logFmt.bal

import ballerina/io;
import ballerina/jballerina.java;

public function main() {

    LogRecord logRecord = {
        time: "2021-05-04T10:32:13.220+05:30",
        level: "DEBUG",
        module: "foo/bar",
        message: "debug \n message",
        "username": "Alex",
        "id": 845315
    };
    string logMessage = printLogFmtExtern(logRecord);
    io:println(logMessage);

}

type LogRecord record {
    string time;
    string level;
    string module;
    string message;
};

isolated function printLogFmtExtern(LogRecord logRecord) returns string {
    string message = "";
    foreach [string, anydata] [k, v] in logRecord.entries() {
        string value;
        match k {
            "time"|"level" => {
                value = v.toString();
            }
            "module" => {
                value = v.toString();
                if value == "" {
                    value = string `\"${value}\"`;
                }
            }
            _ => {
                if v is string {
                    value = string `${escape(v.toString())}`;
                } else {
                    value = v.toString();
                }
            }
        }

        if message == "" {
            message = message + string `${k} = ${value}`;
        } else {
            message = message + string ` ${k} = ${value}`;
        }
    }
    return message;
}


isolated function escape(string msg) returns string {
    // return regex:replaceAll(msg, "\n", "\\n");
    handle temp = escapseExternal(java:fromString(msg), java:fromString("\n"), java:fromString("\\n"));
    io:println(temp);
    string? updatedString = java:toString(temp);
    if (updatedString is string) {
        return updatedString.toBalString();
    } else {
        // Should never reach here.
        error e = error(string `error occurred while replacing`);
        panic e;
    }
}

// public isolated function replaceAll(string originalString, string regex, string replacement) returns string {
//     handle value = replaceAllExternal(java:fromString(originalString), java:fromString(regex),
//                                       java:fromString(replacement));
//     io:println(value);
//     string? updatedString = java:toString(value);
//     if (updatedString is string) {
//         return updatedString;
//     } else {
//         // Should never reach here.
//         error e = error(string `error occurred while replacing ${regex} in ${originalString}`);
//         panic e;
//     }
// }

// isolated function replaceAllExternal(handle originalString, handle regex, handle replacement) returns handle = @java:Method {
//     name: "replaceAll",
//     'class: "java.lang.String",
//     paramTypes: ["java.lang.String", "java.lang.String"]
// } external;

public isolated function escapseExternal(handle receiver, handle target, handle replacement) returns handle = @java:Method {
    'class: "java.lang.String",
    name: "replace"
} external;