//go:build enable_antithesis_sdk

package internal

import (
	"encoding/json"
	"log"
	"math/rand"
	"os"
)

func Json_data(v any) error {
	if data, err := json.Marshal(v); err != nil {
		return err
	} else {
		handler.output(string(data))
		return nil
	}
}

func Get_random() uint64 {
	return handler.random()
}

func Notify(edge uint64) bool {
	return handler.notify(edge)
}

func InitCoverage(num_edges uint64, symbols string) uint64 {
	return handler.init_coverage(num_edges, symbols)
}

type libHandler interface {
	output(message string)
	random() uint64
	notify(edge uint64) bool
	init_coverage(num_edges uint64, symbols string) uint64
}

const (
	errorLogLinePrefix       = "[* antithesis-sdk-go *]"
)

var handler libHandler

type localHandler struct {
	outputFile *os.File // can be nil
}

func (h *localHandler) output(message string) {
	msg_len := len(message)
	if msg_len == 0 {
		return
	}
	if h.outputFile != nil {
		h.outputFile.WriteString(message + "\n")
	}
}

func (h *localHandler) random() uint64 {
	return rand.Uint64()
}

func (h *localHandler) notify(edge uint64) bool {
	return false
}

func (h *localHandler) init_coverage(num_edges uint64, symbols string) uint64 {
	return 0
}

func init() {
	handler = init_in_antithesis()
	if handler == nil {
		// Otherwise fallback to the local handler.
		handler = openLocalHandler()
	}
}

// If `localOutputEnvVar` is set to a non-empty path, attempt to open that path and truncate the file
// to serve as the log file of the local handler.
// Otherwise, we don't have a log file, and logging is a no-op in the local handler.
func openLocalHandler() *localHandler {
	path, is_set := os.LookupEnv(localOutputEnvVar)
	if !is_set || len(path) == 0 {
		return &localHandler{nil}
	}

	// Open the file R/W (create if needed and possible)
	file, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE, 0644)
	if err != nil {
		log.Printf("%s Failed to open path %s: %v", errorLogLinePrefix, path, err)
		file = nil
	} else if err = file.Truncate(0); err != nil {
		log.Printf("%s Failed to truncate file at %s: %v", errorLogLinePrefix, path, err)
		file = nil
	}

	return &localHandler{file}
}