// server.js
import express from "express";
import { v4 as uuidv4 } from "uuid";
import fs from "fs";
import path from "path";
import { spawn } from "child_process";
import multer from "multer";
import { fileURLToPath } from "url";
import { dirname } from "path";

// Import our generators
import { SceneParser } from "./scripts/scene_parser.js";
import { SceneGraphGenerator } from "./scripts/scene_graph_generator.js";
import { CodeGenerator } from "./scripts/code_generator.js";
import { DebugReportGenerator } from "./scripts/debug_report_generator.js";
import { ThreeJSGLBGenerator } from "./scripts/glb_generator_threejs.js";

const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const app = express();
app.use(express.json({ limit: "10mb" }));

const TMP = path.join(process.cwd(), "tmp");
if (!fs.existsSync(TMP)) fs.mkdirSync(TMP, { recursive: true });

// For texture upload (optional)
const upload = multer({ dest: path.join(TMP, "uploads/") });

// Cache Three.js availability check
let threeJSAvailable = null;
let threeJSCheckPromise = null;

async function checkThreeJS() {
  if (threeJSAvailable !== null) {
    return threeJSAvailable;
  }

  if (threeJSCheckPromise) {
    return threeJSCheckPromise;
  }

  threeJSCheckPromise = (async () => {
    try {
      await import('three');
      threeJSAvailable = true;
      return true;
    } catch (error) {
      threeJSAvailable = false;
      return false;
    } finally {
      threeJSCheckPromise = null;
    }
  })();

  return threeJSCheckPromise;
}

// Check Three.js on startup
checkThreeJS();

// Default Blender path based on OS
const DEFAULT_BLENDER_PATH = process.platform === 'win32'
  ? "C:\\Program Files\\Blender Foundation\\Blender 5.0\\blender.exe"
  : "/usr/bin/blender"; // Standard Linux path

// Check Blender availability
function checkBlender() {
  const blenderPath = process.env.BLENDER_PATH || DEFAULT_BLENDER_PATH;

  try {
    // on Linux, we might check if 'blender' command exists if path is not absolute
    if (fs.existsSync(blenderPath)) {
      return {
        configured: true,
        path: blenderPath,
        status: "available"
      };
    } else {
      return {
        configured: false,
        path: blenderPath,
        status: "not found"
      };
    }
  } catch (error) {
    console.error("Error checking blender:", error);
    return {
      configured: false,
      path: blenderPath,
      status: "error checking"
    };
  }
}

/**
 * GET /api/health
 * Application health and status endpoint
 */
app.get("/api/health", async (req, res) => {
  console.log("Health check requested");
  try {
    const threeJSAvail = await checkThreeJS();
    const blenderInfo = checkBlender();

    const health = {
      status: "healthy",
      timestamp: new Date().toISOString(),
      uptime: process.uptime(),
      version: "2.0.0",
      services: {
        parser: "available",
        sceneGraph: "available",
        codeGenerator: "available",
        debugReport: "available",
        threeJS: threeJSAvail ? "available" : "not available",
        blender: blenderInfo.status,
        blenderPath: blenderInfo.path,
        blenderConfigured: blenderInfo.configured
      },
      system: {
        nodeVersion: process.version,
        platform: process.platform,
        memory: {
          used: Math.round(process.memoryUsage().heapUsed / 1024 / 1024) + " MB",
          total: Math.round(process.memoryUsage().heapTotal / 1024 / 1024) + " MB"
        }
      }
    };

    res.json(health);
  } catch (error) {
    console.error("Health check error:", error);
    res.status(500).json({ status: "error", message: error.message });
  }
});

/**
 * GET /generate
 * Information about the /generate endpoint
 */
app.get("/generate", (req, res) => {
  res.json({
    message: "This endpoint only accepts POST requests",
    method: "POST",
    description: "Generate a GLB file from a scene description",
    contentType: "application/json",
    example: {
      curl: 'curl -X POST http://localhost:3000/generate -H "Content-Type: application/json" -d @example_scene.json -o result.glb',
      body: {
        sceneName: "test_scene",
        objects: [
          { type: "cube", location: [1, 0, 0], size: 0.8, color: [1, 0, 0, 1] },
          { type: "sphere", location: [-1, 0, 0], radius: 0.6, color: [0.2, 0.7, 0.3, 1] }
        ],
        lights: [
          { type: "POINT", location: [2, 2, 3], energy: 200 }
        ],
        sun_energy: 3.0
      }
    },
    multipart: "You can also send multipart/form-data with a 'texture' file and 'scene' JSON field",
    note: "See example_scene.json for a complete example"
  });
});

/**
 * POST /generate
 * Accepts either:
 * 1. Text description: { "description": "Create a magical forest..." }
 * 2. Structured JSON: { "sceneName": "test", "objects": [...], ... }
 * 3. Multipart form with 'description' text field or 'scene' JSON field
 *
 * Returns a ZIP file containing:
 * - scene.glb
 * - scene-graph.json
 * - generation-code.js
 * - generation-script.py
 * - debug-report.txt
 */

// Store active generation statuses
const activeGenerations = new Map();

// Helper function to send status update
function sendStatusUpdate(id, status, message, progress = null) {
  if (activeGenerations.has(id)) {
    activeGenerations.get(id).status = status;
    activeGenerations.get(id).message = message;
    activeGenerations.get(id).progress = progress;
    activeGenerations.get(id).timestamp = new Date().toISOString();
  }
}

app.post("/generate", upload.single("texture"), async (req, res) => {
  const id = uuidv4();
  activeGenerations.set(id, {
    status: "starting",
    message: "Initializing generation...",
    progress: 0,
    timestamp: new Date().toISOString()
  });

  try {
    let sceneData = {};
    let description = null;

    sendStatusUpdate(id, "parsing", "Analyzing description...", 10);

    // Handle multipart form data
    if (req.body.description) {
      description = req.body.description;
    } else if (req.body.scene) {
      try {
        sceneData = typeof req.body.scene === 'string' ? JSON.parse(req.body.scene) : req.body.scene;
      } catch (e) {
        description = req.body.scene;
      }
    } else if (req.body && Object.keys(req.body).length) {
      if (req.body.description) {
        description = req.body.description;
      } else {
        sceneData = req.body;
      }
    }

    if (req.file) {
      sceneData.avatar_texture = path.resolve(req.file.path);
    }

    if (description) {
      const parser = new SceneParser();
      sceneData = parser.parse(description);
    }

    sendStatusUpdate(id, "preparing", "Creating workspace...", 20);

    const workDir = path.join(TMP, id);
    if (!fs.existsSync(workDir)) {
      fs.mkdirSync(workDir, { recursive: true });
    }

    const jsonPath = path.join(workDir, "scene-data.json");
    const glbPath = path.join(workDir, "scene.glb");
    const graphPath = path.join(workDir, "scene-graph.json");
    const codeJSPath = path.join(workDir, "generation-code.js");
    const codePyPath = path.join(workDir, "generation-script.py");
    const debugPath = path.join(workDir, "debug-report.txt");

    sendStatusUpdate(id, "saving", "Saving scene data...", 30);
    fs.writeFileSync(jsonPath, JSON.stringify(sceneData, null, 2));
    console.log(`Scene data saved to: ${jsonPath}`);

    sendStatusUpdate(id, "graph", "Generating scene graph...", 40);
    const graphGenerator = new SceneGraphGenerator();
    const sceneGraph = graphGenerator.generate(sceneData);
    fs.writeFileSync(graphPath, JSON.stringify(sceneGraph, null, 2));

    sendStatusUpdate(id, "code", "Generating code files...", 50);
    const codeGenerator = new CodeGenerator();
    const nodeJSCode = codeGenerator.generateNodeJS(sceneGraph, sceneData);
    const pythonCode = codeGenerator.generateBlenderPython(sceneGraph, sceneData);
    fs.writeFileSync(codeJSPath, nodeJSCode);
    fs.writeFileSync(codePyPath, pythonCode);

    sendStatusUpdate(id, "glb", "Generating GLB file...", 60);
    let glbGenerated = false;
    let generationLog = [];
    let warnings = [];
    let errors = [];
    let threeJSSuccess = false;

    // Only try Three.js - no Blender fallback
    try {
      sendStatusUpdate(id, "glb", "Attempting Three.js generation...", 65);
      const threeJSGenerator = new ThreeJSGLBGenerator();
      const result = await threeJSGenerator.generate(sceneData, glbPath);
      if (result.success && fs.existsSync(glbPath)) {
        const stats = fs.statSync(glbPath);
        if (stats.size > 0) {
          glbGenerated = true;
          threeJSSuccess = true;
          generationLog.push("GLB generated successfully using Three.js");
          sendStatusUpdate(id, "glb", "GLB generated successfully using Three.js", 90);
        } else {
          errors.push("GLB file was created but is empty (0 bytes)");
          generationLog.push("GLB file is empty");
        }
      } else {
        errors.push(`Three.js generation failed: ${result.error || 'Unknown error'}`);
        generationLog.push(`Three.js generation failed: ${result.error || 'Unknown error'}`);
      }
    } catch (error) {
      errors.push(`Three.js generation error: ${error.message}`);
      generationLog.push(`Three.js error: ${error.message}`);
      console.error("Three.js generation error:", error);
    }

    sendStatusUpdate(id, "debug", "Generating debug report...", 95);
    const debugGenerator = new DebugReportGenerator();
    const debugReport = debugGenerator.generate(sceneData, sceneGraph, generationLog, warnings, errors);
    fs.writeFileSync(debugPath, debugReport);

    sendStatusUpdate(id, "complete", "Generation complete!", 100);

    // Verify which files actually exist
    const files = {
      glb: fs.existsSync(glbPath) ? `/download/${id}/scene.glb` : null,
      sceneGraph: fs.existsSync(graphPath) ? `/download/${id}/scene-graph.json` : null,
      codeJS: fs.existsSync(codeJSPath) ? `/download/${id}/generation-code.js` : null,
      codePy: fs.existsSync(codePyPath) ? `/download/${id}/generation-script.py` : null,
      debug: fs.existsSync(debugPath) ? `/download/${id}/debug-report.txt` : null
    };

    // If GLB wasn't generated, add a more helpful error
    if (!glbGenerated && !fs.existsSync(glbPath)) {
      errors.push("GLB file was not generated. Check the debug report for details.");
      console.error(`GLB file missing at: ${glbPath}`);
      console.error(`Files in directory:`, fs.existsSync(workDir) ? fs.readdirSync(workDir) : "Directory doesn't exist");
    }

    res.json({
      success: glbGenerated && fs.existsSync(glbPath),
      sceneName: sceneData.sceneName || "generated_scene",
      id: id,
      files: files,
      filesExist: {
        glb: fs.existsSync(glbPath),
        sceneGraph: fs.existsSync(graphPath),
        codeJS: fs.existsSync(codeJSPath),
        codePy: fs.existsSync(codePyPath),
        debug: fs.existsSync(debugPath)
      },
      summary: {
        nodes: sceneGraph.nodes?.length || 0,
        meshes: sceneGraph.meshes?.length || 0,
        materials: sceneGraph.materials?.length || 0,
        lights: sceneGraph.lights?.length || 0,
        hasAvatar: sceneData.avatar?.present || false,
        hasAudio: (sceneData.audio?.ambient?.length || 0) + (sceneData.audio?.spatial?.length || 0) > 0,
        hasEffects: Object.keys(sceneData.effects || {}).length > 0
      },
      warnings: warnings,
      errors: errors
    });

    // Clean up after 5 minutes
    setTimeout(() => {
      activeGenerations.delete(id);
    }, 5 * 60 * 1000);

  } catch (err) {
    console.error(err);
    sendStatusUpdate(id, "error", `Error: ${err.message}`, null);
    res.status(500).json({ error: err.message, stack: err.stack, id: id });
  }
});

/**
 * GET /api/status/:id
 * Get live status of a generation
 */
app.get("/api/status/:id", (req, res) => {
  const { id } = req.params;
  const status = activeGenerations.get(id);

  if (!status) {
    return res.status(404).json({ error: "Generation not found" });
  }

  res.json(status);
});

/**
 * GET /download/:id/:filename
 * Download generated files
 */
app.get("/download/:id/:filename", (req, res) => {
  try {
    const { id, filename } = req.params;
    const filePath = path.join(TMP, id, filename);

    console.log(`Download request: ${filename} from ${filePath}`);

    if (!fs.existsSync(filePath)) {
      console.error(`File not found: ${filePath}`);
      console.error(`Directory exists: ${fs.existsSync(path.dirname(filePath))}`);
      if (fs.existsSync(path.dirname(filePath))) {
        console.error(`Files in directory:`, fs.readdirSync(path.dirname(filePath)));
      }
      return res.status(404).json({
        error: "File not found",
        path: filePath,
        message: `The file ${filename} was not generated. Check the debug report for details.`
      });
    }

    const stats = fs.statSync(filePath);
    if (stats.size === 0) {
      return res.status(404).json({
        error: "File is empty",
        message: `The file ${filename} exists but is empty (0 bytes). Generation may have failed.`
      });
    }

    const ext = path.extname(filename).toLowerCase();
    const contentTypes = {
      '.glb': 'model/gltf-binary',
      '.json': 'application/json',
      '.js': 'application/javascript',
      '.py': 'text/x-python',
      '.txt': 'text/plain'
    };

    res.setHeader("Content-Type", contentTypes[ext] || 'application/octet-stream');
    res.setHeader("Content-Disposition", `attachment; filename="${filename}"`);
    res.setHeader("Content-Length", stats.size);

    const stream = fs.createReadStream(filePath);
    stream.on('error', (err) => {
      console.error(`Stream error for ${filePath}:`, err);
      if (!res.headersSent) {
        res.status(500).json({ error: `Failed to read file: ${err.message}` });
      }
    });
    stream.pipe(res);
  } catch (err) {
    console.error(`Download error:`, err);
    if (!res.headersSent) {
      res.status(500).json({ error: err.message, stack: err.stack });
    }
  }
});

/**
 * GET /api/status
 * Get API status and capabilities
 */
app.get("/api/status", (req, res) => {
  res.json({
    status: "running",
    version: "2.0.0",
    capabilities: {
      textParsing: true,
      threeJSGeneration: true,
      blenderGeneration: checkBlender().configured,
      sceneGraph: true,
      codeGeneration: true,
      debugReports: true
    },
    endpoints: {
      "POST /generate": "Generate GLB from text description or structured JSON",
      "GET /download/:id/:filename": "Download generated files",
      "GET /api/status": "Get API status"
    }
  });
});

/**
 * GET /
 * Serve the HTML UI
 */
app.get("/", (req, res) => {
  const htmlPath = path.join(__dirname, "public", "index.html");
  if (fs.existsSync(htmlPath)) {
    res.sendFile(htmlPath);
  } else {
    res.status(404).json({ error: "HTML file not found", message: "Please check your deployment." });
  }
});

// Static files (after route handlers to avoid conflicts)
app.use(express.static("public"));

// Global error handler
app.use((err, req, res, next) => {
  console.error("Unhandled error:", err);
  if (!res.headersSent) {
    res.status(500).json({
      error: "Internal Server Error",
      message: err.message
    });
  }
});

const PORT = process.env.PORT || 3000;
app.listen(PORT, () => {
  console.log(`GLB Generation Engine running on http://localhost:${PORT}`);
  console.log(`UI available at http://localhost:${PORT}`);
  console.log(`API documentation at http://localhost:${PORT}/api/status`);
});