# VPC
resource "aws_vpc" "main" {
  cidr_block = var.vpc_cidr
}

# Subnets
resource "aws_subnet" "public" {
  count             = length(var.public_subnet_cidrs)
  vpc_id            = aws_vpc.main.id
  cidr_block        = var.public_subnet_cidrs[count.index]
  availability_zone = var.availability_zones[count.index]
  map_public_ip_on_launch = true
}

resource "aws_subnet" "private" {
  count             = length(var.private_subnet_cidrs)
  vpc_id            = aws_vpc.main.id
  cidr_block        = var.private_subnet_cidrs[count.index]
  availability_zone = var.availability_zones[count.index]
}

# Internet Gateway
resource "aws_internet_gateway" "main" {
  vpc_id = aws_vpc.main.id
}

# Route Table for Public Subnets
resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = aws_internet_gateway.main.id
  }
}

resource "aws_route_table_association" "public" {
  count          = length(aws_subnet.public)
  subnet_id      = aws_subnet.public[count.index].id
  route_table_id = aws_route_table.public.id
}

# NAT Gateway
resource "aws_eip" "nat" {
  vpc = true
}

resource "aws_nat_gateway" "main" {
  allocation_id = aws_eip.nat.id
  subnet_id     = aws_subnet.public[0].id
}

# Route Table for Private Subnets
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.main.id
  }
}

resource "aws_route_table_association" "private" {
  count          = length(aws_subnet.private)
  subnet_id      = aws_subnet.private[count.index].id
  route_table_id = aws_route_table.private.id
}