Add config and corresponding tests

Author: Pavan-Rana

internal/config/config.go

@@ -1 +1,45 @@
-// internal/config/config.go
+package config
+
+import (
+	"os"
+	"time"
+
+	"github.com/Pavan-Rana/rate-limiter/internal/limiter"
+)
+
+type Config struct {
+	RedisAddr     string
+	GRPCAddr      string
+	HTTPAddr      string
+	defaultPolicy limiter.Policy
+	policies      map[string]limiter.Policy // per-API-key overrides
+}
+
+func Load() (*Config, error) {
+	return &Config{
+		RedisAddr: getEnv("REDIS_ADDR", "localhost:6379"),
+		GRPCAddr:  getEnv("GRPC_ADDR", ":50051"),
+		HTTPAddr:  getEnv("HTTP_ADDR", ":8080"),
+		defaultPolicy: limiter.Policy{
+			Limit:  100,
+			Window: time.Minute,
+		},
+		policies: make(map[string]limiter.Policy),
+	}, nil
+}
+
+func (c *Config) PolicyFor(apiKey string) (limiter.Policy, bool) {
+	p, ok := c.policies[apiKey]
+	return p, ok
+}
+
+func (c *Config) GetDefault() limiter.Policy {
+	return c.defaultPolicy
+}
+
+func getEnv(key, fallback string) string {
+	if v := os.Getenv(key); v != "" {
+		return v
+	}
+	return fallback
+}

internal/config/config_test.go

@@ -1 +1,108 @@
-// internal/config/config_test.go
+package config
+
+import (
+	"os"
+	"testing"
+	"time"
+
+	"github.com/Pavan-Rana/rate-limiter/internal/limiter"
+)
+
+func TestLoad_Defaults(t *testing.T) {
+	// Clear env to test fallbacks
+	os.Unsetenv("REDIS_ADDR")
+	os.Unsetenv("GRPC_ADDR")
+	os.Unsetenv("HTTP_ADDR")
+
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+
+	if cfg.RedisAddr != "localhost:6379" {
+		t.Errorf("expected RedisAddr localhost:6379, got %s", cfg.RedisAddr)
+	}
+
+	if cfg.GRPCAddr != ":50051" {
+		t.Errorf("expected GRPCAddr :50051, got %s", cfg.GRPCAddr)
+	}
+
+	if cfg.HTTPAddr != ":8080" {
+		t.Errorf("expected HTTPAddr :8080, got %s", cfg.HTTPAddr)
+	}
+}
+
+func TestLoad_FromEnv(t *testing.T) {
+	os.Setenv("REDIS_ADDR", "redis:1234")
+	os.Setenv("GRPC_ADDR", ":9999")
+	os.Setenv("HTTP_ADDR", ":7777")
+
+	defer os.Unsetenv("REDIS_ADDR")
+	defer os.Unsetenv("GRPC_ADDR")
+	defer os.Unsetenv("HTTP_ADDR")
+
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("expected no error, got %v", err)
+	}
+
+	if cfg.RedisAddr != "redis:1234" {
+		t.Errorf("expected RedisAddr redis:1234, got %s", cfg.RedisAddr)
+	}
+
+	if cfg.GRPCAddr != ":9999" {
+		t.Errorf("expected GRPCAddr :9999, got %s", cfg.GRPCAddr)
+	}
+
+	if cfg.HTTPAddr != ":7777" {
+		t.Errorf("expected HTTPAddr :7777, got %s", cfg.HTTPAddr)
+	}
+}
+
+func TestGetDefaultPolicy(t *testing.T) {
+	cfg, _ := Load()
+
+	p := cfg.GetDefault()
+
+	if p.Limit != 100 {
+		t.Errorf("expected limit 100, got %d", p.Limit)
+	}
+
+	if p.Window != time.Minute {
+		t.Errorf("expected window 1 minute, got %v", p.Window)
+	}
+}
+
+func TestPolicyFor_NotFound(t *testing.T) {
+	cfg, _ := Load()
+
+	_, ok := cfg.PolicyFor("nonexistent")
+
+	if ok {
+		t.Errorf("expected policy to not exist")
+	}
+}
+
+func TestPolicyFor_Found(t *testing.T) {
+	cfg, _ := Load()
+
+	testPolicy := limiter.Policy{
+		Limit:  50,
+		Window: time.Second * 30,
+	}
+
+	cfg.policies["test-key"] = testPolicy
+
+	p, ok := cfg.PolicyFor("test-key")
+	if !ok {
+		t.Fatalf("expected policy to exist")
+	}
+
+	if p.Limit != 50 {
+		t.Errorf("expected limit 50, got %d", p.Limit)
+	}
+
+	if p.Window != 30*time.Second {
+		t.Errorf("expected window 30s, got %v", p.Window)
+	}
+}