provider "aws" {
  region     = "ap-south-1"
  access_key = "AKIA5YKGNPEXMXI3AEUM"
  secret_key = "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"
  default_tags {
    tags = {

      "Env"     = var.project_env,
      "Project" = var.project_name
    }
  }
}


# Should you choose to have a nat gateway to allow internet connectivity on private subnet

variable "nat" {
  type    = bool
  default = "false"

}


# Fetaching the details of the availablity zones

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

locals {
  az = length(data.aws_availability_zones.az.names)

}

# 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                   = local.az
  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                   = local.az
  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 if var =true

resource "aws_eip" "ip_true" {

  count = var.nat == true ? 1 : 0
  vpc   = true
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-Nat"
  }
}



resource "aws_nat_gateway" "nat_true" {
  count         = var.nat == true ? 1 : 0
  allocation_id = aws_eip.ip_true[0].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"
  }
}

# Creating route table if var = true

resource "aws_route_table" "private_true" {
  count  = var.nat == true ? 1 : 0
  vpc_id = aws_vpc.main.id

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


# Creating route table if var = false

resource "aws_route_table" "private_false" {
  count  = var.nat == false ? 1 : 0
  vpc_id = aws_vpc.main.id
  tags = {
    "Name" = "${var.project_name}-${var.project_env}-private"
  }
}



#Association with the route table

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

resource "aws_route_table_association" "nat_enabled" {
  count          = var.nat == true ? local.az : 0
  subnet_id      = aws_subnet.private["${count.index}"].id
  route_table_id = aws_route_table.private_true[0].id
}

resource "aws_route_table_association" "nat_disabled" {
  count          = var.nat == false ? local.az : 0
  subnet_id      = aws_subnet.private["${count.index}"].id
  route_table_id = aws_route_table.private_false[0].id
}