import { spawnSync } from "node:child_process";
import fs from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";

import tailwindcss from "@tailwindcss/vite";
import vue from "@vitejs/plugin-vue";
import { parse } from "smol-toml";
import { defineConfig, type Plugin } from "vite";

const webRoot = path.dirname(fileURLToPath(import.meta.url));
const workspaceRoot = path.resolve(webRoot, "../..");

type TomlTable = Record<string, unknown>;

function isTable(value: unknown): value is TomlTable {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}

function deepMerge(base: TomlTable, overlay: TomlTable): TomlTable {
  const next: TomlTable = { ...base };
  for (const [key, value] of Object.entries(overlay)) {
    const existing = next[key];
    if (isTable(existing) && isTable(value)) {
      next[key] = deepMerge(existing, value);
    } else {
      next[key] = value;
    }
  }
  return next;
}

function readToml(filePath: string): TomlTable {
  if (!fs.existsSync(filePath)) {
    return {};
  }
  return parse(fs.readFileSync(filePath, "utf8")) as TomlTable;
}

/**
 * Same load order as `AppConfig::load` in the Rust server:
 * default.toml → {APP_ENV}.toml. Env overrides stay on the server.
 */
function loadAppConfig(): TomlTable {
  const configDir = process.env.APP_CONFIG_DIR
    ? path.resolve(process.env.APP_CONFIG_DIR)
    : path.join(workspaceRoot, "config");
  const env = process.env.APP_ENV ?? "development";
  return deepMerge(
    readToml(path.join(configDir, "default.toml")),
    readToml(path.join(configDir, `${env}.toml`)),
  );
}

function section(config: TomlTable, name: string): TomlTable {
  const value = config[name];
  return isTable(value) ? value : {};
}

function generateApiFromSpec(): void {
  const script = path.join(workspaceRoot, "scripts/generate-api.mjs");
  const spec = path.join(workspaceRoot, "packages/contracts/openapi.json");
  if (!fs.existsSync(script) || !fs.existsSync(spec)) {
    return;
  }
  const result = spawnSync(process.execPath, [script], {
    cwd: workspaceRoot,
    stdio: "inherit",
  });
  if (result.status !== 0) {
    throw new Error("OpenAPI client generation failed");
  }
}

function openapiClientPlugin(): Plugin {
  const specPath = path.join(workspaceRoot, "packages/contracts/openapi.json");
  return {
    name: "openapi-client",
    buildStart() {
      generateApiFromSpec();
      this.addWatchFile(specPath);
    },
    handleHotUpdate(ctx) {
      if (ctx.file === specPath) {
        generateApiFromSpec();
      }
    },
  };
}

const appConfig = loadAppConfig();
const server = section(appConfig, "server");
const frontend = section(appConfig, "frontend");

const backendHost = String(server.host ?? "127.0.0.1");
const backendPort = Number(server.port ?? 8080);
const frontendHost = String(frontend.host ?? "127.0.0.1");
const frontendPort = Number(frontend.port ?? 5173);
const backendOrigin = `http://${backendHost}:${backendPort}`;

export default defineConfig({
  plugins: [vue(), tailwindcss(), openapiClientPlugin()],
  resolve: {
    alias: {
      "@": path.join(webRoot, "src"),
    },
  },
  server: {
    host: frontendHost,
    port: frontendPort,
    strictPort: true,
    proxy: {
      "/api": { target: backendOrigin, changeOrigin: true, ws: true },
      "/health": { target: backendOrigin, changeOrigin: true },
    },
  },
  preview: {
    host: frontendHost,
    port: frontendPort,
    proxy: {
      "/api": { target: backendOrigin, changeOrigin: true },
      "/health": { target: backendOrigin, changeOrigin: true },
    },
  },
});