package core

import (
	"os"
	"strings"
	"time"

	"gopkg.in/yaml.v3"
)

// Config represents the application configuration.
type Config struct {
	Server        ServerConfig        `yaml:"server"`
	Database      DatabaseConfig      `yaml:"database"`
	Storage       StorageConfig       `yaml:"storage"`
	OAuth         OAuthConfig         `yaml:"oauth"`
	Transcription TranscriptionConfig `yaml:"transcription"`
	Webhooks      []WebhookConfig     `yaml:"webhooks"`
	Channels      ChannelsConfig      `yaml:"channels"`
}

type ServerConfig struct {
	Host string `yaml:"host"`
	Port int    `yaml:"port"`
}

type DatabaseConfig struct {
	Path string `yaml:"path"`
}

type StorageConfig struct {
	Path string `yaml:"path"`
}

type OAuthConfig struct {
	Issuer         string        `yaml:"issuer"`
	SigningKey     string        `yaml:"signing_key"`
	AccessTokenTTL time.Duration `yaml:"access_token_ttl"`
	Clients        []OAuthClient `yaml:"clients"`
}

type OAuthClient struct {
	ID     string   `yaml:"id"`
	Secret string   `yaml:"secret"`
	Scopes []string `yaml:"scopes"`
}

type TranscriptionConfig struct {
	Provider string `yaml:"provider"`
	APIKey   string `yaml:"api_key"`
	Model    string `yaml:"model"`
}

type WebhookConfig struct {
	URL    string   `yaml:"url"`
	Secret string   `yaml:"secret"`
	Events []string `yaml:"events"`
}

type ChannelsConfig struct {
	Email    *EmailChannelConfig    `yaml:"email"`
	WhatsApp *WhatsAppChannelConfig `yaml:"whatsapp"`
	Signal   *SignalChannelConfig   `yaml:"signal"`
}

type EmailChannelConfig struct {
	Enabled bool       `yaml:"enabled"`
	IMAP    IMAPConfig `yaml:"imap"`
	SMTP    SMTPConfig `yaml:"smtp"`
}

type IMAPConfig struct {
	Host     string `yaml:"host"`
	Port     int    `yaml:"port"`
	Username string `yaml:"username"`
	Password string `yaml:"password"`
	TLS      string `yaml:"tls"`
}

type SMTPConfig struct {
	Host     string `yaml:"host"`
	Port     int    `yaml:"port"`
	Username string `yaml:"username"`
	Password string `yaml:"password"`
	TLS      string `yaml:"tls"`
}

type WhatsAppChannelConfig struct {
	Enabled bool   `yaml:"enabled"`
	DataDir string `yaml:"data_dir"`
}

type SignalChannelConfig struct {
	Enabled bool   `yaml:"enabled"`
	APIURL  string `yaml:"api_url"`
	Account string `yaml:"account"`
}

// LoadConfig reads and parses the configuration file.
func LoadConfig(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}

	// Expand environment variables with default value support (${VAR:-default})
	expanded := os.Expand(string(data), func(key string) string {
		// Handle ${VAR:-default} syntax
		if idx := strings.Index(key, ":-"); idx != -1 {
			envKey := key[:idx]
			defaultVal := key[idx+2:]
			if val := os.Getenv(envKey); val != "" {
				return val
			}
			return defaultVal
		}
		return os.Getenv(key)
	})

	var cfg Config
	if err := yaml.Unmarshal([]byte(expanded), &cfg); err != nil {
		return nil, err
	}

	// Set defaults
	if cfg.Server.Host == "" {
		cfg.Server.Host = "0.0.0.0"
	}
	if cfg.Server.Port == 0 {
		cfg.Server.Port = 8040
	}
	if cfg.Database.Path == "" {
		cfg.Database.Path = "./mc.db"
	}
	if cfg.Storage.Path == "" {
		cfg.Storage.Path = "./attachments"
	}
	if cfg.OAuth.AccessTokenTTL == 0 {
		cfg.OAuth.AccessTokenTTL = time.Hour
	}

	return &cfg, nil
}

// HasScope checks if a client has a specific scope.
func (c *OAuthClient) HasScope(scope string) bool {
	for _, s := range c.Scopes {
		if s == scope || s == "admin" {
			return true
		}
		// Check wildcard (e.g., "messages:*" matches "messages:read")
		if strings.HasSuffix(s, ":*") {
			prefix := strings.TrimSuffix(s, "*")
			if strings.HasPrefix(scope, prefix) {
				return true
			}
		}
	}
	return false
}