package main

import (
  "fmt"
  "net/http"
  "flag"
  "log"
  "os"
  "io"
  "path/filepath"
)

func main() {
  var save bool
  var headers bool

  flag.BoolVar(&save, "O", false, "output file to local disk")
  flag.BoolVar(&headers, "I", false, "inspect headers")
  flag.Parse()

  if flag.NArg() == 0 { log.Fatal("USAGE: curl [-O] [-I] URL") }

  target_url := flag.Args()[0]

  resp, err := http.Get(target_url)
  if err != nil { log.Fatal(err) }

  if headers {
    for key, values := range resp.Header {
      for _, val := range values {
        fmt.Printf("%s: %s\n", key, val)
      }
    }
  } else if save {
    output := filepath.Base(resp.Request.URL.Path)

    out, err := os.Create(output)
    if err != nil { log.Fatal(err) }

    io.Copy(out, resp.Body)
  } else {
    io.Copy(os.Stdout, resp.Body)
  }
}