package yaml

import (
	"context"
	"encoding"
	"fmt"
	"io"
	"math"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/goccy/go-yaml/ast"
	"github.com/goccy/go-yaml/internal/errors"
	"github.com/goccy/go-yaml/parser"
	"github.com/goccy/go-yaml/printer"
	"github.com/goccy/go-yaml/token"
	"golang.org/x/xerrors"
)

const (
	// DefaultIndentSpaces default number of space for indent
	DefaultIndentSpaces = 2
)

// Encoder writes YAML values to an output stream.
type Encoder struct {
	writer                     io.Writer
	opts                       []EncodeOption
	indent                     int
	indentSequence             bool
	singleQuote                bool
	isFlowStyle                bool
	isJSONStyle                bool
	useJSONMarshaler           bool
	anchorCallback             func(*ast.AnchorNode, interface{}) error
	anchorPtrToNameMap         map[uintptr]string
	useLiteralStyleIfMultiline bool
	commentMap                 map[*Path]*Comment
	written                    bool

	line        int
	column      int
	offset      int
	indentNum   int
	indentLevel int
}

// 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, opts ...EncodeOption) *Encoder {
	return &Encoder{
		writer:             w,
		opts:               opts,
		indent:             DefaultIndentSpaces,
		anchorPtrToNameMap: map[uintptr]string{},
		line:               1,
		column:             1,
		offset:             0,
	}
}

// Close closes the encoder by writing any remaining data.
// It does not write a stream terminating string "...".
func (e *Encoder) Close() error {
	return nil
}

// 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{}) error {
	return e.EncodeContext(context.Background(), v)
}

// EncodeContext writes the YAML encoding of v to the stream with context.Context.
func (e *Encoder) EncodeContext(ctx context.Context, v interface{}) error {
	node, err := e.EncodeToNodeContext(ctx, v)
	if err != nil {
		return errors.Wrapf(err, "failed to encode to node")
	}
	if err := e.setCommentByCommentMap(node); err != nil {
		return errors.Wrapf(err, "failed to set comment by comment map")
	}
	if !e.written {
		e.written = true
	} else {
		// write document separator
		e.writer.Write([]byte("---\n"))
	}
	var p printer.Printer
	e.writer.Write(p.PrintNode(node))
	return nil
}

// EncodeToNode convert v to ast.Node.
func (e *Encoder) EncodeToNode(v interface{}) (ast.Node, error) {
	return e.EncodeToNodeContext(context.Background(), v)
}

// EncodeToNodeContext convert v to ast.Node with context.Context.
func (e *Encoder) EncodeToNodeContext(ctx context.Context, v interface{}) (ast.Node, error) {
	for _, opt := range e.opts {
		if err := opt(e); err != nil {
			return nil, errors.Wrapf(err, "failed to run option for encoder")
		}
	}
	node, err := e.encodeValue(ctx, reflect.ValueOf(v), 1)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to encode value")
	}
	return node, nil
}

func (e *Encoder) setCommentByCommentMap(node ast.Node) error {
	if e.commentMap == nil {
		return nil
	}
	for path, comment := range e.commentMap {
		n, err := path.FilterNode(node)
		if err != nil {
			return errors.Wrapf(err, "failed to filter node")
		}
		comments := []*token.Token{}
		for _, text := range comment.Texts {
			comments = append(comments, token.New(text, text, nil))
		}
		commentGroup := ast.CommentGroup(comments)
		switch comment.Position {
		case CommentLinePosition:
			if err := n.SetComment(commentGroup); err != nil {
				return errors.Wrapf(err, "failed to set comment")
			}
		case CommentHeadPosition:
			parent := ast.Parent(node, n)
			if parent == nil {
				return ErrUnsupportedHeadPositionType(node)
			}
			switch node := parent.(type) {
			case *ast.MappingValueNode:
				if err := node.SetComment(commentGroup); err != nil {
					return errors.Wrapf(err, "failed to set comment")
				}
			case *ast.MappingNode:
				if err := node.SetComment(commentGroup); err != nil {
					return errors.Wrapf(err, "failed to set comment")
				}
			default:
				return ErrUnsupportedHeadPositionType(node)
			}
		default:
			return ErrUnknownCommentPositionType
		}
	}
	return nil
}

func (e *Encoder) encodeDocument(doc []byte) (ast.Node, error) {
	f, err := parser.ParseBytes(doc, 0)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to parse yaml")
	}
	for _, docNode := range f.Docs {
		if docNode.Body != nil {
			return docNode.Body, nil
		}
	}
	return nil, nil
}

func (e *Encoder) isInvalidValue(v reflect.Value) bool {
	if !v.IsValid() {
		return true
	}
	kind := v.Type().Kind()
	if kind == reflect.Ptr && v.IsNil() {
		return true
	}
	if kind == reflect.Interface && v.IsNil() {
		return true
	}
	return false
}

type jsonMarshaler interface {
	MarshalJSON() ([]byte, error)
}

func (e *Encoder) canEncodeByMarshaler(v reflect.Value) bool {
	if !v.CanInterface() {
		return false
	}
	iface := v.Interface()
	switch iface.(type) {
	case BytesMarshalerContext:
		return true
	case BytesMarshaler:
		return true
	case InterfaceMarshalerContext:
		return true
	case InterfaceMarshaler:
		return true
	case time.Time:
		return true
	case time.Duration:
		return true
	case encoding.TextMarshaler:
		return true
	case jsonMarshaler:
		return e.useJSONMarshaler
	}
	return false
}

func (e *Encoder) encodeByMarshaler(ctx context.Context, v reflect.Value, column int) (ast.Node, error) {
	iface := v.Interface()

	if marshaler, ok := iface.(BytesMarshalerContext); ok {
		doc, err := marshaler.MarshalYAML(ctx)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to MarshalYAML")
		}
		node, err := e.encodeDocument(doc)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode document")
		}
		return node, nil
	}

	if marshaler, ok := iface.(BytesMarshaler); ok {
		doc, err := marshaler.MarshalYAML()
		if err != nil {
			return nil, errors.Wrapf(err, "failed to MarshalYAML")
		}
		node, err := e.encodeDocument(doc)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode document")
		}
		return node, nil
	}

	if marshaler, ok := iface.(InterfaceMarshalerContext); ok {
		marshalV, err := marshaler.MarshalYAML(ctx)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to MarshalYAML")
		}
		return e.encodeValue(ctx, reflect.ValueOf(marshalV), column)
	}

	if marshaler, ok := iface.(InterfaceMarshaler); ok {
		marshalV, err := marshaler.MarshalYAML()
		if err != nil {
			return nil, errors.Wrapf(err, "failed to MarshalYAML")
		}
		return e.encodeValue(ctx, reflect.ValueOf(marshalV), column)
	}

	if t, ok := iface.(time.Time); ok {
		return e.encodeTime(t, column), nil
	}

	if t, ok := iface.(time.Duration); ok {
		return e.encodeDuration(t, column), nil
	}

	if marshaler, ok := iface.(encoding.TextMarshaler); ok {
		doc, err := marshaler.MarshalText()
		if err != nil {
			return nil, errors.Wrapf(err, "failed to MarshalText")
		}
		node, err := e.encodeDocument(doc)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode document")
		}
		return node, nil
	}

	if e.useJSONMarshaler {
		if marshaler, ok := iface.(jsonMarshaler); ok {
			jsonBytes, err := marshaler.MarshalJSON()
			if err != nil {
				return nil, errors.Wrapf(err, "failed to MarshalJSON")
			}
			doc, err := JSONToYAML(jsonBytes)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to convert json to yaml")
			}
			node, err := e.encodeDocument(doc)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to encode document")
			}
			return node, nil
		}
	}

	return nil, xerrors.Errorf("does not implemented Marshaler")
}

func (e *Encoder) encodeValue(ctx context.Context, v reflect.Value, column int) (ast.Node, error) {
	if e.isInvalidValue(v) {
		return e.encodeNil(), nil
	}
	if e.canEncodeByMarshaler(v) {
		node, err := e.encodeByMarshaler(ctx, v, column)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode by marshaler")
		}
		return node, nil
	}
	switch v.Type().Kind() {
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		return e.encodeInt(v.Int()), nil
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
		return e.encodeUint(v.Uint()), nil
	case reflect.Float32:
		return e.encodeFloat(v.Float(), 32), nil
	case reflect.Float64:
		return e.encodeFloat(v.Float(), 64), nil
	case reflect.Ptr:
		anchorName := e.anchorPtrToNameMap[v.Pointer()]
		if anchorName != "" {
			aliasName := anchorName
			alias := ast.Alias(token.New("*", "*", e.pos(column)))
			alias.Value = ast.String(token.New(aliasName, aliasName, e.pos(column)))
			return alias, nil
		}
		return e.encodeValue(ctx, v.Elem(), column)
	case reflect.Interface:
		return e.encodeValue(ctx, v.Elem(), column)
	case reflect.String:
		return e.encodeString(v.String(), column), nil
	case reflect.Bool:
		return e.encodeBool(v.Bool()), nil
	case reflect.Slice:
		if mapSlice, ok := v.Interface().(MapSlice); ok {
			return e.encodeMapSlice(ctx, mapSlice, column)
		}
		return e.encodeSlice(ctx, v)
	case reflect.Array:
		return e.encodeArray(ctx, v)
	case reflect.Struct:
		if v.CanInterface() {
			if mapItem, ok := v.Interface().(MapItem); ok {
				return e.encodeMapItem(ctx, mapItem, column)
			}
			if t, ok := v.Interface().(time.Time); ok {
				return e.encodeTime(t, column), nil
			}
		}
		return e.encodeStruct(ctx, v, column)
	case reflect.Map:
		return e.encodeMap(ctx, v, column), nil
	default:
		return nil, xerrors.Errorf("unknown value type %s", v.Type().String())
	}
}

func (e *Encoder) pos(column int) *token.Position {
	return &token.Position{
		Line:        e.line,
		Column:      column,
		Offset:      e.offset,
		IndentNum:   e.indentNum,
		IndentLevel: e.indentLevel,
	}
}

func (e *Encoder) encodeNil() *ast.NullNode {
	value := "null"
	return ast.Null(token.New(value, value, e.pos(e.column)))
}

func (e *Encoder) encodeInt(v int64) *ast.IntegerNode {
	value := fmt.Sprint(v)
	return ast.Integer(token.New(value, value, e.pos(e.column)))
}

func (e *Encoder) encodeUint(v uint64) *ast.IntegerNode {
	value := fmt.Sprint(v)
	return ast.Integer(token.New(value, value, e.pos(e.column)))
}

func (e *Encoder) encodeFloat(v float64, bitSize int) ast.Node {
	if v == math.Inf(0) {
		value := ".inf"
		return ast.Infinity(token.New(value, value, e.pos(e.column)))
	} else if v == math.Inf(-1) {
		value := "-.inf"
		return ast.Infinity(token.New(value, value, e.pos(e.column)))
	} else if math.IsNaN(v) {
		value := ".nan"
		return ast.Nan(token.New(value, value, e.pos(e.column)))
	}
	value := strconv.FormatFloat(v, 'g', -1, bitSize)
	if !strings.Contains(value, ".") && !strings.Contains(value, "e") {
		// append x.0 suffix to keep float value context
		value = fmt.Sprintf("%s.0", value)
	}
	return ast.Float(token.New(value, value, e.pos(e.column)))
}

func (e *Encoder) isNeedQuoted(v string) bool {
	if e.isJSONStyle {
		return true
	}
	if e.useLiteralStyleIfMultiline && strings.ContainsAny(v, "\n\r") {
		return false
	}
	if e.isFlowStyle && strings.ContainsAny(v, `]},'"`) {
		return true
	}
	if token.IsNeedQuoted(v) {
		return true
	}
	return false
}

func (e *Encoder) encodeString(v string, column int) *ast.StringNode {
	if e.isNeedQuoted(v) {
		if e.singleQuote {
			v = quoteWith(v, '\'')
		} else {
			v = strconv.Quote(v)
		}
	}
	return ast.String(token.New(v, v, e.pos(column)))
}

func (e *Encoder) encodeBool(v bool) *ast.BoolNode {
	value := fmt.Sprint(v)
	return ast.Bool(token.New(value, value, e.pos(e.column)))
}

func (e *Encoder) encodeSlice(ctx context.Context, value reflect.Value) (*ast.SequenceNode, error) {
	if e.indentSequence {
		e.column += e.indent
	}
	column := e.column
	sequence := ast.Sequence(token.New("-", "-", e.pos(column)), e.isFlowStyle)
	for i := 0; i < value.Len(); i++ {
		node, err := e.encodeValue(ctx, value.Index(i), column)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode value for slice")
		}
		sequence.Values = append(sequence.Values, node)
	}
	if e.indentSequence {
		e.column -= e.indent
	}
	return sequence, nil
}

func (e *Encoder) encodeArray(ctx context.Context, value reflect.Value) (*ast.SequenceNode, error) {
	if e.indentSequence {
		e.column += e.indent
	}
	column := e.column
	sequence := ast.Sequence(token.New("-", "-", e.pos(column)), e.isFlowStyle)
	for i := 0; i < value.Len(); i++ {
		node, err := e.encodeValue(ctx, value.Index(i), column)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode value for array")
		}
		sequence.Values = append(sequence.Values, node)
	}
	if e.indentSequence {
		e.column -= e.indent
	}
	return sequence, nil
}

func (e *Encoder) encodeMapItem(ctx context.Context, item MapItem, column int) (*ast.MappingValueNode, error) {
	k := reflect.ValueOf(item.Key)
	v := reflect.ValueOf(item.Value)
	value, err := e.encodeValue(ctx, v, column)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to encode MapItem")
	}
	if m, ok := value.(*ast.MappingNode); ok {
		m.AddColumn(e.indent)
	}
	return ast.MappingValue(
		token.New("", "", e.pos(column)),
		e.encodeString(k.Interface().(string), column),
		value,
	), nil
}

func (e *Encoder) encodeMapSlice(ctx context.Context, value MapSlice, column int) (*ast.MappingNode, error) {
	node := ast.Mapping(token.New("", "", e.pos(column)), e.isFlowStyle)
	for _, item := range value {
		value, err := e.encodeMapItem(ctx, item, column)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode MapItem for MapSlice")
		}
		node.Values = append(node.Values, value)
	}
	return node, nil
}

func (e *Encoder) encodeMap(ctx context.Context, value reflect.Value, column int) ast.Node {
	node := ast.Mapping(token.New("", "", e.pos(column)), e.isFlowStyle)
	keys := make([]interface{}, len(value.MapKeys()))
	for i, k := range value.MapKeys() {
		keys[i] = k.Interface()
	}
	sort.Slice(keys, func(i, j int) bool {
		return fmt.Sprint(keys[i]) < fmt.Sprint(keys[j])
	})
	for _, key := range keys {
		k := reflect.ValueOf(key)
		v := value.MapIndex(k)
		value, err := e.encodeValue(ctx, v, column)
		if err != nil {
			return nil
		}
		if value.Type() == ast.MappingType || value.Type() == ast.MappingValueType {
			value.AddColumn(e.indent)
		}
		node.Values = append(node.Values, ast.MappingValue(
			nil,
			e.encodeString(fmt.Sprint(key), column),
			value,
		))
	}
	return node
}

// 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 (e *Encoder) isZeroValue(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 !e.isZeroValue(v.Field(i)) {
				return false
			}
		}
		return true
	}
	return false
}

func (e *Encoder) encodeTime(v time.Time, column int) *ast.StringNode {
	value := v.Format(time.RFC3339Nano)
	if e.isJSONStyle {
		value = strconv.Quote(value)
	}
	return ast.String(token.New(value, value, e.pos(column)))
}

func (e *Encoder) encodeDuration(v time.Duration, column int) *ast.StringNode {
	value := v.String()
	if e.isJSONStyle {
		value = strconv.Quote(value)
	}
	return ast.String(token.New(value, value, e.pos(column)))
}

func (e *Encoder) encodeAnchor(anchorName string, value ast.Node, fieldValue reflect.Value, column int) (*ast.AnchorNode, error) {
	anchorNode := ast.Anchor(token.New("&", "&", e.pos(column)))
	anchorNode.Name = ast.String(token.New(anchorName, anchorName, e.pos(column)))
	anchorNode.Value = value
	if e.anchorCallback != nil {
		if err := e.anchorCallback(anchorNode, fieldValue.Interface()); err != nil {
			return nil, errors.Wrapf(err, "failed to marshal anchor")
		}
		if snode, ok := anchorNode.Name.(*ast.StringNode); ok {
			anchorName = snode.Value
		}
	}
	if fieldValue.Kind() == reflect.Ptr {
		e.anchorPtrToNameMap[fieldValue.Pointer()] = anchorName
	}
	return anchorNode, nil
}

func (e *Encoder) encodeStruct(ctx context.Context, value reflect.Value, column int) (ast.Node, error) {
	node := ast.Mapping(token.New("", "", e.pos(column)), e.isFlowStyle)
	structType := value.Type()
	structFieldMap, err := structFieldMap(structType)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to get struct field map")
	}
	hasInlineAnchorField := false
	var inlineAnchorValue reflect.Value
	for i := 0; i < value.NumField(); i++ {
		field := structType.Field(i)
		if isIgnoredStructField(field) {
			continue
		}
		fieldValue := value.FieldByName(field.Name)
		structField := structFieldMap[field.Name]
		if structField.IsOmitEmpty && e.isZeroValue(fieldValue) {
			// omit encoding
			continue
		}
		ve := e
		if !e.isFlowStyle && structField.IsFlow {
			ve = &Encoder{}
			*ve = *e
			ve.isFlowStyle = true
		}
		value, err := ve.encodeValue(ctx, fieldValue, column)
		if err != nil {
			return nil, errors.Wrapf(err, "failed to encode value")
		}
		if _, ok := value.(*ast.MappingNode); ok {
			value.AddColumn(e.indent)
		}
		var key ast.MapKeyNode = e.encodeString(structField.RenderName, column)
		switch {
		case structField.AnchorName != "":
			anchorNode, err := e.encodeAnchor(structField.AnchorName, value, fieldValue, column)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to encode anchor")
			}
			value = anchorNode
		case structField.IsAutoAlias:
			if fieldValue.Kind() != reflect.Ptr {
				return nil, xerrors.Errorf(
					"%s in struct is not pointer type. but required automatically alias detection",
					structField.FieldName,
				)
			}
			anchorName := e.anchorPtrToNameMap[fieldValue.Pointer()]
			if anchorName == "" {
				return nil, xerrors.Errorf(
					"cannot find anchor name from pointer address for automatically alias detection",
				)
			}
			aliasName := anchorName
			alias := ast.Alias(token.New("*", "*", e.pos(column)))
			alias.Value = ast.String(token.New(aliasName, aliasName, e.pos(column)))
			value = alias
			if structField.IsInline {
				// if both used alias and inline, output `<<: *alias`
				key = ast.MergeKey(token.New("<<", "<<", e.pos(column)))
			}
		case structField.AliasName != "":
			aliasName := structField.AliasName
			alias := ast.Alias(token.New("*", "*", e.pos(column)))
			alias.Value = ast.String(token.New(aliasName, aliasName, e.pos(column)))
			value = alias
			if structField.IsInline {
				// if both used alias and inline, output `<<: *alias`
				key = ast.MergeKey(token.New("<<", "<<", e.pos(column)))
			}
		case structField.IsInline:
			isAutoAnchor := structField.IsAutoAnchor
			if !hasInlineAnchorField {
				hasInlineAnchorField = isAutoAnchor
			}
			if isAutoAnchor {
				inlineAnchorValue = fieldValue
			}
			mapNode, ok := value.(ast.MapNode)
			if !ok {
				return nil, xerrors.Errorf("inline value is must be map or struct type")
			}
			mapIter := mapNode.MapRange()
			for mapIter.Next() {
				key := mapIter.Key()
				value := mapIter.Value()
				keyName := key.GetToken().Value
				if structFieldMap.isIncludedRenderName(keyName) {
					// if declared same key name, skip encoding this field
					continue
				}
				key.AddColumn(-e.indent)
				value.AddColumn(-e.indent)
				node.Values = append(node.Values, ast.MappingValue(nil, key, value))
			}
			continue
		case structField.IsAutoAnchor:
			anchorNode, err := e.encodeAnchor(structField.RenderName, value, fieldValue, column)
			if err != nil {
				return nil, errors.Wrapf(err, "failed to encode anchor")
			}
			value = anchorNode
		}
		node.Values = append(node.Values, ast.MappingValue(nil, key, value))
	}
	if hasInlineAnchorField {
		node.AddColumn(e.indent)
		anchorName := "anchor"
		anchorNode := ast.Anchor(token.New("&", "&", e.pos(column)))
		anchorNode.Name = ast.String(token.New(anchorName, anchorName, e.pos(column)))
		anchorNode.Value = node
		if e.anchorCallback != nil {
			if err := e.anchorCallback(anchorNode, value.Addr().Interface()); err != nil {
				return nil, errors.Wrapf(err, "failed to marshal anchor")
			}
			if snode, ok := anchorNode.Name.(*ast.StringNode); ok {
				anchorName = snode.Value
			}
		}
		if inlineAnchorValue.Kind() == reflect.Ptr {
			e.anchorPtrToNameMap[inlineAnchorValue.Pointer()] = anchorName
		}
		return anchorNode, nil
	}
	return node, nil
}