gol4ng/logger

package provider

import (
    "fmt"
    "io"
    "os"
    "time"

    "github.com/gol4ng/logger/writer"
)

// TimeFileProvider provide a new file (io.Writer) having named with a given filename format
// ex: `provider.TimeFileProvider("fake_format_%s", "2006-01-02")` will create a file named "fake_format_2019-08-17" (i.e fake_format_<ISO_8601_DATE>)
func TimeFileProvider(fileNameFormat string, timeFormat string) writer.Provider {
    return func(w io.Writer) (io.Writer, error) {
        // if the provider already have an open io.writer when it is called, close it
        // (i.e: close current file and create a new one)
        if w != nil {
            if _w, ok := w.(io.Closer); ok {
                if err := _w.Close(); err != nil {
                    return nil, err
                }
            }
        }
        // create a file (io.Writer) having the given filename format
        return os.OpenFile(
            fmt.Sprintf(fileNameFormat, time.Now().Format(timeFormat)),
            os.O_CREATE|os.O_APPEND|os.O_WRONLY,
            0666,
        )
    }
}