package fhelp

// auto run protoc with the correct args

import (
	"bufio"
	"fmt"
	"os"
	"strings"

	"github.com/google/uuid"
	"go.wit.com/log"
	"golang.org/x/text/cases"
	"golang.org/x/text/language"
)

/*
This verifies a .proto file conforms to the autogenpb standard

That means, for "toy.proto", there MUST exist:

message toy {
}
message toys {
}

this parses the .proto file and handles anything with `autogenpb: `
does the fruit.proto file have "message Fruits"
does it have a Uuid & valid version ?

This returns (UUID, Version, error on failure)
*/
func ValidProtobuf(filename string) (string, string, error) {
	filebase := strings.TrimSuffix(filename, ".proto")
	base := cases.Title(language.English, cases.NoLower).String(filebase)
	pluralBase := base + "s" // to conform to autogenpb, it must have an added 's'

	file, err := os.Open(filename)
	if err != nil {
		return "", "", err
	}
	defer file.Close()
	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()

		prefix := "message " + pluralBase + " {"
		if !strings.HasPrefix(line, prefix) {
			// log.Info("nope", prefix, "line", line)
			// nope, not this line
			continue
		}

		scanner.Scan()
		line = scanner.Text()
		fields := strings.Fields(line)
		if len(fields) < 2 {
			noUuidExit(filename)
			return "", "", fmt.Errorf("proto file does not have a UUID")
		}
		// log.Info("GOT LINE", line)
		if fields[0] == "string" && fields[1] != "uuid" {
			noUuidExit(filename)
			return "", "", fmt.Errorf("proto file does not have a UUID")
		}
		// ok, uuid is here
		UUID := parseUuid(line)
		if UUID == "" {
			noUuidExit(filename)
			return "", "", fmt.Errorf("proto file does not have a UUID")
		}
		log.Info("found UUID:", UUID)
		scanner.Scan()
		line = scanner.Text()
		fields = strings.Fields(line)
		// log.Info("GOT LINE", line)
		if fields[0] == "string" && fields[1] != "version" {
			noUuidExit(filename)
			return "", "", fmt.Errorf("proto file does not have a version")
		}
		// found "version", the .proto file conforms
		version := parseVersion(line)
		if version == "" {
			noUuidExit(filename)
			return "", "", fmt.Errorf("proto file does not have a version")
		}
		log.Info("found Version:", version)
		return UUID, version, nil
	}
	// right now, noPluralMessage does os.Exit(-1)
	noPluralMessageExit(filename)
	return "", "", fmt.Errorf("proto file does not have message %s", pluralBase)
}

func parseUuid(line string) string {
	fields := strings.Split(line, "autogenpb:uuid:")
	if len(fields) < 2 {
		return ""
	}
	end := fields[1]
	fields = strings.Fields(end)
	uuid := fields[0]
	uuid = strings.Trim(uuid, "`")
	// log.Info("fhelp.parseUuid() uuid =", uuid)
	return uuid
}

func parseVersion(line string) string {
	fields := strings.Split(line, "autogenpb:version:")
	if len(fields) < 2 {
		return ""
	}
	end := fields[1]
	fields = strings.Fields(end)
	ver := fields[0]
	ver = strings.Trim(ver, "`")
	// log.Info("fhelp.parseVersion() ver =", ver)
	return ver
}

func noPluralMessageExit(filename string) {
	filebase := strings.TrimSuffix(filename, ".proto")
	base := cases.Title(language.English, cases.NoLower).String(filebase)

	log.Info("")
	log.Info("###########################################################################")
	log.Info("Your proto file", filename, "does not contain the correct 'message' definitions")
	log.Info("")
	log.Info("For autogenpb to work on your file", filename, ", you must have both names exactly:")
	log.Info("")
	log.Printf("message %s {\n", base)
	log.Info("}")
	log.Printf("message %s {\n", base+"s")
	log.Info("}")
	log.Info("")
	log.Info("###########################################################################")
	badExit(fmt.Errorf("proto file error %s", filename))
}

// message Fruits {	        	// `autogenpb:marshal` `autogenpb:mutex`
// 	string   uuid	        = 1;    // `autogenpb:uuid:be926ad9-f07f-484c-adf2-d96eeabf3079`
// 	string   version        = 2;    // `autogenpb:version:v0.0.1`
// 	repeated Fruit Fruits   = 3;    // THIS MUST BE "Fruit" and then "Fruit" + "s"
// }

func noUuidExit(filename string) {
	filebase := strings.TrimSuffix(filename, ".proto")
	base := cases.Title(language.English, cases.NoLower).String(filebase)
	id := uuid.New()

	log.Info("")
	log.Info("###########################################################################")
	log.Info("Your proto file", filename, "is incorrect for 'message' ", base+"s")
	log.Info("")
	log.Info("For autogenpb to work on your file", filename, ",", base+"s must be exactly:")
	log.Info("")
	log.Info("message", base+"s", "{	        	// `autogenpb:marshal` `autogenpb:mutex`")
	log.Info(" 	string   uuid	        = 1;    // `autogenpb:uuid:" + id.String() + "`")
	log.Info(" 	string   version        = 2;    // `autogenpb:version:v0.0.1`")
	log.Info(" 	repeated", base, base+"s", "   = 3;    // THIS MUST BE ", base, " and then ", base+"s")
	log.Info("}")
	log.Info("")
	log.Info("If you don't have a UUID, you can use the randomly generated one here")
	log.Info("")
	log.Info("If you wish to ignore this, set PROTOBUF_REGRET=true")
	log.Info("You will probably regret not trying to follow the standard here. This format is used as a 'handshake'.")
	log.Info("###########################################################################")
	if os.Getenv("PROTOBUF_REGRET") == "true" {
		log.Info("PROTOBUF_REGRET=true was set")
		log.Info("###########################################################################")
		return
	}
	badExit(fmt.Errorf("proto file error %s", filename))
}

func userInstructions() {
	log.Info("This is likely because you don't have protoc and protoc-gen-go installed")
	log.Info("")
	log.Info("On debian, you can:")
	log.Info("   apt install protobuf-compiler   # for protoc")
	log.Info("   apt install protoc-gen-go       # for protoc-gen-go")
	log.Info("")
}