import express from 'express';
import { createServer as createViteServer } from 'vite';
import fs from 'node:fs';
import path from 'node:path';
import process from 'node:process';
import zlib from 'node:zlib';
import { fileURLToPath } from 'node:url';

type ProjectStatus = 'pending' | 'completed' | 'processing';

interface UserRecord {
  id: number;
  name: string;
  account: string;
  password: string;
  department: string;
  date: string;
}

interface ProjectRecord {
  id: string;
  name: string;
  createTime: string;
  status: ProjectStatus;
  dicomCount: number;
  hasModel: boolean;
  dicomPath: string;
  modelPath: string;
  modelCount: number;
  stlFiles: string[];
  maskFormats: Array<'nii' | 'nii.gz'>;
}

interface SessionRecord {
  authenticated: boolean;
  account: string | null;
  lastUpdated: string;
}

interface AppState {
  users: UserRecord[];
  projects: ProjectRecord[];
  session: SessionRecord;
  updatedAt: string;
}

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const repoRoot = path.resolve(__dirname, '..');
const dataDir = path.join(__dirname, 'data');
const exportDir = path.join(__dirname, 'exports');
const statePath = path.join(dataDir, 'state.json');
const dicomDir = path.join(repoRoot, 'Head_CT_DICOM');
const modelDir = path.join(repoRoot, 'Head_CT_ReConstruct');

function today() {
  return new Intl.DateTimeFormat('sv-SE', { timeZone: 'Asia/Shanghai' }).format(new Date());
}

function now() {
  return new Date().toISOString();
}

function ensureDir(dir: string) {
  fs.mkdirSync(dir, { recursive: true });
}

function listFiles(dir: string, extension: string) {
  if (!fs.existsSync(dir)) {
    return [];
  }

  return fs
    .readdirSync(dir, { withFileTypes: true })
    .filter((entry) => entry.isFile() && entry.name.toLowerCase().endsWith(extension))
    .map((entry) => entry.name)
    .sort((a, b) => a.localeCompare(b, 'zh-Hans-CN'));
}

function publicUser(user: UserRecord) {
  const { password: _password, ...rest } = user;
  return rest;
}

function publicSession(state: AppState) {
  const user = state.session.account
    ? state.users.find((candidate) => candidate.account === state.session.account)
    : null;

  return {
    authenticated: state.session.authenticated && Boolean(user),
    currentUser: user
      ? {
          id: user.id,
          name: user.name,
          account: user.account,
          department: user.department,
        }
      : null,
    lastUpdated: state.session.lastUpdated,
  };
}

function buildDefaultProject(): ProjectRecord {
  const stlFiles = listFiles(modelDir, '.stl');

  return {
    id: 'head-ct-demo',
    name: '头部 CT 模型逆向体素化演示',
    createTime: today(),
    status: 'completed',
    dicomCount: listFiles(dicomDir, '.dcm').length,
    hasModel: stlFiles.length > 0,
    dicomPath: 'Head_CT_DICOM',
    modelPath: 'Head_CT_ReConstruct',
    modelCount: stlFiles.length,
    stlFiles,
    maskFormats: ['nii', 'nii.gz'],
  };
}

function defaultState(): AppState {
  return {
    users: [
      { id: 1, name: 'Admin', account: 'admin', password: '123456', department: 'admin', date: today() },
      { id: 2, name: 'Doctor Li', account: 'doctor_li', password: '123456', department: '肝胆外科', date: today() },
    ],
    projects: [buildDefaultProject()],
    session: { authenticated: false, account: null, lastUpdated: now() },
    updatedAt: now(),
  };
}

function normalizeState(state: AppState): AppState {
  return {
    ...state,
    projects: [buildDefaultProject()],
  };
}

function readState(): AppState {
  ensureDir(dataDir);

  if (!fs.existsSync(statePath)) {
    const initialState = defaultState();
    writeState(initialState);
    return initialState;
  }

  try {
    const raw = fs.readFileSync(statePath, 'utf8');
    return normalizeState(JSON.parse(raw) as AppState);
  } catch {
    const recoveredState = defaultState();
    writeState(recoveredState);
    return recoveredState;
  }
}

function writeState(state: AppState) {
  ensureDir(dataDir);
  fs.writeFileSync(statePath, JSON.stringify({ ...state, updatedAt: now() }, null, 2));
}

function createNiftiMask(project: ProjectRecord, compressed: boolean) {
  const width = 64;
  const height = 64;
  const depth = 64;
  const headerSize = 348;
  const voxOffset = 352;
  const voxelCount = width * height * depth;
  const data = Buffer.alloc(voxelCount);
  const center = [width / 2, height / 2, depth / 2];

  for (let z = 0; z < depth; z += 1) {
    for (let y = 0; y < height; y += 1) {
      for (let x = 0; x < width; x += 1) {
        const dx = (x - center[0]) / 18;
        const dy = (y - center[1]) / 15;
        const dz = (z - center[2]) / 20;
        const index = z * width * height + y * width + x;
        const radius = dx * dx + dy * dy + dz * dz;

        if (radius < 1) {
          data[index] = 1;
        }

        const tumorDx = (x - 42) / 8;
        const tumorDy = (y - 30) / 7;
        const tumorDz = (z - 34) / 7;
        if (tumorDx * tumorDx + tumorDy * tumorDy + tumorDz * tumorDz < 1) {
          data[index] = 2;
        }
      }
    }
  }

  const header = Buffer.alloc(voxOffset);
  header.writeInt32LE(headerSize, 0);
  header.writeInt16LE(3, 40);
  header.writeInt16LE(width, 42);
  header.writeInt16LE(height, 44);
  header.writeInt16LE(depth, 46);
  header.writeInt16LE(1, 48);
  header.writeInt16LE(1, 50);
  header.writeInt16LE(1, 52);
  header.writeInt16LE(1, 54);
  header.writeInt16LE(2, 70);
  header.writeInt16LE(8, 72);
  header.writeFloatLE(1, 76);
  header.writeFloatLE(1, 80);
  header.writeFloatLE(1, 84);
  header.writeFloatLE(1, 88);
  header.writeFloatLE(voxOffset, 108);
  header.writeFloatLE(1, 112);
  header.write('ReVoxelSeg demo mask', 148, 'ascii');
  header.write(`Project ${project.id}`, 228, 'ascii');
  header.write('n+1\0', 344, 'ascii');

  const nifti = Buffer.concat([header, data]);
  return compressed ? zlib.gzipSync(nifti) : nifti;
}

async function startServer() {
  const app = express();
  const host = process.argv.includes('--host') ? process.argv[process.argv.indexOf('--host') + 1] : '0.0.0.0';
  const portArg = process.argv.includes('--port') ? process.argv[process.argv.indexOf('--port') + 1] : process.env.PORT;
  const port = Number(portArg ?? 4000);

  ensureDir(exportDir);
  app.use(express.json());

  app.get('/api/health', (_req, res) => {
    res.json({ ok: true, service: 'revoxelseg-dicom', time: now() });
  });

  app.get('/api/session', (_req, res) => {
    res.json(publicSession(readState()));
  });

  app.post('/api/login', (req, res) => {
    const { account, password } = req.body as { account?: string; password?: string };
    const state = readState();
    const user = state.users.find((candidate) => candidate.account === account && candidate.password === password);

    if (!user) {
      res.status(401).json({ message: '账号或密码错误' });
      return;
    }

    state.session = { authenticated: true, account: user.account, lastUpdated: now() };
    writeState(state);
    res.json(publicSession(state));
  });

  app.post('/api/logout', (_req, res) => {
    const state = readState();
    state.session = { authenticated: false, account: null, lastUpdated: now() };
    writeState(state);
    res.json(publicSession(state));
  });

  app.get('/api/users', (_req, res) => {
    res.json(readState().users.map(publicUser));
  });

  app.get('/api/projects', (_req, res) => {
    res.json(readState().projects);
  });

  app.get('/api/projects/:projectId', (req, res) => {
    const project = readState().projects.find((candidate) => candidate.id === req.params.projectId);
    if (!project) {
      res.status(404).json({ message: '项目不存在' });
      return;
    }
    res.json(project);
  });

  app.get('/api/overview', (_req, res) => {
    const state = readState();
    const dicomCount = state.projects.reduce((sum, project) => sum + project.dicomCount, 0);
    const modelCount = state.projects.reduce((sum, project) => sum + project.modelCount, 0);

    res.json({
      totalProjects: state.projects.length,
      processedProjects: state.projects.filter((project) => project.status === 'completed').length,
      dicomCount,
      modelCount,
      chartData: [
        { name: 'Mon', projects: 1, processing: 12 },
        { name: 'Tue', projects: 1, processing: 28 },
        { name: 'Wed', projects: 1, processing: 44 },
        { name: 'Thu', projects: 1, processing: 58 },
        { name: 'Fri', projects: 1, processing: 76 },
        { name: 'Sat', projects: 1, processing: 90 },
        { name: 'Sun', projects: state.projects.length, processing: 100 },
      ],
    });
  });

  app.post('/api/demo/reset', (_req, res) => {
    const state = defaultState();
    writeState(state);
    res.json({ ok: true, projects: state.projects, users: state.users.map(publicUser) });
  });

  app.post('/api/projects/:projectId/export-mask', (req, res) => {
    const state = readState();
    const project = state.projects.find((candidate) => candidate.id === req.params.projectId);

    if (!project) {
      res.status(404).json({ message: '项目不存在' });
      return;
    }

    const format = req.query.format === 'nii' ? 'nii' : 'nii.gz';
    const compressed = format === 'nii.gz';
    const mask = createNiftiMask(project, compressed);
    const filename = `${project.id}-segmentation-mask.${format}`;
    const outputPath = path.join(exportDir, filename);
    fs.writeFileSync(outputPath, mask);

    res.setHeader('Content-Type', compressed ? 'application/gzip' : 'application/octet-stream');
    res.setHeader('Content-Disposition', `attachment; filename="${filename}"`);
    res.send(mask);
  });

  if (process.env.NODE_ENV === 'production') {
    app.use(express.static(path.join(__dirname, 'dist')));
    app.get('*', (_req, res) => {
      res.sendFile(path.join(__dirname, 'dist', 'index.html'));
    });
  } else {
    const vite = await createViteServer({
      server: { middlewareMode: true, hmr: { port: 24679 } },
      appType: 'spa',
    });
    app.use(vite.middlewares);
  }

  app.listen(port, host, () => {
    console.log(`ReVoxelSeg DICOM server ready at http://${host}:${port}/`);
  });
}

startServer().catch((error) => {
  console.error(error);
  process.exit(1);
});