resource "aws_cloudfront_origin_access_control" "form" {
  name                              = "${local.project}-oac"
  description                       = "OAC for the meal-order-manager form origin bucket"
  origin_access_control_origin_type = "s3"
  signing_behavior                  = "always"
  signing_protocol                  = "sigv4"
}

resource "aws_cloudfront_distribution" "form" {
  enabled             = true
  is_ipv6_enabled     = true
  http_version        = "http2and3"
  comment             = "meal-order-manager form hosting"
  default_root_object = "index.html"
  price_class         = "PriceClass_100"
  aliases             = [var.domain_name]

  # Shared org CloudFront WAF (audit M-17), resolved from Parameter Store.
  web_acl_id = data.aws_ssm_parameter.app_web_acl_arn.value

  origin {
    origin_id                = "S3FormOrigin"
    domain_name              = aws_s3_bucket.form.bucket_regional_domain_name
    origin_access_control_id = aws_cloudfront_origin_access_control.form.id
  }

  default_cache_behavior {
    target_origin_id       = "S3FormOrigin"
    viewer_protocol_policy = "redirect-to-https"
    allowed_methods        = ["GET", "HEAD"]
    cached_methods         = ["GET", "HEAD"]
    compress               = true

    # AWS managed policy: CachingDisabled. The form HTML is republished weekly
    # and read through a signed API, so a stale edge copy is worse than an
    # origin fetch.
    cache_policy_id = "4135ea2d-6df8-44a3-9df3-4b5a84be39ad"
  }

  # A request for an object the private origin does not hold returns 403, not
  # 404. Rewriting it to the form keeps deep links working, matching the SAM
  # template.
  custom_error_response {
    error_code         = 403
    response_code      = 200
    response_page_path = "/index.html"
  }

  restrictions {
    geo_restriction {
      restriction_type = "none"
    }
  }

  viewer_certificate {
    acm_certificate_arn      = data.aws_acm_certificate.orders.arn
    ssl_support_method       = "sni-only"
    minimum_protocol_version = "TLSv1.2_2021"
  }

  lifecycle {
    prevent_destroy = true
  }
}