import type {
  ISmartAiCacheOptions,
  ToolSet,
  ModelMessage,
  LanguageModelV3,
  ProviderOptions,
  TSmartAiCacheRetention,
  TSmartAiCacheSetting,
} from './plugins.js';

export type { ProviderOptions };
export type IAgentCacheOptions = ISmartAiCacheOptions;
export type TAgentCacheRetention = TSmartAiCacheRetention;
export type TAgentCacheSetting = TSmartAiCacheSetting;

export interface IAgentToolCallRecord {
  toolName: string;
  input: unknown;
  output?: unknown;
  error?: string;
}

export interface IAgentRunOptions {
  /** The LanguageModelV3 to use — from smartai.getModel() */
  model: LanguageModelV3;
  /** Initial user message or task description */
  prompt: string;
  /** System prompt override */
  system?: string;
  /** Tools available to the agent */
  tools?: ToolSet;
  /** Provider-specific AI SDK request options passed through to streamText() */
  providerOptions?: ProviderOptions;
  /** Stable session id used as provider prompt-cache affinity key where supported. */
  sessionId?: string;
  /** Prompt-cache policy. Default: 'auto'. Set false to disable smartagent cache defaults. */
  cache?: TAgentCacheSetting;
  /**
   * Maximum number of LLM↔tool round trips.
   * Each step may execute multiple tools in parallel.
   * Default: 20
   */
  maxSteps?: number;
  /** Prior conversation messages to include */
  messages?: ModelMessage[];
  /** Called for each streamed text delta */
  onToken?: (delta: string) => void;
  /** Called when the model starts a streamed reasoning summary */
  onReasoningStart?: (id: string, providerMetadata?: unknown) => void;
  /** Called for each streamed reasoning summary delta */
  onReasoningDelta?: (id: string, delta: string, providerMetadata?: unknown) => void;
  /** Called when a streamed reasoning summary completes */
  onReasoningEnd?: (id: string, text: string, providerMetadata?: unknown) => void;
  /** Called when a tool call starts */
  onToolCall?: (toolName: string, input: unknown) => void;
  /** Called when a tool call completes */
  onToolResult?: (toolName: string, result: unknown) => void;
  /**
   * Validate the completed run. Return a string to reject the run and reprompt,
   * or return void to accept the result.
   */
  validateCompletion?: (result: IAgentRunResult) => Promise<string | void> | string | void;
  /** Number of validation-triggered reprompts allowed. Default: 0 */
  maxValidationRetries?: number;
  /**
   * Called when total token usage approaches the model's context limit.
   * Receives the full message history and must return a compacted replacement.
   * If not provided, runAgent throws a ContextOverflowError instead.
   */
  onContextOverflow?: (messages: ModelMessage[]) => Promise<ModelMessage[]>;
  /** AbortSignal to cancel the run mid-flight */
  abort?: AbortSignal;
}

export interface IAgentRunResult {
  /** Final text output from the model */
  text: string;
  /** All messages in the completed conversation */
  messages: ModelMessage[];
  /** Total steps taken */
  steps: number;
  /** Finish reason from the final step */
  finishReason: string;
  /** Accumulated token usage across all steps */
  usage: {
    inputTokens: number;
    outputTokens: number;
    totalTokens: number;
    cacheReadTokens: number;
    cacheWriteTokens: number;
  };
  /** Tool calls observed during the run, including inputs and outputs/errors when available */
  toolCalls: IAgentToolCallRecord[];
}

export class ContextOverflowError extends Error {
  constructor(message = 'Agent context limit reached and no onContextOverflow handler provided') {
    super(message);
    this.name = 'ContextOverflowError';
  }
}