package json

import (
	"reflect"

	"github.com/goccy/go-json/internal/decoder"
)

// CreatePath creates JSON Path.
//
// JSON Path rule
// $   : root object or element. The JSON Path format must start with this operator, which refers to the outermost level of the JSON-formatted string.
// .   : child operator. You can identify child values using dot-notation.
// ..  : recursive descent.
// []  : subscript operator. If the JSON object is an array, you can use brackets to specify the array index.
// [*] : all objects/elements for array.
//
// Reserved words must be properly escaped when included in Path.
//
// Escape Rule
// single quote style escape: e.g.) `$['a.b'].c`
// double quote style escape: e.g.) `$."a.b".c`
func CreatePath(p string) (*Path, error) {
	path, err := decoder.PathString(p).Build()
	if err != nil {
		return nil, err
	}
	return &Path{path: path}, nil
}

// Path represents JSON Path.
type Path struct {
	path *decoder.Path
}

// RootSelectorOnly whether only the root selector ($) is used.
func (p *Path) RootSelectorOnly() bool {
	return p.path.RootSelectorOnly
}

// UsedSingleQuotePathSelector whether single quote-based escaping was done when building the JSON Path.
func (p *Path) UsedSingleQuotePathSelector() bool {
	return p.path.SingleQuotePathSelector
}

// UsedSingleQuotePathSelector whether double quote-based escaping was done when building the JSON Path.
func (p *Path) UsedDoubleQuotePathSelector() bool {
	return p.path.DoubleQuotePathSelector
}

// Extract extracts a specific JSON string.
func (p *Path) Extract(data []byte, optFuncs ...DecodeOptionFunc) ([][]byte, error) {
	return extractFromPath(p, data, optFuncs...)
}

// PathString returns original JSON Path string.
func (p *Path) PathString() string {
	return p.path.String()
}

// Unmarshal extract and decode the value of the part corresponding to JSON Path from the input data.
func (p *Path) Unmarshal(data []byte, v interface{}, optFuncs ...DecodeOptionFunc) error {
	contents, err := extractFromPath(p, data, optFuncs...)
	if err != nil {
		return err
	}
	results := make([]interface{}, 0, len(contents))
	for _, content := range contents {
		var result interface{}
		if err := Unmarshal(content, &result); err != nil {
			return err
		}
		results = append(results, result)
	}
	if err := decoder.AssignValue(reflect.ValueOf(results), reflect.ValueOf(v)); err != nil {
		return err
	}
	return nil
}

// Get extract and substitute the value of the part corresponding to JSON Path from the input value.
func (p *Path) Get(src, dst interface{}) error {
	return p.path.Get(reflect.ValueOf(src), reflect.ValueOf(dst))
}