feat: refactor Knowledge Base (#8384)

Co-authored-by: icarus <eurfelux@gmail.com>
Co-authored-by: eeee0717 <chentao020717@outlook.com>

src/main/knowledge/preprocess/PreprocessingService.ts

@@ -0,0 +1,63 @@
+import PreprocessProvider from '@main/knowledge/preprocess/PreprocessProvider'
+import { loggerService } from '@main/services/LoggerService'
+import { windowService } from '@main/services/WindowService'
+import type { FileMetadata, KnowledgeBaseParams, KnowledgeItem } from '@types'
+
+const logger = loggerService.withContext('PreprocessingService')
+
+class PreprocessingService {
+  public async preprocessFile(
+    file: FileMetadata,
+    base: KnowledgeBaseParams,
+    item: KnowledgeItem,
+    userId: string
+  ): Promise<FileMetadata> {
+    let fileToProcess: FileMetadata = file
+    // Check if preprocessing is configured and applicable (e.g., for PDFs)
+    if (base.preprocessProvider && file.ext.toLowerCase() === '.pdf') {
+      try {
+        const provider = new PreprocessProvider(base.preprocessProvider.provider, userId)
+
+        // Check if file has already been preprocessed
+        const alreadyProcessed = await provider.checkIfAlreadyProcessed(file)
+        if (alreadyProcessed) {
+          logger.debug(`File already preprocessed, using cached result: ${file.path}`)
+          return alreadyProcessed
+        }
+
+        // Execute preprocessing
+        logger.debug(`Starting preprocess for scanned PDF: ${file.path}`)
+        const { processedFile, quota } = await provider.parseFile(item.id, file)
+        fileToProcess = processedFile
+
+        // Notify the UI
+        const mainWindow = windowService.getMainWindow()
+        mainWindow?.webContents.send('file-preprocess-finished', {
+          itemId: item.id,
+          quota: quota
+        })
+      } catch (err) {
+        logger.error(`Preprocessing failed: ${err}`)
+        // If preprocessing fails, re-throw the error to be handled by the caller
+        throw new Error(`Preprocessing failed: ${err}`)
+      }
+    }
+
+    return fileToProcess
+  }
+
+  public async checkQuota(base: KnowledgeBaseParams, userId: string): Promise<number> {
+    try {
+      if (base.preprocessProvider && base.preprocessProvider.type === 'preprocess') {
+        const provider = new PreprocessProvider(base.preprocessProvider.provider, userId)
+        return await provider.checkQuota()
+      }
+      throw new Error('No preprocess provider configured')
+    } catch (err) {
+      logger.error(`Failed to check quota: ${err}`)
+      throw new Error(`Failed to check quota: ${err}`)
+    }
+  }
+}
+
+export const preprocessingService = new PreprocessingService()