feat(db): add PostgreSqlService with pg driver

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/services/database/postgresql.ts

@@ -0,0 +1,161 @@
+import { Pool } from 'pg'
+import type {
+  IDatabaseService,
+  DatabaseType,
+  QueryResult,
+  PostgreSqlConfig
+} from '../../types/database.types'
+import { createLogger, trackDuration } from '../logger'
+
+const log = createLogger('PostgreSqlService')
+
+export type { PostgreSqlConfig } from '../../types/database.types'
+
+export class PostgreSqlService implements IDatabaseService {
+  /** Database type identifier */
+  readonly type: DatabaseType = 'postgresql'
+
+  private pool: Pool | null = null
+  private config: PostgreSqlConfig
+
+  constructor(config: PostgreSqlConfig) {
+    this.config = config
+  }
+
+  /**
+   * Connect to PostgreSQL database
+   */
+  async connect(): Promise<void> {
+    if (this.pool) {
+      log.warn('Already connected to PostgreSQL')
+      throw new Error('Already connected to PostgreSQL')
+    }
+
+    try {
+      this.pool = new Pool({
+        host: this.config.host,
+        port: this.config.port,
+        user: this.config.user,
+        password: this.config.password,
+        database: this.config.database,
+        max: this.config.maxPoolSize ?? 10
+      })
+
+      // Test connection
+      const client = await this.pool.connect()
+      client.release()
+
+      log.info('Connected to PostgreSQL', {
+        host: this.config.host,
+        port: this.config.port,
+        database: this.config.database
+      })
+    } catch (error) {
+      this.pool = null
+      log.error('Failed to connect to PostgreSQL', {
+        host: this.config.host,
+        port: this.config.port,
+        database: this.config.database,
+        error
+      })
+      throw new Error(`Failed to connect to PostgreSQL: ${(error as Error).message}`)
+    }
+  }
+
+  /**
+   * Disconnect from PostgreSQL database
+   */
+  async disconnect(): Promise<void> {
+    if (!this.pool) {
+      return
+    }
+
+    try {
+      await this.pool.end()
+      this.pool = null
+      log.info('Disconnected from PostgreSQL')
+    } catch (error) {
+      log.error('Failed to disconnect from PostgreSQL', { error })
+      throw new Error(`Failed to disconnect from PostgreSQL: ${(error as Error).message}`)
+    }
+  }
+
+  /**
+   * Check if connected to PostgreSQL database
+   */
+  isConnected(): boolean {
+    return this.pool !== null
+  }
+
+  /**
+   * Execute a query and return results
+   */
+  async query(sql: string, params?: any[]): Promise<QueryResult> {
+    if (!this.pool) {
+      throw new Error('Not connected to PostgreSQL. Call connect() first.')
+    }
+
+    const sqlPreview = sql.substring(0, 100)
+    const paramCount = params?.length ?? 0
+
+    try {
+      const { result: queryResult } = await trackDuration(
+        async () => {
+          const result = await this.pool!.query(sql, params)
+
+          // Extract column names from fields
+          const columns = result.fields ? result.fields.map((field) => field.name) : []
+
+          // Result rows
+          const rows = (result.rows as Record<string, unknown>[]) || []
+          const rowCount = result.rowCount ?? rows.length
+
+          return { rows, columns, rowCount }
+        },
+        { operationName: 'PostgreSqlService.query' }
+      )
+
+      log.debug('Query executed', { sqlPreview, rowCount: queryResult.rowCount, paramCount })
+      return queryResult
+    } catch (error) {
+      log.error('PostgreSQL query failed', { sqlPreview, paramCount, error })
+      throw new Error(`PostgreSQL query failed: ${(error as Error).message}`)
+    }
+  }
+
+  /**
+   * Execute multiple queries in a transaction
+   */
+  async transaction(queries: { sql: string; params?: any[] }[]): Promise<void> {
+    if (!this.pool) {
+      throw new Error('Not connected to PostgreSQL. Call connect() first.')
+    }
+
+    const queryCount = queries.length
+    log.info('Transaction started', { queryCount })
+
+    const client = await this.pool.connect()
+
+    try {
+      await client.query('BEGIN')
+
+      for (let i = 0; i < queries.length; i++) {
+        const { sql, params } = queries[i]
+        await client.query(sql, params)
+        log.debug('Transaction query executed', {
+          index: i,
+          sqlPreview: sql.substring(0, 100)
+        })
+      }
+
+      await client.query('COMMIT')
+      log.info('Transaction committed', { queryCount })
+    } catch (error) {
+      await client.query('ROLLBACK')
+      log.warn('Transaction rolled back', { queryCount, error })
+      throw new Error(`PostgreSQL transaction failed: ${(error as Error).message}`)
+    } finally {
+      client.release()
+    }
+  }
+}