package config

import (
	"os"
	"testing"
)

func TestLoadConfig(t *testing.T) {
	// Save original env values
	originalEnv := make(map[string]string)
	envVars := []string{
		"PORT", "FRONTEND_URL",
		"DB_HOST", "DB_PORT", "DB_USER", "DB_PASSWORD", "DB_NAME",
		"FIREBASE_PROJECT_ID", "FIREBASE_STORAGE_BUCKET", "FIREBASE_CREDENTIALS_FILE",
	}
	for _, key := range envVars {
		originalEnv[key] = os.Getenv(key)
		os.Unsetenv(key)
	}
	defer func() {
		// Restore original env values
		for key, value := range originalEnv {
			if value != "" {
				os.Setenv(key, value)
			} else {
				os.Unsetenv(key)
			}
		}
	}()

	tests := []struct {
		name    string
		setup   func()
		wantErr bool
	}{
		{
			name: "valid config",
			setup: func() {
				os.Setenv("DB_USER", "test_user")
				os.Setenv("DB_PASSWORD", "test_password")
				os.Setenv("DB_NAME", "test_db")
				os.Setenv("FIREBASE_PROJECT_ID", "test-project")
				os.Setenv("FIREBASE_STORAGE_BUCKET", "test-bucket.appspot.com")
				os.Setenv("FIREBASE_CREDENTIALS_FILE", "./test-credentials.json")
			},
			wantErr: false,
		},
		{
			name: "missing DB_USER",
			setup: func() {
				os.Setenv("DB_PASSWORD", "test_password")
				os.Setenv("DB_NAME", "test_db")
				os.Setenv("FIREBASE_PROJECT_ID", "test-project")
				os.Setenv("FIREBASE_STORAGE_BUCKET", "test-bucket.appspot.com")
				os.Setenv("FIREBASE_CREDENTIALS_FILE", "./test-credentials.json")
			},
			wantErr: true,
		},
		{
			name: "missing FIREBASE_PROJECT_ID",
			setup: func() {
				os.Setenv("DB_USER", "test_user")
				os.Setenv("DB_PASSWORD", "test_password")
				os.Setenv("DB_NAME", "test_db")
				os.Setenv("FIREBASE_STORAGE_BUCKET", "test-bucket.appspot.com")
				os.Setenv("FIREBASE_CREDENTIALS_FILE", "./test-credentials.json")
			},
			wantErr: true,
		},
		{
			name: "uses defaults for optional fields",
			setup: func() {
				os.Setenv("DB_USER", "test_user")
				os.Setenv("DB_PASSWORD", "test_password")
				os.Setenv("DB_NAME", "test_db")
				os.Setenv("FIREBASE_PROJECT_ID", "test-project")
				os.Setenv("FIREBASE_STORAGE_BUCKET", "test-bucket.appspot.com")
				os.Setenv("FIREBASE_CREDENTIALS_FILE", "./test-credentials.json")
			},
			wantErr: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			// Clean up env before each test
			for _, key := range envVars {
				os.Unsetenv(key)
			}

			tt.setup()

			cfg, err := LoadConfig()
			if (err != nil) != tt.wantErr {
				t.Errorf("LoadConfig() error = %v, wantErr %v", err, tt.wantErr)
				return
			}

			if !tt.wantErr && cfg == nil {
				t.Error("LoadConfig() returned nil config without error")
				return
			}

			if !tt.wantErr {
				// Verify defaults are used
				if cfg.Port == "" {
					t.Error("Port should have default value")
				}
				if cfg.DBHost == "" {
					t.Error("DBHost should have default value")
				}
			}
		})
	}
}

func TestConfig_Validate(t *testing.T) {
	tests := []struct {
		name    string
		config  *Config
		wantErr bool
	}{
		{
			name: "valid config",
			config: &Config{
				DBUser:                  "user",
				DBPassword:              "password",
				DBName:                  "dbname",
				FirebaseProjectID:       "project-id",
				FirebaseStorageBucket:   "bucket.appspot.com",
				FirebaseCredentialsFile: "./credentials.json",
			},
			wantErr: false,
		},
		{
			name: "missing DB_USER",
			config: &Config{
				DBPassword:              "password",
				DBName:                  "dbname",
				FirebaseProjectID:       "project-id",
				FirebaseStorageBucket:   "bucket.appspot.com",
				FirebaseCredentialsFile: "./credentials.json",
			},
			wantErr: true,
		},
		{
			name: "missing FIREBASE_PROJECT_ID",
			config: &Config{
				DBUser:                  "user",
				DBPassword:              "password",
				DBName:                  "dbname",
				FirebaseStorageBucket:   "bucket.appspot.com",
				FirebaseCredentialsFile: "./credentials.json",
			},
			wantErr: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			err := tt.config.Validate()
			if (err != nil) != tt.wantErr {
				t.Errorf("Config.Validate() error = %v, wantErr %v", err, tt.wantErr)
			}
		})
	}
}

func TestLoadConfig_EnvFilePrecedence(t *testing.T) {
	// This test verifies that .env.local overrides .env values
	// Note: This is a conceptual test - actual file loading would require test files

	// Save original env
	originalPort := os.Getenv("PORT")
	defer func() {
		if originalPort != "" {
			os.Setenv("PORT", originalPort)
		} else {
			os.Unsetenv("PORT")
		}
	}()

	// Set required vars
	os.Setenv("DB_USER", "test")
	os.Setenv("DB_PASSWORD", "test")
	os.Setenv("DB_NAME", "test")
	os.Setenv("FIREBASE_PROJECT_ID", "test")
	os.Setenv("FIREBASE_STORAGE_BUCKET", "test.appspot.com")
	os.Setenv("FIREBASE_CREDENTIALS_FILE", "./test.json")

	// Test that LoadConfig works
	cfg, err := LoadConfig()
	if err != nil {
		t.Fatalf("LoadConfig() error = %v", err)
	}

	if cfg == nil {
		t.Fatal("LoadConfig() returned nil")
	}

	// Verify it uses default PORT if not set
	if cfg.Port == "" {
		t.Error("Port should have default value")
	}
}