Add some(what) working code and some documentation

Initial commit.

Successfully pulls a message from an inbox that actually contains a
message.

Not perfect; there's some duplication which could be simplified, and
there's the issue of panics when there are no messages available.

But it's late, and I'm off to sleep now. Good night.

README.md

@@ -0,0 +1,37 @@
+# go-mailin8
+
+Display the latest mail from a temporary Mailinator email address, at
+the command line.
+
+Useful for getting confirmation emails for throwaway purposes, or for
+testing.
+
+This is a version of a [bash script I
+made](https://gist.github.com/StevenMaude/914e9187c09027866fe88958798acb7e)
+that uses [jq](https://stedolan.github.io/jq/). However, this Go version
+requires no other dependencies.
+
+## Build
+
+`go build`
+
+## Usage
+
+1. Send, or get an email sent to a Mailinator email address of your
+   choosing.
+2. Note the local-part (the part before @, e.g.
+   `[email protected]`).
+3. Run `go-mailin8 <local-part of email address>`
+
+## Notes
+
+NB: you may get unpredictable results from the server if you run this
+too often in a short time. See TODO.
+
+## TODO:
+
+* Fix panics on no messages.
+* Consider introducing slight pauses between requests to try and
+  improve reliability.
+* Possibly consider selecting other than latest message (though outside
+  of my original use case).

main.go

@@ -0,0 +1,165 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+)
+
+/* Full mail struct for posterity; generated from https://mholt.github.io/json-to-go/
+type AutoGenerated struct {
+	Data struct {
+		Fromfull string `json:"fromfull"`
+		Headers struct {
+			MimeVersion string `json:"mime-version"`
+			Date string `json:"date"`
+			Subject string `json:"subject"`
+			XSgEid string `json:"x-sg-eid"`
+			MessageID string `json:"message-id"`
+			Received string `json:"received"`
+			From string `json:"from"`
+			ContentType string `json:"content-type"`
+			To string `json:"to"`
+			DkimSignature string `json:"dkim-signature"`
+		} `json:"headers"`
+		Subject string `json:"subject"`
+		RequestID string `json:"requestId"`
+		Parts []struct {
+			Headers struct {
+				ContentTransferEncoding string `json:"content-transfer-encoding"`
+				ContentType string `json:"content-type"`
+			} `json:"headers"`
+			Body string `json:"body"`
+		} `json:"parts"`
+		From string `json:"from"`
+		Origfrom string `json:"origfrom"`
+		To string `json:"to"`
+		ID string `json:"id"`
+		Time int64 `json:"time"`
+		SecondsAgo int `json:"seconds_ago"`
+	} `json:"data"`
+} */
+
+type mail struct {
+	Data struct {
+		Subject string `json:"subject"`
+		Parts   []struct {
+			Body string `json:"body"`
+		} `json:"parts"`
+		From string `json:"from"`
+	} `json:"data"`
+}
+
+// TODO: consider dropping most of this. Can get from the message itself.
+type mailboxDetails struct {
+	PublicMsgs []struct {
+		FromFull string `json:"fromfull"`
+		Subject  string `json:"subject"`
+		ID       string `json:"id"`
+		To       string `json:"to"`
+	} `json:"public_msgs"`
+}
+
+func getMailboxDetails(localPart string) (mailboxDetails, error) {
+	webInboxURL := "https://www.mailinator.com/api/webinbox2?x=0&public_to=" + localPart
+	fmt.Println("Retrieving URL:", webInboxURL)
+
+	mbxDetails := mailboxDetails{}
+	resp, err := http.Get(webInboxURL)
+	if err != nil {
+		return mbxDetails, err
+	}
+
+	defer resp.Body.Close()
+	err = json.NewDecoder(resp.Body).Decode(&mbxDetails)
+	if err != nil {
+		return mbxDetails, err
+	}
+	return mbxDetails, err
+}
+
+func getCookies(mbxDetails mailboxDetails) ([]*http.Cookie, error) {
+	// TODO: consider allow to retrieve more than one message.
+	// TODO: fix panic on no messages.
+	// TODO: just pass in the single message; avoid duplication?
+	// TODO: confirm that first item is the latest message (but I think
+	// it is from previous testing of the bash script).
+	latestMsg := mbxDetails.PublicMsgs[0]
+
+	// This request is for nothing but getting required cookies.
+	// Otherwise, the subsequent request fails.
+	inboxURL := "https://www.mailinator.com/inbox2.jsp?public_to=" + latestMsg.To
+	fmt.Println("Retrieving URL:", inboxURL)
+
+	inboxResp, err := http.Get(inboxURL)
+	defer inboxResp.Body.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	cookies := inboxResp.Cookies()
+	return cookies, err
+}
+
+func getMail(mbxDetails mailboxDetails, cookies []*http.Cookie) error {
+	// TODO: consider allow to retrieve more than one message.
+	// TODO: fix panic on no messages.
+	// TODO: just pass in the single message; avoid duplication?
+	// TODO: confirm that first item is the latest message (but I think
+	// it is from previous testing of the bash script).
+	latestMsg := mbxDetails.PublicMsgs[0]
+
+	msgURL := "https://www.mailinator.com/fetchmail?msgid=" + latestMsg.ID + "&zone=public"
+	fmt.Println("Retrieving URL:", msgURL)
+	req, err := http.NewRequest("GET", msgURL, nil)
+
+	for _, c := range cookies {
+		req.AddCookie(c)
+	}
+
+	client := &http.Client{}
+
+	mailResp, err := client.Do(req)
+	defer mailResp.Body.Close()
+	if err != nil {
+		return err
+	}
+
+	mailMessage := mail{}
+	err = json.NewDecoder(mailResp.Body).Decode(&mailMessage)
+	if err != nil {
+		return err
+	}
+
+	fmt.Println("\nFrom   :", mailMessage.Data.From)
+	fmt.Println("Subject:", mailMessage.Data.Subject)
+	fmt.Println("\n", mailMessage.Data.Parts[0].Body)
+	return nil
+}
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Println("Usage: mailin8 <local-part>")
+		os.Exit(1)
+	}
+
+	localPart := os.Args[1]
+	mbxDetails, err := getMailboxDetails(localPart)
+	if err != nil {
+		fmt.Println("failed to get message ID:", err)
+		os.Exit(1)
+	}
+
+	cookies, err := getCookies(mbxDetails)
+	if err != nil {
+		fmt.Println("failed to get cookies:", err)
+		os.Exit(1)
+	}
+
+	err = getMail(mbxDetails, cookies)
+	if err != nil {
+		fmt.Println("failed to get mail:", err)
+		os.Exit(1)
+	}
+}