import express from "express";
import crypto from "node:crypto";

const app = express();
app.use(express.json({ limit: "10mb" }));

const PORT = Number(process.env.PORT || 3080);
const OPENCLAW_BASE_URL = process.env.OPENCLAW_BASE_URL || "http://gateway:18789";
const OPENCLAW_BEARER_TOKEN = process.env.OPENCLAW_BEARER_TOKEN || "";
const OPENCLAW_MODELS = (process.env.OPENCLAW_MODELS || "openclaw-main")
  .split(",")
  .map((s) => s.trim())
  .filter(Boolean);

function nowSeconds() {
  return Math.floor(Date.now() / 1000);
}

function makeId(prefix) {
  return `${prefix}-${crypto.randomUUID()}`;
}

function pseudoModelToAgent(model) {
  if (!model) return "main";

  if (model.startsWith("openclaw-")) {
    return model.slice("openclaw-".length);
  }

  if (model.startsWith("openclaw:")) {
    return model.slice("openclaw:".length);
  }

  if (model.startsWith("agent:")) {
    return model.slice("agent:".length);
  }

  return model;
}

function agentToOpenClawModel(agent) {
  return `openclaw:${agent}`;
}

function flattenContent(content) {
  if (typeof content === "string") return content;

  if (Array.isArray(content)) {
    return content
      .map((part) => {
        if (!part) return "";
        if (typeof part === "string") return part;
        if (part?.type === "text") return part.text || "";
        if (part?.type === "input_text") return part.text || "";
        if (typeof part?.text === "string") return part.text;
        return "";
      })
      .join("\n");
  }

  if (content == null) return "";

  if (typeof content === "object") {
    if (typeof content.text === "string") return content.text;
    return JSON.stringify(content);
  }

  return String(content);
}

function normalizeMessages(messages = []) {
  if (!Array.isArray(messages)) return [];

  return messages
    .filter((m) => m && typeof m === "object")
    .map((m) => ({
      role:
        typeof m.role === "string" && m.role.length
          ? m.role
          : "user",
      content: flattenContent(m.content),
    }))
    .filter((m) => m.content !== undefined);
}

function extractAssistantTextFromResponsesApi(payload) {
  if (!payload) return "";

  if (typeof payload.output_text === "string" && payload.output_text.length) {
    return payload.output_text;
  }

  const output = Array.isArray(payload.output) ? payload.output : [];
  const texts = [];

  for (const item of output) {
    if (item?.type === "message" && Array.isArray(item.content)) {
      for (const part of item.content) {
        if (part?.type === "output_text" && typeof part.text === "string") {
          texts.push(part.text);
        }
        if (part?.type === "text" && typeof part.text === "string") {
          texts.push(part.text);
        }
      }
    }
  }

  return texts.join("\n").trim();
}

function buildOpenClawInput(messages = []) {
  if (!Array.isArray(messages)) return [];

  return messages
    .filter((m) => m && typeof m === "object")
    .map((m) => ({
      role:
        typeof m.role === "string" && m.role.length
          ? m.role
          : "user",
      content: [
        {
          type: "input_text",
          text: flattenContent(m.content) || "",
        },
      ],
    }));
}

function buildChatCompletionResponse({ model, content, finishReason = "stop" }) {
  return {
    id: makeId("chatcmpl"),
    object: "chat.completion",
    created: nowSeconds(),
    model,
    choices: [
      {
        index: 0,
        message: {
          role: "assistant",
          content,
        },
        finish_reason: finishReason,
      },
    ],
    usage: {
      prompt_tokens: 0,
      completion_tokens: 0,
      total_tokens: 0,
    },
  };
}

function sseWrite(res, obj) {
  res.write(`data: ${JSON.stringify(obj)}\n\n`);
}

app.get("/health", (_req, res) => {
  res.json({ ok: true });
});

app.get("/v1/models", (_req, res) => {
  res.json({
    object: "list",
    data: OPENCLAW_MODELS.map((modelId) => ({
      id: modelId,
      object: "model",
      created: 0,
      owned_by: "openclaw",
    })),
  });
});

app.post("/v1/chat/completions", async (req, res) => {
  try {
    const {
      model,
      messages = [],
      stream = false,
      user,
      temperature,
      max_tokens,
    } = req.body || {};
    console.log("Incoming model:", model);
    console.log("Incoming messages preview:", JSON.stringify(messages?.slice?.(0, 3), null, 2));
    const agent = pseudoModelToAgent(model || OPENCLAW_MODELS[0] || "openclaw-hermes");
    const openclawModel = agentToOpenClawModel(agent);

    const normalizedMessages = normalizeMessages(messages);
    if (!normalizedMessages.length) {
      return res.status(400).json({
        error: {
          message: "No valid messages were provided",
          type: "invalid_request_error",
        },
      });
    }
    const derivedUser =
      user ||
      req.header("x-conversation-id") ||
      req.header("x-session-id") ||
      `librechat-${crypto.randomUUID()}`;

    const body = {
      model: openclawModel,
      input: buildOpenClawInput(normalizedMessages),
      user: derivedUser,
      temperature,
      max_output_tokens: max_tokens,
      stream: false
    };

    const headers = {
      "content-type": "application/json",
    };

    if (OPENCLAW_BEARER_TOKEN) {
      headers.authorization = `Bearer ${OPENCLAW_BEARER_TOKEN}`;
    }

    const upstream = await fetch(`${OPENCLAW_BASE_URL}/v1/responses`, {
      method: "POST",
      headers,
      body: JSON.stringify(body),
    });

    const text = await upstream.text();

    if (!upstream.ok) {
      res.status(upstream.status).json({
        error: {
          message: text || "OpenClaw upstream error",
          type: "upstream_error",
        },
      });
      return;
    }

    const payload = JSON.parse(text);
    const assistantText = extractAssistantTextFromResponsesApi(payload);

    if (!stream) {
      res.json(
        buildChatCompletionResponse({
          model: model || OPENCLAW_MODELS[0] || "openclaw-main",
          content: assistantText,
        })
      );
      return;
    }

    res.setHeader("Content-Type", "text/event-stream");
    res.setHeader("Cache-Control", "no-cache, no-transform");
    res.setHeader("Connection", "keep-alive");

    sseWrite(res, {
      id: makeId("chatcmpl"),
      object: "chat.completion.chunk",
      created: nowSeconds(),
      model: model || OPENCLAW_MODELS[0] || "openclaw-main",
      choices: [
        {
          index: 0,
          delta: { role: "assistant" },
          finish_reason: null,
        },
      ],
    });

    if (assistantText) {
      sseWrite(res, {
        id: makeId("chatcmpl"),
        object: "chat.completion.chunk",
        created: nowSeconds(),
        model: model || OPENCLAW_MODELS[0] || "openclaw-main",
        choices: [
          {
            index: 0,
            delta: { content: assistantText },
            finish_reason: null,
          },
        ],
      });
    }

    sseWrite(res, {
      id: makeId("chatcmpl"),
      object: "chat.completion.chunk",
      created: nowSeconds(),
      model: model || OPENCLAW_MODELS[0] || "openclaw-main",
      choices: [
        {
          index: 0,
          delta: {},
          finish_reason: "stop",
        },
      ],
    });

    res.write("data: [DONE]\n\n");
    res.end();
  } catch (err) {
    res.status(500).json({
      error: {
        message: err instanceof Error ? err.message : "Internal server error",
        type: "server_error",
      },
    });
  }
});

app.listen(PORT, () => {
  console.log(`openclaw-librechat-bridge listening on ${PORT}`);
});