import type { KubernetesObject, V1Deployment } from "@kubernetes/client-node";
import type { ComposeSpecification } from "../schema/docker.d";
import { LABELS } from "../const";
import {
  applyResource,
  getStaleResources,
  listManagedResources,
  sortResources,
} from "../lib/apply";
import {
  DATABASE_NAMESPACE,
  getComposePostgresClaims,
  getRoleCredentials,
  listManagedDatabaseResources,
  reconcilePostgresClaims,
  type PostgresClaim,
  type RoleCredentials,
} from "../lib/database";
import {
  buildNamespaceGraphs,
  fetchNamespaceObjects,
  type NamespaceGraph,
} from "../lib/graph";
import {
  planRollback,
  rollbackDeployment,
  type RollbackCandidate,
} from "../lib/rollback";
import {
  listManagedDeployments,
  restartDeployment,
  scaleDeployment,
  waitForDeploymentRollout,
} from "../lib/shared";
import {
  getComposeS3Claims,
  getS3Credentials,
  listManagedStorageResources,
  reconcileS3Claims,
  STORAGE_NAMESPACE,
  type S3Claim,
} from "../lib/storage";

export const WORKSPACE_UID_LABEL = "kuber.dev/workspace-uid";
export const WORKSPACE_PROJECT_LABEL = "kuber.dev/project";

export const RESERVED_NAMESPACES = new Set([
  "default",
  "kube-system",
  "kube-public",
  "kube-node-lease",
  "kuber-system",
  DATABASE_NAMESPACE,
  STORAGE_NAMESPACE,
]);

export type Workspace = {
  project: string;
  uid: string;
};

export type NamespaceRecord = {
  uid?: string;
  labels?: Record<string, string>;
};

export type NamespaceSafety = {
  project: string;
  status: "missing" | "owned" | "external" | "different-workspace";
  namespaceUid?: string;
};

export type ResourceIdentity = {
  apiVersion: string;
  kind: string;
  name: string;
  namespace?: string;
  uid: string;
  workspaceUid: string;
};

export type ResourcePlan = {
  desired: KubernetesObject[];
  stale: ResourceIdentity[];
};

export type DownPlan = {
  full: boolean;
  retained: ResourceIdentity[];
  delete: ResourceIdentity[];
};

export type CredentialMetadata = {
  service: string;
  provider: "postgres" | "s3";
  principal: string;
  resource: string;
  secretNamespace: string;
  secretName?: string;
};

export type ManagementDependencies = {
  readNamespace(project: string): Promise<NamespaceRecord | undefined>;
  listDeployments(project: string): Promise<V1Deployment[]>;
  scaleDeployment(
    project: string,
    name: string,
    replicas: number,
  ): Promise<unknown>;
  restartDeployment(project: string, name: string): Promise<unknown>;
  waitForDeployment(
    project: string,
    name: string,
    timeoutMs?: number,
  ): Promise<void>;
  fetchGraphObjects(project: string): Promise<KubernetesObject[]>;
  planRollback(project: string, names?: string[]): Promise<RollbackCandidate[]>;
  rollbackDeployment(
    project: string,
    candidate: RollbackCandidate,
  ): Promise<unknown>;
  listProjectResources(project: string): Promise<KubernetesObject[]>;
  listDatabaseResources(project: string): Promise<KubernetesObject[]>;
  listStorageResources(project: string): Promise<KubernetesObject[]>;
  findStaleResources(
    project: string,
    desired: KubernetesObject[],
  ): Promise<KubernetesObject[]>;
  applyResource(resource: KubernetesObject): Promise<KubernetesObject>;
  deleteResource(identity: ResourceIdentity): Promise<void>;
  reconcileDatabases(
    project: string,
    compose: ComposeSpecification,
  ): Promise<Record<string, Record<string, string>>>;
  getDatabaseCredentials(username: string): Promise<RoleCredentials>;
  reconcileStorage(
    project: string,
    compose: ComposeSpecification,
  ): Promise<Record<string, Record<string, string>>>;
  getStorageCredentials(claim: S3Claim): Promise<Record<string, string>>;
};

export type ManagementService = ReturnType<typeof createManagementService>;

const defaultOperations: Omit<
  ManagementDependencies,
  "readNamespace" | "deleteResource"
> = {
  listDeployments: async () => listManagedDeployments(),
  scaleDeployment: async (_project, name, replicas) =>
    scaleDeployment(name, replicas),
  restartDeployment: async (_project, name) => restartDeployment(name),
  waitForDeployment: async (_project, name, timeoutMs) =>
    waitForDeploymentRollout(name, timeoutMs),
  fetchGraphObjects: fetchNamespaceObjects,
  planRollback: async (_project, names) => planRollback(names),
  rollbackDeployment: async (_project, candidate) =>
    rollbackDeployment(candidate),
  listProjectResources: listManagedResources,
  listDatabaseResources: listManagedDatabaseResources,
  listStorageResources: listManagedStorageResources,
  findStaleResources: getStaleResources,
  applyResource,
  reconcileDatabases: reconcilePostgresClaims,
  getDatabaseCredentials: getRoleCredentials,
  reconcileStorage: reconcileS3Claims,
  getStorageCredentials: getS3Credentials,
};

export function managementDependencies(
  infrastructure: Pick<
    ManagementDependencies,
    "readNamespace" | "deleteResource"
  >,
  overrides: Partial<ManagementDependencies> = {},
): ManagementDependencies {
  return { ...defaultOperations, ...infrastructure, ...overrides };
}

function validateWorkspace(workspace: Workspace): void {
  if (!workspace.uid.trim()) throw new Error("Workspace UID is required");
  if (
    !workspace.project ||
    workspace.project.length > 63 ||
    !/^[a-z0-9](?:[-a-z0-9]*[a-z0-9])?$/.test(workspace.project)
  ) {
    throw new Error(`Invalid project namespace ${workspace.project}`);
  }
  if (RESERVED_NAMESPACES.has(workspace.project)) {
    throw new Error(`Namespace ${workspace.project} is reserved`);
  }
}

function resourceName(resource: KubernetesObject): string {
  const name = resource.metadata?.name;
  if (!resource.apiVersion || !resource.kind || !name) {
    throw new Error("Resources require apiVersion, kind, and metadata.name");
  }
  return name;
}

function assertResourceOwnership(
  workspace: Workspace,
  resource: KubernetesObject,
): void {
  const owner = resource.metadata?.labels?.[WORKSPACE_UID_LABEL];
  if (owner !== workspace.uid) {
    throw new Error(
      `${resource.kind}/${resourceName(resource)} is not owned by workspace ${workspace.uid}`,
    );
  }
}

function identity(
  workspace: Workspace,
  resource: KubernetesObject,
): ResourceIdentity {
  assertResourceOwnership(workspace, resource);
  const uid = resource.metadata?.uid;
  if (!uid) {
    throw new Error(
      `${resource.kind}/${resourceName(resource)} has no UID deletion precondition`,
    );
  }
  return {
    apiVersion: resource.apiVersion!,
    kind: resource.kind!,
    name: resourceName(resource),
    namespace: resource.metadata?.namespace,
    uid,
    workspaceUid: workspace.uid,
  };
}

function labelDesired(
  workspace: Workspace,
  resource: KubernetesObject,
): KubernetesObject {
  const name = resourceName(resource);
  const namespace =
    resource.kind === "Namespace"
      ? undefined
      : (resource.metadata?.namespace ?? workspace.project);
  if (resource.kind === "Namespace" && name !== workspace.project) {
    throw new Error(
      `Cannot manage namespace ${name} from project ${workspace.project}`,
    );
  }
  if (namespace && namespace !== workspace.project) {
    throw new Error(
      `Cannot manage ${resource.kind}/${name} in namespace ${namespace}`,
    );
  }
  const existingOwner = resource.metadata?.labels?.[WORKSPACE_UID_LABEL];
  if (existingOwner && existingOwner !== workspace.uid) {
    throw new Error(`${resource.kind}/${name} belongs to another workspace`);
  }
  return {
    ...resource,
    metadata: {
      ...resource.metadata,
      name,
      namespace,
      labels: {
        ...resource.metadata?.labels,
        ...LABELS,
        [WORKSPACE_PROJECT_LABEL]: workspace.project,
        [WORKSPACE_UID_LABEL]: workspace.uid,
      },
    },
  };
}

function labelExternal(
  workspace: Workspace,
  resource: KubernetesObject,
  namespace: string,
): KubernetesObject {
  const name = resourceName(resource);
  if (resource.metadata?.namespace !== namespace) {
    throw new Error(
      `${resource.kind}/${name} is outside expected namespace ${namespace}`,
    );
  }
  const existingOwner = resource.metadata?.labels?.[WORKSPACE_UID_LABEL];
  if (existingOwner && existingOwner !== workspace.uid) {
    throw new Error(`${resource.kind}/${name} belongs to another workspace`);
  }
  const { status: _status, ...body } = resource as KubernetesObject & {
    status?: unknown;
  };
  return {
    ...body,
    metadata: {
      ...body.metadata,
      labels: {
        ...body.metadata?.labels,
        [WORKSPACE_PROJECT_LABEL]: workspace.project,
        [WORKSPACE_UID_LABEL]: workspace.uid,
      },
    },
  };
}

function deploymentNames(deployments: V1Deployment[]): string[] {
  return deployments
    .map((deployment) => deployment.metadata?.name)
    .filter((name): name is string => Boolean(name));
}

function selectTargets(all: string[], requested?: string[]): string[] {
  if (!requested) return all;
  const unique = [...new Set(requested)];
  const available = new Set(all);
  for (const name of unique) {
    if (!available.has(name))
      throw new Error(`No managed deployment named ${name}`);
  }
  return unique;
}

export function createManagementService(dependencies: ManagementDependencies) {
  async function namespaceSafety(
    workspace: Workspace,
  ): Promise<NamespaceSafety> {
    validateWorkspace(workspace);
    const namespace = await dependencies.readNamespace(workspace.project);
    if (!namespace) return { project: workspace.project, status: "missing" };
    const managed =
      namespace.labels?.["app.kubernetes.io/managed-by"] ===
      LABELS["app.kubernetes.io/managed-by"];
    if (!managed) {
      return {
        project: workspace.project,
        status: "external",
        namespaceUid: namespace.uid,
      };
    }
    if (namespace.labels?.[WORKSPACE_UID_LABEL] !== workspace.uid) {
      return {
        project: workspace.project,
        status: "different-workspace",
        namespaceUid: namespace.uid,
      };
    }
    return {
      project: workspace.project,
      status: "owned",
      namespaceUid: namespace.uid,
    };
  }

  async function assertSafe(
    workspace: Workspace,
    allowMissing = false,
  ): Promise<NamespaceSafety> {
    const safety = await namespaceSafety(workspace);
    if (
      safety.status === "owned" ||
      (allowMissing && safety.status === "missing")
    ) {
      return safety;
    }
    throw new Error(
      `Namespace ${workspace.project} is ${safety.status}; refusing workspace mutation`,
    );
  }

  async function targets(workspace: Workspace, names?: string[]) {
    await assertSafe(workspace);
    return selectTargets(
      deploymentNames(await dependencies.listDeployments(workspace.project)),
      names,
    );
  }

  async function ownExternalResources(
    workspace: Workspace,
    namespace: string,
    resources: KubernetesObject[],
  ): Promise<void> {
    for (const resource of resources) {
      await dependencies.applyResource(
        labelExternal(workspace, resource, namespace),
      );
    }
  }

  async function deleteResources(
    workspace: Workspace,
    resources: ResourceIdentity[],
  ): Promise<void> {
    await assertSafe(workspace);
    for (const resource of resources) {
      if (!resource.uid || resource.workspaceUid !== workspace.uid) {
        throw new Error(
          `${resource.kind}/${resource.name} has an invalid workspace deletion identity`,
        );
      }
    }
    for (const resource of resources) {
      await dependencies.deleteResource(resource);
    }
  }

  async function planDown(
    workspace: Workspace,
    full = false,
  ): Promise<DownPlan> {
    const safety = await assertSafe(workspace);
    const projectResources = sortResources(
      await dependencies.listProjectResources(workspace.project),
    );
    const retainedResources = full
      ? []
      : projectResources.filter(
          (resource) =>
            resource.kind === "Ingress" ||
            resource.kind === "PersistentVolumeClaim",
        );
    const deleteResources = full
      ? [...projectResources]
      : projectResources.filter(
          (resource) => !retainedResources.includes(resource),
        );

    if (full) {
      deleteResources.push(
        ...(await dependencies.listDatabaseResources(workspace.project)),
        ...(await dependencies.listStorageResources(workspace.project)),
      );
      if (!safety.namespaceUid) {
        throw new Error(
          `Namespace ${workspace.project} has no UID deletion precondition`,
        );
      }
      deleteResources.push({
        apiVersion: "v1",
        kind: "Namespace",
        metadata: {
          name: workspace.project,
          uid: safety.namespaceUid,
          labels: {
            ...LABELS,
            [WORKSPACE_PROJECT_LABEL]: workspace.project,
            [WORKSPACE_UID_LABEL]: workspace.uid,
          },
        },
      });
    }

    return {
      full,
      retained: retainedResources.map((item) => identity(workspace, item)),
      delete: sortResources(deleteResources)
        .reverse()
        .map((item) => identity(workspace, item)),
    };
  }

  return {
    namespaceSafety,

    async graphStatus(
      workspace: Workspace,
      options: { includeIdle?: boolean } = {},
    ): Promise<NamespaceGraph[]> {
      await assertSafe(workspace);
      return buildNamespaceGraphs(
        await dependencies.fetchGraphObjects(workspace.project),
        options,
      );
    },

    async stop(workspace: Workspace, names?: string[]): Promise<string[]> {
      const selected = await targets(workspace, names);
      const selectedSet = new Set(selected);
      const hpas = (await dependencies.listProjectResources(workspace.project))
        .filter(
          (resource) =>
            resource.apiVersion === "autoscaling/v2" &&
            resource.kind === "HorizontalPodAutoscaler" &&
            resource.metadata?.name !== undefined &&
            selectedSet.has(resource.metadata.name),
        )
        .map((resource) => identity(workspace, resource));
      if (hpas.length > 0) {
        await deleteResources(workspace, hpas);
      }
      for (const name of selected) {
        await dependencies.scaleDeployment(workspace.project, name, 0);
      }
      return selected;
    },

    async restart(workspace: Workspace, names?: string[]): Promise<string[]> {
      const selected = await targets(workspace, names);
      for (const name of selected) {
        await dependencies.restartDeployment(workspace.project, name);
      }
      return selected;
    },

    async rollback(
      workspace: Workspace,
      names?: string[],
      timeoutMs?: number,
    ): Promise<RollbackCandidate[]> {
      await assertSafe(workspace);
      const candidates = await dependencies.planRollback(
        workspace.project,
        names,
      );
      for (const candidate of candidates) {
        await dependencies.rollbackDeployment(workspace.project, candidate);
      }
      for (const candidate of candidates) {
        await dependencies.waitForDeployment(
          workspace.project,
          candidate.name,
          timeoutMs,
        );
      }
      return candidates;
    },

    databaseCredentialsMetadata(
      compose: ComposeSpecification,
    ): CredentialMetadata[] {
      return getComposePostgresClaims(compose).map((claim: PostgresClaim) => ({
        service: claim.service,
        provider: "postgres",
        principal: claim.username,
        resource: claim.database,
        secretNamespace: DATABASE_NAMESPACE,
        secretName: claim.secretName,
      }));
    },

    async reconcileDatabases(
      workspace: Workspace,
      compose: ComposeSpecification,
    ) {
      await assertSafe(workspace, true);
      const environment = await dependencies.reconcileDatabases(
        workspace.project,
        compose,
      );
      await ownExternalResources(
        workspace,
        DATABASE_NAMESPACE,
        await dependencies.listDatabaseResources(workspace.project),
      );
      return environment;
    },

    async getDatabaseCredentials(workspace: Workspace, username: string) {
      await assertSafe(workspace);
      const databases = await dependencies.listDatabaseResources(
        workspace.project,
      );
      const database = databases.find(
        (resource) =>
          resource.kind === "Database" &&
          (resource as KubernetesObject & { spec?: { owner?: string } }).spec
            ?.owner === username,
      );
      if (!database) {
        throw new Error(
          `Database role ${username} is not managed by this workspace`,
        );
      }
      assertResourceOwnership(workspace, database);
      return dependencies.getDatabaseCredentials(username);
    },

    storageCredentialsMetadata(
      compose: ComposeSpecification,
    ): CredentialMetadata[] {
      return getComposeS3Claims(compose).map((claim) => ({
        service: claim.service,
        provider: "s3",
        principal: claim.key,
        resource: claim.bucket,
        secretNamespace: STORAGE_NAMESPACE,
      }));
    },

    async reconcileStorage(
      workspace: Workspace,
      compose: ComposeSpecification,
    ) {
      await assertSafe(workspace, true);
      const environment = await dependencies.reconcileStorage(
        workspace.project,
        compose,
      );
      await ownExternalResources(
        workspace,
        STORAGE_NAMESPACE,
        await dependencies.listStorageResources(workspace.project),
      );
      return environment;
    },

    async getStorageCredentials(workspace: Workspace, claim: S3Claim) {
      await assertSafe(workspace);
      const resources = await dependencies.listStorageResources(
        workspace.project,
      );
      const key = resources.find(
        (resource) =>
          resource.kind === "GarageKey" &&
          resource.metadata?.name === claim.key,
      );
      const bucket = resources.find(
        (resource) =>
          resource.kind === "GarageBucket" &&
          resource.metadata?.name === claim.bucket,
      );
      if (!key || !bucket) {
        throw new Error(
          `S3 claim ${claim.key}/${claim.bucket} is not managed by this workspace`,
        );
      }
      assertResourceOwnership(workspace, key);
      assertResourceOwnership(workspace, bucket);
      return dependencies.getStorageCredentials(claim);
    },

    async planResources(
      workspace: Workspace,
      desired: KubernetesObject[],
    ): Promise<ResourcePlan> {
      await assertSafe(workspace, true);
      const labeled = sortResources(
        desired.map((item) => labelDesired(workspace, item)),
      );
      const stale = await dependencies.findStaleResources(
        workspace.project,
        labeled,
      );
      return {
        desired: labeled,
        stale: sortResources(stale)
          .reverse()
          .map((item) => identity(workspace, item)),
      };
    },

    async applyResources(
      workspace: Workspace,
      resources: KubernetesObject[],
    ): Promise<KubernetesObject[]> {
      await assertSafe(workspace, true);
      const applied: KubernetesObject[] = [];
      for (const resource of sortResources(
        resources.map((item) => labelDesired(workspace, item)),
      )) {
        applied.push(await dependencies.applyResource(resource));
      }
      return applied;
    },

    async waitForResources(
      workspace: Workspace,
      deploymentTargets: string[],
      timeoutMs?: number,
    ): Promise<void> {
      const selected = await targets(workspace, deploymentTargets);
      for (const name of selected) {
        await dependencies.waitForDeployment(
          workspace.project,
          name,
          timeoutMs,
        );
      }
    },

    deleteResources,

    planDown,

    async down(workspace: Workspace, full = false): Promise<DownPlan> {
      const plan = await planDown(workspace, full);
      await deleteResources(workspace, plan.delete);
      return plan;
    },
  };
}