const fs = require('fs');
const csvParse = require('csv-parse/lib/sync');
const { snakeToCamelCase } = require('../utils');

const KNOWN_BASE_CLASSES = {
    303: 'InvalidDCError',
    400: 'BadRequestError',
    401: 'UnauthorizedError',
    403: 'ForbiddenError',
    404: 'NotFoundError',
    406: 'AuthKeyError',
    420: 'FloodError',
    500: 'ServerError',
    503: 'TimedOutError',
};

/**
 * Gets the corresponding class name for the given error code,
 * this either being an integer (thus base error name) or str.
 */
const getClassName = errorCode => {
    if (typeof errorCode === 'number') {
        return (
            KNOWN_BASE_CLASSES[Math.abs(errorCode)] ||
            'RPCError' + errorCode.toString().replace('-', 'Neg')
        );
    }

    return snakeToCamelCase(
        errorCode
            .replace('FIRSTNAME', 'FIRST_NAME')
            .replace('SLOWMODE', 'SLOW_MODE')
            .toLowerCase(),
        'Error'
    );
};

class TelegramError {
    constructor(codes, name, description) {
        // TODO Some errors have the same name but different integer codes
        // Should these be split into different files or doesn't really matter?
        // Telegram isn't exactly consistent with returned errors anyway.
        this.intCode = codes[0];
        this.stringCode = name;
        this.subclass = getClassName(codes[0]);
        this.subclassExists = Math.abs(codes[0]) in KNOWN_BASE_CLASSES;
        this.description = description;

        this.hasCaptures = name.includes('_X');

        if (this.hasCaptures) {
            this.name = getClassName(name.replace('_X', ''));
            this.pattern = name.replace('_X', '_(\\d+)');
            this.captureName = description.match(/{(\w+)}/)[1];
        } else {
            this.name = getClassName(name);
            this.pattern = name;
            this.captureName = null;
        }
    }
}

/**
 * Parses the input CSV file with columns (name, error codes, description)
 * and yields `Error` instances as a result.
 */
const parseErrors = function*(csvFile) {
    const f = csvParse(fs.readFileSync(csvFile, { encoding: 'utf-8' })).slice(
        1
    );

    for (let line = 0; line < f.length; line++) {
        if (f[line].length !== 3) {
            throw new Error(
                `Columns count mismatch, unquoted comma in desc? (line ${line +
                    2})`
            );
        }

        let [name, codes, description] = f[line];

        codes =
            codes === ''
                ? [400]
                : codes.split(' ').map(x => {
                      if (isNaN(x)) {
                          throw new Error(
                              `Not all codes are integers (line ${line + 2})`
                          );
                      }

                      return Number(x);
                  });

        yield new TelegramError(codes, name, description);
    }
};

module.exports = {
    KNOWN_BASE_CLASSES,
    TelegramError,
    parseErrors,
};