import { existsSync } from "node:fs";
import { join } from "node:path";
import cors from "cors";
import express from "express";
import { z } from "zod";
import { AzureImageService } from "./azure-service";
import { TemplateService } from "./template-service";

const findAppRoot = (): string => {
  const candidates = [join(__dirname, "../../.."), join(__dirname, "../..")];

  for (const candidate of candidates) {
    if (existsSync(join(candidate, "templates.json"))) {
      return candidate;
    }
  }

  throw new Error("Unable to resolve app root");
};

const queryLocation = z.object({ location: z.string().min(1) });
const queryOffer = z.object({ location: z.string().min(1), publisher: z.string().min(1) });
const querySku = z.object({ location: z.string().min(1), publisher: z.string().min(1), offer: z.string().min(1) });
const queryVersion = z.object({ location: z.string().min(1), publisher: z.string().min(1), offer: z.string().min(1), sku: z.string().min(1) });

const renderBody = z.object({
  templateFile: z.string().min(1),
  selection: z.object({
    location: z.string().min(1),
    publisher: z.string().min(1),
    offer: z.string().min(1),
    sku: z.string().min(1),
    version: z.string().min(1)
  })
});

const makeApp = () => {
  const app = express();
  const port = Number.parseInt(process.env.PORT ?? "3000", 10);
  const host = process.env.HOST ?? "0.0.0.0";
  const subscriptionId = process.env.AZURE_SUBSCRIPTION_ID;

  app.use(cors());
  app.use(express.json());

  const azure = subscriptionId ? new AzureImageService(subscriptionId) : null;
  const templates = new TemplateService();

  app.get("/api/health", (_req, res) => {
    if (!subscriptionId) {
      res.status(500).json({
        status: "error",
        message: "Missing AZURE_SUBSCRIPTION_ID"
      });
      return;
    }

    res.json({ status: "ok" });
  });

  const requireAzure = (): AzureImageService => {
    if (!azure) {
      throw new Error("Missing AZURE_SUBSCRIPTION_ID");
    }

    return azure;
  };

  app.get("/api/locations", async (_req, res, next) => {
    try {
      res.json(await requireAzure().getLocations());
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/publishers", async (req, res, next) => {
    try {
      const { location } = queryLocation.parse(req.query);
      res.json(await requireAzure().getPublishers(location));
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/offers", async (req, res, next) => {
    try {
      const { location, publisher } = queryOffer.parse(req.query);
      res.json(await requireAzure().getOffers(location, publisher));
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/skus", async (req, res, next) => {
    try {
      const { location, publisher, offer } = querySku.parse(req.query);
      res.json(await requireAzure().getSkus(location, publisher, offer));
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/versions", async (req, res, next) => {
    try {
      const { location, publisher, offer, sku } = queryVersion.parse(req.query);
      res.json(await requireAzure().getVersions(location, publisher, offer, sku));
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/vm-skus", async (req, res, next) => {
    try {
      const { location } = queryLocation.parse(req.query);
      res.json(await requireAzure().getVmSkus(location));
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/templates", (_req, res) => {
    res.json(templates.getTemplates());
  });

  app.post("/api/render", (req, res, next) => {
    try {
      const payload = renderBody.parse(req.body);
      const rendered = templates.render(payload.templateFile, payload.selection);
      res.json({ rendered });
    } catch (error) {
      next(error);
    }
  });

  app.get("/api/sku-export", async (req, res, next) => {
    try {
      const { location, publisher, offer } = querySku.parse(req.query);
      const skus = await requireAzure().getSkus(location, publisher, offer);
      res.json({ rendered: templates.buildSkuExport(skus) });
    } catch (error) {
      next(error);
    }
  });

  app.use((err: unknown, _req: express.Request, res: express.Response, _next: express.NextFunction) => {
    if (err instanceof z.ZodError) {
      res.status(400).json({ message: "Invalid request", issues: err.issues });
      return;
    }

    const message = err instanceof Error ? err.message : "Unexpected error";
    res.status(500).json({ message });
  });

  const frontendRoot = join(findAppRoot(), "dist/frontend");
  if (existsSync(frontendRoot)) {
    app.use(express.static(frontendRoot));
    app.get(/^(?!\/api).*/, (_req, res) => {
      res.sendFile(join(frontendRoot, "index.html"));
    });
  }

  return { app, port, host };
};

if (require.main === module) {
  const { app, port, host } = makeApp();
  const server = app.listen(port, host, () => {
    // eslint-disable-next-line no-console
    console.log(`azure-image-chooser listening on ${host}:${port}`);
  });

  let shuttingDown = false;
  const shutdown = (signal: NodeJS.Signals) => {
    if (shuttingDown) {
      return;
    }

    shuttingDown = true;
    // eslint-disable-next-line no-console
    console.log(`received ${signal}, shutting down`);
    server.close((error) => {
      if (error) {
        // eslint-disable-next-line no-console
        console.error("graceful shutdown failed", error);
        process.exit(1);
      }

      process.exit(0);
    });

    // Force-exit if connections do not close in time.
    setTimeout(() => {
      // eslint-disable-next-line no-console
      console.error("shutdown timeout reached, forcing exit");
      process.exit(1);
    }, 10_000).unref();
  };

  process.on("SIGTERM", shutdown);
  process.on("SIGINT", shutdown);
}

export { makeApp };