import fs from 'node:fs/promises';
import path from 'node:path';
import { DatabaseSync } from 'node:sqlite';
import { defineConfig } from 'vite';
import react from '@vitejs/plugin-react';

const dataDirectory = path.resolve(process.cwd(), 'data');
const sqlitePath = path.join(dataDirectory, 'flow.db');
const seedJsonPath = path.join(dataDirectory, 'flow-db.json');

let database;

async function readSeedJson() {
  try {
    const raw = await fs.readFile(seedJsonPath, 'utf8');
    return JSON.parse(raw);
  } catch (error) {
    if (error.code === 'ENOENT') return null;
    throw error;
  }
}

async function getDatabase() {
  if (database) return database;

  await fs.mkdir(dataDirectory, { recursive: true });
  database = new DatabaseSync(sqlitePath);
  database.exec(`
    CREATE TABLE IF NOT EXISTS app_state (
      id INTEGER PRIMARY KEY CHECK (id = 1),
      content TEXT NOT NULL,
      program_states TEXT NOT NULL,
      updated_at TEXT NOT NULL
    )
  `);

  const existing = database.prepare('SELECT id FROM app_state WHERE id = 1').get();
  if (!existing) {
    const seed = await readSeedJson();
    if (seed) writeDatabase(seed);
  } else {
    const seed = await readSeedJson();
    const row = database.prepare('SELECT content FROM app_state WHERE id = 1').get();
    const existingContent = row ? JSON.parse(row.content) : null;
    const existingExtraCount = existingContent?.extraPrograms?.length ?? 0;
    const seedExtraCount = seed?.content?.extraPrograms?.length ?? 0;

    if (existingExtraCount === 0 && seedExtraCount > 0) {
      writeDatabase(seed);
    }
  }

  return database;
}

async function readDatabase() {
  const db = await getDatabase();
  const row = db
    .prepare('SELECT content, program_states AS programStates, updated_at AS updatedAt FROM app_state WHERE id = 1')
    .get();

  if (!row) return null;

  return {
    content: JSON.parse(row.content),
    programStates: JSON.parse(row.programStates),
    updatedAt: row.updatedAt
  };
}

async function writeDatabase(data) {
  const db = await getDatabase();
  const updatedAt = new Date().toISOString();
  const content = data.content ?? {};
  const programStates = data.programStates ?? {};

  db.prepare(`
    INSERT INTO app_state (id, content, program_states, updated_at)
    VALUES (1, ?, ?, ?)
    ON CONFLICT(id) DO UPDATE SET
      content = excluded.content,
      program_states = excluded.program_states,
      updated_at = excluded.updated_at
  `).run(JSON.stringify(content), JSON.stringify(programStates), updatedAt);

  return {
    content,
    programStates,
    updatedAt
  };
}

function readRequestBody(request) {
  return new Promise((resolve, reject) => {
    let body = '';

    request.on('data', (chunk) => {
      body += chunk;
      if (body.length > 5_000_000) {
        reject(new Error('Request body is too large'));
        request.destroy();
      }
    });

    request.on('end', () => resolve(body));
    request.on('error', reject);
  });
}

function sendJson(response, statusCode, payload) {
  response.statusCode = statusCode;
  response.setHeader('Content-Type', 'application/json; charset=utf-8');
  response.end(JSON.stringify(payload));
}

function serverDatabasePlugin() {
  return {
    name: 'flow-server-sqlite-database',
    configureServer(server) {
      server.middlewares.use('/api/state', async (request, response) => {
        try {
          if (request.method === 'GET') {
            const data = await readDatabase();
            if (!data) {
              sendJson(response, 404, { error: 'Database is empty' });
              return;
            }
            sendJson(response, 200, data);
            return;
          }

          if (request.method === 'PUT' || request.method === 'PATCH') {
            const current = request.method === 'PATCH' ? (await readDatabase()) ?? {} : {};
            const body = await readRequestBody(request);
            const payload = body ? JSON.parse(body) : {};
            const nextData = await writeDatabase({
              ...current,
              ...payload
            });
            sendJson(response, 200, nextData);
            return;
          }

          response.statusCode = 405;
          response.end();
        } catch (error) {
          sendJson(response, 500, { error: error.message });
        }
      });
    }
  };
}

export default defineConfig({
  plugins: [react(), serverDatabasePlugin()]
});