initial project setup

.gitignore

@@ -0,0 +1,40 @@
+# Binaries
+/arcline-email
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Output of `go env GOPATH`
+/go/
+
+# Dependency vendor directory
+vendor/
+
+# Go workspace
+go.work
+go.work.sum
+
+# Environment / secrets
+*.env
+.env*
+*.pem
+*.key
+
+# Config (use arcline-email.example.toml as template)
+arcline-email.toml
+
+# Editor
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# OS
+.DS_Store
+Thumbs.db

arcline-email.example.toml

@@ -0,0 +1,25 @@
+# arcline-email configuration
+# Copy to arcline-email.toml and adjust for your environment.
+
+[server]
+hostname = "mail.example.com"
+
+[smtp]
+inbound_addr       = ":25"
+submission_addr    = ":587"
+submission_tls_addr = ":465"
+
+[imap]
+addr     = ":143"
+tls_addr = ":993"
+
+[tls]
+cert_file = "/etc/arcline-email/cert.pem"
+key_file  = "/etc/arcline-email/key.pem"
+
+[storage]
+maildir_root = "/var/mail"
+
+[logging]
+level  = "info"   # debug | info | warn | error
+format = "json"   # json | text

cmd/arcline-email/main.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"context"
+	"flag"
+	"log/slog"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"arcline-email/config"
+)
+
+func main() {
+	cfgPath := flag.String("config", "arcline-email.toml", "path to config file")
+	flag.Parse()
+
+	cfg, err := config.Load(*cfgPath)
+	if err != nil {
+		slog.Error("failed to load config", "err", err)
+		os.Exit(1)
+	}
+
+	logger := newLogger(cfg.Logging)
+	slog.SetDefault(logger)
+
+	slog.Info("arcline-email starting", "hostname", cfg.Server.Hostname)
+
+	// TODO: initialize and start servers (SMTP, IMAP)
+
+	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
+	defer stop()
+
+	<-ctx.Done()
+	slog.Info("shutdown signal received")
+	stop() // release signal resources before shutdown
+
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	// TODO: call server.Shutdown(shutdownCtx) for each listener
+	_ = shutdownCtx
+
+	slog.Info("shutdown complete")
+}
+
+func newLogger(cfg config.LoggingConfig) *slog.Logger {
+	var level slog.Level
+	if err := level.UnmarshalText([]byte(cfg.Level)); err != nil {
+		level = slog.LevelInfo
+	}
+
+	opts := &slog.HandlerOptions{Level: level}
+
+	if cfg.Format == "text" {
+		return slog.New(slog.NewTextHandler(os.Stdout, opts))
+	}
+	return slog.New(slog.NewJSONHandler(os.Stdout, opts))
+}

config/config.go

@@ -0,0 +1,78 @@
+package config
+
+import (
+	"fmt"
+
+	"github.com/BurntSushi/toml"
+)
+
+type Config struct {
+	Server  ServerConfig  `toml:"server"`
+	SMTP    SMTPConfig    `toml:"smtp"`
+	IMAP    IMAPConfig    `toml:"imap"`
+	TLS     TLSConfig     `toml:"tls"`
+	Storage StorageConfig `toml:"storage"`
+	Logging LoggingConfig `toml:"logging"`
+}
+
+type ServerConfig struct {
+	Hostname string `toml:"hostname"`
+}
+
+type SMTPConfig struct {
+	InboundAddr       string `toml:"inbound_addr"`
+	SubmissionAddr    string `toml:"submission_addr"`
+	SubmissionTLSAddr string `toml:"submission_tls_addr"`
+}
+
+type IMAPConfig struct {
+	Addr    string `toml:"addr"`
+	TLSAddr string `toml:"tls_addr"`
+}
+
+type TLSConfig struct {
+	CertFile string `toml:"cert_file"`
+	KeyFile  string `toml:"key_file"`
+}
+
+type StorageConfig struct {
+	MaildirRoot string `toml:"maildir_root"`
+}
+
+type LoggingConfig struct {
+	Level  string `toml:"level"`  // debug, info, warn, error
+	Format string `toml:"format"` // json, text
+}
+
+// Load reads the TOML config file at path, applying defaults for any missing fields.
+func Load(path string) (*Config, error) {
+	cfg := defaults()
+	if _, err := toml.DecodeFile(path, cfg); err != nil {
+		return nil, fmt.Errorf("decode %s: %w", path, err)
+	}
+	return cfg, nil
+}
+
+func defaults() *Config {
+	return &Config{
+		Server: ServerConfig{
+			Hostname: "localhost",
+		},
+		SMTP: SMTPConfig{
+			InboundAddr:       ":25",
+			SubmissionAddr:    ":587",
+			SubmissionTLSAddr: ":465",
+		},
+		IMAP: IMAPConfig{
+			Addr:    ":143",
+			TLSAddr: ":993",
+		},
+		Storage: StorageConfig{
+			MaildirRoot: "/var/mail",
+		},
+		Logging: LoggingConfig{
+			Level:  "info",
+			Format: "json",
+		},
+	}
+}

go.mod

@@ -0,0 +1,5 @@
+module arcline-email
+
+go 1.25.8
+
+require github.com/BurntSushi/toml v1.6.0 // indirect

go.sum

@@ -0,0 +1,2 @@
+github.com/BurntSushi/toml v1.6.0 h1:dRaEfpa2VI55EwlIW72hMRHdWouJeRF7TPYhI+AUQjk=
+github.com/BurntSushi/toml v1.6.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=

todo.md

@@ -3,12 +3,12 @@
 ## Phase 1: MVP (Core Mail Flow)
 
 ### Project Setup
-- [ ] Initialize Go module (`go mod init arcline-email`)
+- [x] Initialize Go module (`go mod init arcline-email`)
-- [ ] Set up directory structure (`cmd/`, `internal/`, `config/`)
+- [x] Set up directory structure (`cmd/`, `internal/`, `config/`)
-- [ ] Add `.gitignore`
+- [x] Add `.gitignore`
-- [ ] Wire up config parsing (TOML)
+- [x] Wire up config parsing (TOML)
-- [ ] Structured logging (`log/slog`)
+- [x] Structured logging (`log/slog`)
-- [ ] Graceful shutdown (signal handling)
+- [x] Graceful shutdown (signal handling)
 
 ### SMTP — Inbound (Port 25)
 - [ ] Basic SMTP listener using `emersion/go-smtp`