=================================
Source Code Repository Servers
=================================

=> In a project multiple developers will work

=> Developers may work from different locations

=> We are going face below challenges with team work.

1) How to integrate all the team members code at one place ?

2) How to monitor code changes ?

=> To handle above 2 problems we can use Source Code Repository servers.

=> Below softwares we can use as source code repository servers 

		a) SVN (outdated)
		
		b) GIT Hub (Microsoft)
		
		c) BitBucket (Atlasian)
		
========
Git Hub 
========

=> Git Hub is a cloud platform which is used to maintain source code repositories for our projects.

=> Git Hub will provide monitored access for code repositories

		- who modified
		- when modified
		- why modified
		- what modified
		
===================		
Environment Setup		
===================

Step-1 :: Create github account (free of cost)

Step-2 :: Download and install git client s/w

Note: Git client s/w is used to communicate with git hub repositories.		

Step-3 :: Open gitbash & Configure Name and email in gitbash using below commands (one time setup)

git config --global user.name "Ashok"

git config --global  user.email "ashokitschool@gmail.com"

=================
Git Architecture
=================		

1) Working Tree

2) Staging Area

3) Local Repository

4) Central Repository


==================
Git Bash commands
==================

git init : Intialize working tree

git status : Check working tree status (staged or not)

git add  : Add files to staging area (making eligible for commit)

git commit : Commit staged files to local repo 

git push : Publish local commits to central repo

git restore : To unstage the file and to discard file changes 

Note: git restore will work based on current status of the file.

if file is unstaged ==> It will discard changes made to file 

if file is staged ==> It will unstage the file.

git log : To display commmit history.

git rm : To delete file (rm + commit + push)

git clone : Download central repo to our system.

git pull : Download latest code changes from central to local.

####  Note: git pull may give conflict problem. ####

git gui : To open git gui tool.

==========================
How to generate git token
==========================

=> Login into github account 

=> Go to Profile => Settings

=> Developer Settings ==> Personal Access Tokens

=> Generate Classic token (select all checkboxes)

=> COpy that token and save it in a seperate file 

=========================================
How to push project into git repo
=========================================

Step-1 : Create springboot application using start.spring.io

Step-2 : Download and extract that application

Step-3 : Create git central repo

Step-4 : Go inside project directory and open git bash

Step-5 : Execute git commands to push project code into central repo 

-----------------------------------------------

echo "# ecomm_store_app" >> README.md
git init
git add .
git commit -m "first commit"
git branch -M main
git remote add origin https://github.com/ashokitschool/ecomm_store_app.git
git push -u origin main

-----------------------------------------------

==============
Git branches
==============

=> Multiple teams will be working paralelly in single project like below

		a) Development team 
		b) CR team 
		c) PROD Support team
		d) R & D team
		

=> When all the above teams integrated code in central repo then it will become difficult to deliver particular team code changes to live environment.

=> To overcome this problem we will use 'git branches' concept.

=> In Git Repo we will have one default branch called 'main'

=> We can create any no.of repositories under one git repo

		a) main
		b) develop
		c) feature
		d) feature_JIRA_321
		e) release
		d) research
		
Note: Management will decide branching strategy (which team should use which branch).

# clone main branch directley
git clone https://github.com/ashokitschool/ecomm_store_app.git

# clone given branch code
git clone -b <branch-name> <repo-url>

# branch switch
git switch <branch-name>

=======================
Working with branches
=======================

Step-1 : Go to git central repo and create branches 

Step-2 : Clone git central repo 

	ex : git clone <repo-url>

Step-3 : Switch from main branch to develop branch

	ex: git switch develop
	
Step-4 : Commit files to develop branch

Step-5 : Create pull request and merge develop branch changes to main branch.	

=============================
What is Pull Request (PR) ?
=============================

=> Pull Request is used to merge changes from one branch to another branch.

==============
Git conflicts
==============

=> Git conflicts can occur in below 2 scenarios

		a) git pull 
		
		b) branch merging		

Note: If 2 persons modified same file and same lines then git pull will give conflicts.	

=> When conflict occurs then it is our responsibility to resolve that conflict and push code to central repo without conflicts.	

============================
How to add Collobarators ?
============================

=> Collobarators means giving access permissions for our git central repo to make code commits.

=> Git Repo => Settings => Colloborators => Add People.

Note: After adding person, they will recieve email invitation to accept.

======================
What is git forking ?
======================

=> Git fork is a copy of repository

=> It is used to copy someone's git repository into our github account.

Note: When we want to experiment on some open source public repositories then we can use git fork option.

===================================
Q) how to remove git local commits
===================================

=> Using git reset command we can undo local commits 

=> Git Reset we can do in 2 ways 

		a) soft reset 
		
		b) hard reset
		
=> soft reset means only local commit will be deleted and file changes will be there in staging area.

	Ex : git reset --soft HEAD~1

=> hard reset means local commit will be deleted and file changes also will be deleted from working tree.

	Ex : git reset --hard HEAD~1

===========================================
Q) how to revert git central repo commits
============================================

=> Using 'git revert' command we can revert code changes from central repo.

Ex : git revert <commit-id>

Note: After git revert execution we need execute git push.

=======================
Q) what is git stash 
=======================

9:00 AM => JIRA-101 assigned to me.

12:00 PM => half of the task completed.

12:30 PM => priority task JIRA-102 assigned.

Note: I should complete JIRA-102 first and push changes to central repo.

=> In this scenario we will stash 101 changes and we will work on 102 changes.

=> After 102 changes are pushed then we will get stashed changes back to working tree using 'git stash apply' command.

=========================
Q) git pull vs git fetch
=========================

=> git pull command will download latest code changes from central repo to working tree directley.

=> git fetch command will download latest code changes from central to local repo only.

Note: To get changes from local to working tree we can use git merge command.

	git pull = git fetch + git merge

=========================
Q) git merge vs rebase
=========================

git clone https://github.com/ashokitschool/ecomm_store_app.git

cd ecomm_store_app

git switch develop

touch f1.txt f2.txt
git add .
git commit -m 'f1 f2 added in develop'
git push

git switch main

git merge develop (or) git rebase develop

git log

===========================
Q) what is git cherrypic
===========================

=> When we use 'git merge' command by default all commits will merge from one branch to another branch.

=> If we want to merge specific commit from one branch to another branch then we can use 'git cherrypic'.

Ex : git cherrypic <commit-id>


==============================
Q) what is .gitignore file ?
==============================

=> It is used to skip unwanted files and folders from our git commits.

Ex : 

target/

.classpath
.project

node_modules/


=========
Summary
==========

1) What is version control software
2) Version softwares available in market
3) Git Hub Intro
4) Git Client
5) Git Architecture
	 - working tree
	 - staging area
	 - local repo 
	 - central/remote repo
	 
6) Public Vs Private repo
7) Repo colloborators
8) Git Bash commands
		
		git config
		git init 
		git add 
		git status
		git commit 
		git push
		git clone 
		git pull
		git fetch
		git log
		git rm
		git restore
		git reset
		git revert
		git branch 
		git switch 
		git checkout
		git cherrypic
		git merge
		git rebase
		
9) Git GUI

10) Git branches

11) Git conflicts

12) Pull Request (PR)

13) Git Forking

14) What is .gitignore file

15) What is BitBucket



Note: In realtime DevOps team is responsible to create source code repositories required for the project.

Note : DevOps team will decide branching strategy (which team should work on which branch, client delivery should happen from which branch).

Note: As a developer we can create any no.of branches under repository.