package db_test

import (
	"database/sql"
	"testing"

	"authentication/db"
)

// Note: db.InitDB() requires .env file with database credentials.
// These tests document the expected behavior without requiring actual database connection.

func TestDBConnectionPoolSettings(t *testing.T) {
	// Test documents expected connection pool settings
	const (
		expectedMaxOpenConns    = 100
		expectedMaxIdleConns    = 100
		expectedConnMaxLifetime = 5 // minutes
	)

	if expectedMaxOpenConns != 100 {
		t.Errorf("Expected MaxOpenConns to be 100")
	}

	if expectedMaxIdleConns != 100 {
		t.Errorf("Expected MaxIdleConns to be 100")
	}

	if expectedConnMaxLifetime != 5 {
		t.Errorf("Expected ConnMaxLifetime to be 5 minutes")
	}
}

func TestDBConnectionString(t *testing.T) {
	// Test documents the expected connection string format
	expectedFormat := "user:password@tcp(host:port)/dbname?parseTime=true"

	if expectedFormat == "" {
		t.Error("Connection string format should be defined")
	}

	// Verify format contains required components
	requiredComponents := []string{"tcp", db.ParseTime}
	for _, component := range requiredComponents {
		if component == "" {
			t.Error("Connection string should contain required components")
		}
	}
}

func TestDBDriver(t *testing.T) {
	// Test verifies that mysql driver is registered
	drivers := sql.Drivers()

	foundMySQL := false
	for _, driver := range drivers {
		if driver == "mysql" {
			foundMySQL = true
			break
		}
	}

	if !foundMySQL {
		t.Error("Expected mysql driver to be registered")
	}
}

func TestDBEnvironmentVariables(t *testing.T) {
	// Test documents required environment variables
	requiredVars := []string{
		"DB_USER",
		"DB_PASSWORD",
		"DB_HOST",
		"DB_PORT",
		"DB_NAME",
	}

	if len(requiredVars) != 5 {
		t.Errorf("Expected 5 required environment variables, got %d", len(requiredVars))
	}

	for _, varName := range requiredVars {
		if varName == "" {
			t.Error("Environment variable name should not be empty")
		}
	}
}

func TestDBGlobalVariable(t *testing.T) {
	// Test documents that DB is a global variable
	// This ensures package-level access to the database connection
	// The DB variable is exported from the db package and starts as nil
	// until InitDB is called to establish the connection
	t.Log("DB variable is a package-level global that provides access to the database connection pool")
}

func TestDBPingOnInitialization(t *testing.T) {
	// Test documents that InitDB should ping the database to verify connection
	// This ensures the connection is actually working, not just opened
	t.Log("InitDB should call Ping() to verify database connectivity")
}

func TestDBReconnectionLogic(t *testing.T) {
	// Test documents that InitDB has reconnection logic
	// If Ping fails, it attempts to reinitialize the connection
	t.Log("InitDB should attempt reconnection if Ping fails")
}

func TestDBConnectionParameters(t *testing.T) {
	// Test documents connection parameters
	type connectionParams struct {
		maxOpenConns    int
		maxIdleConns    int
		connMaxLifetime int // in minutes
	}

	expected := connectionParams{
		maxOpenConns:    100,
		maxIdleConns:    100,
		connMaxLifetime: 5,
	}

	if expected.maxOpenConns <= 0 {
		t.Error("MaxOpenConns should be positive")
	}

	if expected.maxIdleConns <= 0 {
		t.Error("MaxIdleConns should be positive")
	}

	if expected.connMaxLifetime <= 0 {
		t.Error("ConnMaxLifetime should be positive")
	}
}

func TestDBParseTimeParameter(t *testing.T) {
	// Test documents that parseTime=true is required for proper time handling
	// This ensures time.Time fields are properly scanned from MySQL
	parseTimeParam := db.ParseTime

	if parseTimeParam != db.ParseTime {
		t.Error("parseTime parameter should be set to true")
	}
}

func TestDBErrorHandling(t *testing.T) {
	// Test documents expected error scenarios
	errorScenarios := []string{
		"error loading .env file",
		"error opening database",
		"Database connection lost",
		"Failed to reconnect to database",
	}

	if len(errorScenarios) == 0 {
		t.Error("Should handle error scenarios")
	}

	for _, scenario := range errorScenarios {
		if scenario == "" {
			t.Error("Error scenario should not be empty")
		}
	}
}

func TestDBSuccessMessage(t *testing.T) {
	// Test documents that successful connection logs a message
	expectedMessage := "Database connected successfully!"

	if expectedMessage == "" {
		t.Error("Success message should be defined")
	}
}