const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const { exec } = require('child_process');
const { promisify } = require('util');
const { spawn } = require('child_process');
const { v4: uuidv4 } = require('uuid');
const { getResolvedAppDir, findClientPath } = require('../core/paths');
const { setupWaylandEnvironment, setupGpuEnvironment } = require('../utils/platformUtils');
const { saveUsername, saveInstallPath, loadJavaPath, getUuidForUser, getAuthServerUrl, getAuthDomain, loadVersionBranch, loadVersionClient, saveVersionClient } = require('../core/config');
const { resolveJavaPath, getJavaExec, getBundledJavaPath, detectSystemJava, JAVA_EXECUTABLE } = require('./javaManager');
const { getLatestClientVersion } = require('../services/versionManager');
const { updateGameFiles } = require('./gameManager');
const { syncModsForCurrentProfile } = require('./modManager');
const { getUserDataPath } = require('../utils/userDataMigration');

// Client patcher for custom auth server (sanasol.ws)
let clientPatcher = null;
try {
  clientPatcher = require('../utils/clientPatcher');
} catch (err) {
  console.log('[Launcher] Client patcher not available:', err.message);
}

const execAsync = promisify(exec);

// Fetch tokens from the auth server (properly signed with server's Ed25519 key)
async function fetchAuthTokens(uuid, name) {
  const authServerUrl = getAuthServerUrl();
  try {
    console.log(`Fetching auth tokens from ${authServerUrl}/game-session/child`);

    const response = await fetch(`${authServerUrl}/game-session/child`, {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        uuid: uuid,
        name: name,
        scopes: ['hytale:server', 'hytale:client']
      })
    });

    if (!response.ok) {
      throw new Error(`Auth server returned ${response.status}`);
    }

    const data = await response.json();
    console.log('Auth tokens received from server');

    return {
      identityToken: data.IdentityToken || data.identityToken,
      sessionToken: data.SessionToken || data.sessionToken
    };
  } catch (error) {
    console.error('Failed to fetch auth tokens:', error.message);
    // Fallback to local generation if server unavailable
    return generateLocalTokens(uuid, name);
  }
}

// Fallback: Generate tokens locally (won't pass signature validation but allows offline testing)
function generateLocalTokens(uuid, name) {
  console.log('Using locally generated tokens (fallback mode)');
  const authServerUrl = getAuthServerUrl();
  const now = Math.floor(Date.now() / 1000);
  const exp = now + 36000;

  const header = Buffer.from(JSON.stringify({
    alg: 'EdDSA',
    kid: '2025-10-01',
    typ: 'JWT'
  })).toString('base64url');

  const identityPayload = Buffer.from(JSON.stringify({
    sub: uuid,
    name: name,
    username: name,
    entitlements: ['game.base'],
    scope: 'hytale:server hytale:client',
    iat: now,
    exp: exp,
    iss: authServerUrl,
    jti: uuidv4()
  })).toString('base64url');

  const sessionPayload = Buffer.from(JSON.stringify({
    sub: uuid,
    scope: 'hytale:server',
    iat: now,
    exp: exp,
    iss: authServerUrl,
    jti: uuidv4()
  })).toString('base64url');

  const signature = crypto.randomBytes(64).toString('base64url');

  return {
    identityToken: `${header}.${identityPayload}.${signature}`,
    sessionToken: `${header}.${sessionPayload}.${signature}`
  };
}

async function launchGame(playerName = 'Player', progressCallback, javaPathOverride, installPathOverride, gpuPreference = 'auto', branchOverride = null) {
  const branch = branchOverride || loadVersionBranch();
  const customAppDir = getResolvedAppDir(installPathOverride);
  const customGameDir = path.join(customAppDir, branch, 'package', 'game', 'latest');
  const customJreDir = path.join(customAppDir, branch, 'package', 'jre', 'latest');
  
  // NEW 2.1.2: Use centralized UserData location
  const userDataDir = getUserDataPath();

  const gameLatest = customGameDir;
  let clientPath = findClientPath(gameLatest);

  if (!clientPath) {
    throw new Error('Game is not installed. Please install the game first.');
  }

  saveUsername(playerName);
  if (installPathOverride) {
    saveInstallPath(installPathOverride);
  }

  const configuredJava = (javaPathOverride !== undefined && javaPathOverride !== null
    ? javaPathOverride
    : loadJavaPath() || '').trim();
  let javaBin = null;

  if (configuredJava) {
    javaBin = await resolveJavaPath(configuredJava);
    if (!javaBin) {
      throw new Error(`Configured Java path not found: ${configuredJava}`);
    }
  } else {
    javaBin = getJavaExec(customJreDir);

    if (!getBundledJavaPath(customJreDir)) {
      const fallback = await detectSystemJava();
      if (fallback) {
        javaBin = fallback;
      } else {
        throw new Error('Java runtime not found. Please install the game first or configure Java path.');
      }
    }
  }

  const uuid = getUuidForUser(playerName);

  // Fetch tokens from auth server
  if (progressCallback) {
    progressCallback('Fetching authentication tokens...', null, null, null, null);
  }
  const { identityToken, sessionToken } = await fetchAuthTokens(uuid, playerName);

  // Patch client and server binaries to use custom auth server (BEFORE signing on macOS)
  // FORCE patch on every launch to ensure consistency
  const authDomain = getAuthDomain();
  if (clientPatcher) {
    try {
      if (progressCallback) {
        progressCallback('Patching game for custom server...', null, null, null, null);
      }
      console.log(`Force patching game binaries for ${authDomain}...`);

      const patchResult = await clientPatcher.ensureClientPatched(gameLatest, (msg, percent) => {
        // console.log(`[Patcher] ${msg}`);
        if (progressCallback && msg) {
          progressCallback(msg, percent, null, null, null);
        }
      });

      if (patchResult.success) {
        console.log(`Game patched successfully (${patchResult.patchCount} total occurrences)`);
        if (patchResult.client) {
          console.log(`  Client: ${patchResult.client.patchCount || 0} occurrences`);
        }
        if (patchResult.server) {
          console.log(`  Server: ${patchResult.server.patchCount || 0} occurrences`);
        }
      } else {
        console.warn('Game patching failed:', patchResult.error);
      }
    } catch (patchError) {
      console.warn('Game patching failed (game may not connect to custom server):', patchError.message);
    }
  }

  // macOS: Sign binaries AFTER patching so the patched binaries have valid signatures
  if (process.platform === 'darwin') {
    try {
      const appBundle = path.join(gameLatest, 'Client', 'Hytale.app');
      const serverDir = path.join(gameLatest, 'Server');

      const signPath = async (targetPath, deep = false) => {
        await execAsync(`xattr -cr "${targetPath}"`).catch(() => { });
        const deepFlag = deep ? '--deep ' : '';
        await execAsync(`codesign --force ${deepFlag}--sign - "${targetPath}"`).catch(() => { });
      };

      if (fs.existsSync(appBundle)) {
        await signPath(appBundle, true);
        console.log('Signed macOS app bundle (after patching)');
      } else {
        await signPath(path.dirname(clientPath), true);
        console.log('Signed macOS client binary (after patching)');
      }

      if (javaBin && fs.existsSync(javaBin)) {
        let jreRoot = path.dirname(path.dirname(javaBin));
        if (jreRoot.endsWith('Home')) {
          jreRoot = path.dirname(path.dirname(jreRoot));
        }
        await signPath(jreRoot, true);
        await signPath(javaBin, false);
        console.log('Signed Java runtime');
      }

      if (fs.existsSync(serverDir)) {
        await execAsync(`xattr -cr "${serverDir}"`).catch(() => { });
        await execAsync(`find "${serverDir}" -type f -perm +111 -exec codesign --force --sign - {} \\;`).catch(() => { });
        console.log('Signed server binaries (after patching)');
      }

      if (javaBin && fs.existsSync(javaBin)) {
        const javaWrapperPath = path.join(path.dirname(javaBin), 'java-wrapper');
        const wrapperScript = `#!/bin/bash
# Java wrapper for macOS - adds --disable-sentry to fix Sentry hang issue
REAL_JAVA="${javaBin}"
ARGS=("$@")
for i in "\${!ARGS[@]}"; do
  if [[ "\${ARGS[$i]}" == *"HytaleServer.jar"* ]]; then
    ARGS=("\${ARGS[@]:0:$((i+1))}" "--disable-sentry" "\${ARGS[@]:$((i+1))}")
    break
  fi
done
exec "$REAL_JAVA" "\${ARGS[@]}"
`;
        fs.writeFileSync(javaWrapperPath, wrapperScript, { mode: 0o755 });
        await signPath(javaWrapperPath, false);
        console.log('Created java wrapper with --disable-sentry fix');
        javaBin = javaWrapperPath;
      }
    } catch (signError) {
      console.log('Notice: macOS signing step failed:', signError.message);
      console.log('The game may still launch if Gatekeeper allows it');
    }
  }

  const args = [
    '--app-dir', gameLatest,
    '--java-exec', javaBin,
    '--auth-mode', 'authenticated',
    '--uuid', uuid,
    '--name', playerName,
    '--identity-token', identityToken,
    '--session-token', sessionToken,
    '--user-dir', userDataDir
  ];

  if (progressCallback) {
    progressCallback('Starting game...', null, null, null, null);
  }

  // Ensure mods are synced for the active profile before launching
  try {
    console.log('Syncing mods for active profile before launch...');
    if (progressCallback) progressCallback('Syncing mods...', null, null, null, null);
    await syncModsForCurrentProfile();
  } catch (syncError) {
    console.error('Failed to sync mods before launch:', syncError);
    // Continue anyway? Or fail? 
    // Warn user but continue might be safer to avoid blocking play if sync is just glitchy
  }

  console.log('Starting game...');
  console.log(`Command: "${clientPath}" ${args.join(' ')}`);

   const env = { ...process.env };

   const waylandEnv = setupWaylandEnvironment();
   Object.assign(env, waylandEnv);

   const gpuEnv = setupGpuEnvironment(gpuPreference);
   Object.assign(env, gpuEnv);

   // Linux memory allocator fixes for "free(): invalid pointer" crashes
   // on Steam Deck (glibc 2.41) and Ubuntu LTS
   if (process.platform === 'linux') {
     // Option 1: Disable glibc heap validation
     env.MALLOC_CHECK_ = '0';

     // Option 2: Try to use jemalloc if available (more robust allocator)
     // User can set HYTALE_USE_JEMALLOC=1 to enable
     if (process.env.HYTALE_USE_JEMALLOC === '1') {
       const jemalloc = require('fs').existsSync('/usr/lib/libjemalloc.so.2')
         ? '/usr/lib/libjemalloc.so.2'
         : require('fs').existsSync('/usr/lib/x86_64-linux-gnu/libjemalloc.so.2')
           ? '/usr/lib/x86_64-linux-gnu/libjemalloc.so.2'
           : null;

       if (jemalloc) {
         env.LD_PRELOAD = jemalloc + (env.LD_PRELOAD ? ':' + env.LD_PRELOAD : '');
         console.log(`Linux: Using jemalloc allocator (${jemalloc})`);
       } else {
         console.log('Linux: jemalloc not found, using glibc with MALLOC_CHECK_=0');
       }
     } else {
       console.log('Linux: Using glibc with MALLOC_CHECK_=0 (set HYTALE_USE_JEMALLOC=1 to try jemalloc)');
     }
   }

  try {
    let spawnOptions = {
      stdio: ['ignore', 'pipe', 'pipe'],
      detached: true,
      env: env
    };

    if (process.platform === 'win32') {
      spawnOptions.shell = false;
      spawnOptions.windowsHide = true;
    }

    const child = spawn(clientPath, args, spawnOptions);

    console.log(`Game process started with PID: ${child.pid}`);

    let hasExited = false;
    let outputReceived = false;

    child.stdout.on('data', (data) => {
      outputReceived = true;
      console.log(`Game output: ${data.toString().trim()}`);
    });

    child.stderr.on('data', (data) => {
      outputReceived = true;
      console.error(`Game error: ${data.toString().trim()}`);
    });

    child.on('error', (error) => {
      hasExited = true;
      console.error(`Failed to start game process: ${error.message}`);
      if (progressCallback) {
        progressCallback(`Failed to start game: ${error.message}`, -1, null, null, null);
      }
    });

    child.on('exit', (code, signal) => {
      hasExited = true;
      if (code !== null) {
        console.log(`Game process exited with code ${code}`);
        if (code !== 0 && progressCallback) {
          progressCallback(`Game exited with error code ${code}`, -1, null, null, null);
        }
      } else if (signal) {
        console.log(`Game process terminated by signal ${signal}`);
      }
    });

    // Monitor game process status in background
    setTimeout(() => {
      if (!hasExited) {
        console.log('Game appears to be running successfully');
        child.unref();
        if (progressCallback) {
          progressCallback('Game launched successfully', 100, null, null, null);
        }
      } else if (!outputReceived) {
        console.warn('Game process exited immediately with no output - possible issue with game files or dependencies');
      }
    }, 3000);

    // Return immediately, don't wait for setTimeout
    return { success: true, installed: true, launched: true, pid: child.pid };
  } catch (spawnError) {
    console.error(`Error spawning game process: ${spawnError.message}`);
    if (progressCallback) {
      progressCallback(`Error launching game: ${spawnError.message}`, -1, null, null, null);
    }
    throw spawnError;
  }
}

async function launchGameWithVersionCheck(playerName = 'Player', progressCallback, javaPathOverride, installPathOverride, gpuPreference = 'auto', branchOverride = null) {
  try {
    const branch = branchOverride || loadVersionBranch();
    
    if (progressCallback) {
      progressCallback('Checking for updates...', 0, null, null, null);
    }

    const installedVersion = loadVersionClient();
    const latestVersion = await getLatestClientVersion(branch);

    console.log(`Installed version: ${installedVersion}, Latest version: ${latestVersion} (branch: ${branch})`);

    let needsUpdate = false;
    if (!installedVersion || installedVersion !== latestVersion) {
      needsUpdate = true;
      console.log('Version mismatch or not installed, update required');
    }

    if (needsUpdate) {
      if (progressCallback) {
        progressCallback('Game update required, starting update process...', 10, null, null, null);
      }

      const customAppDir = getResolvedAppDir(installPathOverride);
      const customGameDir = path.join(customAppDir, branch, 'package', 'game', 'latest');
      const customToolsDir = path.join(customAppDir, 'butler');
      const customCacheDir = path.join(customAppDir, 'cache');

      try {
        await updateGameFiles(latestVersion, progressCallback, customGameDir, customToolsDir, customCacheDir, branch);
        console.log('Game updated successfully, patching will be forced on launch...');

        if (progressCallback) {
          progressCallback('Preparing game launch...', 90, null, null, null);
        }
        await new Promise(resolve => setTimeout(resolve, 3000));

      } catch (updateError) {
        console.error('Update failed:', updateError);
        if (progressCallback) {
          progressCallback(`Update failed: ${updateError.message}`, -1, null, null, null);
        }
        throw updateError;
      }
    }

    if (progressCallback) {
      progressCallback('Launching game...', 80, null, null, null);
    }

    const launchResult = await launchGame(playerName, progressCallback, javaPathOverride, installPathOverride, gpuPreference, branch);
    
    // Ensure we always return a result
    if (!launchResult) {
      console.error('launchGame returned null/undefined, creating fallback response');
      return { success: false, error: 'Game launch failed - no response from launcher' };
    }
    
    return launchResult;
  } catch (error) {
    console.error('Error in version check and launch:', error);
    if (progressCallback) {
      progressCallback(`Error: ${error.message}`, -1, null, null, null);
    }
    // Always return an error response instead of throwing
    return { success: false, error: error.message || 'Unknown launch error' };
  }
}

module.exports = {
  launchGame,
  launchGameWithVersionCheck
};