package render

import (
	"math"
	"net/http"
	"strconv"

	"github.com/SigNoz/signoz/pkg/errors"
	jsoniter "github.com/json-iterator/go"
	"github.com/tidwall/gjson"
)

const (
	// Non-standard status code (originally introduced by nginx) for the case when a client closes
	// the connection while the server is still processing the request.
	statusClientClosedConnection = 499
)

var json = jsoniter.ConfigCompatibleWithStandardLibrary

type SuccessResponse struct {
	Status string      `json:"status" required:"true"`
	Data   interface{} `json:"data,omitempty" required:"true"`
}

type ErrorResponse struct {
	Status string       `json:"status" required:"true"`
	Error  *errors.JSON `json:"error" required:"true"`
}

func Success(rw http.ResponseWriter, httpCode int, data interface{}) {
	body, err := json.Marshal(&SuccessResponse{Status: StatusSuccess.s, Data: data})
	if err != nil {
		Error(rw, err)
		return
	}

	if httpCode == 0 {
		httpCode = http.StatusOK
	}

	rw.Header().Set("Content-Type", "application/json")

	rw.WriteHeader(httpCode)
	_, _ = rw.Write(body)
}

func ErrorCodeFromBody(body []byte) string {
	code := gjson.GetBytes(body, "error.code").String()

	// This should never return empty since we only call this function on responses that were generated by us.
	// If it does return empty, the codebase has failed to use render package for error responses somewhere, and we should fix that instead of trying to handle it here.
	if code == "" {
		return errors.CodeUnset.String()
	}

	return code
}

func ErrorTypeFromStatusCode(statusCode int) string {
	// We are losing the exact type information here, but we can at least capture the error code and message for better observability.
	// To get the exact type, we would need some changes in the render package to include the error type in the response, which we can consider in the future if there is a need for it.
	switch statusCode {
	case http.StatusBadRequest:
		return errors.TypeInvalidInput.String()
	case http.StatusNotFound:
		return errors.TypeNotFound.String()
	case http.StatusConflict:
		return errors.TypeAlreadyExists.String()
	case http.StatusUnauthorized:
		return errors.TypeUnauthenticated.String()
	case http.StatusNotImplemented:
		return errors.TypeUnsupported.String()
	case http.StatusForbidden:
		return errors.TypeForbidden.String()
	case statusClientClosedConnection:
		return errors.TypeCanceled.String()
	case http.StatusGatewayTimeout:
		return errors.TypeTimeout.String()
	case http.StatusUnavailableForLegalReasons:
		return errors.TypeLicenseUnavailable.String()
	case http.StatusTooManyRequests:
		return errors.TypeTooManyRequests.String()
	default:
		return errors.TypeInternal.String()
	}
}

func Error(rw http.ResponseWriter, cause error) {
	// Derive the http code from the error type
	t, _, _, _, _, _ := errors.Unwrapb(cause)

	httpCode := http.StatusInternalServerError
	switch t {
	case errors.TypeInvalidInput:
		httpCode = http.StatusBadRequest
	case errors.TypeNotFound:
		httpCode = http.StatusNotFound
	case errors.TypeAlreadyExists:
		httpCode = http.StatusConflict
	case errors.TypeUnauthenticated:
		httpCode = http.StatusUnauthorized
	case errors.TypeUnsupported:
		httpCode = http.StatusNotImplemented
	case errors.TypeForbidden:
		httpCode = http.StatusForbidden
	case errors.TypeCanceled:
		httpCode = statusClientClosedConnection
	case errors.TypeTimeout:
		httpCode = http.StatusGatewayTimeout
	case errors.TypeFatal:
		httpCode = http.StatusInternalServerError
	case errors.TypeLicenseUnavailable:
		httpCode = http.StatusUnavailableForLegalReasons
	case errors.TypeTooManyRequests:
		httpCode = http.StatusTooManyRequests
	}

	body, err := json.Marshal(&ErrorResponse{Status: StatusError.s, Error: errors.AsJSON(cause)})
	if err != nil {
		// this should never be the case
		http.Error(rw, err.Error(), http.StatusInternalServerError)
		return
	}

	// Retry-After carries the explicit delay declared via
	// errors.WithRetryAfter. Set it before WriteHeader so headers go on the wire.
	d := errors.RetryDelayOf(cause)
	if d.Seconds() > 0 {
		rw.Header().Set("Retry-After", strconv.Itoa(int(math.Ceil(d.Seconds()))))
	}

	rw.Header().Set("Content-Type", "application/json")
	rw.WriteHeader(httpCode)
	_, _ = rw.Write(body)
}