import fs from 'node:fs';
import { spawn } from 'node:child_process';
import path from 'node:path';
import { defineConfig } from 'vite';

function generatedPages(directory) {
  const inputs = {};
  for (const entry of fs.readdirSync(directory, { withFileTypes: true })) {
    const filePath = path.join(directory, entry.name);
    if (entry.isDirectory()) Object.assign(inputs, generatedPages(filePath));
    else if (entry.name === 'index.html') {
      const relativePath = path.relative('.generated', filePath);
      const key = relativePath.endsWith('/index.html')
        ? relativePath.slice(0, -'/index.html'.length)
        : relativePath;
      inputs[key] = path.resolve(filePath);
    }
  }
  return inputs;
}

function contentGenerator() {
  let timer;
  let generator;
  let rerun = false;

  const generate = (server) => {
    if (generator) {
      rerun = true;
      return;
    }

    generator = spawn(process.execPath, ['generator.js'], { stdio: 'inherit' });
    generator.on('error', (error) => {
      console.error(`Content generation failed: ${error.message}`);
    });
    generator.on('close', (code) => {
      generator = undefined;
      if (code === 0) server.ws.send({ type: 'full-reload' });
      if (rerun) {
        rerun = false;
        generate(server);
      }
    });
  };

  return {
    name: 'content-generator',
    configureServer(server) {
      const sources = [
        path.resolve('notes'),
        path.resolve('posts'),
        path.resolve('README.md'),
        path.resolve('THIRD_PARTY_LICENSES.md'),
        path.resolve('external.json'),
        path.resolve('generator.js'),
        path.resolve('html.js'),
      ];
      server.watcher.add(sources);
      server.watcher.on('all', (event, file) => {
        if (!['add', 'change', 'unlink'].includes(event)) return;
        const isMarkdown = file.endsWith('.md') && (file.startsWith(`${path.resolve('notes')}/`) || file.startsWith(`${path.resolve('posts')}/`));
        const isExternal = file === path.resolve('external.json');
        const isStandaloneMarkdown = file === resolve('README.md') || file === path.resolve('THIRD_PARTY_LICENSES.md');
        const isGenerator = file === path.resolve('generator.js') || file === path.resolve('html.js');
        if (!isMarkdown && !isStandaloneMarkdown && !isExternal && !isGenerator) return;
        clearTimeout(timer);
        timer = setTimeout(() => {
          generate(server);
        }, 100);
      });
    },
  };
}

export default defineConfig({
  plugins: [contentGenerator()],
  root: '.generated',
  publicDir: '../public',
  resolve: {
    alias: {
      '/src': path.resolve('src'),
    },
  },
  server: {
    watch: {
      ignored: ['**/.generated/**'],
    },
  },
  build: {
    outDir: path.resolve('dist'),
    emptyOutDir: true,
    rollupOptions: {
      input: generatedPages('.generated'),
    },
  },
});