const express = require("express");
const { z } = require("zod");
const prisma = require("./db");
const { parseServerImport } = require("./importParser");
const { asIntegerPort, normalizeEndpoint, normalizeIp, normalizeMethod, serviceTarget } = require("./utils");

const router = express.Router();

const serverSchema = z.object({
  name: z.string().trim().min(1),
  ipAddress: z.string().trim().min(1),
  description: z.string().optional().nullable(),
  proxyPort: z.coerce.number().int().min(1).max(65535).optional().nullable(),
  proxyPath: z.string().trim().optional().nullable(),
});

const serviceSchema = z.object({
  serverId: z.string().min(1),
  name: z.string().trim().min(1),
  port: z.coerce.number().int().min(1).max(65535),
  endpoint: z.string().trim().optional().nullable(),
  method: z.string().optional().nullable(),
  requestTemplate: z.any().optional().nullable(),
  notes: z.string().optional().nullable(),
});

function includeServices() {
  return {
    services: {
      orderBy: [{ port: "asc" }, { name: "asc" }],
    },
  };
}

async function findConflicts(parsedServers) {
  const conflicts = [];
  const duplicates = [];
  const newServers = [];
  const newServices = [];

  for (const server of parsedServers) {
    const existingServer = await prisma.server.findUnique({
      where: { ipAddress: server.ipAddress },
      include: { services: true },
    });

    if (!existingServer) {
      newServers.push(server);
    } else {
      const sameServer =
        existingServer.name === server.name && (existingServer.description || null) === (server.description || null);
      if (!sameServer) {
        conflicts.push({
          type: "server",
          ipAddress: server.ipAddress,
          existing: {
            id: existingServer.id,
            name: existingServer.name,
            description: existingServer.description,
          },
          incoming: {
            name: server.name,
            description: server.description,
          },
        });
      }
    }

    const batch = new Map();

    for (const service of server.services) {
      const prior = batch.get(service.name);
      if (prior) {
        if (prior.port === service.port) {
          duplicates.push({
            type: "service",
            serverIp: server.ipAddress,
            name: service.name,
            port: service.port,
          });
          continue;
        }
        conflicts.push({
          type: "service",
          serverIp: server.ipAddress,
          key: service.name,
          existing: { name: prior.name, port: prior.port },
          incoming: { name: service.name, port: service.port },
        });
        newServices.push({ serverId: existingServer?.id, serverIp: server.ipAddress, ...service });
        continue;
      }
      batch.set(service.name, service);

      if (!existingServer) {
        newServices.push({ serverIp: server.ipAddress, ...service });
        continue;
      }

      const existingSamePort = existingServer.services.find(
        (item) => item.name === service.name && item.port === service.port,
      );
      if (existingSamePort) {
        duplicates.push({
          type: "service",
          serverIp: server.ipAddress,
          name: service.name,
          port: service.port,
        });
        continue;
      }

      const existingDiffPort = existingServer.services.find(
        (item) => item.name === service.name && item.port !== service.port,
      );
      if (existingDiffPort) {
        conflicts.push({
          type: "service",
          serverIp: server.ipAddress,
          key: service.name,
          existing: { name: existingDiffPort.name, port: existingDiffPort.port, method: existingDiffPort.method },
          incoming: { name: service.name, port: service.port, method: service.method },
        });
      }

      newServices.push({ serverId: existingServer.id, serverIp: server.ipAddress, ...service });
    }
  }

  return { conflicts, duplicates, newServers, newServices };
}

async function applyImport(parsedServers, mode, client = prisma) {
  const result = {
    serversCreated: 0,
    serversUpdated: 0,
    servicesCreated: 0,
    servicesUpdated: 0,
    duplicatesSkipped: 0,
  };

  const guard = async (operation) => {
    try {
      return await operation();
    } catch (error) {
      if (error.code === "P2002") {
        result.duplicatesSkipped += 1;
        return null;
      }
      console.error("applyImport guard failure:", error.code || error.name, error.message);
      throw error;
    }
  };

  for (const server of parsedServers) {
    const existingServer = await client.server.findUnique({
      where: { ipAddress: server.ipAddress },
      include: { services: true },
    });

    let savedServer = existingServer;
    if (!existingServer) {
      savedServer = await client.server.create({
        data: {
          name: server.name,
          ipAddress: server.ipAddress,
          description: server.description,
          proxyPort: server.proxyPort ?? null,
          proxyPath: server.proxyPath ?? null,
        },
      });
      result.serversCreated += 1;
    } else if (mode === "overwrite") {
      savedServer = await client.server.update({
        where: { id: existingServer.id },
        data: {
          name: server.name,
          description: server.description,
          proxyPort: server.proxyPort ?? undefined,
          proxyPath: server.proxyPath ?? undefined,
        },
      });
      result.serversUpdated += 1;
    }

    const seen = new Set();

    for (const service of server.services) {
      const key = `${service.name}:${service.port}`;
      if (seen.has(key)) {
        result.duplicatesSkipped += 1;
        continue;
      }
      seen.add(key);

      const existingSamePort = existingServer?.services.find(
        (item) => item.name === service.name && item.port === service.port,
      );

      if (!existingSamePort) {
        await guard(() =>
          client.service.create({
            data: {
              serverId: savedServer.id,
              name: service.name,
              port: service.port,
              endpoint: service.endpoint,
              method: service.method,
              requestTemplate: service.requestTemplate,
              notes: service.notes,
            },
          }),
        );
        result.servicesCreated += 1;
      } else if (mode === "overwrite") {
        await guard(() =>
          client.service.update({
            where: { id: existingSamePort.id },
            data: {
              name: service.name,
              method: service.method,
              requestTemplate: service.requestTemplate,
              notes: service.notes,
            },
          }),
        );
        result.servicesUpdated += 1;
      } else {
        result.duplicatesSkipped += 1;
      }
    }
  }

  return result;
}

router.get("/health", (req, res) => {
  res.json({ ok: true, service: "mtc-reverse-proxy-backend" });
});

router.get("/servers", async (req, res, next) => {
  try {
    const servers = await prisma.server.findMany({
      include: includeServices(),
      orderBy: { name: "asc" },
    });
    res.json(servers);
  } catch (error) {
    next(error);
  }
});

router.post("/servers", async (req, res, next) => {
  try {
    const parsed = serverSchema.parse({
      ...req.body,
      ipAddress: normalizeIp(req.body.ipAddress),
    });
    const data = { ...parsed, proxyPath: parsed.proxyPath || null };
    const server = await prisma.server.create({ data, include: includeServices() });
    res.status(201).json(server);
  } catch (error) {
    next(error);
  }
});

router.post("/services", async (req, res, next) => {
  try {
    const parsed = serviceSchema.parse(req.body);
    const service = await prisma.service.create({
      data: {
        ...parsed,
        endpoint: normalizeEndpoint(parsed.endpoint || "/"),
        method: normalizeMethod(parsed.method),
        port: asIntegerPort(parsed.port),
      },
    });
    res.status(201).json(service);
  } catch (error) {
    next(error);
  }
});

router.patch("/servers/:id", async (req, res, next) => {
  try {
    const parsed = serverSchema.partial().parse({
      ...req.body,
      ipAddress: req.body.ipAddress ? normalizeIp(req.body.ipAddress) : undefined,
    });
    const data = Object.fromEntries(Object.entries(parsed).filter(([, value]) => value !== undefined));
    if (data.proxyPath === "") data.proxyPath = null;
    const server = await prisma.server.update({
      where: { id: req.params.id },
      data,
      include: includeServices(),
    });
    res.json(server);
  } catch (error) {
    next(error);
  }
});

router.delete("/servers/:id", async (req, res, next) => {
  try {
    await prisma.server.delete({ where: { id: req.params.id } });
    res.status(204).end();
  } catch (error) {
    next(error);
  }
});

router.patch("/services/:id", async (req, res, next) => {
  try {
    const parsed = serviceSchema.partial().parse(req.body);
    const data = Object.fromEntries(
      Object.entries({
        ...parsed,
        endpoint: parsed.endpoint ? normalizeEndpoint(parsed.endpoint) : undefined,
        method: parsed.method !== undefined ? normalizeMethod(parsed.method) : undefined,
        port: parsed.port !== undefined ? asIntegerPort(parsed.port) : undefined,
      }).filter(([, value]) => value !== undefined),
    );
    const service = await prisma.service.update({
      where: { id: req.params.id },
      data,
      include: { server: true },
    });
    res.json(service);
  } catch (error) {
    next(error);
  }
});

router.delete("/services/:id", async (req, res, next) => {
  try {
    await prisma.service.delete({ where: { id: req.params.id } });
    res.status(204).end();
  } catch (error) {
    next(error);
  }
});

router.post("/imports/preview", async (req, res, next) => {
  try {
    const { servers, errors } = parseServerImport(req.body);
    const summary = await findConflicts(servers);
    res.json({
      parsed: servers,
      errors,
      ...summary,
      canApply: errors.length === 0 && summary.conflicts.length === 0,
    });
  } catch (error) {
    next(error);
  }
});

router.post("/imports/apply", async (req, res, next) => {
  try {
    const mode = req.body.mode === "overwrite" ? "overwrite" : "skip";
    const payload = req.body.payload || req.body;
    const { servers, errors } = parseServerImport(payload);
    const summary = await findConflicts(servers);

    if (errors.length > 0) {
      res.status(400).json({ message: "Import JSON has validation errors.", errors });
      return;
    }

    if (summary.conflicts.length > 0 && mode !== "overwrite") {
      res.status(409).json({ message: "Import has conflicts that need confirmation.", ...summary });
      return;
    }

    const applied = await prisma.$transaction(
      (tx) => applyImport(servers, mode, tx),
      { maxWait: 15000, timeout: 60000 },
    );
    res.json({ message: "Import applied.", applied });
  } catch (error) {
    next(error);
  }
});

router.post("/services/:id/reverse-proxy", async (req, res, next) => {
  try {
    const service = await prisma.service.findUnique({
      where: { id: req.params.id },
      include: { server: true },
    });

    if (!service) {
      res.status(404).json({ message: "Service not found." });
      return;
    }

    const server = service.server;
    const gateway =
      server.proxyPort != null
        ? {
            port: server.proxyPort,
            path: normalizeEndpoint(server.proxyPath || "/api/nginx/app"),
          }
        : null;
    const target = gateway
      ? `http://${server.ipAddress}:${gateway.port}${gateway.path}`
      : serviceTarget(server, service);
    const controller = new AbortController();
    const timeout = setTimeout(() => controller.abort(), Number(process.env.REVERSE_PROXY_TIMEOUT_MS || 15000));
    const method = normalizeMethod(req.body.method || service.method);
    const suppliedBody = req.body.body !== undefined ? req.body.body : service.requestTemplate;
    const body = gateway
      ? {
          ...(suppliedBody && typeof suppliedBody === "object" && !Array.isArray(suppliedBody) ? suppliedBody : {}),
          domain: service.name,
          port: service.port,
        }
      : suppliedBody;

    const response = await fetch(target, {
      method,
      headers: {
        "content-type": "application/json",
      },
      body: method === "GET" ? undefined : JSON.stringify(body || {}),
      signal: controller.signal,
    });

    clearTimeout(timeout);
    const text = await response.text();
    let data = text;
    try {
      data = text ? JSON.parse(text) : null;
    } catch {
      data = text;
    }

    res.json({
      target,
      status: response.status,
      ok: response.ok,
      data,
    });
  } catch (error) {
    if (error.name === "AbortError") {
      res.status(504).json({ message: "Reverse proxy request timed out." });
      return;
    }
    next(error);
  }
});

module.exports = router;