package main

// will this help things?
// this is a hack for testing for now
// cram a mutex in the pb.go file

import (
	"fmt"
	"io"
	"os"
	"strings"

	"go.wit.com/log"
)

func (msg *MsgName) getLockname(s string) string {
	if msg.NoMutex {
		// return "bad"
		return msg.Lockname
	}
	// leave this function stubbed in for development of autogenpb
	//	if argv.Mutex {
	//		// use the mutex lock from the modified protoc.pb.go file
	//		return s + ".Lock"
	//		// return s // causes Marshal() to panic? always use the variable name 'Lock'?
	//	}
	// a single global lock by struct name
	return msg.Lockname
}

func (pf *File) syncLock(w io.Writer) {
	var LOCK string = pf.Filebase + "Mu" // this should be lowercase. do not export the Mutex

	fmt.Fprintln(w, "// a simple global lock")
	fmt.Fprintln(w, "var "+LOCK+" sync.RWMutex")
	fmt.Fprintln(w, "")
	/*
		// this was a note, but the note is wrong. it seems to work fine. my example/ code was wrong. I think. notsure

		fmt.Fprintln(w, "")
		fmt.Fprintln(w, "// this is needed because it seems Marshal() fails if locks are in the structs (?)")
		fmt.Fprintln(w, "// this might just be a syntactical runtime error. notsure.")
		fmt.Fprintln(w, "// maybe this autogen tool will help someone that actually knows what is going on inside")
		fmt.Fprintln(w, "// go/src/google.golang.org/protobuf/proto/proto_methods.go")
		fmt.Fprintln(w, "// go/src/google.golang.org/protobuf/proto/encode.go")
		fmt.Fprintln(w, "// my guess is that Marshal() needs to be told to ignore sync.RWMutex as it ephemeral and can't be stored")
	*/
}

func (pb *Files) addMutex(f *File) error {
	fullname := f.Pbfilename
	// log.Info("pb filename:", fullname)
	data, err := os.ReadFile(fullname)
	if err != nil {
		log.Info("pb filename failed to read:", err)
		return err
	}

	// check if autogenpb has already looked at this file
	for _, line := range strings.Split(string(data), "\n") {
		if strings.Contains(line, "autogenpb DO NOT EDIT") {
			// log.Info("autogenpb has already been run on", fullname)
			return nil
		}
	}

	w, _ := os.OpenFile(f.Pbfilename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)

	// the default is to insert a mutex directly into the struct
	if argv.Mutex {
		pbHeaderComment(w)
	}

	lines := strings.Split(string(data), "\n")
	for _, line := range lines {
		if strings.HasPrefix(line, "package ") {
			// log.Info("CHANGING package:", line, "to package:", f.Package)
			if f.Package != "" {
				fmt.Fprintln(w, "package", f.Package, "// autogenpb changed the package name")
			}
			// log.Info("CHANGING package:", line, "to package:main")
			// fmt.Fprintln(w, "package "+"main")
			continue
		}
		// the default is to insert a mutex directly into the struct
		if !argv.Mutex {
			// mutex is not to be added, only fix the package name
			fmt.Fprintln(w, line)
			continue
		}

		if msg := f.structMatch(line); msg == nil {
			fmt.Fprintln(w, line)
		} else {
			fmt.Fprintln(w, line)
			if !argv.Mutex {
				fmt.Fprintln(w, "\t// sync.RWMutex // skipped. argv was  --mutex=false")
				fmt.Fprintln(w, "")
				continue
			}
			if msg.NoMutex {
				fmt.Fprintln(w, "\t// sync.RWMutex // skipped. protobuf file has `autogenpb:nomutex`")
				fmt.Fprintln(w, "")
				continue
			}
			if argv.MutexName == "" {
				fmt.Fprintln(w, "\tsync.RWMutex // auto-added by go.wit.com/apps/autogenpb") // this must be 'Lock' or Marshal() panics?
				fmt.Fprintln(w, "")
			} else {
				fmt.Fprintf(w, "\t%s sync.RWMutex // auto-added by go.wit.com/apps/autogenpb\n", argv.MutexName) // this must be 'Lock' or Marshal() panics?
				fmt.Fprintln(w, "")
			}
		}
	}
	if argv.Mutex {
		// verify every structure was found
		for _, msg := range f.MsgNames {
			if !msg.MutexFound && msg.DoMutex {
				return fmt.Errorf("addMutex() parse didn't work for %s", msg.Name)
			}
		}
	}
	return nil
}

// is this struct supposed to have a Mutex added?
func (pf *File) structMatch(line string) *MsgName {
	var msg *MsgName
	var start string

	msg = pf.Bases
	start = "type " + msg.Name + " struct {"
	if strings.HasPrefix(line, start) {
		msg.setupMutex(pf.Filebase + "Mu")
		return msg
	}

	// ONLY PASS THIS IF YOU DO NOT WANT TO USE MARSHAL()

	msg = pf.Base
	start = "type " + msg.Name + " struct {"
	if strings.HasPrefix(line, start) {
		msg.setupMutex(pf.Filebase + "Mu")
		return msg
	}

	for _, msg = range pf.MsgNames {
		start = "type " + msg.Name + " struct {"
		if strings.HasPrefix(line, start) {
			msg.setupMutex(pf.Filebase + "Mu")
			return msg
		}
	}
	return nil
}

// nameMu should probably be lowercase.
// notsure if it ever makes sense to export a mutex or even if you can
func (msg *MsgName) setupMutex(nameMu string) {
	msg.MutexFound = true
	if msg.NoMutex {
		msg.Lockname = nameMu
		return
	}
	if argv.MutexName == "" {
		msg.Lockname = "x"
	} else {
		msg.Lockname = "x." + argv.MutexName
	}
}