# Golang Large Function Refactoring

## Simple One

### FROM (❌)

if (isAlimSick) {
	var isAlimRequiredDoctor = isRequiredAssistanceFromHospital(isSick, alimPaitent);
	if(isAlimRequiredDoctor) {
		var findAllHospitals = GetHospitals(...);
		
		var suitableHospital = GetSuitableHospital(findAllHospitals, alimPaitent);
	
		return suitableHospital;
	}
}

### TO (✔)

if (isAlimNotSick) {
	return null;
}


// alim sick

var isAlimRequiredDoctor = isRequiredAssistanceFromHospital(isSick, alimPaitent);

if (!isAlimRequiredDoctor) {
	return null;
}


var findAllHospitals = GetHospitals(...);

var suitableHospital = GetSuitableHospital(findAllHospitals, alimPaitent);

return suitableHospital;

## Comparing

- [Version 1](https://pastebin.ubuntu.com/p/PyKrZknY5r/)
- [Version 2](https://pastebin.ubuntu.com/p/vR6zhCnC5Z/)
- [Version 3](https://pastebin.ubuntu.com/p/kZWPhzhJ5T/)

## Version 1 : Initial

[Version 1](https://pastebin.ubuntu.com/p/PyKrZknY5r/) Current code is in level 4 nesting. Which is too complex in terms of unit testing.

Our goal is to reduce that code branching or nesting to level 1, by following all the review guides from [Golang code review guides by Md. Alim Ul Karim](https://hackmd.io/@akarimevatix/golang-review-guides)

### Level 4 nesting indications


package main

import (
	"fmt"
	"strings"

	"github.com/jinzhu/copier"
)

func makeFinalTimezone(timezoneNames []TimezoneName, wikiCsv []WikiTimezone) {
	var finalTimezone []FinalTimezone
	copier.Copy(&finalTimezone, &wikiCsv)

	for index, wiki := range wikiCsv {
		if wiki.TimezoneName == "-" {
			var foundInNamesByDatabaseName = searchInTimezoneNames(timezoneNames, wiki.DatabaseName)
			if foundInNamesByDatabaseName == "-" {
				fmt.Println("Not Found In Timezones for", wiki.DatabaseName)

				if strings.Contains(wiki.Notes, "Link to") {
					// Get value from Link To
					fmt.Println("Get Link to For wiki.DatabaseName", wiki.Notes)

					// split with Link To
					searchingFor := strings.TrimSpace(wiki.Notes[7:])
					fmt.Println("Split searchingFor ::", searchingFor)
					var foundInNames = searchInTimezoneNames(timezoneNames, searchingFor)

					if foundInNames != "-" {
						finalTimezone[index].TimezoneName = foundInNames
					} else {
						foundInWiki := searchInWikiByLinkToNote(wikiCsv, searchingFor)
						finalTimezone[index].TimezoneName = foundInWiki
					}
				}
			} else {
				finalTimezone[index].TimezoneName = foundInNamesByDatabaseName
			}
		}
	}

	fmt.Printf("Field: %+v\n", finalTimezone)
	writeFinalCSV(finalTimezone)
}

## Version 2 : Improved

[Version 2](https://pastebin.ubuntu.com/p/vR6zhCnC5Z/)

package main

import (
	"fmt"
	"strings"

	"github.com/jinzhu/copier"

	"gitlab.com/evatix-go/localization/cmd/main/constants"
)

type InvalidTimezoneInputParameters struct {
	hasInvalidTimezoneName bool
	timezoneNames          *[]TimezoneName
	wikiCsv                *[]WikiTimezone
	wiki                   *WikiTimezone
	finalTimezone          *FinalTimezone
	finalTimezones         *[]FinalTimezone
	index                  int
}

func makeFinalTimezone(
	timezoneNames *[]TimezoneName,
	wikiCsv *[]WikiTimezone,
) {
    	var finalTimezones *[]FinalTimezone
	copier.Copy(&finalTimezones, wikiCsv)	

	for index, wiki := range *wikiCsv {
		finalTimezone := (*finalTimezones)[index]

		invalidTimezoneInputParameters := InvalidTimezoneInputParameters{
			hasInvalidTimezoneName: hasInvalidTimeZoneName(wiki.TimezoneName),
			timezoneNames:          timezoneNames,
			wikiCsv:                wikiCsv,
			wiki:                   &wiki,
			finalTimezone:          &finalTimezone,
			finalTimezones:         finalTimezones,
			index:                  index,
		}

		ProcessInvalidTimezoneName(&invalidTimezoneInputParameters)
	}

	fmt.Printf("Field: %+v\n", finalTimezones)
	writeFinalCSV(finalTimezones)
}

func ProcessInvalidTimezoneName(
	invalidTimezoneInputParameters *InvalidTimezoneInputParameters,
) {
	var foundInNamesByDatabaseName = searchInTimezoneNames(
		invalidTimezoneInputParameters.timezoneNames,
		invalidTimezoneInputParameters.wiki.DatabaseName)

	if hasValidTimeZoneName(foundInNamesByDatabaseName) {
		invalidTimezoneInputParameters.finalTimezone.TimezoneName = foundInNamesByDatabaseName
	} else {
		// invalid case , foundInNamesByDatabaseName == constants.InvalidEntryWithHyphen
		fmt.Println("Not Found In Timezones for", invalidTimezoneInputParameters.wiki.DatabaseName)

		populatedTimezone := GetPopulatedTimezoneNameInTimezone(
			invalidTimezoneInputParameters.timezoneNames,
			invalidTimezoneInputParameters.wikiCsv,
			invalidTimezoneInputParameters.wiki,
			invalidTimezoneInputParameters.finalTimezone)

		// here this step is redundant, just calling GetPopulatedTimezoneNameInTimezone
		// should be suffice, then it is doing some magic,
		// which requires future investigation on how it is set to the list again
		// any mistake in understanding could cause lots of hours.
		// As as result, to keep things simple, always get value and put the updated one
		// so that it make sense and also goes by the review process, not reassigning to the same variable again.

		finalTimezones := *invalidTimezoneInputParameters.finalTimezones
		finalTimezones[invalidTimezoneInputParameters.index] = *populatedTimezone
	}
}

// Finds Timezone name using the last part of
// Links to keyword and then puts the right
// timezone name in the FinalTimezone object and returns it.
func GetPopulatedTimezoneNameInTimezone(
	timezoneNames *[]TimezoneName,
	wikiCsv *[]WikiTimezone,
	wiki *WikiTimezone,
	finalTimezone *FinalTimezone,
) *FinalTimezone {
	isNotContainsLinkTo := !strings.Contains(wiki.Notes, constants.LinksTo)

	if isNotContainsLinkTo {
		// the first rejection case
		return finalTimezone
	}

	// here we are expecting that constants.LinksTo exist
	// notes contains constants.LinksTo

	// Get value from Link To
	fmt.Println("Get Link to For wiki.DatabaseName", wiki.Notes)

	// split with Link To
	searchingFor := strings.TrimSpace(wiki.Notes[7:])
	fmt.Println("Split searchingFor ::", searchingFor)
	foundInNames := searchInTimezoneNames(timezoneNames, searchingFor)
	hasTimezoneName := hasValidTimeZoneName(foundInNames)

	if hasTimezoneName {
		finalTimezone.TimezoneName = foundInNames

		return finalTimezone
	}

	foundInWiki := searchInWikiByLinkToNote(*wikiCsv, searchingFor)
	finalTimezone.TimezoneName = foundInWiki

	return finalTimezone
}

### Important Notes

// here this step is redundant, just calling GetTimezoneNameFromLinksToReference
// should be suffice, then it is doing some magic,
// which requires future investigation on how it is set to the list again
// any mistake in understanding could cause lots of hours.
// As as result, to keep things simple, always get value and put the updated one
// so that it make sense and also goes by the review process, not reassigning to the same variable again.

## Version 3 : Final Improvements

[Version 3](https://pastebin.ubuntu.com/p/kZWPhzhJ5T/)
Use return value as best practice to apply all the review parameters.

Here we have at most level 1 nesting.

package main

import (
	"fmt"
	"strings"

	"github.com/jinzhu/copier"

	"gitlab.com/evatix-go/localization/cmd/main/constants"
)

type InvalidTimezoneInputParameters struct {
	hasInvalidTimezoneName bool
	timezoneNames          *[]TimezoneName
	wikiCsv                *[]WikiTimezone
	wiki                   *WikiTimezone
	finalTimezones         *[]FinalTimezone
	index                  int
}

func makeFinalTimezone(
	timezoneNames *[]TimezoneName,
	wikiCsv *[]WikiTimezone,
) {
	finalTimezones := getCopyFromWikiToFinalTimezones(wikiCsv)

	for index, wiki := range *wikiCsv {
		invalidTimezoneInputParameters := InvalidTimezoneInputParameters{
			hasInvalidTimezoneName: hasInvalidTimeZoneName(wiki.TimezoneName),
			timezoneNames:          timezoneNames,
			wikiCsv:                wikiCsv,
			wiki:                   &wiki,
			finalTimezones:         finalTimezones,
			index:                  index,
		}

		ProcessInvalidTimezoneName(&invalidTimezoneInputParameters)
	}

	fmt.Printf("Field: %+v\n", finalTimezones)
	writeFinalCSV(finalTimezones)
}

func ProcessInvalidTimezoneName(
	invalidTimezoneInputParameters *InvalidTimezoneInputParameters,
) {
	foundInNamesByDatabaseName := searchInTimezoneNames(
		invalidTimezoneInputParameters.timezoneNames,
		invalidTimezoneInputParameters.wiki.DatabaseName)

	index := invalidTimezoneInputParameters.index
	finalTimezones := *invalidTimezoneInputParameters.finalTimezones
	finalTimezone := finalTimezones[index]
	finalTimezone.TimezoneName = GetTimezoneFinalNameInCaseOfInvalid(
		invalidTimezoneInputParameters,
		foundInNamesByDatabaseName)    
    
	// needs to be assigned back
	finalTimezones[index] = finalTimezone
}

func getCopyFromWikiToFinalTimezones(
    fromWikiCsv *[]WikiTimezone) *[]FinalTimezone {
	var toFinalTimezones []FinalTimezone
	wikiCopier := *fromWikiCsv
    
        // https://github.com/jinzhu/copier
        // it doesn't work with pointer to pointer directly.
	copier.Copy(&toFinalTimezones, &wikiCopier)

	return &toFinalTimezones
}

func GetTimezoneFinalNameInCaseOfInvalid(
	invalidTimezoneInputParameters *InvalidTimezoneInputParameters,
        foundInNamesByDatabaseName string,
) string {
	if hasValidTimeZoneName(foundInNamesByDatabaseName) {
		return foundInNamesByDatabaseName
	}

	// invalid case , foundInNamesByDatabaseName == constants.InvalidEntryWithHyphen
	fmt.Println("Not Found In Timezones for", invalidTimezoneInputParameters.wiki.DatabaseName)

	timeZoneFinalName := GetTimezoneNameFromLinksToReference(
		invalidTimezoneInputParameters.timezoneNames,
		invalidTimezoneInputParameters.wikiCsv,
		invalidTimezoneInputParameters.wiki)

	return timeZoneFinalName
}

// Finds Timezone name using the last part of
// Links to keyword and then puts the right
// timezone name in the FinalTimezone object and returns it.
func GetTimezoneNameFromLinksToReference(
	timezoneNames *[]TimezoneName,
	wikiCsv *[]WikiTimezone,
	wiki *WikiTimezone,
) string {
	isNotContainsLinkTo := !strings.Contains(wiki.Notes, constants.LinksTo)
	if isNotContainsLinkTo {
		return constants.InvalidEntryWithHyphen
	}

	// here we are expecting that constants.LinksTo exist
	fmt.Println("Get Link to For wiki.DatabaseName", wiki.Notes)
	searchingFor := strings.TrimSpace(wiki.Notes[7:])
	fmt.Println("Split searchingFor ::", searchingFor)
	foundInNames := searchInTimezoneNames(timezoneNames, searchingFor)
	hasTimezoneName := hasValidTimeZoneName(foundInNames)

	if hasTimezoneName {
		return foundInNames
	}

	foundInWiki := searchInWikiByLinkToNote(*wikiCsv, searchingFor)

	return foundInWiki
}