main.tf

provider "aws" {
  region = var.region
}

resource "aws_iam_role" "lambda_exec_role" {
  name = "lambda_exec_role"
  assume_role_policy = <<EOF
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Action": "sts:AssumeRole",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Effect": "Allow"
    }
  ]
}
EOF
}

resource "aws_iam_role_policy" "lambda_policy" {
  name   = "lambda_dynamodb_policy"
  role   = aws_iam_role.lambda_exec_role.id

  policy = jsonencode({
    Version = "2012-10-17"
    Statement = [
      {
        Action = [
          "dynamodb:PutItem",
          "dynamodb:GetItem",
          "dynamodb:UpdateItem",
          "dynamodb:DeleteItem"
        ]
        Effect   = "Allow"
        Resource = aws_dynamodb_table.users_table.arn
      },
      {
        Action = "logs:CreateLogGroup"
        Effect = "Allow"
        Resource = "arn:aws:logs:*:*:*"
      },
      {
        Action = [
          "logs:CreateLogStream",
          "logs:PutLogEvents"
        ]
        Effect = "Allow"
        Resource = "arn:aws:logs:*:*:log-group:/aws/lambda/*:*"
      }
    ]
  })
}


resource "aws_lambda_function" "users_lambda" {
  function_name = "users_lambda"
  role          = aws_iam_role.lambda_exec_role.arn
  handler       = "lambda_function.lambda_handler"
  runtime       = "python3.8"

  filename = "${path.module}/lambda.zip" # Pointing to the local file

  environment {
    variables = {
      table_name = aws_dynamodb_table.users_table.name
    }
  }
}

resource "aws_dynamodb_table" "users_table" {
  name         = "users_table"
  billing_mode = "PAY_PER_REQUEST"
  hash_key     = "user_id"

  attribute {
    name = "user_id"
    type = "S"
  }
}

# API Gateway setup
resource "aws_api_gateway_rest_api" "users_api" {
  name = "users_api"
}

resource "aws_api_gateway_resource" "users_resource" {
  rest_api_id = aws_api_gateway_rest_api.users_api.id
  parent_id   = aws_api_gateway_rest_api.users_api.root_resource_id
  path_part   = "users"
}

resource "aws_api_gateway_method" "users_method" {
  rest_api_id   = aws_api_gateway_rest_api.users_api.id
  resource_id   = aws_api_gateway_resource.users_resource.id
  http_method   = "POST"
  authorization = "NONE"
}

resource "aws_api_gateway_integration" "users_integration" {
  rest_api_id             = aws_api_gateway_rest_api.users_api.id
  resource_id             = aws_api_gateway_resource.users_resource.id
  http_method             = aws_api_gateway_method.users_method.http_method
  integration_http_method = "POST"
  type                    = "AWS_PROXY"
  uri                     = aws_lambda_function.users_lambda.invoke_arn
}

resource "aws_lambda_permission" "allow_api_gateway" {
  statement_id  = "AllowExecutionFromAPIGateway"
  action        = "lambda:InvokeFunction"
  function_name = aws_lambda_function.users_lambda.arn
  principal     = "apigateway.amazonaws.com"
  source_arn    = "${aws_api_gateway_rest_api.users_api.execution_arn}/*/*"
}

resource "aws_api_gateway_deployment" "users_deployment" {
  depends_on = [aws_api_gateway_integration.users_integration]
  rest_api_id = aws_api_gateway_rest_api.users_api.id
  stage_name  = "prod"
}

output "api_gateway_url" {
  value = "${aws_api_gateway_deployment.users_deployment.invoke_url}/users"
}

output "lambda_function_arn" {
  value = aws_lambda_function.users_lambda.arn
}

output "dynamodb_table_name" {
  value = aws_dynamodb_table.users_table.name
}