package app

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

	"github.com/go-chi/render"
)

// ErrResponse renderer type for handling all sorts of errors.
type ErrResponse struct {
	Err            error `json:"-"` // low-level runtime error
	HTTPStatusCode int   `json:"-"` // http response status code

	StatusText string `json:"status"`          // user-level status message
	AppCode    int64  `json:"code,omitempty"`  // application-specific error code
	ErrorText  string `json:"error,omitempty"` // application-level error message, for debugging
}

// Render sets the application-specific error code in AppCode.
func (e *ErrResponse) Render(w http.ResponseWriter, r *http.Request) error {
	render.Status(r, e.HTTPStatusCode)
	return nil
}

// ErrInvalidRequest returns status 422 Unprocessable Entity including error message.
func ErrInvalidRequest(err error) render.Renderer {
	return &ErrResponse{
		Err:            err,
		HTTPStatusCode: http.StatusUnprocessableEntity,
		StatusText:     http.StatusText(http.StatusUnprocessableEntity),
		ErrorText:      err.Error(),
	}
}

// ErrValidationResponse renderer for handling validation errors.
type ErrValidationResponse struct {
	*ErrResponse
	Errors string `json:"errors,omitempty"`
}

// Render sets the application-specific error code in AppCode.
func (ev *ErrValidationResponse) Render(w http.ResponseWriter, r *http.Request) error {
	render.Status(r, ev.ErrResponse.HTTPStatusCode)
	return nil
}

// ErrValidation returns status 422 Unprocessable Entity stating validation errors.
func ErrValidation(valErrors error) render.Renderer {
	b, _ := json.Marshal(valErrors)
	return &ErrValidationResponse{
		&ErrResponse{
			Err:            nil,
			HTTPStatusCode: http.StatusUnprocessableEntity,
			StatusText:     http.StatusText(http.StatusUnprocessableEntity),
			ErrorText:      "object validation error",
		},
		string(b),
	}
}

// ErrRender returns status 422 Unprocessable Entity rendering response error.
func ErrRender(err error) render.Renderer {
	return &ErrResponse{
		Err:            err,
		HTTPStatusCode: http.StatusUnprocessableEntity,
		StatusText:     http.StatusText(http.StatusUnprocessableEntity),
		ErrorText:      err.Error(),
	}
}

var (
	// ErrBadRequest return status 400 Bad Request for malformed request body.
	ErrBadRequest = &ErrResponse{HTTPStatusCode: http.StatusBadRequest, StatusText: http.StatusText(http.StatusBadRequest)}

	// ErrNotFound returns status 404 Not Found for invalid resource request.
	ErrNotFound = &ErrResponse{HTTPStatusCode: http.StatusNotFound, StatusText: http.StatusText(http.StatusNotFound)}

	// ErrInternalServerError returns status 500 Internal Server Error.
	ErrInternalServerError = &ErrResponse{HTTPStatusCode: http.StatusInternalServerError, StatusText: http.StatusText(http.StatusInternalServerError)}
)