First commit

.gitignore

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+.DS_Store
+*.env
+books

Dockerfile

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+# Stage 1: Build
+FROM golang:1.24-alpine AS builder
+
+WORKDIR /app
+
+# Install dependencies for CGO + SQLite
+RUN apk add --no-cache gcc musl-dev sqlite-dev
+
+COPY go.mod ./
+COPY go.sum ./
+RUN go mod download
+
+COPY . ./
+RUN go build -o kindle-sender
+
+# Stage 2: Run
+FROM alpine:latest
+
+WORKDIR /app
+
+COPY --from=builder /app/kindle-sender .
+
+# Required for sending mail (ca-certificates)
+RUN apk add --no-cache ca-certificates
+
+ENV WATCH_DIR=/books
+
+VOLUME ["/books"]
+
+CMD ["./kindle-sender"]

go.mod

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+module github.com/ramatevish/kindle-sender
+
+go 1.24.3
+
+require (
+	github.com/jinzhu/inflection v1.0.0 // indirect
+	github.com/jinzhu/now v1.1.5 // indirect
+	github.com/mattn/go-sqlite3 v1.14.28 // indirect
+	golang.org/x/sys v0.13.0 // indirect
+	golang.org/x/text v0.20.0 // indirect
+	gorm.io/driver/sqlite v1.5.7 // indirect
+	gorm.io/gorm v1.30.0 // indirect
+)

go.sum

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+github.com/jinzhu/inflection v1.0.0 h1:K317FqzuhWc8YvSVlFMCCUb36O/S9MCKRDI7QkRKD/E=
+github.com/jinzhu/inflection v1.0.0/go.mod h1:h+uFLlag+Qp1Va5pdKtLDYj+kHp5pxUVkryuEj+Srlc=
+github.com/jinzhu/now v1.1.5 h1:/o9tlHleP7gOFmsnYNz3RGnqzefHA47wQpKrrdTIwXQ=
+github.com/jinzhu/now v1.1.5/go.mod h1:d3SSVoowX0Lcu0IBviAWJpolVfI5UJVZZ7cO71lE/z8=
+github.com/mattn/go-sqlite3 v1.14.28 h1:ThEiQrnbtumT+QMknw63Befp/ce/nUPgBPMlRFEum7A=
+github.com/mattn/go-sqlite3 v1.14.28/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
+golang.org/x/sys v0.13.0 h1:Af8nKPmuFypiUBjVoU9V20FiaFXOcuZI21p0ycVYYGE=
+golang.org/x/sys v0.13.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/text v0.20.0 h1:gK/Kv2otX8gz+wn7Rmb3vT96ZwuoxnQlY+HlJVj7Qug=
+golang.org/x/text v0.20.0/go.mod h1:D4IsuqiFMhST5bX19pQ9ikHC2GsaKyk/oF+pn3ducp4=
+gorm.io/driver/sqlite v1.5.7 h1:8NvsrhP0ifM7LX9G4zPB97NwovUakUxc+2V2uuf3Z1I=
+gorm.io/driver/sqlite v1.5.7/go.mod h1:U+J8craQU6Fzkcvu8oLeAQmi50TkwPEhHDEjQZXDah4=
+gorm.io/gorm v1.30.0 h1:qbT5aPv1UH8gI99OsRlvDToLxW5zR7FzS9acZDOZcgs=
+gorm.io/gorm v1.30.0/go.mod h1:8Z33v652h4//uMA76KjeDH8mJXPm1QNCYrMeatR0DOE=

main.go

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+package main
+
+import (
+	"bytes"
+	"crypto/md5"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"io"
+	"log"
+	"mime/multipart"
+	"mime/quotedprintable"
+	"net/smtp"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+var (
+	smtpHost     = os.Getenv("SMTP_HOST")
+	smtpPort     = os.Getenv("SMTP_PORT")
+	smtpUser     = os.Getenv("SMTP_USER")
+	smtpPassword = os.Getenv("SMTP_PASSWORD")
+	senderEmail  = os.Getenv("SENDER_EMAIL")
+	recipient    = os.Getenv("RECIPIENT_EMAIL")
+	watchDir     = os.Getenv("WATCH_DIR")
+	db           *gorm.DB
+)
+
+type SentFile struct {
+	ID     uint      `gorm:"primaryKey"`
+	Path   string
+	Hash   string    `gorm:"uniqueIndex"`
+	SentAt time.Time
+}
+
+func isEbookFile(name string) bool {
+	lower := strings.ToLower(name)
+	return strings.HasSuffix(lower, ".mobi") || strings.HasSuffix(lower, ".epub") ||
+		strings.HasSuffix(lower, ".pdf") || strings.HasSuffix(lower, ".azw3")
+}
+
+func sendEmailWithAttachment(filePath string) error {
+	data, err := os.ReadFile(filePath)
+	if err != nil {
+		return fmt.Errorf("failed to read file: %w", err)
+	}
+
+	var buf bytes.Buffer
+	writer := multipart.NewWriter(&buf)
+
+	header := map[string]string{
+		"From":         senderEmail,
+		"To":           recipient,
+		"Subject":      "Ebook Delivery",
+		"MIME-Version": "1.0",
+		"Content-Type": "multipart/mixed; boundary=\"" + writer.Boundary() + "\"",
+	}
+
+	for k, v := range header {
+		fmt.Fprintf(&buf, "%s: %s\r\n", k, v)
+	}
+	fmt.Fprint(&buf, "\r\n")
+
+	textPart, _ := writer.CreatePart(map[string][]string{
+		"Content-Type":              {"text/plain; charset=utf-8"},
+		"Content-Transfer-Encoding": {"quoted-printable"},
+	})
+	qp := quotedprintable.NewWriter(textPart)
+	qp.Write([]byte("Attached is your ebook."))
+	qp.Close()
+
+	attachmentHeader := map[string][]string{
+		"Content-Type":              {"application/octet-stream"},
+		"Content-Transfer-Encoding": {"base64"},
+		"Content-Disposition":       {fmt.Sprintf("attachment; filename=\"%s\"", filepath.Base(filePath))},
+	}
+	attachmentPart, _ := writer.CreatePart(attachmentHeader)
+	encoded := make([]byte, base64.StdEncoding.EncodedLen(len(data)))
+	base64.StdEncoding.Encode(encoded, data)
+	attachmentPart.Write(encoded)
+
+	writer.Close()
+
+	auth := smtp.PlainAuth("", smtpUser, smtpPassword, smtpHost)
+	return smtp.SendMail(smtpHost+":"+smtpPort, auth, senderEmail, []string{recipient}, buf.Bytes())
+}
+
+func fileHash(path string) (string, error) {
+	f, err := os.Open(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+
+	h := md5.New()
+	if _, err := io.Copy(h, f); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(h.Sum(nil)), nil
+}
+
+func hasBeenSent(hash string) bool {
+	var file SentFile
+	err := db.Where("hash = ?", hash).First(&file).Error
+	return err == nil
+}
+
+func markAsSent(filePath, hash string) {
+	err := db.Create(&SentFile{
+		Path:   filePath,
+		Hash:   hash,
+		SentAt: time.Now().UTC(),
+	}).Error
+	if err != nil {
+		log.Printf("DB error marking file as sent: %v", err)
+	}
+}
+
+func setupDatabase() error {
+	dbPath := filepath.Join(watchDir, "sent_files.db")
+	database, err := gorm.Open(sqlite.Open(dbPath), &gorm.Config{})
+	if err != nil {
+		return err
+	}
+	db = database
+	return db.AutoMigrate(&SentFile{})
+}
+
+func scanAndSendEbooks() {
+	err := filepath.Walk(watchDir, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() || !isEbookFile(info.Name()) {
+			return nil
+		}
+		hash, err := fileHash(path)
+		if err != nil {
+			log.Printf("Error hashing file %s: %v", path, err)
+			return nil
+		}
+		if hasBeenSent(hash) {
+			log.Printf("Already sent (hash match): %s\n", path)
+			return nil
+		}
+		log.Printf("Detected ebook file: %s\n", path)
+		time.Sleep(1 * time.Second)
+		if err := sendEmailWithAttachment(path); err != nil {
+			log.Printf("Error sending email: %v\n", err)
+		} else {
+			markAsSent(path, hash)
+			log.Printf("Sent %s to %s\n", path, recipient)
+		}
+		return nil
+	})
+	if err != nil {
+		log.Printf("Error walking directory: %v\n", err)
+	}
+}
+
+func main() {
+	if watchDir == "" {
+		log.Fatal("WATCH_DIR environment variable is required")
+	}
+
+	if err := setupDatabase(); err != nil {
+		log.Fatalf("Failed to setup database: %v", err)
+	}
+
+	log.Printf("Scanning folder: %s\n", watchDir)
+	for {
+		scanAndSendEbooks()
+		time.Sleep(10 * time.Second)
+	}
+}