initial project setup

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",
+		},
+	}
+}