package errors

import (
	"encoding/json"
	"fmt"
	"net/http"
)

// Returns a SettableError formatted from the message, with the specified status.
// Errorf passes the heavy lifting off to fmt.Errorf, and returns a similar error.
// If one error is passed in the format, this will return an UnwrappableError.
// If more than one error is passed in the format, this will return an UnwrappableErrors.
//
// The Msg method may also be formatted.
//
// If you want a different user message, use Msg, such as:
//
//	err := errors.Errorf(http.StatusNotFound, "%w", sqlError).SetMsg("user not found %d", userId)
func Errorf(status int, format string, parts ...any) SettableError {
	meta := make(map[string]any)
	if len(parts) == 0 {
		return &erf{status, format, "", meta}
	}

	err := fmt.Errorf(format, parts...)
	msg := err.Error()
	er := &erf{status, msg, "", meta}
	if we, ok := err.(wrappedError); ok {
		return &wrapErr{er, we.Unwrap()}
	}
	if wes, ok := err.(wrappedErrors); ok {
		return &wrapErrs{er, wes.Unwrap()}
	}
	return er
}

var _ ResponsableError = new(erf)
var _ SettableError = new(erf)
var _ json.Marshaler = new(erf)

type erf struct {
	stat int
	err  string
	msg  string
	meta map[string]any
}

func (e *erf) Status() int {
	if e.stat < http.StatusContinue || e.stat >= 600 {
		e.stat = http.StatusInternalServerError
	}
	return e.stat
}

func (e *erf) Error() string {
	return e.err
}

func (e *erf) Msg() string {
	if e.msg == "" {
		return e.err
	}
	return e.msg
}

func (e *erf) SetStatus(status int) SettableError {
	// Status already handles invalid values, so we'll just ignore this.
	if status < http.StatusContinue || status >= 600 {
		return e
	}
	e.stat = status
	return e
}

func (e *erf) SetMsg(msg string, parts ...any) SettableError {
	e.msg = msg
	if len(parts) > 0 {
		e.msg = fmt.Sprintf(msg, parts...)
	}
	return e
}

func (e *erf) SetField(field string, value any) SettableError {
	e.meta[field] = value
	return e
}

func (e *erf) JSON() any {
	m := e.meta
	m["error"] = e.Msg()
	return m
}

func (e *erf) MarshalJSON() ([]byte, error) {
	return json.Marshal(e.JSON())
}

var _ UnwrappableError = new(wrapErr)

type wrapErr struct {
	*erf
	err error
}

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

var _ UnwrappableErrors = new(wrapErrs)

type wrapErrs struct {
	*erf
	errs []error
}

func (e *wrapErrs) Unwrap() []error {
	return e.errs
}