package yaml

import (

	"encoding"

	"fmt"

	"io"

	"reflect"

	"regexp"

	"sort"

	"strconv"

	"strings"

	"time"

	"unicode/utf8"

)

// jsonNumber is the interface of the encoding/json.Number datatype.

// Repeating the interface here avoids a dependency on encoding/json, and also

// supports other libraries like jsoniter, which use a similar datatype with

// the same interface. Detecting this interface is useful when dealing with

// structures containing json.Number, which is a string under the hood. The

// encoder should prefer the use of Int64(), Float64() and string(), in that

// order, when encoding this type.

type jsonNumber interface {

	Float64() (float64, error)

	Int64() (int64, error)

	String() string

}

type encoder struct {

	emitter yaml_emitter_t

	event   yaml_event_t

	out     []byte

	flow    bool

	// doneInit holds whether the initial stream_start_event has been

	// emitted.

	doneInit bool

}

func newEncoder() *encoder {

	e := &encoder{}

	yaml_emitter_initialize(&e.emitter)

	yaml_emitter_set_output_string(&e.emitter, &e.out)

	yaml_emitter_set_unicode(&e.emitter, true)

	return e

}

func newEncoderWithWriter(w io.Writer) *encoder {

	e := &encoder{}

	yaml_emitter_initialize(&e.emitter)

	yaml_emitter_set_output_writer(&e.emitter, w)

	yaml_emitter_set_unicode(&e.emitter, true)

	return e

}

func (e *encoder) init() {

	if e.doneInit {

		return

	}

	yaml_stream_start_event_initialize(&e.event, yaml_UTF8_ENCODING)

	e.emit()

	e.doneInit = true

}

func (e *encoder) finish() {

	e.emitter.open_ended = false

	yaml_stream_end_event_initialize(&e.event)

	e.emit()

}

func (e *encoder) destroy() {

	yaml_emitter_delete(&e.emitter)

}

func (e *encoder) emit() {

	// This will internally delete the e.event value.

	e.must(yaml_emitter_emit(&e.emitter, &e.event))

}

func (e *encoder) must(ok bool) {

	if !ok {

		msg := e.emitter.problem

		if msg == "" {

			msg = "unknown problem generating YAML content"

		}

		failf("%s", msg)

	}

}

func (e *encoder) marshalDoc(tag string, in reflect.Value) {

	e.init()

	yaml_document_start_event_initialize(&e.event, nil, nil, true)

	e.emit()

	e.marshal(tag, in)

	yaml_document_end_event_initialize(&e.event, true)

	e.emit()

}

func (e *encoder) marshal(tag string, in reflect.Value) {

	if !in.IsValid() || in.Kind() == reflect.Ptr && in.IsNil() {

		e.nilv()

		return

	}

	iface := in.Interface()

	switch m := iface.(type) {

	case jsonNumber:

		integer, err := m.Int64()

		if err == nil {

			// In this case the json.Number is a valid int64

			in = reflect.ValueOf(integer)

			break

		}

		float, err := m.Float64()

		if err == nil {

			// In this case the json.Number is a valid float64

			in = reflect.ValueOf(float)

			break

		}

		// fallback case - no number could be obtained

		in = reflect.ValueOf(m.String())

	case time.Time, *time.Time:

		// Although time.Time implements TextMarshaler,

		// we don't want to treat it as a string for YAML

		// purposes because YAML has special support for

		// timestamps.

	case Marshaler:

		v, err := m.MarshalYAML()

		if err != nil {

			fail(err)

		}

		if v == nil {

			e.nilv()

			return

		}

		in = reflect.ValueOf(v)

	case encoding.TextMarshaler:

		text, err := m.MarshalText()

		if err != nil {

			fail(err)

		}

		in = reflect.ValueOf(string(text))

	case nil:

		e.nilv()

		return

	}

	switch in.Kind() {

	case reflect.Interface:

		e.marshal(tag, in.Elem())

	case reflect.Map:

		e.mapv(tag, in)

	case reflect.Ptr:

		if in.Type() == ptrTimeType {

			e.timev(tag, in.Elem())

		} else {

			e.marshal(tag, in.Elem())

		}

	case reflect.Struct:

		if in.Type() == timeType {

			e.timev(tag, in)

		} else {

			e.structv(tag, in)

		}

	case reflect.Slice, reflect.Array:

		if in.Type().Elem() == mapItemType {

			e.itemsv(tag, in)

		} else {

			e.slicev(tag, in)

		}

	case reflect.String:

		e.stringv(tag, in)

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

		if in.Type() == durationType {

			e.stringv(tag, reflect.ValueOf(iface.(time.Duration).String()))

		} else {

			e.intv(tag, in)

		}

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

		e.uintv(tag, in)

	case reflect.Float32, reflect.Float64:

		e.floatv(tag, in)

	case reflect.Bool:

		e.boolv(tag, in)

	default:

		panic("cannot marshal type: " + in.Type().String())

	}

}

func (e *encoder) mapv(tag string, in reflect.Value) {

	e.mappingv(tag, func() {

		keys := keyList(in.MapKeys())

		sort.Sort(keys)

		for _, k := range keys {

			e.marshal("", k)

			e.marshal("", in.MapIndex(k))

		}

	})

}

func (e *encoder) itemsv(tag string, in reflect.Value) {

	e.mappingv(tag, func() {

		slice := in.Convert(reflect.TypeOf([]MapItem{})).Interface().([]MapItem)

		for _, item := range slice {

			e.marshal("", reflect.ValueOf(item.Key))

			e.marshal("", reflect.ValueOf(item.Value))

		}

	})

}

func (e *encoder) structv(tag string, in reflect.Value) {

	sinfo, err := getStructInfo(in.Type())

	if err != nil {

		panic(err)

	}

	e.mappingv(tag, func() {

		for _, info := range sinfo.FieldsList {

			var value reflect.Value

			if info.Inline == nil {

				value = in.Field(info.Num)

			} else {

				value = in.FieldByIndex(info.Inline)

			}

			if info.OmitEmpty && isZero(value) {

				continue

			}

			e.marshal("", reflect.ValueOf(info.Key))

			e.flow = info.Flow

			e.marshal("", value)

		}

		if sinfo.InlineMap >= 0 {

			m := in.Field(sinfo.InlineMap)

			if m.Len() > 0 {

				e.flow = false

				keys := keyList(m.MapKeys())

				sort.Sort(keys)

				for _, k := range keys {

					if _, found := sinfo.FieldsMap[k.String()]; found {

						panic(fmt.Sprintf("Can't have key %q in inlined map; conflicts with struct field", k.String()))

					}

					e.marshal("", k)

					e.flow = false

					e.marshal("", m.MapIndex(k))

				}

			}

		}

	})

}

func (e *encoder) mappingv(tag string, f func()) {

	implicit := tag == ""

	style := yaml_BLOCK_MAPPING_STYLE

	if e.flow {

		e.flow = false

		style = yaml_FLOW_MAPPING_STYLE

	}

	yaml_mapping_start_event_initialize(&e.event, nil, []byte(tag), implicit, style)

	e.emit()

	f()

	yaml_mapping_end_event_initialize(&e.event)

	e.emit()

}

func (e *encoder) slicev(tag string, in reflect.Value) {

	implicit := tag == ""

	style := yaml_BLOCK_SEQUENCE_STYLE

	if e.flow {

		e.flow = false

		style = yaml_FLOW_SEQUENCE_STYLE

	}

	e.must(yaml_sequence_start_event_initialize(&e.event, nil, []byte(tag), implicit, style))

	e.emit()

	n := in.Len()

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

		e.marshal("", in.Index(i))

	}

	e.must(yaml_sequence_end_event_initialize(&e.event))

	e.emit()

}

// isBase60 returns whether s is in base 60 notation as defined in YAML 1.1.

//

// The base 60 float notation in YAML 1.1 is a terrible idea and is unsupported

// in YAML 1.2 and by this package, but these should be marshalled quoted for

// the time being for compatibility with other parsers.

func isBase60Float(s string) (result bool) {

	// Fast path.

	if s == "" {

		return false

	}

	c := s[0]

	if !(c == '+' || c == '-' || c >= '0' && c <= '9') || strings.IndexByte(s, ':') < 0 {

		return false

	}

	// Do the full match.

	return base60float.MatchString(s)

}

// From http://yaml.org/type/float.html, except the regular expression there

// is bogus. In practice parsers do not enforce the "\.[0-9_]*" suffix.

var base60float = regexp.MustCompile(`^[-+]?[0-9][0-9_]*(?::[0-5]?[0-9])+(?:\.[0-9_]*)?$`)

func (e *encoder) stringv(tag string, in reflect.Value) {

	var style yaml_scalar_style_t

	s := in.String()

	canUsePlain := true

	switch {

	case !utf8.ValidString(s):

		if tag == yaml_BINARY_TAG {

			failf("explicitly tagged !!binary data must be base64-encoded")

		}

		if tag != "" {

			failf("cannot marshal invalid UTF-8 data as %s", shortTag(tag))

		}

		// It can't be encoded directly as YAML so use a binary tag

		// and encode it as base64.

		tag = yaml_BINARY_TAG

		s = encodeBase64(s)

	case tag == "":

		// Check to see if it would resolve to a specific

		// tag when encoded unquoted. If it doesn't,

		// there's no need to quote it.

		rtag, _ := resolve("", s)

		canUsePlain = rtag == yaml_STR_TAG && !isBase60Float(s)

	}

	// Note: it's possible for user code to emit invalid YAML

	// if they explicitly specify a tag and a string containing

	// text that's incompatible with that tag.

	switch {

	case strings.Contains(s, "\n"):

		style = yaml_LITERAL_SCALAR_STYLE

	case canUsePlain:

		style = yaml_PLAIN_SCALAR_STYLE

	default:

		style = yaml_DOUBLE_QUOTED_SCALAR_STYLE

	}

	e.emitScalar(s, "", tag, style)

}

func (e *encoder) boolv(tag string, in reflect.Value) {

	var s string

	if in.Bool() {

		s = "true"

	} else {

		s = "false"

	}

	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) intv(tag string, in reflect.Value) {

	s := strconv.FormatInt(in.Int(), 10)

	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) uintv(tag string, in reflect.Value) {

	s := strconv.FormatUint(in.Uint(), 10)

	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) timev(tag string, in reflect.Value) {

	t := in.Interface().(time.Time)

	s := t.Format(time.RFC3339Nano)

	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) floatv(tag string, in reflect.Value) {

	// Issue #352: When formatting, use the precision of the underlying value

	precision := 64

	if in.Kind() == reflect.Float32 {

		precision = 32

	}

	s := strconv.FormatFloat(in.Float(), 'g', -1, precision)

	switch s {

	case "+Inf":

		s = ".inf"

	case "-Inf":

		s = "-.inf"

	case "NaN":

		s = ".nan"

	}

	e.emitScalar(s, "", tag, yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) nilv() {

	e.emitScalar("null", "", "", yaml_PLAIN_SCALAR_STYLE)

}

func (e *encoder) emitScalar(value, anchor, tag string, style yaml_scalar_style_t) {

	implicit := tag == ""

	e.must(yaml_scalar_event_initialize(&e.event, []byte(anchor), []byte(tag), []byte(value), implicit, implicit, style))

	e.emit()

}