import (
    "log/slog"

    "github.com/newmo-oss/ergo"
)

// Simple error
// Stack trace is automatically attached
err := ergo.New("failed to process request")

// With attributes
err := ergo.New("user not found", slog.String("user_id", "12345"), slog.Int("status_code", 404))

// Wrap with additional context
// Stack trace is attached if not present
if err := doSomething(); err != nil {
    return ergo.Wrap(err, "failed to execute operation", slog.String("operation", "process"))
}

// Define error codes
// NewCode automatically captures the package path from the stack trace,
// so codes with the same key name from different packages can be distinguished
var (
    ErrCodeNotFound = ergo.NewCode("NotFound", "resource not found")
    ErrCodeInvalid  = ergo.NewCode("Invalid", "invalid input")
)

func doSomething() error {
    // Create error
    err := ergo.New("user not found", slog.String("user_id", "12345"))

    // Add code to error
    err = ergo.WithCode(err, ErrCodeNotFound)

    // Retrieve error code
    code := ergo.CodeOf(err)
    if code == ErrCodeNotFound {
        // handle not found error
    }

    // String representation of error code
    // Formatted as: package-path.Key: Message
    fmt.Println(code.String()) // github.com/yourorg/yourapp/service.NotFound: resource not found
}

// Iterate over all attributes (including parent errors)
for attr := range ergo.AttrsAll(err) {
    fmt.Printf("%s: %v\n", attr.Key, attr.Value)
}

// Get stack trace
st := ergo.StackTraceOf(err)
if st != nil {
    fmt.Printf("Stack trace: %v\n", st)
}

// Always use NewSentinel for package-level constants
// NewSentinel creates lightweight errors without stack traces, attributes, or error codes
var (
    ErrInvalidInput = ergo.NewSentinel("invalid input")
    ErrTimeout      = ergo.NewSentinel("operation timeout")
)

// Compare with sentinel errors
if errors.Is(err, ErrTimeout) {
    // handle timeout
}

err := ergo.New("operation failed", slog.String("key1", "value1"), slog.Int("key2", 100))
fmt.Printf("%v\n", err)   // operation failed
fmt.Printf("%+v\n", err)  // operation failed: key1=value1,key2=100