# Fetaching the details of the availablity zones

data "aws_availability_zones" "az" {
  state = "available"
}

# creating VPC

resource "aws_vpc" "main" {
  cidr_block           = var.vpc_cidr
  instance_tenancy     = "default"
  enable_dns_support   = true
  enable_dns_hostnames = true
  tags = {
    Name = "${var.project_name}-${var.project_env}"
  }
}

#Creating IGW

resource "aws_internet_gateway" "igw" {
  vpc_id = aws_vpc.main.id
  tags = {
    Name = "${var.project_name}-${var.project_env}"
  }
}
# Creating subnets

resource "aws_subnet" "public" {
  count                   = 3
  vpc_id                  = aws_vpc.main.id
  cidr_block              = cidrsubnet(var.vpc_cidr, 3, count.index)
  availability_zone       = data.aws_availability_zones.az.names["${count.index}"]
  map_public_ip_on_launch = true
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-public-${count.index + 1}"

  }
}

resource "aws_subnet" "private" {
  count                   = 3
  vpc_id                  = aws_vpc.main.id
  cidr_block              = cidrsubnet(var.vpc_cidr, 3, count.index + 3)
  availability_zone       = data.aws_availability_zones.az.names["${count.index}"]
  map_public_ip_on_launch = false
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-private-${count.index + 1}"

  }
}

# creating elastic IP for NAT G/W

resource "aws_eip" "ip" {
  vpc = true
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-"
  }
}


# creating NAT gateway

resource "aws_nat_gateway" "nat" {
  allocation_id = aws_eip.ip.id
  subnet_id     = aws_subnet.public[0].id
  tags = {
    "Name" = "${var.project_name}-${var.project_env}"
  }

  depends_on = [aws_internet_gateway.igw]

}

# Creating Route table

resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.igw.id
  }
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-public"
  }
}
resource "aws_route_table" "private" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block     = "0.0.0.0/0"
    nat_gateway_id = aws_nat_gateway.nat.id
  }
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-private"
  }
}


#Association with the route table

resource "aws_route_table_association" "public" {
  count          = 3
  subnet_id      = aws_subnet.public["${count.index}"].id
  route_table_id = aws_route_table.public.id
}

resource "aws_route_table_association" "private" {
  count          = 3
  subnet_id      = aws_subnet.private["${count.index}"].id
  route_table_id = aws_route_table.private.id
}

# Creating Security group

resource "aws_security_group" "bastion" {
  name_prefix = "${var.project_name}-${var.project_env}-bastion-"
  description = "Allow ssh from my IP only"
  vpc_id      = aws_vpc.main.id

  ingress {
    description      = "22 from my IP"
    from_port        = 22
    to_port          = 22
    protocol         = "tcp"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }

  egress {
    from_port        = 0
    to_port          = 0
    protocol         = "-1"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }

  tags = {
    Name = "${var.project_name}-${var.project_env}-bastion"
  }
}

resource "aws_security_group" "frontend" {
  name_prefix = "${var.project_name}-${var.project_env}-frontend-"
  description = "Allow http,https and ssh"
  vpc_id      = aws_vpc.main.id
  ingress {
    description      = "HTTP port"
    from_port        = 80
    to_port          = 80
    protocol         = "tcp"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }
  ingress {
    description      = "HTTPS port"
    from_port        = 443
    to_port          = 443
    protocol         = "tcp"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }

  ingress {
    description      = "22 from my IP"
    from_port        = 22
    to_port          = 22
    protocol         = "tcp"
    security_groups  = [aws_security_group.bastion.id]
    ipv6_cidr_blocks = ["::/0"]
  }

  egress {
    from_port        = 0
    to_port          = 0
    protocol         = "-1"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }

  tags = {
    Name = "${var.project_name}-${var.project_env}-frontend"
  }
}

resource "aws_security_group" "backend" {
  name_prefix = "${var.project_name}-${var.project_env}-backend-"
  description = "Allow mysql and ssh port only"
  vpc_id      = aws_vpc.main.id

  ingress {
    description      = "22 from Bastion"
    from_port        = 22
    to_port          = 22
    protocol         = "tcp"
    security_groups  = [aws_security_group.bastion.id]
    ipv6_cidr_blocks = ["::/0"]
  }
  ingress {
    description      = "MYSQL IP"
    from_port        = 3306
    to_port          = 3306
    protocol         = "tcp"
    security_groups  = [aws_security_group.frontend.id]
    ipv6_cidr_blocks = ["::/0"]
  }

  egress {
    from_port        = 0
    to_port          = 0
    protocol         = "-1"
    cidr_blocks      = ["0.0.0.0/0"]
    ipv6_cidr_blocks = ["::/0"]
  }

  tags = {
    Name = "${var.project_name}-${var.project_env}-backend"
  }
}

# Creating ec2-instance

resource "aws_instance" "bastion" {
  ami                    = var.ami
  subnet_id              = aws_subnet.public[0].id
  instance_type          = var.instance_type
  key_name               = "mumbai-new"
  vpc_security_group_ids = [aws_security_group.bastion.id]
  user_data              = file("bastion.sh")
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-bastion"
  }

}

resource "aws_instance" "frontend" {
  ami                    = var.ami
  subnet_id              = aws_subnet.public[0].id
  instance_type          = var.instance_type
  key_name               = "mumbai-new"
  vpc_security_group_ids = [aws_security_group.frontend.id]
  user_data              = file("frontend.sh")
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-frontend"
  }
}

resource "aws_instance" "backend" {
  ami                    = var.ami
  subnet_id              = aws_subnet.private[0].id
  instance_type          = var.instance_type
  key_name               = "mumbai-new"
  vpc_security_group_ids = [aws_security_group.backend.id]
  user_data              = file("backend.sh")
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-backend"
  }
}