			mtypef, mvalf := mtype.Field(i), mval.Field(i)

			opts := tomlOptions(mtypef)

			if opts.include && (!opts.omitempty || !isZero(mvalf)) {

				val, err := e.valueToToml(mtypef.Type, mvalf)

				if err != nil {

					return nil, err

				}

				tval.SetWithOptions(opts.name, SetOptions{

					Comment:   opts.comment,

					Commented: opts.commented,

					Multiline: opts.multiline,

				}, val)

			}

		}

	case reflect.Map:

		for _, key := range mval.MapKeys() {

			mvalf := mval.MapIndex(key)

			val, err := e.valueToToml(mtype.Elem(), mvalf)

			if err != nil {

				return nil, err

			}

			if e.quoteMapKeys {

				keyStr, err := tomlValueStringRepresentation(key.String(), "", e.arraysOneElementPerLine)

				if err != nil {

					return nil, err

				}

				tval.SetPath([]string{keyStr}, val)

			} else {

				tval.Set(key.String(), val)

			}

		}

	}

	return tval, nil

}

// Convert given marshal slice to slice of Toml trees

func (e *Encoder) valueToTreeSlice(mtype reflect.Type, mval reflect.Value) ([]*Tree, error) {

	tval := make([]*Tree, mval.Len(), mval.Len())

	for i := 0; i < mval.Len(); i++ {

		val, err := e.valueToTree(mtype.Elem(), mval.Index(i))

		if err != nil {

			return nil, err

		}

		tval[i] = val

	}

	return tval, nil

}

// Convert given marshal slice to slice of toml values

func (e *Encoder) valueToOtherSlice(mtype reflect.Type, mval reflect.Value) (interface{}, error) {

	tval := make([]interface{}, mval.Len(), mval.Len())

	for i := 0; i < mval.Len(); i++ {

		val, err := e.valueToToml(mtype.Elem(), mval.Index(i))

		if err != nil {

			return nil, err

		}

		tval[i] = val

	}

	return tval, nil

}

// Convert given marshal value to toml value

func (e *Encoder) valueToToml(mtype reflect.Type, mval reflect.Value) (interface{}, error) {

	if mtype.Kind() == reflect.Ptr {

		return e.valueToToml(mtype.Elem(), mval.Elem())

	}

	switch {

	case isCustomMarshaler(mtype):

		return callCustomMarshaler(mval)

	case isTree(mtype):

		return e.valueToTree(mtype, mval)

	case isTreeSlice(mtype):

		return e.valueToTreeSlice(mtype, mval)

	case isOtherSlice(mtype):

		return e.valueToOtherSlice(mtype, mval)

	default:

		switch mtype.Kind() {

		case reflect.Bool:

			return mval.Bool(), nil

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

			return mval.Int(), nil

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

			return mval.Uint(), nil

		case reflect.Float32, reflect.Float64:

			return mval.Float(), nil

		case reflect.String:

			return mval.String(), nil

		case reflect.Struct:

			return mval.Interface().(time.Time), nil

		default:

			return nil, fmt.Errorf("Marshal can't handle %v(%v)", mtype, mtype.Kind())

		}

	}

}

// Unmarshal attempts to unmarshal the Tree into a Go struct pointed by v.

// Neither Unmarshaler interfaces nor UnmarshalTOML functions are supported for

// sub-structs, and only definite types can be unmarshaled.

func (t *Tree) Unmarshal(v interface{}) error {

	d := Decoder{tval: t}

	return d.unmarshal(v)

}

// Marshal returns the TOML encoding of Tree.

// See Marshal() documentation for types mapping table.

func (t *Tree) Marshal() ([]byte, error) {

	var buf bytes.Buffer

	err := NewEncoder(&buf).Encode(t)

	return buf.Bytes(), err

}

// Unmarshal parses the TOML-encoded data and stores the result in the value

// pointed to by v. Behavior is similar to the Go json encoder, except that there

// is no concept of an Unmarshaler interface or UnmarshalTOML function for

// sub-structs, and currently only definite types can be unmarshaled to (i.e. no

// `interface{}`).

//

// The following struct annotations are supported:

//

//   toml:"Field" Overrides the field's name to map to.

//

// See Marshal() documentation for types mapping table.

func Unmarshal(data []byte, v interface{}) error {

	t, err := LoadReader(bytes.NewReader(data))

	if err != nil {

		return err

	}

	return t.Unmarshal(v)

}

// Decoder reads and decodes TOML values from an input stream.

type Decoder struct {

	r    io.Reader

	tval *Tree

	encOpts

}

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

func NewDecoder(r io.Reader) *Decoder {

	return &Decoder{

		r:       r,

		encOpts: encOptsDefaults,

	}

}

// Decode reads a TOML-encoded value from it's input

// and unmarshals it in the value pointed at by v.

//

// See the documentation for Marshal for details.

func (d *Decoder) Decode(v interface{}) error {

	var err error

	d.tval, err = LoadReader(d.r)

	if err != nil {

		return err

	}

	return d.unmarshal(v)

}

func (d *Decoder) unmarshal(v interface{}) error {

	mtype := reflect.TypeOf(v)

	if mtype.Kind() != reflect.Ptr || mtype.Elem().Kind() != reflect.Struct {

		return errors.New("Only a pointer to struct can be unmarshaled from TOML")

	}

	sval, err := d.valueFromTree(mtype.Elem(), d.tval)

	if err != nil {

		return err

	}

	reflect.ValueOf(v).Elem().Set(sval)

	return nil

}

// Convert toml tree to marshal struct or map, using marshal type

func (d *Decoder) valueFromTree(mtype reflect.Type, tval *Tree) (reflect.Value, error) {

	if mtype.Kind() == reflect.Ptr {

		return d.unwrapPointer(mtype, tval)

	}

	var mval reflect.Value

	switch mtype.Kind() {

	case reflect.Struct:

		mval = reflect.New(mtype).Elem()