"""Grafana stack: imported VPC, EC2 (Grafana OSS), ALB, SG, Route53, IAM, backup.

The only non-serverless piece in this repo (self-hosted Grafana OSS on a
t4g.small, ARM64, AL2023). Reachability: an internet-facing ALB whose security
group only admits the office CIDRs — there is no Client VPN in the account, so
"VPN-only" is realized as office-IP restriction (the same pattern syslog-server
uses). The instance sits in private subnets, reachable only from the ALB SG and
administered via SSM Session Manager (no SSH, no key pair).

Dashboards/datasources are provisioned as code: CDK uploads ``grafana/`` to an S3
config prefix; instance user-data syncs it on boot and a systemd timer re-syncs,
so the running box is never the source of truth. The gp3 root volume is RETAINed
and snapshotted daily by DLM; ``grafana.db`` lives there.

Config (cdk.json context): grafanaVpcId, grafanaAzs, grafana{Public,Private}SubnetIds,
grafanaDomain, officeCidrs, wildcardCertArn, hostedZoneId/Name, athenaPluginVersion.
"""

import os

from aws_cdk import (
    CfnTag,
    Stack,
    Tags,
)
from aws_cdk import (
    aws_certificatemanager as acm,
)
from aws_cdk import (
    aws_dlm as dlm,
)
from aws_cdk import (
    aws_ec2 as ec2,
)
from aws_cdk import (
    aws_elasticloadbalancingv2 as elbv2,
)
from aws_cdk import (
    aws_elasticloadbalancingv2_targets as elbv2_targets,
)
from aws_cdk import (
    aws_iam as iam,
)
from aws_cdk import (
    aws_route53 as route53,
)
from aws_cdk import (
    aws_route53_targets as route53_targets,
)
from aws_cdk import (
    aws_s3 as s3,
)
from aws_cdk import (
    aws_s3_deployment as s3deploy,
)
from constructs import Construct

EXPORTS_BUCKET = "apm-wo-analysis-exports-328440206208"
CONFIG_PREFIX = "grafana-config"
BACKUP_TAG = "apm-grafana-backup"
GRAFANA_DIR = os.path.join(os.path.dirname(__file__), "..", "..", "grafana")
USERDATA_PATH = os.path.join(
    os.path.dirname(__file__), "..", "assets", "grafana_userdata.sh"
)


class GrafanaStack(Stack):
    def __init__(self, scope: Construct, construct_id: str, **kwargs) -> None:
        super().__init__(scope, construct_id, **kwargs)

        ctx = self.node.try_get_context
        domain = ctx("grafanaDomain")

        # Import the shared seahaven-vpc by explicit attributes (no context
        # lookup, so the offline synth test needs no AWS credentials).
        vpc = ec2.Vpc.from_vpc_attributes(
            self,
            "SeahavenVpc",
            vpc_id=ctx("grafanaVpcId"),
            availability_zones=ctx("grafanaAzs"),
            public_subnet_ids=ctx("grafanaPublicSubnetIds"),
            private_subnet_ids=ctx("grafanaPrivateSubnetIds"),
        )

        # ----- Security groups -----
        alb_sg = ec2.SecurityGroup(
            self,
            "AlbSg",
            vpc=vpc,
            description="apm-wo grafana ALB",
            allow_all_outbound=True,
        )
        for cidr in ctx("officeCidrs"):
            alb_sg.add_ingress_rule(
                ec2.Peer.ipv4(cidr), ec2.Port.tcp(443), f"HTTPS from office {cidr}"
            )

        instance_sg = ec2.SecurityGroup(
            self,
            "InstanceSg",
            vpc=vpc,
            description="apm-wo grafana instance",
            allow_all_outbound=True,
        )
        instance_sg.add_ingress_rule(
            alb_sg, ec2.Port.tcp(3000), "Grafana HTTP from the ALB only"
        )

        # ----- Instance role: Athena query + Glue read + S3 (no static keys) -----
        role = iam.Role(
            self,
            "GrafanaInstanceRole",
            assumed_by=iam.ServicePrincipal("ec2.amazonaws.com"),
            managed_policies=[
                # Session Manager admin access; no SSH / bastion / key pair.
                iam.ManagedPolicy.from_aws_managed_policy_name(
                    "AmazonSSMManagedInstanceCore"
                )
            ],
        )
        role.add_to_policy(
            iam.PolicyStatement(
                sid="AthenaQuery",
                actions=[
                    "athena:StartQueryExecution",
                    "athena:StopQueryExecution",
                    "athena:GetQueryExecution",
                    "athena:GetQueryResults",
                    "athena:GetWorkGroup",
                    "athena:ListWorkGroups",
                ],
                resources=[
                    f"arn:aws:athena:{self.region}:{self.account}:workgroup/apm-wo-analysis"
                ],
            )
        )
        role.add_to_policy(
            iam.PolicyStatement(
                sid="GlueReadOnly",
                actions=[
                    "glue:GetDatabase",
                    "glue:GetDatabases",
                    "glue:GetTable",
                    "glue:GetTables",
                    "glue:GetPartition",
                    "glue:GetPartitions",
                ],
                resources=[
                    f"arn:aws:glue:{self.region}:{self.account}:catalog",
                    f"arn:aws:glue:{self.region}:{self.account}:database/apm_wo_analysis",
                    f"arn:aws:glue:{self.region}:{self.account}:table/apm_wo_analysis/*",
                ],
            )
        )
        bucket = s3.Bucket.from_bucket_name(self, "Exports", EXPORTS_BUCKET)
        # Read the analytics snapshots; read+write athena-results (query output).
        bucket.grant_read(role, "analytics/*")
        bucket.grant_read_write(role, "athena-results/*")
        # Config sync reads the grafana-config prefix.
        bucket.grant_read(role, f"{CONFIG_PREFIX}/*")

        # ----- Instance (Grafana OSS via user-data) -----
        with open(USERDATA_PATH, encoding="utf-8") as fh:
            userdata_script = fh.read()
        userdata_script = (
            userdata_script.replace("__CONFIG_BUCKET__", EXPORTS_BUCKET)
            .replace("__CONFIG_PREFIX__", CONFIG_PREFIX)
            .replace("__PLUGIN_VERSION__", ctx("athenaPluginVersion"))
        )
        user_data = ec2.UserData.for_linux()
        user_data.add_commands(userdata_script)

        instance = ec2.Instance(
            self,
            "Grafana",
            vpc=vpc,
            vpc_subnets=ec2.SubnetSelection(
                subnet_type=ec2.SubnetType.PRIVATE_WITH_EGRESS
            ),
            instance_type=ec2.InstanceType("t4g.small"),
            machine_image=ec2.MachineImage.latest_amazon_linux2023(
                cpu_type=ec2.AmazonLinuxCpuType.ARM_64
            ),
            security_group=instance_sg,
            role=role,
            user_data=user_data,
            require_imdsv2=True,
            block_devices=[
                ec2.BlockDevice(
                    device_name="/dev/xvda",
                    # RETAIN the gp3 root volume (grafana.db lives here), encrypted.
                    volume=ec2.BlockDeviceVolume.ebs(
                        20,
                        volume_type=ec2.EbsDeviceVolumeType.GP3,
                        delete_on_termination=False,
                        encrypted=True,
                    ),
                )
            ],
        )
        Tags.of(instance).add(BACKUP_TAG, "true")

        # ----- ALB (internet-facing, office-IP-restricted, HTTPS) -----
        cert = acm.Certificate.from_certificate_arn(
            self, "WildcardCert", ctx("wildcardCertArn")
        )
        alb = elbv2.ApplicationLoadBalancer(
            self,
            "Alb",
            vpc=vpc,
            internet_facing=True,
            security_group=alb_sg,
            vpc_subnets=ec2.SubnetSelection(subnet_type=ec2.SubnetType.PUBLIC),
        )
        listener = alb.add_listener(
            "Https",
            port=443,
            protocol=elbv2.ApplicationProtocol.HTTPS,
            certificates=[cert],
            # Do NOT auto-open 0.0.0.0/0 on 443 — the ALB SG already scopes
            # ingress to the office CIDRs. open=True would undo that.
            open=False,
        )
        listener.add_targets(
            "GrafanaTarget",
            port=3000,
            protocol=elbv2.ApplicationProtocol.HTTP,
            targets=[elbv2_targets.InstanceTarget(instance, 3000)],
            health_check=elbv2.HealthCheck(
                path="/api/health", healthy_http_codes="200"
            ),
        )

        # ----- Route53 alias grafana.seahaven.com -> ALB -----
        zone = route53.HostedZone.from_hosted_zone_attributes(
            self,
            "SeahavenZone",
            hosted_zone_id=ctx("hostedZoneId"),
            zone_name=ctx("hostedZoneName"),
        )
        route53.ARecord(
            self,
            "GrafanaAlias",
            zone=zone,
            record_name=domain.split(".")[0],
            target=route53.RecordTarget.from_alias(
                route53_targets.LoadBalancerTarget(alb)
            ),
        )

        # ----- Dashboards-as-code: upload grafana/ to the S3 config prefix -----
        s3deploy.BucketDeployment(
            self,
            "GrafanaConfig",
            sources=[s3deploy.Source.asset(GRAFANA_DIR)],
            destination_bucket=bucket,
            destination_key_prefix=CONFIG_PREFIX,
            prune=True,
        )

        # ----- Daily DLM snapshot of the (tagged) instance's volume -----
        dlm_role = iam.Role(
            self,
            "DlmRole",
            assumed_by=iam.ServicePrincipal("dlm.amazonaws.com"),
            managed_policies=[
                iam.ManagedPolicy.from_aws_managed_policy_name(
                    "service-role/AWSDataLifecycleManagerServiceRole"
                )
            ],
        )
        dlm.CfnLifecyclePolicy(
            self,
            "GrafanaBackup",
            description="Daily snapshot of the apm-wo grafana volume",
            state="ENABLED",
            execution_role_arn=dlm_role.role_arn,
            policy_details=dlm.CfnLifecyclePolicy.PolicyDetailsProperty(
                resource_types=["INSTANCE"],
                target_tags=[CfnTag(key=BACKUP_TAG, value="true")],
                schedules=[
                    dlm.CfnLifecyclePolicy.ScheduleProperty(
                        name="daily",
                        create_rule=dlm.CfnLifecyclePolicy.CreateRuleProperty(
                            interval=24, interval_unit="HOURS", times=["07:00"]
                        ),
                        retain_rule=dlm.CfnLifecyclePolicy.RetainRuleProperty(count=7),
                    )
                ],
            ),
        )