import type {
  Attachment,
  Message,
  MessageControl,
  MessageProvenance,
  MessageReceipt,
  MessageReceiptStatus,
  SessionInfo,
  SessionRegistration,
} from "../types.ts";

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function isHerdrLocation(value: unknown): boolean {
  if (!isRecord(value)) return false;
  if (value.status === "not_hosted") return true;
  if (value.status === "unavailable") {
    return typeof value.paneId === "string"
      && (value.reason === "herdr_unavailable"
        || value.reason === "unsupported"
        || value.reason === "command_failed"
        || value.reason === "pane_missing"
        || value.reason === "invalid_response")
      && (value.detail === undefined || typeof value.detail === "string");
  }
  if (value.status !== "current" || !isRecord(value.workspace) || !isRecord(value.tab)) return false;
  return typeof value.workspace.id === "string"
    && typeof value.workspace.label === "string"
    && typeof value.tab.id === "string"
    && typeof value.tab.label === "string"
    && typeof value.paneId === "string"
    && typeof value.refreshedAt === "number";
}

function isMessageReceiptStatus(value: unknown): value is MessageReceiptStatus {
  return value === "receiver_received"
    || value === "queued"
    || value === "injected"
    || value === "acknowledged"
    || value === "expired"
    || value === "cancelled"
    || value === "superseded"
    || value === "cancellation_requested";
}

export function isMessageReceipt(value: unknown): value is MessageReceipt {
  if (!isRecord(value)) {
    return false;
  }
  if (typeof value.messageId !== "string" || !isMessageReceiptStatus(value.status) || typeof value.timestamp !== "number") {
    return false;
  }
  return value.detail === undefined || typeof value.detail === "string";
}

export function isMessageControl(value: unknown): value is MessageControl {
  if (!isRecord(value)) {
    return false;
  }
  if (typeof value.messageId !== "string" || typeof value.timestamp !== "number") {
    return false;
  }
  if (value.action !== "cancel" && value.action !== "supersede") {
    return false;
  }
  if (value.supersededBy !== undefined && typeof value.supersededBy !== "string") {
    return false;
  }
  return value.detail === undefined || typeof value.detail === "string";
}

function isAttachment(value: unknown): value is Attachment {
  if (!isRecord(value)) {
    return false;
  }

  if (
    value.type !== "file"
    && value.type !== "snippet"
    && value.type !== "context"
  ) {
    return false;
  }

  if (typeof value.name !== "string" || typeof value.content !== "string") {
    return false;
  }

  return value.language === undefined || typeof value.language === "string";
}

function isMessageProvenance(value: unknown): value is MessageProvenance {
  if (!isRecord(value)) {
    return false;
  }
  return value.type === "extension_outbox"
    && typeof value.extensionId === "string"
    && typeof value.extensionName === "string"
    && typeof value.requestId === "string";
}

function isCrossMachineProvenance(value: unknown): boolean {
  if (
    !isRecord(value)
    || value.type !== "ssh-relay"
    || value.version !== 1
    || value.trust !== "ssh-asserted"
    || !isRecord(value.origin)
  ) return false;
  return typeof value.origin.name === "string"
    && typeof value.origin.sessionId === "string"
    && typeof value.origin.machine === "string";
}

export function isMessage(value: unknown): value is Message {
  if (!isRecord(value)) {
    return false;
  }

  if (typeof value.id !== "string" || typeof value.timestamp !== "number") {
    return false;
  }

  for (const key of ["senderSequence", "brokerReceivedAt", "brokerDeliveredAt", "receiverReceivedAt", "injectedAt"] as const) {
    if (value[key] !== undefined && typeof value[key] !== "number") {
      return false;
    }
  }

  if (value.supersedes !== undefined && typeof value.supersedes !== "string") {
    return false;
  }

  if (value.retryOf !== undefined && typeof value.retryOf !== "string") {
    return false;
  }

  if (value.replyTo !== undefined && typeof value.replyTo !== "string") {
    return false;
  }

  if (value.expectsReply !== undefined && typeof value.expectsReply !== "boolean") {
    return false;
  }

  if (value.provenance !== undefined && !isMessageProvenance(value.provenance)) {
    return false;
  }
  if (value.crossMachine !== undefined && !isCrossMachineProvenance(value.crossMachine)) {
    return false;
  }

  if (!isRecord(value.content) || typeof value.content.text !== "string") {
    return false;
  }

  return value.content.attachments === undefined
    || (Array.isArray(value.content.attachments) && value.content.attachments.every(isAttachment));
}

/** Canonical authored-message identity used by the broker's replay guard. */
export function messageDeliveryFingerprint(message: Message, targetId: string): string {
  return JSON.stringify({
    targetId,
    text: message.content.text,
    attachments: message.content.attachments,
    replyTo: message.replyTo,
    expectsReply: message.expectsReply,
    supersedes: message.supersedes,
    retryOf: message.retryOf,
    provenance: message.provenance,
    crossMachine: message.crossMachine,
  });
}

export function isSessionInfo(value: unknown): value is SessionInfo {
  if (!isRecord(value)) {
    return false;
  }

  if (
    typeof value.id !== "string"
    || typeof value.cwd !== "string"
    || typeof value.model !== "string"
    || typeof value.pid !== "number"
    || typeof value.startedAt !== "number"
    || typeof value.lastActivity !== "number"
  ) {
    return false;
  }

  if (value.endpointEpoch !== undefined && typeof value.endpointEpoch !== "string") {
    return false;
  }

  if (value.name !== undefined && typeof value.name !== "string") {
    return false;
  }

  if (value.runtimeFallbackAlias !== undefined && typeof value.runtimeFallbackAlias !== "boolean") {
    return false;
  }

  if (value.status !== undefined && typeof value.status !== "string") {
    return false;
  }

  if (value.peerUid !== undefined && typeof value.peerUid !== "number") {
    return false;
  }

  for (const key of ["contextPct", "contextTokens", "contextWindow"] as const) {
    if (value[key] !== undefined && typeof value[key] !== "number") {
      return false;
    }
  }

  if (value.tmuxPane !== undefined && typeof value.tmuxPane !== "string") {
    return false;
  }
  if (value.herdrPaneId !== undefined && typeof value.herdrPaneId !== "string") {
    return false;
  }
  if (value.herdrLocation !== undefined && !isHerdrLocation(value.herdrLocation)) {
    return false;
  }

  return value.trustedLocal === undefined || typeof value.trustedLocal === "boolean";
}

export function isSessionId(value: unknown): value is string {
  return typeof value === "string" && value.trim().length > 0;
}

export function isSessionRegistration(value: unknown): value is SessionRegistration {
  if (!isRecord(value)) {
    return false;
  }

  if (
    typeof value.cwd !== "string"
    || typeof value.model !== "string"
    || typeof value.pid !== "number"
    || typeof value.startedAt !== "number"
    || typeof value.lastActivity !== "number"
  ) {
    return false;
  }

  if (value.name !== undefined && typeof value.name !== "string") {
    return false;
  }
  if (value.runtimeFallbackAlias !== undefined && typeof value.runtimeFallbackAlias !== "boolean") {
    return false;
  }
  if (value.extensions !== undefined && !Array.isArray(value.extensions)) {
    return false;
  }
  if (value.tmuxPane !== undefined && typeof value.tmuxPane !== "string") {
    return false;
  }
  if (value.herdrPaneId !== undefined && typeof value.herdrPaneId !== "string") {
    return false;
  }
  if (value.herdrSessionPath !== undefined && typeof value.herdrSessionPath !== "string") {
    return false;
  }

  return value.status === undefined || typeof value.status === "string";
}