package config

import (
	"fmt"
	"os"
	"strings"

	"github.com/joho/godotenv"
)

// Config holds all application configuration loaded from environment variables.
type Config struct {
	// IMAP settings
	IMAPHost string
	IMAPPort string
	IMAPUser string
	IMAPPass string

	// SMTP settings
	SMTPHost string
	SMTPPort string
	SMTPUser string
	SMTPPass string

	// OpenClaw settings
	OpenClawURL    string
	OpenClawAPIKey string

	// Bridge settings
	BridgeCallbackToken string
	SystemEmail         string
	WhitelistEmails     []string

	// Optional
	IMAPProxyURL string

	// Server
	ListenAddr string

	// Public callback base URL for OpenClaw callbacks
	CallbackBaseURL string
}

// Load reads .env (if present) and populates Config from environment variables.
// Returns an error if any required variable is missing.
func Load() (*Config, error) {
	// Best-effort load .env — ignore error if file doesn't exist.
	_ = godotenv.Load()

	cfg := &Config{
		IMAPHost:            os.Getenv("IMAP_HOST"),
		IMAPPort:            os.Getenv("IMAP_PORT"),
		IMAPUser:            os.Getenv("IMAP_USER"),
		IMAPPass:            os.Getenv("IMAP_PASS"),
		SMTPHost:            os.Getenv("SMTP_HOST"),
		SMTPPort:            os.Getenv("SMTP_PORT"),
		SMTPUser:            os.Getenv("SMTP_USER"),
		SMTPPass:            os.Getenv("SMTP_PASS"),
		OpenClawURL:         os.Getenv("OPENCLAW_URL"),
		OpenClawAPIKey:      os.Getenv("OPENCLAW_API_KEY"),
		BridgeCallbackToken: os.Getenv("BRIDGE_CALLBACK_TOKEN"),
		SystemEmail:         os.Getenv("SYSTEM_EMAIL"),
		IMAPProxyURL:        os.Getenv("IMAP_PROXY_URL"),
		ListenAddr:          os.Getenv("LISTEN_ADDR"),
		CallbackBaseURL:     os.Getenv("CALLBACK_BASE_URL"),
	}

	if raw := os.Getenv("WHITELIST_EMAILS"); raw != "" {
		for _, email := range strings.Split(raw, ",") {
			if trimmed := strings.TrimSpace(email); trimmed != "" {
				cfg.WhitelistEmails = append(cfg.WhitelistEmails, trimmed)
			}
		}
	}

	if cfg.ListenAddr == "" {
		cfg.ListenAddr = ":8080"
	}
	if cfg.CallbackBaseURL == "" {
		cfg.CallbackBaseURL = "http://localhost"
	}

	if err := cfg.validate(); err != nil {
		return nil, err
	}

	return cfg, nil
}

// validate checks that all required configuration values are present.
func (c *Config) validate() error {
	required := map[string]string{
		"IMAP_HOST":              c.IMAPHost,
		"IMAP_PORT":              c.IMAPPort,
		"IMAP_USER":              c.IMAPUser,
		"IMAP_PASS":              c.IMAPPass,
		"SMTP_HOST":              c.SMTPHost,
		"SMTP_PORT":              c.SMTPPort,
		"SMTP_USER":              c.SMTPUser,
		"SMTP_PASS":              c.SMTPPass,
		"OPENCLAW_URL":           c.OpenClawURL,
		"BRIDGE_CALLBACK_TOKEN":  c.BridgeCallbackToken,
		"SYSTEM_EMAIL":           c.SystemEmail,
	}

	var missing []string
	for name, val := range required {
		if val == "" {
			missing = append(missing, name)
		}
	}

	if len(missing) > 0 {
		return fmt.Errorf("missing required config: %s", strings.Join(missing, ", "))
	}

	return nil
}