Initial commit

internal/config/config.go

@@ -0,0 +1,169 @@
+// @tag config
+// @tag core
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"os"
+	"strconv"
+	"time"
+
+	"github.com/eleksir/pekoe/internal/logger"
+)
+
+// Constants for default values - chosen to be production-ready defaults
+const (
+	DefaultBind         = "0.0.0.0"
+	DefaultPort         = 6379
+	DefaultMaxClients   = 10000
+	DefaultReadTimeout  = 0                 // 0 means no timeout (blocking I/O)
+	DefaultWriteTimeout = 0                 // 0 means no timeout
+	DefaultMaxMsgBytes  = 512 * 1024 * 1024 // 512 MB - allows large messages
+	DefaultLogLevel     = "info"
+	DefaultLogFile      = "" // empty = stdout only
+	DefaultPidFile      = "" // empty = no PID file created
+)
+
+type Config struct {
+	Bind         string `json:"bind"`
+	Port         int    `json:"port"`
+	MaxClients   int    `json:"max_clients"`
+	ReadTimeout  int    `json:"read_timeout"`  // in seconds, 0 = no timeout
+	WriteTimeout int    `json:"write_timeout"` // in seconds, 0 = no timeout
+	MaxMsgBytes  int    `json:"max_message_bytes"`
+	LogLevel     string `json:"log_level"`
+	LogFile      string `json:"log_file"` // empty = stdout only
+	PidFile      string `json:"pid_file"` // empty = no PID file
+}
+
+// SetDefaults applies sensible defaults when config values are missing or invalid.
+// This ensures the server can start even with incomplete configuration.
+// nolint: cyclop
+func (c *Config) SetDefaults() {
+	if c.Bind == "" {
+		c.Bind = DefaultBind
+	}
+	if c.Port <= 0 || c.Port > 65535 {
+		c.Port = DefaultPort
+	}
+	if c.MaxClients <= 0 {
+		c.MaxClients = DefaultMaxClients
+	}
+	if c.ReadTimeout < 0 {
+		c.ReadTimeout = 0
+	}
+	if c.WriteTimeout < 0 {
+		c.WriteTimeout = 0
+	}
+	if c.MaxMsgBytes <= 0 {
+		c.MaxMsgBytes = DefaultMaxMsgBytes
+	}
+	if c.LogLevel == "" {
+		c.LogLevel = DefaultLogLevel
+	}
+	if c.LogFile == "" {
+		c.LogFile = DefaultLogFile
+	}
+	if c.PidFile == "" {
+		c.PidFile = DefaultPidFile
+	}
+}
+
+// Validate checks that all configuration values are within acceptable bounds.
+// Returns an error if validation fails, which should prevent server startup.
+func (c *Config) Validate() error {
+	if c.Bind == "" {
+		return fmt.Errorf("bind address cannot be empty")
+	}
+	if net.ParseIP(c.Bind) == nil {
+		return fmt.Errorf("bind must be a valid IP address (e.g. 0.0.0.0, ::, ::1, 192.168.1.1)")
+	}
+	if c.Port <= 0 || c.Port > 65535 {
+		return fmt.Errorf("port must be between 1 and 65535")
+	}
+	if c.MaxClients <= 0 {
+		return fmt.Errorf("max_clients must be positive")
+	}
+	if c.MaxMsgBytes <= 0 {
+		return fmt.Errorf("max_message_bytes must be positive")
+	}
+	// Validate log level against allowed values
+	validLevels := map[string]bool{
+		"debug": true,
+		"info":  true,
+		"warn":  true,
+		"error": true,
+	}
+	if !validLevels[c.LogLevel] {
+		return fmt.Errorf("invalid log_level: %s (must be debug, info, warn, or error)", c.LogLevel)
+	}
+	return nil
+}
+
+// ReadTimeoutDuration converts the config's read timeout (in seconds) to a Duration.
+// Zero means no timeout, allowing the server to block on reads indefinitely.
+func (c *Config) ReadTimeoutDuration() time.Duration {
+	if c.ReadTimeout == 0 {
+		return 0
+	}
+	return time.Duration(c.ReadTimeout) * time.Second
+}
+
+// WriteTimeoutDuration converts the config's write timeout (in seconds) to a Duration.
+func (c *Config) WriteTimeoutDuration() time.Duration {
+	if c.WriteTimeout == 0 {
+		return 0
+	}
+	return time.Duration(c.WriteTimeout) * time.Second
+}
+
+// Load reads and parses the configuration from a JSON file.
+// It applies defaults for missing/invalid values and validates the final config.
+func Load(path string) (*Config, error) {
+	//nolint: gosec
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read config file: %w", err)
+	}
+
+	var cfg Config
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("failed to parse config file: %w", err)
+	}
+
+	// Apply defaults before validation to ensure minimum viable config
+	cfg.SetDefaults()
+
+	if err := cfg.Validate(); err != nil {
+		return nil, fmt.Errorf("config validation failed: %w", err)
+	}
+
+	logger.SetLevel(cfg.LogLevel)
+
+	if cfg.LogFile != "" {
+		if err := logger.SetOutput(cfg.LogFile); err != nil {
+			return nil, fmt.Errorf("failed to set log file: %w", err)
+		}
+	}
+
+	return &cfg, nil
+}
+
+// Addr returns the bind address in host:port format for use in net.Listen.
+// IPv6 addresses are wrapped in brackets: [::]:6379.
+func (c *Config) Addr() string {
+	ip := net.ParseIP(c.Bind)
+	if ip != nil && ip.To4() == nil {
+		// IPv6 address — wrap in brackets
+		return "[" + c.Bind + "]:" + strconv.Itoa(c.Port)
+	}
+	return c.Bind + ":" + strconv.Itoa(c.Port)
+}
+
+// String returns a JSON representation of the config for debugging.
+func (c *Config) String() string {
+	b, _ := json.MarshalIndent(c, "", "  ")
+	return string(b)
+}