/**
 * QR Rápido MCP Server — HTTP/SSE transport (para n8n cloud e clientes remotos)
 *
 * Variáveis de ambiente:
 *   QR_BASE_URL   — URL da API (default: https://qrrapido.site)
 *   PORT          — porta HTTP (default: 3000)
 *   ALLOWED_KEYS  — lista de API keys válidas separadas por vírgula (opcional; vazio = delega à API)
 *
 * Cada request deve enviar o header:   X-API-Key: qr_xxx
 * O server valida a key chamando a API antes de aceitar a sessão MCP.
 *
 * Endpoint n8n: https://mcp.qrrapido.site/mcp  (ou porta 3000 internamente)
 */

import express from "express";
import { Server } from "@modelcontextprotocol/sdk/server/index.js";
import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
import { ListToolsRequestSchema, CallToolRequestSchema } from "@modelcontextprotocol/sdk/types.js";
import { fetch } from "undici";
import { writeFileSync } from "fs";
import { tmpdir } from "os";
import { join } from "path";

const BASE_URL = process.env.QR_BASE_URL || "https://qrrapido.site";
const PORT     = parseInt(process.env.PORT || "3000", 10);

// ── PIX EMV builder ───────────────────────────────────────────────────────────

function pixField(id, value) {
  return `${id}${String(value.length).padStart(2, "0")}${value}`;
}

function removeAccents(text) {
  return text.toUpperCase().normalize("NFD").replace(/[\u0300-\u036f]/g, "").replace(/[^A-Z0-9 ]/g, " ");
}

function crc16(data) {
  let crc = 0xFFFF;
  for (const ch of data) {
    crc ^= ch.charCodeAt(0) << 8;
    for (let i = 0; i < 8; i++)
      crc = (crc & 0x8000) ? ((crc << 1) ^ 0x1021) & 0xFFFF : (crc << 1) & 0xFFFF;
  }
  return crc.toString(16).toUpperCase().padStart(4, "0");
}

function buildPixPayload({ pixKey, amount, merchantName, merchantCity, txId = "***" }) {
  const merchantInfo = pixField("00", "br.gov.bcb.pix") + pixField("01", pixKey);
  const name = removeAccents(merchantName).substring(0, 25);
  const city = removeAccents(merchantCity).substring(0, 15);
  let payload = pixField("00", "01")
    + pixField("26", merchantInfo)
    + pixField("52", "0000")
    + pixField("53", "986");
  if (amount && amount > 0) payload += pixField("54", amount.toFixed(2));
  payload += pixField("58", "BR")
    + pixField("59", name)
    + pixField("60", city)
    + pixField("62", pixField("05", txId.substring(0, 25)))
    + "6304";
  return payload + crc16(payload);
}

// ── API helpers ───────────────────────────────────────────────────────────────

async function callApi(apiKey, body) {
  const res = await fetch(`${BASE_URL}/api/v1/QRManager/generate`, {
    method: "POST",
    headers: { "X-API-Key": apiKey, "Content-Type": "application/json" },
    body: JSON.stringify(body)
  });
  return res.json();
}

async function validateKey(apiKey) {
  // Basic format check — real auth happens on every tool call via the API
  if (!apiKey || !apiKey.startsWith("qr_") || apiKey.length < 20) return false;
  return true;
}

function errorContent(msg) {
  return { content: [{ type: "text", text: `❌ ${msg}` }], isError: true };
}

// ── MCP server factory (uma instância por sessão/request) ─────────────────────

const QR_OUTPUT_SCHEMA = {
  type: "object",
  properties: {
    content: {
      type: "array",
      description: "Array with the QR code image (base64 PNG) and a text summary.",
      items: {
        oneOf: [
          {
            type: "object",
            description: "Base64-encoded QR code image.",
            properties: {
              type: { type: "string", const: "image" },
              data: { type: "string", description: "Base64-encoded image data." },
              mimeType: { type: "string", description: "MIME type, e.g. image/png." }
            },
            required: ["type", "data", "mimeType"]
          },
          {
            type: "object",
            description: "Text summary with timing, cache status, and quota info.",
            properties: {
              type: { type: "string", const: "text" },
              text: { type: "string" }
            },
            required: ["type", "text"]
          }
        ]
      }
    }
  },
  required: ["content"]
};

function createMcpServer(apiKey) {
  const server = new Server(
    { name: "qrrapido", version: "1.0.3" },
    { capabilities: { tools: {} } }
  );

  server.setRequestHandler(ListToolsRequestSchema, async () => ({
    tools: [
      {
        name: "generate_qr",
        description:
          "Generate a QR code for a URL, Wi-Fi network, vCard contact, WhatsApp message, " +
          "email, SMS, or free text. Returns an inline base64 PNG — no file hosting needed. " +
          "For Brazilian PIX payments use generate_pix_qr instead.",
        annotations: {
          title: "Generate QR Code",
          readOnlyHint: false,
          destructiveHint: false,
          idempotentHint: true,
          openWorldHint: true
        },
        inputSchema: {
          type: "object",
          properties: {
            type: {
              type: "string",
              enum: ["url", "wifi", "vcard", "whatsapp", "email", "sms", "texto"],
              description:
                "QR code type. Use 'url' for websites, 'wifi' for network credentials, " +
                "'vcard' for contacts, 'whatsapp' to open a WhatsApp chat, " +
                "'email' for pre-filled emails, 'sms' for text messages, 'texto' for free text."
            },
            content: {
              type: "string",
              description:
                "Content to encode. Examples by type — " +
                "url: 'https://example.com'; " +
                "wifi: 'WIFI:T:WPA;S:MyNet;P:pass123;;'; " +
                "vcard: 'BEGIN:VCARD\\nFN:John\\nTEL:+1234\\nEND:VCARD'; " +
                "whatsapp: '+5511999998888'; " +
                "email: 'user@example.com'; " +
                "sms: '+5511999998888'; " +
                "texto: any plain text."
            },
            format: {
              type: "string",
              enum: ["png", "webp", "svg"],
              default: "png",
              description: "Output image format. PNG is recommended for broadest compatibility."
            },
            size: {
              type: "number",
              default: 400,
              description: "Image size in pixels (width = height). Range: 100–2000. Default: 400."
            },
            primaryColor: {
              type: "string",
              default: "#000000",
              description: "QR module color as hex, e.g. '#1a1a1a'. Default: black (#000000)."
            },
            backgroundColor: {
              type: "string",
              default: "#FFFFFF",
              description: "Background color as hex, e.g. '#FFFFFF'. Default: white (#FFFFFF)."
            }
          },
          required: ["type", "content"]
        },
        outputSchema: QR_OUTPUT_SCHEMA
      },
      {
        name: "generate_pix_qr",
        description:
          "Generate a Brazilian PIX payment QR code (BRCode/EMV standard). " +
          "Builds the payload automatically from the PIX key, amount, recipient name, and city. " +
          "Returns an inline base64 PNG ready to display or share.",
        annotations: {
          title: "Generate PIX QR Code",
          readOnlyHint: false,
          destructiveHint: false,
          idempotentHint: true,
          openWorldHint: true
        },
        inputSchema: {
          type: "object",
          properties: {
            pixKey: {
              type: "string",
              description:
                "PIX key of the recipient. Accepted formats: " +
                "CPF (digits only, e.g. '12345678901'), " +
                "email (e.g. 'user@example.com'), " +
                "phone with country code (e.g. '+5511987654321'), " +
                "or random key (UUID, e.g. '123e4567-e89b-12d3-a456-426614174000')."
            },
            amount: {
              type: "number",
              description:
                "Payment amount in BRL (e.g. 49.90). " +
                "Omit or set to 0 to create an open-value QR code where the payer enters the amount."
            },
            merchantName: {
              type: "string",
              description:
                "Recipient name as it appears in the payer's banking app. " +
                "Max 25 characters. Accents are stripped automatically. Example: 'RICARDO CARNEIRO'."
            },
            merchantCity: {
              type: "string",
              description:
                "Recipient city. Max 15 characters. Accents are stripped automatically. " +
                "Example: 'SAO PAULO'."
            },
            txId: {
              type: "string",
              default: "***",
              description:
                "Optional transaction identifier for reconciliation. Max 25 characters. " +
                "Use '***' (default) to omit. Example: 'PEDIDO123'."
            },
            size: {
              type: "number",
              default: 400,
              description: "Image size in pixels (width = height). Range: 100–2000. Default: 400."
            },
            primaryColor: {
              type: "string",
              default: "#000000",
              description: "QR module color as hex. Default: black (#000000)."
            },
            backgroundColor: {
              type: "string",
              default: "#FFFFFF",
              description: "Background color as hex. Default: white (#FFFFFF)."
            }
          },
          required: ["pixKey", "merchantName", "merchantCity"]
        },
        outputSchema: QR_OUTPUT_SCHEMA
      }
    ]
  }));

  server.setRequestHandler(CallToolRequestSchema, async (req) => {
    const { name } = req.params;
    const args = req.params.arguments ?? {};

    if (name === "generate_pix_qr") {
      const { pixKey, amount, merchantName, merchantCity, txId = "***",
              size = 400, primaryColor = "#000000", backgroundColor = "#FFFFFF" } = args;
      if (!pixKey || !merchantName || !merchantCity)
        return errorContent("pixKey, merchantName and merchantCity are required.");
      let payload;
      try { payload = buildPixPayload({ pixKey, amount, merchantName, merchantCity, txId }); }
      catch (e) { return errorContent(`Failed to build PIX payload: ${e.message}`); }
      let data;
      try { data = await callApi(apiKey, { type: "texto", content: payload, size, primaryColor, backgroundColor }); }
      catch (e) { return errorContent(`API request failed: ${e.message}`); }
      if (!data.success) return errorContent(data.message || "Unknown error");
      return {
        content: [
          { type: "image", data: data.qrCodeBase64, mimeType: data.mimeType || "image/png" },
          {
            type: "text",
            text: [
              `PIX QR code generated successfully`,
              `PIX key: ${pixKey}`,
              `Amount: ${amount ? `BRL ${amount.toFixed(2)}` : "open (payer chooses)"}`,
              `Recipient: ${merchantName} — ${merchantCity}`,
              `Generation time: ${data.generationTimeMs}ms`
            ].join("\n")
          }
        ]
      };
    }

    if (name === "generate_qr") {
      const { type, content, format = "png", size = 400,
              primaryColor = "#000000", backgroundColor = "#FFFFFF" } = args;
      if (!type || !content) return errorContent("'type' and 'content' are required.");
      let data;
      try { data = await callApi(apiKey, { type, content, outputFormat: format, size, primaryColor, backgroundColor }); }
      catch (e) { return errorContent(`API request failed: ${e.message}`); }
      if (!data.success) return errorContent(data.message || "Unknown error");
      return {
        content: [
          { type: "image", data: data.qrCodeBase64, mimeType: data.mimeType || "image/png" },
          {
            type: "text",
            text: [
              `QR code generated successfully`,
              `Generation time: ${data.generationTimeMs}ms`,
              `Cache: ${data.fromCache ? "hit" : "miss"}`,
              data.monthlyQuotaLimit >= 0
                ? `Monthly quota: ${data.monthlyQuotaRemaining}/${data.monthlyQuotaLimit}`
                : `Monthly quota: unlimited`
            ].join("\n")
          }
        ]
      };
    }

    return errorContent(`Unknown tool: ${name}`);
  });

  return server;
}

// ── Express app ───────────────────────────────────────────────────────────────

const app = express();
app.use(express.json());

// Health check (no auth required)
app.get("/health", (_, res) => res.json({ status: "ok", service: "qrrapido-mcp", version: "1.0.3", baseUrl: BASE_URL }));

// MCP endpoint — cada POST cria sessão stateless
app.all("/mcp", async (req, res) => {
  const apiKey = req.headers["x-api-key"] || req.query.key;

  if (!apiKey) {
    res.status(401).json({ error: "X-API-Key header required" });
    return;
  }

  const valid = await validateKey(apiKey);
  if (!valid) {
    res.status(401).json({ error: "Invalid or revoked API key" });
    return;
  }

  const transport = new StreamableHTTPServerTransport({ sessionIdGenerator: undefined });
  const server = createMcpServer(apiKey);

  res.on("close", () => { transport.close(); server.close(); });

  try {
    await server.connect(transport);
    await transport.handleRequest(req, res, req.body);
  } catch (err) {
    if (!res.headersSent)
      res.status(500).json({ error: "Internal server error", detail: err.message });
  }
});

app.listen(PORT, () => {
  console.log(`[qrrapido-mcp-http] HTTP server on port ${PORT}`);
  console.log(`[qrrapido-mcp-http] Base URL: ${BASE_URL}`);
  console.log(`[qrrapido-mcp-http] MCP endpoint: http://localhost:${PORT}/mcp`);
});