import { createHash, randomUUID } from "node:crypto";
import { KUBER_API_VERSION, type ObjectMeta } from "./workspace-store";
import type {
  OperationError,
  OperationEvent,
  OperationState,
} from "../shared/api";
import { redactString, REDACTED } from "./redact";

export const MAX_IDEMPOTENCY_KEY_BYTES = 256;
export const MAX_OPERATION_EVENTS = 256;

export type OperationProgress = {
  resource: {
    apiVersion: string;
    kind: string;
    name: string;
    namespace?: string;
  };
  phase: "apply" | "wait" | "delete";
  state: "started" | "succeeded" | "failed" | "aborted";
};

export type { OperationError, OperationState } from "../shared/api";

export interface Operation {
  apiVersion: typeof KUBER_API_VERSION;
  kind: "Operation";
  metadata: ObjectMeta & { workspaceUid?: string };
  spec: {
    workspaceId: string;
    action: string;
    idempotencyKey: string;
    requestHash: string;
  };
  status: {
    state: OperationState;
    startedAt?: string;
    finishedAt?: string;
    result?: unknown;
    error?: OperationError;
    events?: OperationEvent[];
  };
}

export interface CreateOperationInput {
  workspaceId: string;
  workspaceUid?: string;
  action: string;
  idempotencyKey: string;
  request?: unknown;
}

export class OperationValidationError extends Error {
  readonly code = "OPERATION_INVALID";
}

export class OperationConflictError extends Error {
  readonly code = "OPERATION_CONFLICT";
}

export class OperationNotFoundError extends Error {
  readonly code = "OPERATION_NOT_FOUND";
}

/** createIdempotent must atomically index workspaceId + idempotencyKey. */
export interface OperationPersistence {
  createIdempotent(operation: Operation): Promise<CreatedOperation>;
  get(id: string): Promise<Operation | undefined>;
  list(workspaceId?: string): Promise<Operation[]>;
  replace(operation: Operation, expectedResourceVersion: string): Promise<void>;
}

/** The idempotent operation and whether this caller created its record. */
export interface CreatedOperation {
  operation: Operation;
  created: boolean;
}

export interface OperationStore {
  create(input: CreateOperationInput): Promise<Operation>;
  createOrReuse(input: CreateOperationInput): Promise<CreatedOperation>;
  /**
   * Atomically claims a pending operation for execution. A false result means
   * another request has already moved it out of pending.
   */
  claimExecution(id: string): Promise<Operation | undefined>;
  get(id: string): Promise<Operation | undefined>;
  list(workspaceId?: string): Promise<Operation[]>;
  transition(
    id: string,
    state: OperationState,
    options?: { result?: unknown; error?: OperationError },
  ): Promise<Operation>;
  emit(id: string, progress: OperationProgress): Promise<OperationEvent>;
  events(id: string, after?: number): Promise<OperationEvents>;
}

export interface OperationEvents {
  items: OperationEvent[];
  retainedFirstSequence: number;
  cursorGap: boolean;
}

export interface WorkspaceLease {
  workspaceId: string;
  holder: string;
  expiresAt: string;
  renew(ttlMs?: number): Promise<boolean>;
  release(): Promise<void>;
}

export interface WorkspaceLeaseProvider {
  acquire(
    workspaceId: string,
    holder: string,
    ttlMs?: number,
  ): Promise<WorkspaceLease | undefined>;
}

/**
 * Marks any operation left in a non-terminal state by a previous process as
 * failed. On process restart no synchronous operation can legitimately still be
 * in flight (startup runs before serving), so pending/running records are stale.
 * Best-effort: individual conflicts or failures are logged and skipped so one
 * bad record cannot block recovery.
 */
export async function recoverStaleOperations(
  store: Pick<OperationStore, "list" | "transition">,
): Promise<number> {
  const operations = await store.list();
  let recovered = 0;
  for (const operation of operations) {
    if (
      operation.status.state !== "pending" &&
      operation.status.state !== "running"
    )
      continue;
    const name = operation.metadata.name;
    try {
      await store.transition(name, "failed", {
        error: {
          code: "OPERATION_INTERRUPTED",
          message:
            "Server restarted while the operation was in progress; retry to proceed",
        },
      });
      recovered += 1;
    } catch (error) {
      console.error(
        `Failed to mark stale operation '${name}' as failed during startup recovery`,
        error,
      );
    }
  }
  return recovered;
}

const TRANSITIONS: Record<OperationState, ReadonlySet<OperationState>> = {
  pending: new Set(["running", "failed", "cancelled"]),
  running: new Set(["succeeded", "failed", "cancelled"]),
  succeeded: new Set(),
  failed: new Set(),
  cancelled: new Set(),
};

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

function canonicalJson(value: unknown): string {
  if (value === null || typeof value !== "object") {
    const encoded = JSON.stringify(value);
    if (encoded === undefined)
      throw new OperationValidationError(
        "Operation request must be JSON serializable",
      );
    return encoded;
  }
  if (Array.isArray(value)) return `[${value.map(canonicalJson).join(",")}]`;
  return `{${Object.keys(value as Record<string, unknown>)
    .sort()
    .map(
      (key) =>
        `${JSON.stringify(key)}:${canonicalJson((value as Record<string, unknown>)[key])}`,
    )
    .join(",")}}`;
}

function hashRequest(input: CreateOperationInput): string {
  let request: string;
  try {
    request = canonicalJson(input.request ?? null);
  } catch {
    throw new OperationValidationError(
      "Operation request must be JSON serializable",
    );
  }
  return createHash("sha256")
    .update(`${input.action}\0${request}`)
    .digest("hex");
}

const SENSITIVE_KEY =
  /(?:password|passwd|token|secret|credential|private.?key|access.?key|connection.?string|database.?url)/i;

/** Produces a persistence-safe result while retaining useful operation status. */
export function sanitizeOperationResult(
  value: unknown,
  action?: string,
): unknown {
  if (action === "databases.reconcile" || action === "storage.reconcile") {
    return { redacted: true };
  }
  if (typeof value === "string") return redactString(value);
  if (Array.isArray(value))
    return value.map((item) => sanitizeOperationResult(item));
  if (!value || typeof value !== "object") return value;
  const record = value as Record<string, unknown>;
  const isDataResource =
    record.kind === "Secret" || record.kind === "ConfigMap";
  return Object.fromEntries(
    Object.entries(record).map(([key, item]) => [
      key,
      SENSITIVE_KEY.test(key) ||
      (isDataResource && (key === "data" || key === "stringData"))
        ? REDACTED
        : sanitizeOperationResult(item),
    ]),
  );
}

/** Keep operation error codes stable while preventing provider details from escaping. */
export function sanitizeOperationError(
  error: OperationError,
  action?: string,
): OperationError {
  const message =
    action === "databases.reconcile"
      ? "Database reconciliation failed"
      : action === "storage.reconcile"
        ? "Storage reconciliation failed"
        : redactString(error.message);
  return { code: error.code, message };
}

export class PersistentOperationStore implements OperationStore {
  constructor(
    private readonly persistence: OperationPersistence,
    private readonly now: () => Date = () => new Date(),
    private readonly uid: () => string = randomUUID,
  ) {}

  async create(input: CreateOperationInput): Promise<Operation> {
    return (await this.createOrReuse(input)).operation;
  }

  async createOrReuse(input: CreateOperationInput): Promise<CreatedOperation> {
    if (!input.workspaceId || !input.action.trim()) {
      throw new OperationValidationError(
        "Workspace ID and action are required",
      );
    }
    const keyBytes = Buffer.byteLength(input.idempotencyKey);
    if (!input.idempotencyKey || keyBytes > MAX_IDEMPOTENCY_KEY_BYTES) {
      throw new OperationValidationError(
        `Idempotency key must be 1-${MAX_IDEMPOTENCY_KEY_BYTES} bytes`,
      );
    }
    const now = this.now().toISOString();
    const id = this.uid();
    const operation: Operation = {
      apiVersion: KUBER_API_VERSION,
      kind: "Operation",
      metadata: {
        name: `operation-${id}`,
        uid: id,
        resourceVersion: "1",
        creationTimestamp: now,
        ...(input.workspaceUid && { workspaceUid: input.workspaceUid }),
      },
      spec: {
        workspaceId: input.workspaceId,
        action: input.action,
        idempotencyKey: input.idempotencyKey,
        requestHash: hashRequest(input),
      },
      status: { state: "pending" },
    };
    const stored = await this.persistence.createIdempotent(operation);
    if (stored.operation.spec.requestHash !== operation.spec.requestHash) {
      throw new OperationConflictError(
        "Idempotency key was already used for a different request",
      );
    }
    return { operation: clone(stored.operation), created: stored.created };
  }

  async get(id: string) {
    const operation = await this.persistence.get(id);
    return operation && clone(operation);
  }

  async claimExecution(id: string): Promise<Operation | undefined> {
    try {
      return await this.transition(id, "running");
    } catch (error) {
      if (!(error instanceof OperationConflictError)) throw error;
      return;
    }
  }

  async list(workspaceId?: string) {
    return clone(await this.persistence.list(workspaceId));
  }

  async transition(
    id: string,
    state: OperationState,
    options: { result?: unknown; error?: OperationError } = {},
  ): Promise<Operation> {
    const current = await this.persistence.get(id);
    if (!current)
      throw new OperationNotFoundError(`Operation '${id}' not found`);
    if (!TRANSITIONS[current.status.state].has(state)) {
      throw new OperationConflictError(
        `Cannot transition operation from ${current.status.state} to ${state}`,
      );
    }
    if (state === "succeeded" && options.error) {
      throw new OperationValidationError(
        "Successful operations cannot have errors",
      );
    }
    if (state === "failed" && !options.error) {
      throw new OperationValidationError("Failed operations require an error");
    }
    const timestamp = this.now().toISOString();
    const operation: Operation = clone(current);
    operation.metadata.resourceVersion = String(
      Number(current.metadata.resourceVersion) + 1,
    );
    operation.status = {
      state,
      ...(current.status.startedAt && { startedAt: current.status.startedAt }),
      ...(state === "running" && { startedAt: timestamp }),
      ...(["succeeded", "failed", "cancelled"].includes(state) && {
        finishedAt: timestamp,
      }),
      ...(options.result !== undefined && {
        result: clone(
          sanitizeOperationResult(options.result, current.spec.action),
        ),
      }),
      ...(options.error && {
        error: sanitizeOperationError(options.error, current.spec.action),
      }),
      ...(current.status.events && { events: clone(current.status.events) }),
    };
    await this.persistence.replace(operation, current.metadata.resourceVersion);
    return clone(operation);
  }

  async emit(id: string, progress: OperationProgress): Promise<OperationEvent> {
    const data = sanitizeOperationProgress(progress);
    for (let attempt = 0; attempt < 8; attempt++) {
      const current = await this.persistence.get(id);
      if (!current)
        throw new OperationNotFoundError(`Operation '${id}' not found`);
      const events = current.status.events ?? [];
      const event: OperationEvent = {
        operationId: id,
        sequence: (events.at(-1)?.sequence ?? 0) + 1,
        timestamp: this.now().toISOString(),
        type: "progress",
        data,
      };
      const operation = clone(current);
      operation.metadata.resourceVersion = String(
        Number(current.metadata.resourceVersion) + 1,
      );
      operation.status = {
        ...operation.status,
        events: [...events, event].slice(-MAX_OPERATION_EVENTS),
      };
      try {
        await this.persistence.replace(
          operation,
          current.metadata.resourceVersion,
        );
        return clone(event);
      } catch (error) {
        if (!(error instanceof OperationConflictError) || attempt === 7)
          throw error;
      }
    }
    throw new OperationConflictError("Operation event could not be persisted");
  }

  async events(id: string, after = 0): Promise<OperationEvents> {
    if (!Number.isSafeInteger(after) || after < 0)
      throw new OperationValidationError(
        "Operation event cursor must be a non-negative integer",
      );
    const operation = await this.persistence.get(id);
    if (!operation)
      throw new OperationNotFoundError(`Operation '${id}' not found`);
    const events = operation.status.events ?? [];
    const retainedFirstSequence = events[0]?.sequence ?? 1;
    return {
      items: clone(events.filter((event) => event.sequence > after)),
      retainedFirstSequence,
      cursorGap: after < retainedFirstSequence - 1,
    };
  }
}

function sanitizeOperationProgress(
  progress: OperationProgress,
): OperationProgress {
  const resource = progress.resource;
  if (
    !resource ||
    !resource.apiVersion ||
    !resource.kind ||
    !resource.name ||
    !["apply", "wait", "delete"].includes(progress.phase) ||
    !["started", "succeeded", "failed", "aborted"].includes(progress.state)
  )
    throw new OperationValidationError("Invalid operation progress event");
  return {
    resource: {
      apiVersion: resource.apiVersion.slice(0, 128),
      kind: resource.kind.slice(0, 128),
      name: resource.name.slice(0, 253),
      ...(resource.namespace && {
        namespace: resource.namespace.slice(0, 253),
      }),
    },
    phase: progress.phase,
    state: progress.state,
  };
}

export class MemoryOperationPersistence implements OperationPersistence {
  private readonly operations = new Map<string, Operation>();
  private readonly idempotency = new Map<string, string>();

  async createIdempotent(operation: Operation) {
    const key = `${operation.spec.workspaceId}\0${operation.spec.idempotencyKey}`;
    const existingId = this.idempotency.get(key);
    if (existingId)
      return {
        operation: clone(this.operations.get(existingId)!),
        created: false,
      };
    this.operations.set(operation.metadata.name, clone(operation));
    this.idempotency.set(key, operation.metadata.name);
    return { operation: clone(operation), created: true };
  }

  async get(id: string) {
    const operation = this.operations.get(id);
    return operation && clone(operation);
  }

  async list(workspaceId?: string) {
    return [...this.operations.values()]
      .filter((operation) =>
        workspaceId ? operation.spec.workspaceId === workspaceId : true,
      )
      .sort((a, b) =>
        a.metadata.creationTimestamp.localeCompare(
          b.metadata.creationTimestamp,
        ),
      )
      .map(clone);
  }

  async replace(operation: Operation, expectedResourceVersion: string) {
    const current = this.operations.get(operation.metadata.name);
    if (!current) throw new OperationNotFoundError("Operation not found");
    if (current.metadata.resourceVersion !== expectedResourceVersion) {
      throw new OperationConflictError("Operation was concurrently modified");
    }
    this.operations.set(operation.metadata.name, clone(operation));
  }
}

export class MemoryOperationStore extends PersistentOperationStore {
  constructor(now?: () => Date, uid?: () => string) {
    super(new MemoryOperationPersistence(), now, uid);
  }
}

export class MemoryWorkspaceLeaseProvider implements WorkspaceLeaseProvider {
  private readonly leases = new Map<
    string,
    { holder: string; expiresAt: number; token: string }
  >();

  constructor(private readonly now: () => number = Date.now) {}

  async acquire(workspaceId: string, holder: string, ttlMs = 30_000) {
    if (!workspaceId || !holder || !Number.isFinite(ttlMs) || ttlMs <= 0) {
      throw new OperationValidationError("Invalid workspace lease request");
    }
    const current = this.leases.get(workspaceId);
    if (current && current.expiresAt > this.now()) {
      return undefined;
    }
    const token = randomUUID();
    this.leases.set(workspaceId, {
      holder,
      token,
      expiresAt: this.now() + ttlMs,
    });

    const lease: WorkspaceLease = {
      workspaceId,
      holder,
      expiresAt: new Date(this.now() + ttlMs).toISOString(),
      renew: async (nextTtl = ttlMs) => {
        const active = this.leases.get(workspaceId);
        if (
          !active ||
          active.token !== token ||
          active.expiresAt <= this.now() ||
          nextTtl <= 0
        ) {
          return false;
        }
        active.expiresAt = this.now() + nextTtl;
        lease.expiresAt = new Date(active.expiresAt).toISOString();
        return true;
      },
      release: async () => {
        if (this.leases.get(workspaceId)?.token === token) {
          this.leases.delete(workspaceId);
        }
      },
    };
    return lease;
  }
}