AusPostCode/Barcode.cs

187 lines
5.8 KiB
C#

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
namespace AusPostCode {
public class Barcode {
private readonly struct BarcodeFragment {
public EncodingFormat TypicalFormat { get; }
public int Length { get;}
public int Offset { get; }
public BarcodeFragment(EncodingFormat typicalFormat, int length, int offset) {
TypicalFormat = typicalFormat;
Length = length;
Offset = offset;
}
}
private readonly Dictionary<string, BarcodeFragment> _fragments = new Dictionary<string, BarcodeFragment> {
["FormatControlCode"] = new BarcodeFragment(EncodingFormat.N, 4, 2),
["SortingCode"] = new BarcodeFragment(EncodingFormat.N, 16, 6),
["CustomerInformation2"] = new BarcodeFragment(EncodingFormat.C, 16, 22),
["CustomerInformation3"] = new BarcodeFragment(EncodingFormat.C, 31, 22),
["ErrorCorrection"] = new BarcodeFragment(EncodingFormat.BarToDecimal, 12, - 16),
};
private enum EncodingFormat {
N,
C,
BarToDecimal,
}
private int _formatCode;
private readonly Dictionary<int, string> _formatTable = new Dictionary<int, string> {
[0] = "Null Customer Barcode",
[11] = "Standard Customer Barcode",
[52] = "Customer Business Reply Paid",
[59] = "Customer Barcode 2",
[62] = "Customer Barcode 3",
[67] = "Customer Business Reply Paid",
[72] = "International Business Reply Paid",
[77] = "International Business Reply Paid",
};
public Barcode(string code) {
Code = code;
// - check for start and end bars
if (Code.Substring(0, 2) != "13") {
Warnings.Add("Couldn't find Start Bars");
Code = $"13{Code}";
}
if (Code.Substring(Code.Length - 3, 2) != "13") {
Warnings.Add("Couldn't find End Bars");
Code = $"{Code}13";
}
// process Format Control Code
_formatCode = int.Parse(GetFragment(_fragments["FormatControlCode"]));
Console.WriteLine(Format);
// process Sorting Code Field
SortingCode = int.Parse(GetFragment(_fragments["SortingCode"]));
Console.WriteLine($"Sorting code: {SortingCode}");
// process Customer Information, if necessary
// TODO: actually do this, and get a code to test it on. also, ensure that customer codes are the right length
if (_formatCode == 59) {
Console.WriteLine("This code has a Customer Information field, but I don't know how to process that yet 0uo");
} else if (_formatCode == 62) {
Console.WriteLine("This code has a Customer Information field, but I don't know how to process that yet 0uo");
}
// process Reed-Solomon Error Correction Bars
// TODO: actually validate the barcode
Console.WriteLine(BaseConversion.FromBase(GetFragment(_fragments["ErrorCorrection"]), 64));
}
public int SortingCode { get; set; }
public int CustomerInformation { get; set; }
public string Format => _formatTable.ContainsKey(_formatCode) ? _formatTable[_formatCode] : $"Unknown ({_formatCode})";
private List<string> Warnings { get; } = new List<string>();
private string Code { get; }
private string GetFragment(BarcodeFragment fragment, bool decode = true) {
var data = Code.Substring(fragment.Offset < 0 ? Code.Length + fragment.Offset : fragment.Offset, fragment.Length);
if (!decode) {
return data;
}
// bool badData;
var chunkLength = fragment.TypicalFormat == EncodingFormat.N ? 2 : 3;
var rx = new Regex("^[0123]+$");
var sb = new StringBuilder();
if (!rx.IsMatch(data)) {
throw new ArgumentException("Input length must be a quaternary number.", nameof(data));
}
for (var i = 0; i < data.Length; i += chunkLength) {
var chunk = data.Substring(i, chunkLength);
switch (fragment.TypicalFormat) {
case EncodingFormat.N:
// format N supports the digits 0 through 9, and nothing else.
// digits 0 through 8 are stored as their ternary representations, while 9 is stored as "30".
if (chunk == "30") {
sb.Append(9);
}
else if (chunk.Contains("3")) {
// not a ternary number
throw new ArgumentException($"{chunk} is not a valid identifier for format {data.ToString()}.");
}
else {
sb.Append(BaseConversion.FromBase(chunk, 3));
}
break;
case EncodingFormat.C:
break;
case EncodingFormat.BarToDecimal:
var digitInt = BaseConversion.FromBase(chunk, 4);
sb.Insert(0, BaseConversion.ToBase(digitInt, 64));
break;
default:
throw new ArgumentOutOfRangeException(nameof(fragment.TypicalFormat), fragment.TypicalFormat, null);
}
}
return sb.ToString();
}
private static string Decode(string input, EncodingFormat format) {
// bool badData;
var chunkLength = format == EncodingFormat.N ? 2 : 3;
if (input.Length % 2 != 0) {
throw new ArgumentException($"Input length must be a multiple of {chunkLength}.", nameof(input));
}
var rx = new Regex("^[0123]+$");
if (!rx.IsMatch(input)) {
throw new ArgumentException("Input length must be a quaternary number.", nameof(input));
}
var sb = new StringBuilder();
for (var i = 0; i < input.Length; i += chunkLength) {
var chunk = input.Substring(i, chunkLength);
switch (format) {
case EncodingFormat.N:
// format N supports the digits 0 through 9, and nothing else.
// digits 0 through 8 are stored as their ternary representations, while 9 is stored as "30".
if (chunk == "30") {
sb.Append(9);
}
else if (chunk.Contains("3")) {
// not a ternary number
throw new ArgumentException($"{chunk} is not a valid identifier for format {format.ToString()}.");
}
else {
sb.Append(BaseConversion.FromBase(chunk, 3));
}
break;
case EncodingFormat.C:
break;
case EncodingFormat.BarToDecimal:
break;
default:
throw new ArgumentOutOfRangeException(nameof(format), format, null);
}
}
return sb.ToString();
}
}
}