import type {
  BuildEvent,
  BuildRequest,
  BuildStatus,
  Sha256Digest,
} from "../shared/build-protocol";

export const BUILD_RECORD_API_VERSION = "kuber.astrxl.dev/v1" as const;

export interface BuildRecord {
  apiVersion: typeof BUILD_RECORD_API_VERSION;
  kind: "BuildRecord";
  metadata: {
    name: string;
    resourceVersion: string;
    creationTimestamp: string;
    labels: Record<string, string>;
  };
  spec: {
    request: BuildRequest;
    imageKey: string;
    jobName: string;
    workspaceSubPath: string;
  };
  status: BuildStatus & {
    cancelled?: boolean;
    jobCreated?: boolean;
    logBytes: number;
    logOffset: number;
    nextSequence: number;
    events: BuildEvent[];
  };
}

export interface UploadRecord {
  apiVersion: typeof BUILD_RECORD_API_VERSION;
  kind: "BuildUpload";
  metadata: {
    name: string;
    resourceVersion: string;
    creationTimestamp: string;
  };
  spec: { digest: Sha256Digest; size: number };
  status: { offset: number; data: Uint8Array };
}

export type CreateBuildResult = { record: BuildRecord; created: boolean };

/** Implementations must make createBuild and replace operations atomic. */
export interface BuildStore {
  createBuild(record: BuildRecord): Promise<CreateBuildResult>;
  getBuild(id: string): Promise<BuildRecord | undefined>;
  listBuilds(): Promise<BuildRecord[]>;
  replaceBuild(
    record: BuildRecord,
    expectedResourceVersion: string,
  ): Promise<void>;
  getUpload(digest: Sha256Digest): Promise<UploadRecord | undefined>;
  createUpload(record: UploadRecord): Promise<UploadRecord>;
  replaceUpload(
    record: UploadRecord,
    expectedResourceVersion: string,
  ): Promise<void>;
  deleteUpload(digest: Sha256Digest): Promise<void>;
}

export class BuildStoreConflictError extends Error {
  readonly code = "BUILD_STORE_CONFLICT";
}

function clone<T>(value: T): T {
  return structuredClone(value);
}

function terminal(record: BuildRecord): boolean {
  return (
    record.status.state === "succeeded" || record.status.state === "failed"
  );
}

function sameSpec(left: BuildRecord, right: BuildRecord): boolean {
  return JSON.stringify(left.spec) === JSON.stringify(right.spec);
}

export class MemoryBuildStore implements BuildStore {
  private readonly builds = new Map<string, BuildRecord>();
  private readonly uploads = new Map<Sha256Digest, UploadRecord>();
  private readonly active = new Map<string, string>();

  async createBuild(record: BuildRecord): Promise<CreateBuildResult> {
    const existing = this.builds.get(record.metadata.name);
    if (existing) {
      if (!sameSpec(existing, record)) {
        throw new BuildStoreConflictError(
          "Build ID was already used for a different request",
        );
      }
      return { record: clone(existing), created: false };
    }
    const activeId = this.active.get(record.spec.imageKey);
    if (activeId) {
      const active = this.builds.get(activeId);
      if (active && !terminal(active)) {
        throw new BuildStoreConflictError(
          `Build '${activeId}' is already active for ${record.spec.imageKey}`,
        );
      }
    }
    this.builds.set(record.metadata.name, clone(record));
    this.active.set(record.spec.imageKey, record.metadata.name);
    return { record: clone(record), created: true };
  }

  async getBuild(id: string) {
    const value = this.builds.get(id);
    return value && clone(value);
  }

  async listBuilds() {
    return [...this.builds.values()]
      .sort((a, b) =>
        a.metadata.creationTimestamp.localeCompare(
          b.metadata.creationTimestamp,
        ),
      )
      .map(clone);
  }

  async replaceBuild(record: BuildRecord, expectedResourceVersion: string) {
    const current = this.builds.get(record.metadata.name);
    if (
      !current ||
      current.metadata.resourceVersion !== expectedResourceVersion
    ) {
      throw new BuildStoreConflictError(
        "Build record was concurrently modified",
      );
    }
    if (!sameSpec(current, record)) {
      throw new BuildStoreConflictError("Build specification is immutable");
    }
    if (
      current.status.state === "succeeded" &&
      (record.status.state !== "succeeded" ||
        record.status.digest !== current.status.digest)
    ) {
      throw new BuildStoreConflictError(
        "A successful image digest is immutable",
      );
    }
    this.builds.set(record.metadata.name, clone(record));
    if (
      terminal(record) &&
      this.active.get(record.spec.imageKey) === record.metadata.name
    ) {
      this.active.delete(record.spec.imageKey);
    }
  }

  async getUpload(digest: Sha256Digest) {
    const value = this.uploads.get(digest);
    return value && clone(value);
  }

  async createUpload(record: UploadRecord) {
    const current = this.uploads.get(record.spec.digest);
    if (current) return clone(current);
    this.uploads.set(record.spec.digest, clone(record));
    return clone(record);
  }

  async replaceUpload(record: UploadRecord, expectedResourceVersion: string) {
    const current = this.uploads.get(record.spec.digest);
    if (
      !current ||
      current.metadata.resourceVersion !== expectedResourceVersion
    ) {
      throw new BuildStoreConflictError(
        "Upload record was concurrently modified",
      );
    }
    this.uploads.set(record.spec.digest, clone(record));
  }

  async deleteUpload(digest: Sha256Digest) {
    this.uploads.delete(digest);
  }
}