package system

import (
	"errors"
	"net"
	"os"

	"hakurei.app/container"
	"hakurei.app/message"
)

// OpError is returned by [I.Commit] and [I.Revert].
type OpError struct {
	Op     string
	Err    error
	Msg    string
	Revert bool
}

func (e *OpError) Unwrap() error { return e.Err }
func (e *OpError) Error() string {
	if e.Msg != "" {
		return e.Msg
	}

	switch {
	case errors.As(e.Err, new(*os.PathError)),
		errors.As(e.Err, new(*os.LinkError)),
		errors.As(e.Err, new(*os.SyscallError)),
		errors.As(e.Err, new(*net.OpError)),
		errors.As(e.Err, new(*container.StartError)):
		return e.Err.Error()

	default:
		if !e.Revert {
			return "apply " + e.Op + ": " + e.Err.Error()
		} else {
			return "revert " + e.Op + ": " + e.Err.Error()
		}
	}
}

func (e *OpError) Message() string {
	if m, ok := message.GetMessage(e.Err); ok {
		return m
	}

	switch {
	case e.Msg != "":
		return e.Error()

	default:
		return "cannot " + e.Error()
	}
}

// newOpError returns an [OpError] without a message string.
func newOpError(op string, err error, revert bool) error {
	if err == nil {
		return nil
	}
	return &OpError{op, err, "", revert}
}

// newOpErrorMessage returns an [OpError] with an overriding message string.
func newOpErrorMessage(op string, err error, message string, revert bool) error {
	if err == nil {
		return nil
	}
	return &OpError{op, err, message, revert}
}

func printJoinedError(println func(v ...any), fallback string, err error) {
	var joinErr interface {
		Unwrap() []error
		error
	}
	if !errors.As(err, &joinErr) {
		if m, ok := message.GetMessage(err); ok {
			println(m)
		} else {
			println(fallback, err)
		}
	} else {
		for _, err = range joinErr.Unwrap() {
			if m, ok := message.GetMessage(err); ok {
				println(m)
			} else {
				println(err.Error())
			}
		}
	}
}
