import {
  createOpencode,
  createOpencodeClient,
  type OpencodeClient,
} from "@opencode-ai/sdk/v2";

import { config } from "../config.js";
import { logger } from "../logger.js";

const isDevelopmentDebugLoggingEnabled = process.env.NODE_ENV === "development";

const logDevelopmentDebug = (
  message: string,
  metadata: Record<string, unknown>,
) => {
  if (!isDevelopmentDebugLoggingEnabled) {
    return;
  }
  logger.info(metadata, message);
};

export type RuntimeHealth = {
  healthy: boolean;
  version: string;
};

type RuntimeModelOverride = {
  providerID: string;
  modelID: string;
};

export class OpencodeRuntimeAdapter {
  private clientPromise: Promise<OpencodeClient> | null = null;
  private closeServer: (() => void) | null = null;

  async ensureClient(): Promise<OpencodeClient> {
    if (!this.clientPromise) {
      this.clientPromise = this.bootstrapClient();
    }
    return this.clientPromise;
  }

  async health(): Promise<RuntimeHealth> {
    const client = await this.ensureClient();
    const response = await client.global.health();
    return requireData(response.data, "global.health");
  }

  async createSession(title?: string) {
    const client = await this.ensureClient();
    const response = await client.session.create({
      title,
    });
    return requireData(response.data, "session.create");
  }

  async getSession(id: string) {
    const client = await this.ensureClient();
    const response = await client.session.get({
      sessionID: id,
    });
    return requireData(response.data, "session.get");
  }

  async sendPrompt(sessionId: string, text: string) {
    await this.prompt(sessionId, text);
    // 当前 SDK 响应风格下，prompt() 本身不会直接返回完整 assistant parts，
    // 所以这里紧跟一次 messages() 回读，给上层路由统一消费。
    return this.messages(sessionId);
  }

  async prompt(sessionId: string, text: string, model?: RuntimeModelOverride) {
    const client = await this.ensureClient();
    const startedAt = Date.now();
    logDevelopmentDebug(
      "dispatching opencode session.prompt",
      {
        sessionId,
        model: model ?? null,
        textChars: text.length,
      },
    );
    await client.session.prompt({
      sessionID: sessionId,
      model,
      parts: [{ type: "text", text }],
    });
    logDevelopmentDebug(
      "opencode session.prompt returned",
      {
        sessionId,
        elapsedMs: Math.max(0, Date.now() - startedAt),
      },
    );
  }

  async messages(sessionId: string, limit = 20) {
    const client = await this.ensureClient();
    const messages = await client.session.messages({
      sessionID: sessionId,
      limit,
    });
    return requireData(messages.data, "session.messages");
  }

  async forkSession(sessionId: string, messageId?: string) {
    const client = await this.ensureClient();
    const response = await client.session.fork({
      sessionID: sessionId,
      messageID: messageId,
    });
    return requireData(response.data, "session.fork");
  }

  async abortSession(sessionId: string) {
    const client = await this.ensureClient();
    const response = await client.session.abort({
      sessionID: sessionId,
    });
    return requireData(response.data, "session.abort");
  }

  async waitForSessionIdle(sessionId: string, timeoutMs = config.OPENCODE_TIMEOUT_MS) {
    const client = await this.ensureClient();
    const startedAt = Date.now();

    while (Date.now() - startedAt < timeoutMs) {
      const response = await client.session.status({});
      const statuses = requireData(response.data, "session.status");
      const status = statuses[sessionId];
      if (!status || status.type === "idle") {
        return;
      }
      await delay(100);
    }

    logger.warn(
      { sessionId, timeoutMs },
      "timed out waiting for opencode session to become idle",
    );
  }

  async subscribeEvents() {
    const client = await this.ensureClient();
    const response = await client.event.subscribe();
    return response.stream;
  }

  async dispose(): Promise<void> {
    this.closeServer?.();
    this.closeServer = null;
    this.clientPromise = null;
  }

  private async bootstrapClient(): Promise<OpencodeClient> {
    if (config.OPENCODE_MODE === "client") {
      logger.info(
        {
          baseUrl: config.OPENCODE_CLIENT_BASE_URL,
          mode: config.OPENCODE_MODE,
        },
        "connecting to opencode server in client mode",
      );
      return createOpencodeClient({
        baseUrl: config.OPENCODE_CLIENT_BASE_URL,
      });
    }

    // embedded 模式下，把服务内工具桥地址注入到 opencode 进程环境里，
    // 这样 .opencode/tools 下的自定义工具可以回调本服务。
    process.env.TJWATER_AGENT_INTERNAL_BASE_URL = `http://127.0.0.1:${config.PORT}`;
    process.env.TJWATER_AGENT_INTERNAL_TOKEN =
      config.AGENT_INTERNAL_TOKEN ??
      process.env.TJWATER_AGENT_INTERNAL_TOKEN ??
      "";

    logger.info(
      {
        hostname: config.OPENCODE_HOSTNAME,
        port: config.OPENCODE_PORT,
        model: config.OPENCODE_MODEL,
        mode: config.OPENCODE_MODE,
      },
      "starting opencode server in embedded mode",
    );

    let runtime;
    try {
      runtime = await createOpencode({
        hostname: config.OPENCODE_HOSTNAME,
        port: config.OPENCODE_PORT,
        timeout: config.OPENCODE_TIMEOUT_MS,
        config: {
          model: config.OPENCODE_MODEL,
        },
      });
    } catch (error) {
      if (isMissingOpencodeCli(error)) {
        throw new Error(
          "embedded mode requires the opencode CLI to be installed and available in PATH; otherwise set OPENCODE_MODE=client and provide OPENCODE_CLIENT_BASE_URL",
        );
      }
      throw error;
    }

    this.closeServer = () => {
      runtime.server.close();
    };

    return runtime.client;
  }
}

export const opencodeRuntime = new OpencodeRuntimeAdapter();

function isMissingOpencodeCli(error: unknown): error is NodeJS.ErrnoException {
  return (
    typeof error === "object" &&
    error !== null &&
    "code" in error &&
    (error as NodeJS.ErrnoException).code === "ENOENT"
  );
}

function requireData<T>(data: T | undefined, operation: string): T {
  if (data === undefined) {
    throw new Error(`${operation} returned no data`);
  }
  return data;
}

function delay(ms: number) {
  return new Promise<void>((resolve) => {
    setTimeout(resolve, ms);
  });
}