package config

import (
	"fmt"
	"log"
	"os"
	"path/filepath"

	"github.com/joho/godotenv"
)

// Load reads configuration from environment variables, with optional .env file support.
// It returns a fully populated Config or an error if the .env file failed to load.
// Use ValidateOrFatal() after loading to enforce required fields.
func Load() (*Config, error) {
	cfg := DefaultConfig()

	// Attempt to load .env file from multiple locations
	_ = loadEnvFile()

	// Merge environment variables over defaults
	cfg.mergeEnv()

	return cfg, nil
}

// loadEnvFile tries to load .env from the project root.
// It does not return an error; missing .env is acceptable.
func loadEnvFile() error {
	// Try current directory first
	if err := godotenv.Load(); err == nil {
		return nil
	}

	// Try relative to executable
	if exe, err := os.Executable(); err == nil {
		exeDir := filepath.Dir(exe)
		candidates := []string{
			filepath.Join(exeDir, ".env"),
			filepath.Join(exeDir, "..", ".env"),
			filepath.Join(exeDir, "..", "..", ".env"),
		}
		for _, path := range candidates {
			if _, err := os.Stat(path); err == nil {
				_ = godotenv.Load(path)
				return nil
			}
		}
	}

	return fmt.Errorf(".env not found")
}

// mergeEnv reads all environment variables and overrides config defaults.
func (c *Config) mergeEnv() {
	// Environment
	c.Env = getEnv("ENV", c.Env)
	c.LogLevel = getEnv("LOG_LEVEL", c.LogLevel)
	c.LogFmt = getEnv("LOG_FORMAT", c.LogFmt)

	// Server
	c.Port = getEnvInt("PORT", c.Port)
	c.Host = getEnv("HOST", c.Host)
	c.GinMode = getEnv("GIN_MODE", c.GinMode)

	// Database
	c.DatabaseURL = os.Getenv("DATABASE_URL")
	c.PostgresHost = getEnv("POSTGRES_HOST", c.PostgresHost)
	c.PostgresPort = getEnvInt("POSTGRES_PORT", c.PostgresPort)
	c.PostgresUser = getEnv("POSTGRES_USER", c.PostgresUser)
	c.PostgresPassword = getEnv("POSTGRES_PASSWORD", c.PostgresPassword)
	c.PostgresDB = getEnv("POSTGRES_DB", c.PostgresDB)
	c.PostgresSSLMode = getEnv("POSTGRES_SSLMODE", c.PostgresSSLMode)

	// NATS
	c.NATSUrl = getEnv("NATS_URL", c.NATSUrl)

	// Redis
	c.RedisHost = getEnv("REDIS_HOST", c.RedisHost)
	c.RedisPort = getEnvInt("REDIS_PORT", c.RedisPort)

	// LLM
	c.LLMBaseURL = getEnv("LLM_API_URL", c.LLMBaseURL)
	c.LLMAPIKey = getEnv("LLM_API_KEY", c.LLMAPIKey)
	c.LLMModel = getEnv("LLM_MODEL", c.LLMModel)
	c.LLMFallbackModel = getEnv("LLM_FALLBACK_MODEL", c.LLMFallbackModel)

	// Embedding
	c.EmbeddingAPIURL = getEnv("EMBEDDING_API_URL", c.EmbeddingAPIURL)
	c.EmbeddingModel = getEnv("EMBEDDING_MODEL", c.EmbeddingModel)
	c.EmbeddingAPIKey = getEnv("EMBEDDING_API_KEY", c.EmbeddingAPIKey)

	// Voice
	c.DashScopeAPIKey = getEnv("DASHSCOPE_API_KEY", c.DashScopeAPIKey)
	c.TTSProvider = getEnv("TTS_PROVIDER", c.TTSProvider)
	c.ASRProvider = getEnv("ASR_PROVIDER", c.ASRProvider)

	// Auth
	c.JWTSecret = getEnv("JWT_SECRET", c.JWTSecret)
	c.JWTExpiryHours = getEnvInt("JWT_EXPIRY_HOURS", c.JWTExpiryHours)
	c.AdminUsername = getEnv("ADMIN_USERNAME", c.AdminUsername)
	c.AdminPassword = getEnv("ADMIN_PASSWORD", c.AdminPassword)
	c.RegistrationOpen = getEnvBool("REGISTRATION_ENABLED", c.RegistrationOpen)

	// Internal Service
	c.InternalServiceToken = getEnv("INTERNAL_SERVICE_TOKEN", c.InternalServiceToken)

	// CORS
	c.AllowedOrigins = getEnvSlice("ALLOWED_ORIGINS", c.AllowedOrigins)

	// Background Thinking
	c.EnableBackgroundThinking = getEnvBool("ENABLE_BACKGROUND_THINKING", c.EnableBackgroundThinking)
	c.ThinkIntervalSec = getEnvInt("THINK_INTERVAL_SEC", c.ThinkIntervalSec)
	c.ThinkSilenceTimeoutSec = getEnvInt("THINK_SILENCE_TIMEOUT_SEC", c.ThinkSilenceTimeoutSec)

	// Platform Bridge
	c.PlatformBridgeEnabled = getEnvBool("PLATFORM_BRIDGE_ENABLED", c.PlatformBridgeEnabled)
	c.PlatformChannels = getEnv("PLATFORM_CHANNELS", c.PlatformChannels)

	// IoT
	c.IoTProvider = getEnv("IOT_PROVIDER", c.IoTProvider)
	c.IoTServiceURL = getEnv("IOT_SERVICE_URL", c.IoTServiceURL)

	// RAG & Data
	c.PersonaDir = getEnv("PERSONA_DIR", c.PersonaDir)
	c.KnowledgeDir = getEnv("KNOWLEDGE_DIR", c.KnowledgeDir)
	c.DataDir = getEnv("DATA_DIR", c.DataDir)

	// Search
	c.SearXNGURL = getEnv("SEARXNG_URL", c.SearXNGURL)

	// Host Exec
	c.HostExecBackend = getEnv("HOST_EXEC_BACKEND", c.HostExecBackend)

	// Caddy (production)
	c.Domain = getEnv("DOMAIN", c.Domain)
	c.ACMEEmail = getEnv("ACME_EMAIL", c.ACMEEmail)

	// Ethend (deprecated)
	c.EthendPort = getEnvInt("ETHEND_PORT", c.EthendPort)

	// WebSocket
	c.WSMaxConnections = getEnvInt("WS_MAX_CONNECTIONS", c.WSMaxConnections)
	c.SessionIdleTimeoutMin = getEnvInt("SESSION_IDLE_TIMEOUT_MIN", c.SessionIdleTimeoutMin)

	// Timezone
	c.TZ = getEnv("TZ", c.TZ)
}

// logSanitized prints the loaded config, with sensitive fields redacted.
func (c *Config) LogSanitized() {
	log.Printf("[config] ENV=%s LOG_LEVEL=%s LOG_FORMAT=%s", c.Env, c.LogLevel, c.LogFmt)
	log.Printf("[config] PORT=%d GIN_MODE=%s", c.Port, c.GinMode)
	log.Printf("[config] DB_HOST=%s DB_PORT=%d DB_USER=%s DB_NAME=%s",
		c.PostgresHost, c.PostgresPort, c.PostgresUser, c.PostgresDB)
	log.Printf("[config] NATS_URL=%s REDIS=%s:%d", c.NATSUrl, c.RedisHost, c.RedisPort)
	log.Printf("[config] LLM_URL=%s LLM_MODEL=%s FALLBACK=%s",
		c.LLMBaseURL, c.LLMModel, c.LLMFallbackModel)
	log.Printf("[config] LLM_API_KEY=**** (len=%d)", len(c.LLMAPIKey))
	if c.EmbeddingAPIURL != "" {
		log.Printf("[config] EMBEDDING_URL=%s MODEL=%s", c.EmbeddingAPIURL, c.EmbeddingModel)
	} else {
		log.Printf("[config] EMBEDDING=disabled (using n-gram fallback)")
	}
	log.Printf("[config] IOT_PROVIDER=%s", c.IoTProvider)
	log.Printf("[config] TTS=%s ASR=%s", c.TTSProvider, c.ASRProvider)
	log.Printf("[config] BACKGROUND_THINKING=%v INTERVAL=%ds SILENCE=%ds",
		c.EnableBackgroundThinking, c.ThinkIntervalSec, c.ThinkSilenceTimeoutSec)
	log.Printf("[config] JWT_SECRET=**** (len=%d)", len(c.JWTSecret))
	log.Printf("[config] ADMIN=%s REGISTRATION=%v", c.AdminUsername, c.RegistrationOpen)
}