package encoding

import (

	"sync"

)

// Encoder encodes the contents of v into a byte representation.

// It's primarily used for encoding a map[string]interface{} into a file format.

type Encoder interface {

	Encode(v map[string]interface{}) ([]byte, error)

}

const (

	// ErrEncoderNotFound is returned when there is no encoder registered for a format.

	ErrEncoderNotFound = encodingError("encoder not found for this format")

	// ErrEncoderFormatAlreadyRegistered is returned when an encoder is already registered for a format.

	ErrEncoderFormatAlreadyRegistered = encodingError("encoder already registered for this format")

)

// EncoderRegistry can choose an appropriate Encoder based on the provided format.

type EncoderRegistry struct {

	encoders map[string]Encoder

	mu sync.RWMutex

}

// NewEncoderRegistry returns a new, initialized EncoderRegistry.

func NewEncoderRegistry() *EncoderRegistry {

	return &EncoderRegistry{

		encoders: make(map[string]Encoder),

	}

}

// RegisterEncoder registers an Encoder for a format.

// Registering a Encoder for an already existing format is not supported.

func (e *EncoderRegistry) RegisterEncoder(format string, enc Encoder) error {

	e.mu.Lock()

	defer e.mu.Unlock()

	if _, ok := e.encoders[format]; ok {

		return ErrEncoderFormatAlreadyRegistered

	}

	e.encoders[format] = enc

	return nil

}

func (e *EncoderRegistry) Encode(format string, v map[string]interface{}) ([]byte, error) {

	e.mu.RLock()

	encoder, ok := e.encoders[format]

	e.mu.RUnlock()

	if !ok {

		return nil, ErrEncoderNotFound

	}

	return encoder.Encode(v)

}