class GCodeParser {

    static normalizeInput(raw) {
        if (raw === undefined || raw === null) {
            return '';
        }

        if (Buffer.isBuffer(raw)) {
            raw = raw.toString('utf8');
        }

        return String(raw).trim();
    }

    static splitCommands(input) {
        if (!input) {
            return [];
        }

        // Preserve leading G/M on each segment.
        return input
            .trim()
            .split(/ (?=G|M)/i)
            .map(segment => segment.trim())
            .filter(Boolean);
    }

    static parseCommand(commandString) {
        if (!commandString || commandString.length === 0) {
            return null;
        }

        const tokens = commandString.trim().split(/\s+/);
        if (tokens.length === 0) {
            return null;
        }

        const commandToken = tokens[0].toUpperCase();
        if (!/^[GM]\d+/i.test(commandToken)) {
            return null;
        }

        const params = {};
        for (let i = 1; i < tokens.length; i++) {
            const token = tokens[i].trim();
            if (token.length === 0) {
                continue;
            }
            if (token.length === 1) {
                // Einzelner Buchstabe = Flag ohne Zahlenwert (z. B. 'R' in 'M114 R').
                if (/^[A-Za-z]$/.test(token)) {
                    params[token.toUpperCase()] = true;
                }
                continue;
            }

            const key = token.charAt(0).toUpperCase();
            const valueString = token.substring(1);
            const value = Number(valueString);
            if (!Number.isNaN(value)) {
                params[key] = value;
            }
        }

        return {
            command: commandToken,
            params,
            raw: commandString.trim()
        };
    }

    static parse(raw) {
        const input = this.normalizeInput(raw);
        if (!input) {
            return [];
        }

        if (input.startsWith('$J=')) {
            return this.parse(input.substring(3).trim());
        }

        const commands = this.splitCommands(input)
            .map(commandString => this.parseCommand(commandString))
            .filter(Boolean);

        return commands;
    }
}

module.exports = GCodeParser;