Enhance logging and error handling in configuration loading, content fetching, and AI reply generation

config/config.go

@@ -2,8 +2,11 @@ package config
 
 import (
 	"os"
+	"paraclub-ai-mailer/internal/logger"
+	"strings"
 	"time"
 
+	"github.com/sirupsen/logrus"
 	"gopkg.in/yaml.v3"
 )
 
@@ -46,15 +49,49 @@ type LoggingConfig struct {
 }
 
 func Load(path string) (*Config, error) {
+	logger.WithField("path", path).Debug("Loading configuration file")
+
 	data, err := os.ReadFile(path)
 	if err != nil {
+		logger.WithError(err).Error("Failed to read configuration file")
 		return nil, err
 	}
+	logger.WithField("bytes", len(data)).Debug("Read configuration file")
 
 	var config Config
 	if err := yaml.Unmarshal(data, &config); err != nil {
+		logger.WithError(err).Error("Failed to parse YAML configuration")
 		return nil, err
 	}
 
+	// Resolve environment variables in configuration
+	if strings.HasPrefix(config.IMAP.Password, "${") && strings.HasSuffix(config.IMAP.Password, "}") {
+		envVar := strings.TrimSuffix(strings.TrimPrefix(config.IMAP.Password, "${"), "}")
+		config.IMAP.Password = os.Getenv(envVar)
+		logger.WithField("envVar", envVar).Debug("Resolved IMAP password from environment")
+	}
+
+	if strings.HasPrefix(config.AI.OpenRouterAPIKey, "${") && strings.HasSuffix(config.AI.OpenRouterAPIKey, "}") {
+		envVar := strings.TrimSuffix(strings.TrimPrefix(config.AI.OpenRouterAPIKey, "${"), "}")
+		config.AI.OpenRouterAPIKey = os.Getenv(envVar)
+		logger.WithField("envVar", envVar).Debug("Resolved OpenRouter API key from environment")
+	}
+
+	logger.WithFields(logrus.Fields{
+		"imapServer":      config.IMAP.Server,
+		"imapPort":        config.IMAP.Port,
+		"imapUsername":    config.IMAP.Username,
+		"imapMailboxIn":   config.IMAP.MailboxIn,
+		"imapDraftBox":    config.IMAP.DraftBox,
+		"imapUseTLS":      config.IMAP.UseTLS,
+		"aiModel":         config.AI.Model,
+		"aiTemperature":   config.AI.Temperature,
+		"aiMaxTokens":     config.AI.MaxTokens,
+		"contextUrlCount": len(config.Context.URLs),
+		"pollingInterval": config.Polling.Interval,
+		"loggingLevel":    config.Logging.Level,
+		"loggingFilePath": config.Logging.FilePath,
+	}).Debug("Configuration loaded successfully")
+
 	return &config, nil
 }