import type { JSONObject } from '@ai-sdk/provider';
import type { Context, IdGenerator, ToolSet } from '@ai-sdk/provider-utils';
import type { ServerResponse } from 'node:http';
import type {
  CallWarning,
  FinishReason,
  LanguageModelRequestMetadata,
  ProviderMetadata,
} from '../types';
import type { Source } from '../types/language-model';
import type { LanguageModelResponseMetadata } from '../types/language-model-response-metadata';
import type { LanguageModelUsage } from '../types/usage';
import type { InferUIMessageChunk } from '../ui-message-stream/ui-message-chunks';
import type { UIMessageStreamOnEndCallback } from '../ui-message-stream/ui-message-stream-on-end-callback';
import type { UIMessageStreamResponseInit } from '../ui-message-stream/ui-message-stream-response-init';
import type { InferUIMessageMetadata, UIMessage } from '../ui/ui-messages';
import type { AsyncIterableStream } from '../util/async-iterable-stream';
import type { ErrorHandler } from '../util/error-handler';
import type { ContentPart } from './content-part';
import type { GeneratedFile } from './generated-file';
import type { Output } from './output';
import type {
  InferCompleteOutput,
  InferElementOutput,
  InferPartialOutput,
} from './output-utils';
import type { ReasoningFileOutput, ReasoningOutput } from './reasoning-output';
import type { ResponseMessage } from './response-message';
import type { StepResult, StepResultPerformance } from './step-result';
import type { ToolApprovalRequestOutput } from './tool-approval-request-output';
import type { ToolApprovalResponseOutput } from './tool-approval-response-output';
import type {
  DynamicToolCall,
  StaticToolCall,
  TypedToolCall,
} from './tool-call';
import type { TypedToolError } from './tool-error';
import type { StaticToolOutputDenied } from './tool-output-denied';
import type {
  DynamicToolResult,
  StaticToolResult,
  TypedToolResult,
} from './tool-result';

export type UIMessageStreamOptions<UI_MESSAGE extends UIMessage> = {
  /**
   * The original messages. If they are provided, persistence mode is assumed,
   * and a message ID is provided for the response message.
   */
  originalMessages?: UI_MESSAGE[];

  /**
   * Generate a message ID for the response message.
   *
   * If not provided, no message ID will be set for the response message (unless
   * the original messages are provided and the last message is an assistant message).
   */
  generateMessageId?: IdGenerator;

  onEnd?: UIMessageStreamOnEndCallback<UI_MESSAGE>;

  /**
   * @deprecated Use `onEnd` instead.
   */
  onFinish?: UIMessageStreamOnEndCallback<UI_MESSAGE>;

  /**
   * Extracts message metadata that will be sent to the client.
   *
   * Called on `start` and `finish` events.
   */
  messageMetadata?: (options: {
    part: TextStreamPart<ToolSet>;
  }) => InferUIMessageMetadata<UI_MESSAGE> | undefined;

  /**
   * Send reasoning parts to the client.
   * Default to true.
   */
  sendReasoning?: boolean;

  /**
   * Send source parts to the client.
   * Default to false.
   */
  sendSources?: boolean;

  /**
   * Send the finish event to the client.
   * Set to false if you are using additional streamText calls
   * that send additional data.
   * Default to true.
   */
  sendFinish?: boolean;

  /**
   * Send the message start event to the client.
   * Set to false if you are using additional streamText calls
   * and the message start event has already been sent.
   * Default to true.
   */
  sendStart?: boolean;

  /**
   * Process an error, e.g. to log it. Default to `() => 'An error occurred.'`.
   *
   * @returns error message to include in the data stream.
   */
  onError?: (error: unknown) => string;
};

export type ConsumeStreamOptions = {
  onError?: ErrorHandler;
};

/**
 * A result object for accessing different stream types and additional information.
 */
export interface StreamTextResult<
  TOOLS extends ToolSet,
  RUNTIME_CONTEXT extends Context,
  OUTPUT extends Output,
> {
  /**
   * The content that was generated in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly content: PromiseLike<Array<ContentPart<TOOLS>>>;

  /**
   * The full text that has been generated by the final step.
   *
   * Automatically consumes the stream.
   */
  readonly text: PromiseLike<string>;

  /**
   * The full reasoning that the model has generated.
   *
   * Automatically consumes the stream.
   *
   * @deprecated Use `finalStep.reasoning` instead.
   */
  readonly reasoning: PromiseLike<Array<ReasoningOutput | ReasoningFileOutput>>;

  /**
   * The reasoning that has been generated by the last step.
   *
   * Automatically consumes the stream.
   *
   * @deprecated Use `finalStep.reasoningText` instead.
   */
  readonly reasoningText: PromiseLike<string | undefined>;

  /**
   * Files that have been generated by the model in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly files: PromiseLike<GeneratedFile[]>;

  /**
   * Sources that have been used as references in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly sources: PromiseLike<Source[]>;

  /**
   * The tool calls that have been executed in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly toolCalls: PromiseLike<TypedToolCall<TOOLS>[]>;

  /**
   * The static tool calls that have been executed in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly staticToolCalls: PromiseLike<StaticToolCall<TOOLS>[]>;

  /**
   * The dynamic tool calls that have been executed in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly dynamicToolCalls: PromiseLike<DynamicToolCall[]>;

  /**
   * The static tool results that have been generated in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly staticToolResults: PromiseLike<StaticToolResult<TOOLS>[]>;

  /**
   * The dynamic tool results that have been generated in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly dynamicToolResults: PromiseLike<DynamicToolResult[]>;

  /**
   * The tool results that have been generated in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly toolResults: PromiseLike<TypedToolResult<TOOLS>[]>;

  /**
   * The unified finish reason why the generation finished. Taken from the last step.
   *
   * Automatically consumes the stream.
   */
  readonly finishReason: PromiseLike<FinishReason>;

  /**
   * The raw reason why the generation finished (from the provider). Taken from the last step.
   *
   * Automatically consumes the stream.
   */
  readonly rawFinishReason: PromiseLike<string | undefined>;

  /**
   * The total token usage of the generated response.
   * When there are multiple steps, the usage is the sum of all step usages.
   *
   * Automatically consumes the stream.
   */
  readonly usage: PromiseLike<LanguageModelUsage>;

  /**
   * The total token usage of the generated response.
   * When there are multiple steps, the usage is the sum of all step usages.
   *
   * Automatically consumes the stream.
   *
   * @deprecated Use `usage` instead.
   */
  readonly totalUsage: PromiseLike<LanguageModelUsage>;

  /**
   * Warnings from the model provider (e.g. unsupported settings) in all steps.
   *
   * Automatically consumes the stream.
   */
  readonly warnings: PromiseLike<CallWarning[] | undefined>;

  /**
   * Details for all steps.
   * You can use this to get information about intermediate steps,
   * such as the tool calls or the response headers.
   *
   * Automatically consumes the stream.
   */
  readonly steps: PromiseLike<Array<StepResult<TOOLS, RUNTIME_CONTEXT>>>;

  /**
   * The final step. This is a shortcut for `steps.at(-1)`.
   *
   * Automatically consumes the stream.
   */
  readonly finalStep: PromiseLike<StepResult<TOOLS, RUNTIME_CONTEXT>>;

  /**
   * Additional request information from the last step.
   *
   * Automatically consumes the stream.
   *
   * @deprecated Use `finalStep.request` instead.
   */
  readonly request: PromiseLike<LanguageModelRequestMetadata>;

  /**
   * Additional response information from the last step.
   *
   * Automatically consumes the stream.
   *
   * @deprecated Use `finalStep.response` instead.
   */
  readonly response: PromiseLike<LanguageModelResponseMetadata>;

  /**
   * The accumulated response messages of all steps that were generated during the call.
   *
   * Automatically consumes the stream.
   */
  readonly responseMessages: PromiseLike<Array<ResponseMessage>>;

  /**
   * Additional provider-specific metadata from the last step.
   * Metadata is passed through from the provider to the AI SDK and
   * enables provider-specific results that can be fully encapsulated in the provider.
   *
   * @deprecated Use `finalStep.providerMetadata` instead.
   */
  readonly providerMetadata: PromiseLike<ProviderMetadata | undefined>;

  /**
   * A text stream that returns only the generated text deltas. You can use it
   * as either an AsyncIterable or a ReadableStream. Error parts are not
   * surfaced in this stream. Use the `onError` callback or `stream` to observe
   * them.
   */
  readonly textStream: AsyncIterableStream<string>;

  /**
   * A stream with all events, including text deltas, tool calls, tool results, and
   * errors.
   * You can use it as either an AsyncIterable or a ReadableStream.
   * Only errors that stop the stream, such as network errors, are thrown.
   */
  readonly stream: AsyncIterableStream<TextStreamPart<TOOLS>>;

  /**
   * A stream with all events, including text deltas, tool calls, tool results, and
   * errors.
   * You can use it as either an AsyncIterable or a ReadableStream.
   * Only errors that stop the stream, such as network errors, are thrown.
   *
   * @deprecated Use `stream` instead.
   */
  readonly fullStream: AsyncIterableStream<TextStreamPart<TOOLS>>;

  /**
   * A stream of partial outputs. It uses the `output` specification.
   *
   * @deprecated Use `partialOutputStream` instead.
   */
  readonly experimental_partialOutputStream: AsyncIterableStream<
    InferPartialOutput<OUTPUT>
  >;

  /**
   * A stream of partial parsed outputs. It uses the `output` specification.
   */
  readonly partialOutputStream: AsyncIterableStream<InferPartialOutput<OUTPUT>>;

  /**
   * A stream of individual array elements as they complete.
   * Only available when using `output: Output.array()`.
   */
  readonly elementStream: AsyncIterableStream<InferElementOutput<OUTPUT>>;

  /**
   * The complete parsed output. It uses the `output` specification.
   */
  readonly output: PromiseLike<InferCompleteOutput<OUTPUT>>;

  /**
   * Consumes the stream without processing the parts.
   * This is useful to force the stream to finish.
   * It effectively removes the backpressure and allows the stream to finish,
   * triggering the `onEnd` callback and the promise resolution.
   *
   * If an error occurs, it is passed to the optional `onError` callback.
   */
  consumeStream(options?: ConsumeStreamOptions): PromiseLike<void>;

  /**
   * Converts the result to a UI message stream.
   *
   * @returns A UI message stream.
   *
   * @deprecated Use the standalone `toUIMessageStream` helper from
   *   `'ai'` with `result.stream` instead. This method will be removed
   *   in the next major release.
   */
  toUIMessageStream<UI_MESSAGE extends UIMessage>(
    options?: UIMessageStreamOptions<UI_MESSAGE>,
  ): AsyncIterableStream<InferUIMessageChunk<UI_MESSAGE>>;

  /**
   * Writes UI message stream output to a Node.js response-like object.
   *
   * @deprecated Use the standalone `toUIMessageStream` and
   *   `pipeUIMessageStreamToResponse` helpers from `'ai'` with `result.stream`
   *   instead. This method will be removed in the next major release.
   */
  pipeUIMessageStreamToResponse<UI_MESSAGE extends UIMessage>(
    response: ServerResponse,
    options?: UIMessageStreamResponseInit & UIMessageStreamOptions<UI_MESSAGE>,
  ): Promise<void>;

  /**
   * Writes text delta output to a Node.js response-like object.
   * It sets a `Content-Type` header to `text/plain; charset=utf-8` and
   * writes each text delta as a separate chunk.
   *
   * @param response A Node.js response-like object (ServerResponse).
   * @param init Optional headers, status code, and status text.
   *
   * @deprecated Use the standalone `toTextStream` and
   *   `pipeTextStreamToResponse` helpers from `'ai'` with `result.stream`
   *   instead. This method will be removed in the next major release.
   */
  pipeTextStreamToResponse(
    response: ServerResponse,
    init?: ResponseInit,
  ): Promise<void>;

  /**
   * Converts the result to a streamed response object with a stream data part stream.
   *
   * @returns A response object.
   *
   * @deprecated Use the standalone `toUIMessageStream` and
   *   `createUIMessageStreamResponse` helpers from `'ai'` with `result.stream`
   *   instead. This method will be removed in the next major release.
   */
  toUIMessageStreamResponse<UI_MESSAGE extends UIMessage>(
    options?: UIMessageStreamResponseInit & UIMessageStreamOptions<UI_MESSAGE>,
  ): Response;

  /**
   * Creates a simple text stream response.
   * Each text delta is encoded as UTF-8 and sent as a separate chunk.
   * Non-text-delta events are ignored.
   * @param init Optional headers, status code, and status text.
   *
   * @deprecated Use the standalone `toTextStream` and `createTextStreamResponse`
   *   helpers from `'ai'` with `result.stream` instead. This method will be
   *   removed in the next major release.
   */
  toTextStreamResponse(init?: ResponseInit): Response;
}

export type TextStreamTextDeltaPart = {
  type: 'text-delta';
  id: string;
  providerMetadata?: ProviderMetadata;
  text: string;
};

export type TextStreamTextStartPart = {
  type: 'text-start';
  id: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamTextEndPart = {
  type: 'text-end';
  id: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamReasoningStartPart = {
  type: 'reasoning-start';
  id: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamReasoningEndPart = {
  type: 'reasoning-end';
  id: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamReasoningDeltaPart = {
  type: 'reasoning-delta';
  providerMetadata?: ProviderMetadata;
  id: string;
  text: string;
};

export type TextStreamCustomPart = {
  type: 'custom';
  kind: `${string}.${string}`;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamToolInputStartPart = {
  type: 'tool-input-start';
  id: string;
  toolName: string;
  providerMetadata?: ProviderMetadata;
  toolMetadata?: JSONObject;
  providerExecuted?: boolean;
  dynamic?: boolean;
  title?: string;
};

export type TextStreamToolInputEndPart = {
  type: 'tool-input-end';
  id: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamToolInputDeltaPart = {
  type: 'tool-input-delta';
  id: string;
  delta: string;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamSourcePart = { type: 'source' } & Source;

export type TextStreamFilePart = {
  type: 'file';
  file: GeneratedFile;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamReasoningFilePart = {
  type: 'reasoning-file';
  file: GeneratedFile;
  providerMetadata?: ProviderMetadata;
};

export type TextStreamToolCallPart<TOOLS extends ToolSet> = {
  type: 'tool-call';
} & TypedToolCall<TOOLS>;

export type TextStreamToolResultPart<TOOLS extends ToolSet> = {
  type: 'tool-result';
} & TypedToolResult<TOOLS>;

export type TextStreamToolErrorPart<TOOLS extends ToolSet> = {
  type: 'tool-error';
} & TypedToolError<TOOLS>;

export type TextStreamToolOutputDeniedPart<TOOLS extends ToolSet> = {
  type: 'tool-output-denied';
} & StaticToolOutputDenied<TOOLS>;

export type TextStreamToolApprovalRequestPart<TOOLS extends ToolSet> =
  ToolApprovalRequestOutput<TOOLS>;

export type TextStreamToolApprovalResponsePart<TOOLS extends ToolSet> =
  ToolApprovalResponseOutput<TOOLS>;

export type TextStreamStartStepPart = {
  type: 'start-step';
  request: LanguageModelRequestMetadata;
  warnings: CallWarning[];
};

export type TextStreamFinishStepPart = {
  type: 'finish-step';
  response: Omit<LanguageModelResponseMetadata, 'messages' | 'body'>;
  usage: LanguageModelUsage;
  performance: StepResultPerformance;
  finishReason: FinishReason;
  rawFinishReason: string | undefined;
  providerMetadata: ProviderMetadata | undefined;
};

export type TextStreamStartPart = {
  type: 'start';
};

export type TextStreamFinishPart = {
  type: 'finish';
  finishReason: FinishReason;
  rawFinishReason: string | undefined;
  totalUsage: LanguageModelUsage;
};

export type TextStreamAbortPart = {
  type: 'abort';
  reason?: string;
};

export type TextStreamErrorPart = {
  type: 'error';
  error: unknown;
};

export type TextStreamRawPart = {
  type: 'raw';
  rawValue: unknown;
};

export type TextStreamPart<TOOLS extends ToolSet> =
  | TextStreamTextStartPart
  | TextStreamTextEndPart
  | TextStreamTextDeltaPart
  | TextStreamReasoningStartPart
  | TextStreamReasoningEndPart
  | TextStreamReasoningDeltaPart
  | TextStreamCustomPart
  | TextStreamToolInputStartPart
  | TextStreamToolInputEndPart
  | TextStreamToolInputDeltaPart
  | TextStreamSourcePart
  | TextStreamFilePart
  | TextStreamReasoningFilePart
  | TextStreamToolCallPart<TOOLS>
  | TextStreamToolResultPart<TOOLS>
  | TextStreamToolErrorPart<TOOLS>
  | TextStreamToolOutputDeniedPart<TOOLS>
  | TextStreamToolApprovalRequestPart<TOOLS>
  | TextStreamToolApprovalResponsePart<TOOLS>
  | TextStreamStartStepPart
  | TextStreamFinishStepPart
  | TextStreamStartPart
  | TextStreamFinishPart
  | TextStreamAbortPart
  | TextStreamErrorPart
  | TextStreamRawPart;