package main

import (
	"bufio"
	"bytes"
	"encoding/json"
	"io"
	"log"
	"mime"
	"net/http"
	"os"
	"strings"

	"github.com/emersion/go-message/mail"
)

type Mail struct {
	From    string
	Date    string
	ReplyTo string
	Body    string
	Parts   map[string]string
}

func makeReq(j []byte) {
	req, err := http.NewRequest("POST", "http://localhost:8001/webhook", bytes.NewBuffer(j))
	req.Header.Set("Content-Type", "application/json")
	client := http.Client{}
	res, err := client.Do(req)
	if err != nil {
		log.Fatal(err)
	}
	defer res.Body.Close()
}

// Decodes a RFC 2047 encoded word.
func decode(s string) (string, error) {
	dec := mime.WordDecoder{}
	header, err := dec.DecodeHeader(s)
	if err != nil {
		return "", err
	}

	return header, nil
}

func main() {
	f, err := os.OpenFile("mdawh.log", os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	log.SetOutput(f)

	r := bufio.NewReader(os.Stdin)
	mr, err := mail.CreateReader(r)

	m := Mail{}
	m.Date = mr.Header.Get("Date")
	from, err := decode(mr.Header.Get("From"))
	if err != nil {
		m.From = mr.Header.Get("From")
	} else {
		m.From = from
	}
	m.ReplyTo = mr.Header.Get("Reply-To")

	if err != nil {
		log.Fatal(err)
	}

	parts := make(map[string]string)
	for {
		p, err := mr.NextPart()
		if err == io.EOF {
			break
		} else if err != nil {
			log.Fatal(err)
		}
		switch h := p.Header.(type) {
		case *mail.InlineHeader:
			ct := strings.Split(p.Header.Get("Content-Type"), ";")[0]
			// We didn't find any Content-Type header.
			b, _ := io.ReadAll(p.Body)
			if len(ct) == 0 {
				m.Body = string(b)
			} else {
				parts[ct] = string(b)
				m.Parts = parts
			}

		case *mail.AttachmentHeader:
			filename, _ := h.Filename()
			log.Printf("got attachment: %v\n", filename)
		}
	}

	j, err := json.Marshal(m)
	if err != nil {
		log.Fatal(err)
	}
	makeReq(j)
	log.Printf("sent webhook: %v\n", m.From)
}