package errs

import (
	"encoding/binary"
	"fmt"
	"io"
	"runtime/debug"
)

type Error struct {
	Code       int64
	Msg        string
	StackTrace string

	collection string
	index      string
	err        error // Wrapped error
}

func NewErr(code int64, msg string) *Error {
	return &Error{
		Code: code,
		Msg:  msg,
	}
}

func (e *Error) Error() string {
	if e.collection != "" || e.index != "" {
		return fmt.Sprintf(`[%d] (%s/%s) %s`, e.Code, e.collection, e.index, e.Msg)
	} else {
		return fmt.Sprintf("[%d] %s", e.Code, e.Msg)
	}
}

func (e *Error) Is(rhs error) bool {
	e2, ok := rhs.(*Error)
	if !ok {
		return false
	}
	return e.Code == e2.Code
}

func (e *Error) Unwrap() error {
	return e.err
}

func (e *Error) WithErr(err error) *Error {
	if e2, ok := err.(*Error); ok && e2.Code == e.Code {
		return e2
	}

	e2 := e.WithMsg(err.Error())
	e2.err = err
	return e2
}

func (e *Error) WithMsg(msg string, args ...any) *Error {
	err := *e
	err.Msg += ": " + fmt.Sprintf(msg, args...)
	if len(err.StackTrace) == 0 {
		err.StackTrace = string(debug.Stack())
	}
	return &err
}

func (e *Error) WithCollection(s string) *Error {
	err := *e
	err.collection = s
	return &err
}

func (e *Error) WithIndex(s string) *Error {
	err := *e
	err.index = s
	return &err
}

func (e *Error) msgTruncacted() string {
	if len(e.Msg) > 255 {
		return e.Msg[:255]
	}
	return e.Msg
}

func (e *Error) Write(w io.Writer) error {
	msg := e.msgTruncacted()

	if err := binary.Write(w, binary.LittleEndian, e.Code); err != nil {
		return IO.WithErr(err)
	}

	if _, err := w.Write([]byte{byte(len(msg))}); err != nil {
		return err
	}
	_, err := w.Write([]byte(msg))
	return err
}

func (e *Error) Read(r io.Reader) error {
	var (
		size uint8
	)

	if err := binary.Read(r, binary.LittleEndian, &e.Code); err != nil {
		return IO.WithErr(err)
	}

	if err := binary.Read(r, binary.LittleEndian, &size); err != nil {
		return IO.WithErr(err)
	}

	msgBuf := make([]byte, size)
	if _, err := io.ReadFull(r, msgBuf); err != nil {
		return IO.WithErr(err)
	}

	e.Msg = string(msgBuf)
	return nil
}