import { ipcMain } from 'electron';
import * as fs from 'fs';
import * as path from 'path';
import * as os from 'os';
import * as crypto from 'crypto';
import { exec } from 'child_process';
import axios from 'axios';
import { expandPath } from './file_utils';

let endpoints_in_progress: string[] = [];

export function registerFileHandlers() {
  // Flexible organization: [root]/[prefix_len-char-prefix]/[hash].file
  function get_organized_hashed_path(root: string, hash: string, prefix_len: number = 2) {
    const expanded_root = expandPath(root);
    const prefix = hash.substring(0, Math.max(1, Math.min(prefix_len, 8)));
    const dir = path.join(expanded_root, prefix);
    if (!fs.existsSync(dir)) fs.mkdirSync(dir, { recursive: true });
    return path.join(dir, `${hash}.file`);
  }

  ipcMain.handle('native:check-cache', async (event, { cache_root, hash, hash_prefix_length = 2, verify_hash = false }) => {
    const full_path = get_organized_hashed_path(cache_root, hash, hash_prefix_length);

    if (!fs.existsSync(full_path)) return false;

    if (verify_hash) {
      try {
        const file_buffer = fs.readFileSync(full_path);
        const actual_hash = crypto.createHash('sha256').update(file_buffer).digest('hex');
        return actual_hash === hash;
      } catch (e) {
        return false;
      }
    }

    return true;
  });

  ipcMain.handle('native:download-to-cache', async (event, { url, cache_root, hash, api_key, account_id, hash_prefix_length = 2 }) => {
    const full_path = get_organized_hashed_path(cache_root, hash, hash_prefix_length);
    const tmp_path = `${full_path}.tmp`;

    if (endpoints_in_progress.includes(url)) return { success: true, status: 'in_progress' };

    // 1. If final file exists, skip
    if (fs.existsSync(full_path)) return { success: true, path: full_path, status: 'exists' };

    // 2. Handle stale .tmp files (Legacy "Trust No One" pattern)
    if (fs.existsSync(tmp_path)) {
      const stats = fs.statSync(tmp_path);
      const age_ms = Date.now() - stats.mtimeMs;
      // If the tmp file is older than 5 minutes, assume previous download crashed and delete it
      if (age_ms > 5 * 60 * 1000) {
        console.log(`Native: Deleting stale temp file (${Math.round(age_ms/1000)}s old)`);
        fs.unlinkSync(tmp_path);
      } else {
        return { success: true, status: 'in_progress', detail: 'fresh_tmp_exists' };
      }
    }

    console.log(`Native: Hardened Download -> ${full_path}`);

    try {
      endpoints_in_progress.push(url);
      const response = await axios({
        method: 'get', url, responseType: 'stream',
        headers: {
          'x-aether-api-key': api_key,
          'x-account-id': account_id || ''
        }
      });

      const writer = fs.createWriteStream(tmp_path);
      response.data.pipe(writer);

      await new Promise<void>((resolve, reject) => {
        writer.on('finish', () => resolve());
        writer.on('error', reject);
      });

      // 3. Verify Integrity before renaming (The "Trust No One" Check)
      const file_buffer = fs.readFileSync(tmp_path);
      const actual_hash = crypto.createHash('sha256').update(file_buffer).digest('hex');

      if (actual_hash !== hash) {
        console.error(`Native: Hash Mismatch! Expected ${hash}, got ${actual_hash}`);
        fs.unlinkSync(tmp_path);
        return { success: false, error: 'Integrity check failed: Hash mismatch' };
      }

      fs.renameSync(tmp_path, full_path);
      console.log(`Native: Cache Integrity Verified. File moved to final destination.`);
      return { success: true, path: full_path };
    } catch (error: any) {
      if (fs.existsSync(tmp_path)) fs.unlinkSync(tmp_path);
      return { success: false, error: error.message };
    } finally {
      endpoints_in_progress = endpoints_in_progress.filter(e => e !== url);
    }
  });

  ipcMain.handle('native:launch-from-cache', async (event, { cache_root, hash, temp_root, filename, hash_prefix_length = 2, native_template = null }) => {
    try {
      const source = get_organized_hashed_path(cache_root, hash, hash_prefix_length);
      const expanded_temp = expandPath(temp_root);
      const target = path.join(expanded_temp, filename);

      console.log(`Native: Launching from Cache -> ${filename}`);

      if (!fs.existsSync(source)) {
        return { success: false, error: `File not in cache: ${hash}` };
      }

      if (!fs.existsSync(expanded_temp)) fs.mkdirSync(expanded_temp, { recursive: true });

      // 1. Copy the file to temp folder with original name
      fs.copyFileSync(source, target);

      // 2a. Data-driven launcher template (no rebuild needed for config changes).
      //     Svelte resolves a Launch Profile to a single native_template string.
      //     Format: AppleScript string with {{path}} placeholder, OR "shell:<cmd> {{path}}"
      if (!native_template) {
        return { success: false, error: 'No native template configured for this file' };
      }

      const resolved = native_template.replace(/\{\{path\}\}/g, target);
      if (resolved.startsWith('shell:')) {
        const cmd = resolved.slice(6).trim();
        console.log(`Native: Running custom shell template for ${filename}`);
        return new Promise((resolve_fn) => {
          exec(cmd, (err, stdout, stderr) => {
            if (err) resolve_fn({ success: false, error: err.message, stderr: stderr.trim() });
            else resolve_fn({ success: true, stdout: stdout.trim() });
          });
        });
      }

      console.log(`Native: Running custom AppleScript template for ${filename}`);
      const tmp_script_path = path.join(os.tmpdir(), `ae_launch_${Date.now()}.scpt`);
      return new Promise((resolve_fn) => {
        try {
          fs.writeFileSync(tmp_script_path, resolved.trim());
        } catch (e: any) {
          resolve_fn({ success: false, error: `Failed to write AppleScript temp file: ${e.message}` });
          return;
        }
        exec(`osascript "${tmp_script_path}"`, (err) => {
          try { fs.unlinkSync(tmp_script_path); } catch {}
          if (err) resolve_fn({ success: false, error: err.message });
          else resolve_fn({ success: true });
        });
      });

    } catch (error: any) {
      return { success: false, error: error.message };
    }
  });

  // Thin primitive: copy a cached file to the temp directory with its original filename,
  // then return the resolved path. The caller (Svelte side) decides what to do next —
  // run_osascript, run_cmd, open_local_file, etc.
  //
  // This is the preferred building block for custom launch flows. Use launch_from_cache
  // when Svelte has already resolved a native template; use copy_from_cache_to_temp when
  // you want full control over what happens after the file lands in temp.
  ipcMain.handle('native:copy-from-cache-to-temp', async (event, { cache_root, hash, temp_root, filename, hash_prefix_length = 2 }) => {
    try {
      const source = get_organized_hashed_path(cache_root, hash, hash_prefix_length);

      if (!fs.existsSync(source)) {
        return { success: false, error: `File not in cache: ${hash}` };
      }

      const expanded_temp = expandPath(temp_root);
      const target = path.join(expanded_temp, filename);

      if (!fs.existsSync(expanded_temp)) fs.mkdirSync(expanded_temp, { recursive: true });

      fs.copyFileSync(source, target);
      console.log(`Native: Copied from cache to temp -> ${target}`);

      return { success: true, path: target };
    } catch (error: any) {
      return { success: false, error: error.message };
    }
  });
}
