/**
 * Palantir AIP (AI Platform) API.
 * AIP Agents (blockingContinue, streamingContinue, sessions, RAG context)
 * and Language Model proxy endpoints (OpenAI, Anthropic, xAI, Google).
 *
 * All AIP Agents endpoints require `preview=true` query parameter.
 * Language Models use LLM proxy endpoints at `/api/v2/llm/proxy/`.
 *
 * @see https://www.palantir.com/docs/foundry/api/v2/aip-agents-v2-resources/
 * @see https://www.palantir.com/docs/foundry/api/v2/llm-proxy/
 */

import type { PalantirClient } from "./client.js";
import type {
  AipAgent,
  AipAgentSession,
  AipContinueParams,
  AipContinueResponse,
  AipStreamingChunk,
  LanguageModel,
  ChatCompletionParams,
  ChatCompletionResponse,
  PageResponse,
  PageParams,
} from "./types.js";

export class AipNamespace {
  constructor(private client: PalantirClient) {}

  // ─── AIP Agents ─────────────────────────────────────────────────
  // All endpoints require preview=true

  /** List AIP agents. */
  async listAgents(params?: PageParams): Promise<PageResponse<AipAgent>> {
    return this.client.get("/api/v2/aipAgents/agents", {
      ...params,
      preview: true,
    } as Record<string, unknown>);
  }

  /** Get an AIP agent. */
  async getAgent(agentRid: string): Promise<AipAgent> {
    return this.client.get(`/api/v2/aipAgents/agents/${agentRid}`, {
      preview: true,
    } as Record<string, unknown>);
  }

  // ─── Sessions ───────────────────────────────────────────────────

  /** Create an agent session. */
  async createSession(
    agentRid: string,
    params?: { metadata?: Record<string, unknown> }
  ): Promise<AipAgentSession> {
    return this.client.post(
      `/api/v2/aipAgents/agents/${agentRid}/sessions?preview=true`,
      params
    );
  }

  /** Get a session. */
  async getSession(sessionId: string): Promise<AipAgentSession> {
    return this.client.get(`/api/v2/aipAgents/sessions/${sessionId}`, {
      preview: true,
    } as Record<string, unknown>);
  }

  /** List sessions for the current user. */
  async listSessions(
    params?: PageParams & { agentRid?: string }
  ): Promise<PageResponse<AipAgentSession>> {
    return this.client.get("/api/v2/aipAgents/sessions", {
      ...params,
      preview: true,
    } as Record<string, unknown>);
  }

  // ─── Agent Continue (replaces sendMessage) ──────────────────────

  /**
   * Send a message and wait for the full response (blocking).
   * Uses agent-centric path: /agents/{agentRid}/sessions/{sessionRid}/blockingContinue
   * @see https://www.palantir.com/docs/foundry/api/v2/aip-agents-v2-resources/sessions/blocking-continue-session/
   */
  async blockingContinue(
    agentRid: string,
    sessionRid: string,
    params: AipContinueParams
  ): Promise<AipContinueResponse> {
    return this.client.post(
      `/api/v2/aipAgents/agents/${agentRid}/sessions/${sessionRid}/blockingContinue?preview=true`,
      params
    );
  }

  /**
   * Send a message and receive streaming response chunks.
   * Uses agent-centric path: /agents/{agentRid}/sessions/{sessionRid}/streamingContinue
   * Returns an async iterable of AipStreamingChunk objects.
   * @see https://www.palantir.com/docs/foundry/api/v2/aip-agents-v2-resources/sessions/streaming-continue-session/
   */
  async *streamingContinue(
    agentRid: string,
    sessionRid: string,
    params: AipContinueParams
  ): AsyncGenerator<AipStreamingChunk> {
    const token = await this.client.getAccessToken();

    const url = `${this.client.stackUrl}/api/v2/aipAgents/agents/${agentRid}/sessions/${sessionRid}/streamingContinue?preview=true`;
    const response = await this.client.rawFetch(url, {
      method: "POST",
      headers: {
        Authorization: `Bearer ${token ?? ""}`,
        "Content-Type": "application/json",
        Accept: "text/event-stream",
      },
      body: JSON.stringify(params),
    });

    if (!response.ok) {
      throw new Error(`Streaming continue failed: ${response.status} ${response.statusText}`);
    }

    const reader = response.body?.getReader();
    if (!reader) throw new Error("No response body for streaming");

    const decoder = new TextDecoder();
    let buffer = "";
    let dataBuffer = "";

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split("\n");
      buffer = lines.pop() ?? "";

      for (const line of lines) {
        if (line.startsWith("data: ")) {
          const data = line.slice(6);
          dataBuffer += data;
        } else if (line.startsWith("data:")) {
          // Space-separated continuation per SSE spec
          dataBuffer += line.slice(5);
        } else if (line === "" && dataBuffer) {
          // Empty line = end of event, emit accumulated data
          const trimmed = dataBuffer.trim();
          dataBuffer = "";
          if (trimmed === "[DONE]") return;
          try {
            yield JSON.parse(trimmed) as AipStreamingChunk;
          } catch {
            // Skip malformed chunks
          }
        }
        // Skip event:, id:, retry:, and comment lines
      }
    }

    // Emit any remaining data
    if (dataBuffer.trim()) {
      const trimmed = dataBuffer.trim();
      if (trimmed !== "[DONE]") {
        try {
          yield JSON.parse(trimmed) as AipStreamingChunk;
        } catch {
          // Skip malformed chunks
        }
      }
    }
  }

  // ─── Session Content & Tracing ──────────────────────────────────

  /** Get the content (messages/exchanges) of a session. */
  async getContent(
    agentRid: string,
    sessionRid: string,
  ): Promise<unknown> {
    return this.client.get(
      `/api/v2/aipAgents/agents/${agentRid}/sessions/${sessionRid}/content`,
      { preview: true } as Record<string, unknown>
    );
  }

  /**
   * Cancel an in-progress streamed exchange.
   * @see https://www.palantir.com/docs/foundry/api/v2/aip-agents-v2-resources/sessions/cancel-session/
   */
  async cancel(
    agentRid: string,
    sessionRid: string,
    params?: { messageId?: string; clientResponse?: string }
  ): Promise<void> {
    return this.client.post(
      `/api/v2/aipAgents/agents/${agentRid}/sessions/${sessionRid}/cancel?preview=true`,
      params
    );
  }

  // ─── Language Models (LLM Proxy) ────────────────────────────────
  // Foundry proxies requests to LLM providers via /api/v2/llm/proxy/

  /** List available language models. */
  async listModels(params?: PageParams): Promise<PageResponse<LanguageModel>> {
    return this.client.get("/api/v2/llm/models", params);
  }

  /** Get a specific model. */
  async getModel(modelId: string): Promise<LanguageModel> {
    return this.client.get(`/api/v2/llm/models/${modelId}`);
  }

  /**
   * Chat completion via OpenAI-compatible proxy endpoint.
   * Supports GPT-4, GPT-4o, etc.
   * Requires scope: `api:use-language-models-execute`
   */
  async openaiChatCompletion(
    params: ChatCompletionParams
  ): Promise<ChatCompletionResponse> {
    return this.client.post(
      "/api/v2/llm/proxy/openai/v1/chat/completions",
      params
    );
  }

  /**
   * Chat completion via Anthropic-compatible proxy endpoint.
   * Supports Claude models.
   * Requires scope: `api:use-language-models-execute`
   */
  async anthropicChatCompletion(
    params: Record<string, unknown>
  ): Promise<unknown> {
    return this.client.post(
      "/api/v2/llm/proxy/anthropic/v1/messages",
      params
    );
  }

  /**
   * Chat completion via xAI (Grok) proxy endpoint.
   * Requires scope: `api:use-language-models-execute`
   */
  async xaiChatCompletion(
    params: ChatCompletionParams
  ): Promise<ChatCompletionResponse> {
    return this.client.post(
      "/api/v2/llm/proxy/xai/v1/chat/completions",
      params
    );
  }

  /**
   * Chat completion via Google Gemini proxy endpoint.
   * Requires scope: `api:use-language-models-execute`
   */
  async googleChatCompletion(
    params: Record<string, unknown>
  ): Promise<unknown> {
    return this.client.post(
      "/api/v2/llm/proxy/google/v1/models:generateContent",
      params
    );
  }
}