// Author:  cirakg & claude ai
// Summary: Codabar encoder: start and stop characters A-D (added as A...A when missing), wide bars 2 modules (as zxing).

import Toybox.Lang;

module Codabar {

    const ALPHABET = "0123456789-$:/.+ABCD"; // lint: allow-literal (Codabar character set)
    // Seven elements per character, first element = bit 6, 1 = wide.
    const PATTERNS = [0x003, 0x006, 0x009, 0x060, 0x012, 0x042, 0x021, 0x024, 0x030, 0x048,
        0x00C, 0x018, 0x045, 0x051, 0x054, 0x015, 0x01A, 0x029, 0x00B, 0x00E];
    const FIRST_GUARD = 16; // index of 'A'

    function encode(text as String) as Codes.LinearCode or Codes.CodeError {
        var upper = text.toUpper();
        var chars = upper.toCharArray();
        if (chars.size() == 0) {
            return new Codes.CodeError("Codabar needs some digits");
        }
        var startsGuarded = isGuard(chars[0]);
        var endsGuarded = chars.size() > 1 && isGuard(chars[chars.size() - 1]);
        var note = null;
        if (startsGuarded != endsGuarded) {
            return new Codes.CodeError("Codabar: use start and stop characters (A-D) at both ends or at neither");
        }
        if (!startsGuarded) {
            upper = "A" + upper + "A";
            chars = upper.toCharArray();
            note = "start and stop characters A...A added";
        }
        var m = []b;
        for (var i = 0; i < chars.size(); i++) {
            var v = ALPHABET.find(chars[i].toString());
            var inner = i > 0 && i < chars.size() - 1;
            if (v == null || (inner && v >= FIRST_GUARD)) {
                return new Codes.CodeError("Codabar: '" + chars[i] + "' isn't allowed there (0-9 - $ : / . + between A-D)");
            }
            if (i > 0) {
                m.add(0); // narrow gap
            }
            var pattern = PATTERNS[v] as Number;
            for (var k = 6; k >= 0; k--) {
                var width = ((pattern >> k) & 1) == 1 ? 2 : 1;
                for (var w = 0; w < width; w++) {
                    m.add((6 - k) % 2 == 0 ? 1 : 0);
                }
            }
        }
        m.add(0); // zxing also ends with a narrow gap (inside the quiet zone)
        var code = new Codes.LinearCode(m, upper);
        code.note = note;
        return code;
    }

    function isGuard(c as Char) as Boolean {
        return c >= 'A' && c <= 'D';
    }
}