package action

import (
	"fmt"
	"encoding/json"

	"github.com/ghodss/yaml"
	"github.com/gosuri/uitable"
)

// OutputFormat is a type for capturing supported output formats
type OutputFormat string

// TableFunc is a function that can be used to add rows to a table
type TableFunc func(tbl *uitable.Table)

const (
	Table OutputFormat = "table"
	JSON  OutputFormat = "json"
	YAML  OutputFormat = "yaml"
)

// ErrInvalidFormatType is returned when an unsupported format type is used
var ErrInvalidFormatType = fmt.Errorf("invalid format type")

// String returns the string reprsentation of the OutputFormat
func (o OutputFormat) String() string {
	return string(o)
}

// Marshal uses the specified output format to marshal out the given data. It
// does not support tabular output. For tabular output, use MarshalTable
func (o OutputFormat) Marshal(data interface{}) (byt []byte, err error) {
	switch o {
	case YAML:
		byt, err = yaml.Marshal(data)
	case JSON:
		byt, err = json.Marshal(data)
	default:
		err = ErrInvalidFormatType
	}
	return
}

// MarshalTable returns a formatted table using the given headers. Rows can be
// added to the table using the given TableFunc
func (o OutputFormat) MarshalTable(f TableFunc) ([]byte, error) {
	if o != Table {
		return nil, ErrInvalidFormatType
	}
	tbl := uitable.New()
	if f == nil {
		return []byte{}, nil
	}
	f(tbl)
	return tbl.Bytes(), nil
}

// ParseOutputFormat takes a raw string and returns the matching OutputFormat.
// If the format does not exists, ErrInvalidFormatType is returned
func ParseOutputFormat(s string) (out OutputFormat, err error) {
	switch s {
	case Table.String():
		out, err = Table, nil
	case JSON.String():
		out, err = JSON, nil
	case YAML.String():
		out, err = YAML, nil
	default:
		out, err = "", ErrInvalidFormatType
	}
	return
}