/**
 * Copyright 2019 indece UG (haftungsbeschränkt)
 **/

package ebcdic

import (
	"errors"
)

const mapLength = 0xFF

// Encode encodes an unicode string to an EBCDIC byte array
func Encode(unicodeStr string, codePage int) ([]byte, error) {
	ebcdicMap, ok := mapsUnicodeToEBCDIC[codePage]
	if !ok {
		return nil, errors.New("Unknown code page")
	}

	runes := []rune(unicodeStr)

	ebcdic := make([]byte, len(runes))

	for i, r := range runes {
		switch {
		case ebcdicMap.HasEuroPatch && r == '€':
			// Apply EURO-Patch (character outside of mapLength)
			ebcdic[i] = ebcdicMap.EuroChar
			break
		case r <= mapLength:
			ebcdic[i] = ebcdicMap.Map[r]
			break
		default:
			// If outside of map, replace with 0x00
			ebcdic[i] = 0x00
			break
		}
	}

	return ebcdic, nil
}

// Decode decodes an EBCDIC byte array to an unicode string
func Decode(ebcdic []byte, codePage int) (string, error) {
	ebcdicMap, ok := mapsEBCDICToUnicode[codePage]
	if !ok {
		return "", errors.New("Unknown code page")
	}

	buf := make([]rune, len(ebcdic))

	for i, b := range ebcdic {
		if ebcdicMap.HasEuroPatch && b == ebcdicMap.EuroChar {
			// Apply Euro-Patch
			buf[i] = '€'
		} else {
			buf[i] = ebcdicMap.Map[b]
		}
	}

	return string(buf), nil
}