streamdal/go-sdk

package hostfunc

import (
    "context"
    "fmt"

    "github.com/pkg/errors"
    "github.com/tetratelabs/wazero/api"

    "github.com/streamdal/streamdal/libs/protos/build/go/protos/steps"

    "github.com/streamdal/go-sdk/helper"
)

// KVExists is function that is exported to and called from a Rust WASM module
func (h *HostFunc) KVExists(_ context.Context, module api.Module, ptr, length int32) uint64 {
    // Read request
    request := &steps.KVStep{}

    if err := helper.ReadRequestFromMemory(module, request, ptr, length); err != nil {
        return kvExistsResponse(module, "unable to read KVExistsRequest params: "+err.Error(), true, false)
    }

    if err := validateKVStep(request); err != nil {
        return kvExistsResponse(module, "unable to validate KVExistsRequest: "+err.Error(), true, false)
    }

    // Perform operation
    exists := h.kv.Exists(request.Key)

    msg := fmt.Sprintf("key '%s' does not exist", request.Key)

    if exists {
        msg = fmt.Sprintf("key '%s' exists", request.Key)
    }

    // Return response
    return kvExistsResponse(module, msg, false, exists)
}

// Generates a protobuf response, writes to mem, and returns ptr to mem
func kvExistsResponse(module api.Module, msg string, isError, exists bool) uint64 {
    var status steps.KVStatus

    if exists {
        status = steps.KVStatus_KV_STATUS_SUCCESS
    } else {
        status = steps.KVStatus_KV_STATUS_FAILURE
    }

    if isError {
        status = steps.KVStatus_KV_STATUS_ERROR
    }

    resp := &steps.KVStepResponse{
        Status:  status,
        Message: msg,
        Value:   nil, // KVExists does not fill value
    }

    addr, err := helper.WriteResponseToMemory(module, resp)
    if err != nil {
        panic("unable to write KVExistsResponse to memory: " + err.Error())
    }

    return addr
}

func validateKVStep(request *steps.KVStep) error {
    if request == nil {
        return errors.New("request cannot be nil")
    }

    if request.Key == "" {
        return errors.New("request.Key cannot be empty")
    }

    // TODO: Will eventually want to perform KVAction specific validations; good enough for now

    return nil
}