otiai10/opengraph

package main

import (
    "encoding/json"
    "flag"
    "fmt"
    "net/url"
    "os"

    "github.com/otiai10/opengraph/v2"
)

func main() {
    flagset := flag.CommandLine
    flagset.Usage = func() {
        fmt.Println("Fetch URL and extract OpenGraph meta informations.")
    }
    abs := flagset.Bool("A", false, "populate relative URLs to absolute URLs")
    flagset.Parse(os.Args[1:])
    if err := run(flagset.Args(), *abs); err != nil {
        fmt.Println("Error:", err.Error())
        os.Exit(1)
    }
}

func run(args []string, absolute bool) error {
    if len(args) == 0 {
        return fmt.Errorf("URL must be specified")
    }
    rawurl := args[0]
    u, err := url.Parse(rawurl)
    if err != nil {
        return err
    }
    if u.Scheme == "" {
        u.Scheme = "https"
    }
    og := opengraph.New(u.String())
    if err := og.Fetch(); err != nil {
        return err
    }
    if absolute {
        if err := og.ToAbs(); err != nil {
            return err
        }
    }
    b, err := json.MarshalIndent(og, "", "\t")
    if err != nil {
        return err
    }
    fmt.Printf("%+v\n", string(b))
    return nil
}