/**
 * Copyright 2021 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

locals {
  attached_disks = {
    for disk in var.attached_disks :
    disk.name => merge(disk, {
      options = disk.options == null ? var.attached_disk_defaults : disk.options
    })
  }
  attached_disks_pairs = {
    for pair in setproduct(keys(local.names), keys(local.attached_disks)) :
    "${pair[0]}-${pair[1]}" => { disk_name = pair[1], name = pair[0] }
  }
  attached_region_disks_pairs = {
    for k, v in local.attached_disks_pairs :
    k => v if local.attached_disks[v.disk_name].options.regional
  }
  attached_zone_disks_pairs = {
    for k, v in local.attached_disks_pairs :
    k => v if !local.attached_disks[v.disk_name].options.regional
  }
  on_host_maintenance = (
    var.options.preemptible || var.confidential_compute
    ? "TERMINATE"
    : "MIGRATE"
  )
  iam_members = var.use_instance_template ? {} : {
    for pair in setproduct(keys(var.iam), keys(local.names)) :
    "${pair.0}/${pair.1}" => { role = pair.0, name = pair.1, members = var.iam[pair.0] }
  }
  names = (
    var.use_instance_template ? { (var.name) = 0 } : {
      for i in range(0, var.instance_count) : "${var.name}-${i + 1}" => i
    }
  )
  service_account_email = (
    var.service_account_create
    ? (
      length(google_service_account.service_account) > 0
      ? google_service_account.service_account[0].email
      : null
    )
    : var.service_account
  )
  service_account_scopes = (
    length(var.service_account_scopes) > 0
    ? var.service_account_scopes
    : (
      var.service_account_create
      ? ["https://www.googleapis.com/auth/cloud-platform"]
      : [
        "https://www.googleapis.com/auth/devstorage.read_only",
        "https://www.googleapis.com/auth/logging.write",
        "https://www.googleapis.com/auth/monitoring.write"
      ]
    )
  )
  zones_list = length(var.zones) == 0 ? ["${var.region}-b"] : var.zones
  zones = {
    for name, i in local.names : name => element(local.zones_list, i)
  }
}

resource "google_compute_disk" "disks" {
  for_each = var.use_instance_template ? {} : {
    for k, v in local.attached_zone_disks_pairs :
    k => v if local.attached_disks[v.disk_name].source_type != "attach"
  }
  project = var.project_id
  zone    = local.zones[each.value.name]
  name    = each.key
  type    = local.attached_disks[each.value.disk_name].options.type
  size    = local.attached_disks[each.value.disk_name].size
  image = (
    local.attached_disks[each.value.disk_name].source_type == "image"
    ? local.attached_disks[each.value.disk_name].source
    : null
  )
  snapshot = (
    local.attached_disks[each.value.disk_name].source_type == "snapshot"
    ? local.attached_disks[each.value.disk_name].source
    : null
  )
  labels = merge(var.labels, {
    disk_name = local.attached_disks[each.value.disk_name].name
    disk_type = local.attached_disks[each.value.disk_name].options.type
    # Disk images usually have slashes, which is against label
    # restrictions
    # image     = local.attached_disks[each.value.disk_name].image
  })
  dynamic "disk_encryption_key" {
    for_each = var.encryption != null ? [""] : []
    content {
      raw_key           = var.encryption.disk_encryption_key_raw
      kms_key_self_link = var.encryption.kms_key_self_link
    }
  }
}

resource "google_compute_region_disk" "disks" {
  provider = google-beta
  for_each = var.use_instance_template ? {} : {
    for k, v in local.attached_region_disks_pairs :
    k => v if local.attached_disks[v.disk_name].source_type != "attach"
  }
  project       = var.project_id
  region        = var.region
  replica_zones = var.zones
  name          = each.key
  type          = local.attached_disks[each.value.disk_name].options.type
  size          = local.attached_disks[each.value.disk_name].size
  snapshot = (
    local.attached_disks[each.value.disk_name].source_type == "snapshot"
    ? local.attached_disks[each.value.disk_name].source
    : null
  )
  labels = merge(var.labels, {
    disk_name = local.attached_disks[each.value.disk_name].name
    disk_type = local.attached_disks[each.value.disk_name].options.type
  })
  dynamic "disk_encryption_key" {
    for_each = var.encryption != null ? [""] : []
    content {
      raw_key      = var.encryption.disk_encryption_key_raw
      kms_key_name = var.encryption.kms_key_self_link
    }
  }
}

resource "google_compute_instance" "default" {
  provider                  = google-beta
  for_each                  = var.use_instance_template ? {} : local.names
  project                   = var.project_id
  zone                      = local.zones[each.key]
  name                      = each.key
  hostname                  = var.hostname
  description               = "Managed by the compute-vm Terraform module."
  tags                      = var.tags
  machine_type              = var.instance_type
  min_cpu_platform          = var.min_cpu_platform
  can_ip_forward            = var.can_ip_forward
  allow_stopping_for_update = var.options.allow_stopping_for_update
  deletion_protection       = var.options.deletion_protection
  enable_display            = var.enable_display
  labels                    = var.labels
  metadata = merge(
    var.metadata, try(element(var.metadata_list, each.value), {})
  )

  dynamic "attached_disk" {
    for_each = {
      for resource_name, pair in local.attached_disks_pairs :
      resource_name => local.attached_disks[pair.disk_name]
      if pair.name == each.key
    }
    iterator = config
    content {
      device_name = config.value.name
      mode        = config.value.options.mode
      source = (
        config.value.source_type == "attach"
        ? config.value.source
        : (
          config.value.options.regional
          ? google_compute_region_disk.disks[config.key].id
          : google_compute_disk.disks[config.key].name
        )
      )
    }
  }

  boot_disk {
    initialize_params {
      type  = var.boot_disk.type
      image = var.boot_disk.image
      size  = var.boot_disk.size
    }
    disk_encryption_key_raw = var.encryption != null ? var.encryption.disk_encryption_key_raw : null
    kms_key_self_link       = var.encryption != null ? var.encryption.kms_key_self_link : null
  }

  dynamic "confidential_instance_config" {
    for_each = var.confidential_compute ? [""] : []
    content {
      enable_confidential_compute = true
    }
  }

  dynamic "network_interface" {
    for_each = var.network_interfaces
    iterator = config
    content {
      network    = config.value.network
      subnetwork = config.value.subnetwork
      network_ip = config.value.addresses == null ? null : (
        length(config.value.addresses.internal) == 0
        ? null
        : config.value.addresses.internal[each.value]
      )
      dynamic "access_config" {
        for_each = config.value.nat ? [config.value.addresses] : []
        iterator = addresses
        content {
          nat_ip = addresses.value == null ? null : (
            length(addresses.value.external) == 0 ? null : addresses.value.external[each.value]
          )
        }
      }
      dynamic "alias_ip_range" {
        for_each = config.value.alias_ips != null ? config.value.alias_ips : {}
        iterator = alias_ips
        content {
          subnetwork_range_name = alias_ips.key
          ip_cidr_range         = alias_ips.value[each.value]
        }
      }
    }
  }

  scheduling {
    automatic_restart   = !var.options.preemptible
    on_host_maintenance = local.on_host_maintenance
    preemptible         = var.options.preemptible
  }

  dynamic "scratch_disk" {
    for_each = [
      for i in range(0, var.scratch_disks.count) : var.scratch_disks.interface
    ]
    iterator = config
    content {
      interface = config.value
    }
  }

  service_account {
    email  = local.service_account_email
    scopes = local.service_account_scopes
  }

  dynamic "shielded_instance_config" {
    for_each = var.shielded_config != null ? [var.shielded_config] : []
    iterator = config
    content {
      enable_secure_boot          = config.value.enable_secure_boot
      enable_vtpm                 = config.value.enable_vtpm
      enable_integrity_monitoring = config.value.enable_integrity_monitoring
    }
  }

  # guest_accelerator
}

resource "google_compute_instance_iam_binding" "default" {
  for_each      = local.iam_members
  project       = var.project_id
  zone          = local.zones[each.value.name]
  instance_name = each.value.name
  role          = each.value.role
  members       = each.value.members
  depends_on    = [google_compute_instance.default]
}

resource "google_compute_instance_template" "default" {
  provider         = google-beta
  count            = var.use_instance_template ? 1 : 0
  project          = var.project_id
  region           = var.region
  name_prefix      = "${var.name}-"
  description      = "Managed by the compute-vm Terraform module."
  tags             = var.tags
  machine_type     = var.instance_type
  min_cpu_platform = var.min_cpu_platform
  can_ip_forward   = var.can_ip_forward
  metadata         = var.metadata
  labels           = var.labels

  disk {
    source_image = var.boot_disk.image
    disk_type    = var.boot_disk.type
    disk_size_gb = var.boot_disk.size
    boot         = true
  }

  dynamic "confidential_instance_config" {
    for_each = var.confidential_compute ? [""] : []
    content {
      enable_confidential_compute = true
    }
  }

  dynamic "disk" {
    for_each = local.attached_disks
    iterator = config
    content {
      auto_delete = config.value.options.auto_delete
      device_name = config.value.name
      # Cannot use `source` with any of the fields in
      # [disk_size_gb disk_name disk_type source_image labels]
      disk_type = (
        config.value.source_type != "attach" ? config.value.options.type : null
      )
      disk_size_gb = (
        config.value.source_type != "attach" ? config.value.size : null
      )
      mode = config.value.options.mode
      source_image = (
        config.value.source_type == "image" ? config.value.source : null
      )
      source = (
        config.value.source_type == "attach" ? config.value.source : null
      )
      disk_name = (
        config.value.source_type != "attach" ? config.value.name : null
      )
      type = "PERSISTENT"
    }
  }

  dynamic "network_interface" {
    for_each = var.network_interfaces
    iterator = config
    content {
      network    = config.value.network
      subnetwork = config.value.subnetwork
      dynamic "access_config" {
        for_each = config.value.nat ? [""] : []
        content {}
      }
    }
  }

  scheduling {
    automatic_restart   = !var.options.preemptible
    on_host_maintenance = local.on_host_maintenance
    preemptible         = var.options.preemptible
  }

  service_account {
    email  = local.service_account_email
    scopes = local.service_account_scopes
  }

  lifecycle {
    create_before_destroy = true
  }
}

resource "google_compute_instance_group" "unmanaged" {
  count = (
    var.group != null && !var.use_instance_template ? 1 : 0
  )
  project = var.project_id
  network = (
    length(var.network_interfaces) > 0
    ? var.network_interfaces.0.network
    : ""
  )
  zone        = local.zones_list[0]
  name        = var.name
  description = "Terraform-managed."
  instances = [
    for name, instance in google_compute_instance.default : instance.self_link
  ]
  dynamic "named_port" {
    for_each = var.group.named_ports != null ? var.group.named_ports : {}
    iterator = config
    content {
      name = config.key
      port = config.value
    }
  }
}

resource "google_service_account" "service_account" {
  count        = var.service_account_create ? 1 : 0
  project      = var.project_id
  account_id   = "tf-vm-${var.name}"
  display_name = "Terraform VM ${var.name}."
}