########################################
# Terraform Configuration
########################################
terraform {
  required_version = ">= 1.6.0"

  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
    random = {
      source  = "hashicorp/random"
      version = "~> 3.6"
    }
  }
}

########################################
# Provider Configuration
########################################
provider "aws" {
  region = var.aws_region

  default_tags {
    tags = merge(
      {
        Project     = var.project_name
        Environment = var.environment
        ManagedBy   = "Terraform"
        CreatedBy   = "Aether"
      },
      var.additional_tags
    )
  }
}

########################################
# VPC
########################################
resource "aws_vpc" "main" {
  cidr_block           = var.vpc_cidr
  enable_dns_support   = true
  enable_dns_hostnames = true

  tags = {
    Name = "${var.project_name}-${var.environment}-vpc"
  }
}

########################################
# Public 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       = data.aws_availability_zones.available.names[count.index]
  map_public_ip_on_launch = true

  tags = {
    Name = "${var.project_name}-${var.environment}-public-subnet-${count.index + 1}"
    Type = "public"
  }
}

########################################
# Private Subnets
########################################
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 = data.aws_availability_zones.available.names[count.index]

  tags = {
    Name = "${var.project_name}-${var.environment}-private-subnet-${count.index + 1}"
    Type = "private"
  }
}

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

  tags = {
    Name = "${var.project_name}-${var.environment}-igw"
  }
}

########################################
# Public 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.main.id
  }

  tags = {
    Name = "${var.project_name}-${var.environment}-public-rt"
  }
}

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 (optional)
########################################
resource "aws_eip" "nat" {
  count = var.create_nat_gateway ? 1 : 0

  domain = "vpc"

  tags = {
    Name = "${var.project_name}-${var.environment}-nat-eip"
  }

  depends_on = [aws_internet_gateway.main]
}

resource "aws_nat_gateway" "main" {
  count = var.create_nat_gateway ? 1 : 0

  allocation_id = aws_eip.nat[0].id
  subnet_id     = aws_subnet.public[0].id

  tags = {
    Name = "${var.project_name}-${var.environment}-nat"
  }

  depends_on = [aws_internet_gateway.main]
}

########################################
# Private Route Table
########################################
resource "aws_route_table" "private" {
  vpc_id = aws_vpc.main.id

  tags = {
    Name = "${var.project_name}-${var.environment}-private-rt"
  }
}

resource "aws_route" "private_nat" {
  count = var.create_nat_gateway ? 1 : 0

  route_table_id         = aws_route_table.private.id
  destination_cidr_block = "0.0.0.0/0"
  nat_gateway_id         = aws_nat_gateway.main[0].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
}

########################################
# S3 Bucket for Application Data
########################################
resource "aws_s3_bucket" "app_data" {
  bucket = "${var.project_name}-${var.environment}-app-data-${random_id.bucket_suffix.hex}"

  tags = {
    Name        = "${var.project_name}-${var.environment}-app-data"
    Description = "Application data storage"
  }
}

resource "aws_s3_bucket_versioning" "app_data" {
  bucket = aws_s3_bucket.app_data.id

  versioning_configuration {
    status = var.enable_s3_versioning ? "Enabled" : "Disabled"
  }
}

resource "aws_s3_bucket_public_access_block" "app_data" {
  bucket = aws_s3_bucket.app_data.id

  block_public_acls       = true
  block_public_policy     = true
  ignore_public_acls      = true
  restrict_public_buckets = true
}

########################################
# Random ID for unique bucket naming
########################################
resource "random_id" "bucket_suffix" {
  byte_length = 4
}

########################################
# Data Sources
########################################
data "aws_availability_zones" "available" {
  state = "available"
}

data "aws_caller_identity" "current" {}

data "aws_region" "current" {}