// Copyright 2017-2025 WIT.COM Inc. All rights reserved.
// Use of this source code is governed by the GPL 3.0

package main

import (
	"fmt"
	"iter"
	"os"
	"strings"
	sync "sync"

	"go.wit.com/log"
)

// like 'goimport', but for .proto files

var allTheLines *LinesScanner

func protoReformat(filename string) error {
	// read in the .proto file
	data, err := os.ReadFile(filename)
	if err != nil {
		log.Info("file read failed", filename, err)
		return err
	}

	var inMessage bool
	var newfile string
	var fmtmsg *FormatMsg
	fmtmsg = new(FormatMsg)

	var bigName int64
	var bigType int64

	var allLinesIter iter.Seq[string]
	allLinesIter = makeLineIter(data)
	// gets the max vartype and varname
	for line := range allLinesIter {
		if strings.HasPrefix(line, "message ") {
			inMessage = true
			continue
		}

		// find the end of the message
		if strings.HasPrefix(line, "}") {
			inMessage = false
			formatMessage2(fmtmsg)
			if bigName < fmtmsg.MaxVarname {
				bigName = fmtmsg.MaxVarname
			}
			if bigType < fmtmsg.MaxVartype {
				bigType = fmtmsg.MaxVartype
			}
			fmtmsg = new(FormatMsg)
			continue
		}

		// don't format or change anything when not in a "message {" section
		if !inMessage {
			continue
		}
		fmtmsg.Lines = append(fmtmsg.Lines, line)
	}

	fmtmsg = new(FormatMsg)
	fmtmsg.MaxVarname = bigName
	fmtmsg.MaxVartype = bigType

	// write out the messages
	allTheLines = newLinesScanner(strings.Split(string(data), "\n"))
	for allTheLines.Scan() {
		line := allTheLines.Next()
		if strings.HasPrefix(line, "oneof ") {
			if inMessage {
				// message inception. search for the architect. don't forget your totem
				newmsg := new(FormatMsg)
				newmsg.MaxVarname = bigName
				newmsg.MaxVartype = bigType
				newmsg.Lines = append(newmsg.Lines, line)
				getInceptionMsg(newmsg)
				newmsg.Enums = append(newmsg.Oneofs, newmsg)
				continue
			}
		}

		if strings.HasPrefix(line, "enum ") {
			if inMessage {
				// message inception. search for the architect. don't forget your totem
				newmsg := new(FormatMsg)
				newmsg.MaxVarname = bigName
				newmsg.MaxVartype = bigType
				newmsg.Lines = append(newmsg.Lines, line)
				getInceptionMsg(newmsg)
				newmsg.Enums = append(newmsg.Enums, newmsg)
				continue
			}
		}

		if strings.HasPrefix(line, "message ") {
			if inMessage {
				// message inception. search for the architect. don't forget your totem
				newmsg := new(FormatMsg)
				newmsg.MaxVarname = bigName
				newmsg.MaxVartype = bigType
				newmsg.Lines = append(newmsg.Lines, line)
				getInceptionMsg(newmsg)
				newmsg.InceptionMsgs = append(newmsg.InceptionMsgs, newmsg)
				continue

			}
			inMessage = true
			parts := strings.Fields(line)
			if len(parts) > 3 {
				// hack to actually indent comments on the message line itself. you're welcome
				start := parts[0] + " " + parts[1] + " " + parts[2]
				end := strings.Join(parts[3:], " ")
				offset := int(bigName) + int(bigType) + 16 - len(start)
				pad := fmt.Sprintf("%d", offset)
				hmm := "%s     %" + pad + "s %s"
				line = fmt.Sprintf(hmm, start, " ", end)
			}
			newfile += fmt.Sprintln(line)
			continue
		}

		// find the end of the message
		if strings.HasPrefix(line, "}") {
			inMessage = false
			// format and write the last message to the file
			for _, newline := range formatMessage2(fmtmsg) {
				newfile += fmt.Sprintln(newline)
			}
			newfile += fmt.Sprintln(line)
			fmtmsg = new(FormatMsg)
			fmtmsg.MaxVarname = bigName
			fmtmsg.MaxVartype = bigType
			continue
		}

		// don't format or change anything when not in a "message {" section
		if !inMessage {
			newfile += fmt.Sprintln(line)
			continue
		}

		fmtmsg.Lines = append(fmtmsg.Lines, line)
	}

	pf, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
	if err != nil {
		log.Info("file open error. permissions?", filename, err)
		return err
	}
	newfile = strings.TrimSpace(newfile)
	fmt.Fprintln(pf, newfile)
	pf.Close()

	// for i, s := range slices.Backward(pf.ToSort) {
	return nil
}

// returns vartype, varname, id, end
func tokenMsgVar(line string) (string, string, string, string) {
	parts := strings.Split(line, ";")
	front := parts[0]
	end := strings.Join(parts[1:], ";")

	var id string
	var varname string
	var vartype string

	parts = strings.Fields(front)
	parts, id = slicesPop(parts)
	parts, _ = slicesPop(parts) // this is the "=" sign
	parts, varname = slicesPop(parts)
	vartype = strings.Join(parts, " ")

	return vartype, varname, id, end
}

func slicesPop(parts []string) ([]string, string) {
	if len(parts) == 0 {
		return nil, ""
	}
	if len(parts) == 1 {
		return nil, parts[0]
	}
	x := len(parts)
	end := parts[x-1]
	return parts[0 : x-1], end
}

// 'for x := range' syntax using the smartly done golang 1.24 'iter'
func makeLineIter(data []byte) iter.Seq[string] {
	items := strings.Split(string(data), "\n")
	// log.Println("Made All() Iter.Seq[] with length", len(items))
	return func(yield func(string) bool) {
		for _, v := range items {
			if !yield(v) {
				return
			}
		}
	}
}

func getInceptionMsg(curmsg *FormatMsg) {
	for allTheLines.Scan() {
		line := allTheLines.Next()
		if strings.HasPrefix(line, "}") {
			curmsg.Lines = append(curmsg.Lines, line)
			return
		}
		curmsg.Lines = append(curmsg.Lines, line)
	}
}

func formatMessage2(curmsg *FormatMsg) []string {
	var newmsg []string

	// find the max length of varname and vartype
	for _, line := range curmsg.Lines {
		parts := strings.Split(line, ";")
		if len(parts) < 2 {
			// line is blank or just a comment
			continue
		}

		vartype, varname, _, _ := tokenMsgVar(line)
		if len(vartype) > int(curmsg.MaxVartype) {
			curmsg.MaxVartype = int64(len(vartype))
		}
		if len(varname) > int(curmsg.MaxVarname) {
			curmsg.MaxVarname = int64(len(varname))
		}
	}

	for _, line := range curmsg.Lines {
		line = strings.TrimSpace(line)
		if line == "" {
			newmsg = append(newmsg, line)
			continue
		}
		if strings.HasPrefix(line, "//") {
			pad := fmt.Sprintf("%d", curmsg.MaxVartype+curmsg.MaxVarname+21)
			hmm := "%" + pad + "s %s"
			line = fmt.Sprintf(hmm, " ", line) // todo: compute 50
			newmsg = append(newmsg, line)
			continue
		}
		mt := fmt.Sprintf("%d", curmsg.MaxVartype)
		mv := fmt.Sprintf("%d", curmsg.MaxVarname)

		hmm := "        %-" + mt + "s   %-" + mv + "s     = %-3s %s"

		vartype, varname, id, end := tokenMsgVar(line)
		end = strings.TrimSpace(end)
		id = id + ";"

		newline := fmt.Sprintf(hmm, vartype, varname, id, end)
		newline = strings.TrimRight(newline, " ")
		newmsg = append(newmsg, newline)
	}
	return newmsg
}

// DEFINE THE Lines ITERATOR.
// itializes a new iterator.
func newLinesScanner(things []string) *LinesScanner {
	return &LinesScanner{things: things}
}

type LinesScanner struct {
	sync.Mutex

	things []string
	index  int
}

func (it *LinesScanner) Scan() bool {
	if it.index >= len(it.things) {
		return false
	}
	it.Lock()
	it.index++
	it.Unlock()
	return true
}

// Next() returns the next thing in the array
func (it *LinesScanner) Next() string {
	if it.index-1 == len(it.things) {
		fmt.Println("Next() error in LinesScanner", it.index)
	}
	return strings.TrimSpace(it.things[it.index-1])
}

// END DEFINE THE ITERATOR