package config

import (
	"fmt"
	"strings"
	"sync"

	"github.com/spf13/afero"
)

// Manager manages application configuration with value resolution.
type Manager struct {
	mu            sync.RWMutex
	config        map[string]interface{}
	environment   string
	resolver      *Resolver
	loader        *Loader
	configFile    string
	resolvedCache map[string]interface{}
	fs            afero.Fs
}

// NewManager creates a new configuration manager.
func NewManager() *Manager {
	fs := afero.NewOsFs()
	return &Manager{
		config:        make(map[string]interface{}),
		loader:        NewLoader(fs),
		resolvedCache: make(map[string]interface{}),
		fs:            fs,
	}
}

// SetFs sets the filesystem to use for all file operations.
// This is primarily useful for testing with an in-memory filesystem.
func (m *Manager) SetFs(fs afero.Fs) {
	m.mu.Lock()
	defer m.mu.Unlock()

	m.fs = fs
	m.loader = NewLoader(fs)

	// If we have a resolver, recreate it with the new fs
	if m.resolver != nil {
		gcpProject := ""
		awsRegion := "us-east-1"

		// Try to get the current settings
		if gcpProj := m.getConfigValue("GCPProject", ""); gcpProj != nil {
			if str, ok := gcpProj.(string); ok {
				gcpProject = str
			}
		}
		if awsReg := m.getConfigValue("AWSRegion", "us-east-1"); awsReg != nil {
			if str, ok := awsReg.(string); ok {
				awsRegion = str
			}
		}

		m.resolver = NewResolver(gcpProject, awsRegion, fs)
	}

	// Clear caches as filesystem changed
	m.resolvedCache = make(map[string]interface{})
}

// LoadFile loads configuration from a specific file.
func (m *Manager) LoadFile(configFile string) error {
	m.mu.Lock()
	defer m.mu.Unlock()

	config, err := m.loader.LoadYAML(configFile)
	if err != nil {
		return err
	}

	m.config = config
	m.configFile = configFile
	m.resolvedCache = make(map[string]interface{}) // Clear cache
	return nil
}

// loadConfig loads the configuration from file.
func (m *Manager) loadConfig() error {
	if m.configFile == "" {
		// Try to find config.yaml
		configPath, err := m.loader.FindConfigFile("config.yaml")
		if err != nil {
			return err
		}
		m.configFile = configPath
	}

	config, err := m.loader.LoadYAML(m.configFile)
	if err != nil {
		return err
	}

	m.config = config
	m.resolvedCache = make(map[string]interface{}) // Clear cache
	return nil
}

// SetEnvironment sets the active environment.
func (m *Manager) SetEnvironment(environment string) {
	m.mu.Lock()
	defer m.mu.Unlock()

	m.environment = strings.ToLower(environment)

	// Create resolver with GCP project and AWS region if available
	gcpProject := m.getConfigValue("GCPProject", "")
	awsRegion := m.getConfigValue("AWSRegion", "us-east-1")

	if gcpProjectStr, ok := gcpProject.(string); ok {
		if awsRegionStr, ok := awsRegion.(string); ok {
			m.resolver = NewResolver(gcpProjectStr, awsRegionStr, m.fs)
		}
	}

	// Clear resolved cache when environment changes
	m.resolvedCache = make(map[string]interface{})
}

// Get retrieves a configuration value.
func (m *Manager) Get(key string, defaultValue interface{}) interface{} {
	m.mu.RLock()

	// Ensure config is loaded
	if m.config == nil || len(m.config) == 0 {
		// Need to upgrade to write lock to load config
		m.mu.RUnlock()
		m.mu.Lock()
		// Double-check after acquiring write lock
		if m.config == nil || len(m.config) == 0 {
			if err := m.loadConfig(); err != nil {
				// Config file not found is expected when all values
				// come from environment variables. Only log at debug
				// level to avoid confusing "Failed to load config"
				// messages during normal operation.
				_ = err
				m.mu.Unlock()
				return defaultValue
			}
		}
		// Downgrade back to read lock
		m.mu.Unlock()
		m.mu.RLock()
	}
	defer m.mu.RUnlock()

	// Check cache first
	cacheKey := fmt.Sprintf("config.%s", key)
	if cached, ok := m.resolvedCache[cacheKey]; ok {
		return cached
	}

	// Try environment-specific config first
	var rawValue interface{}
	if m.environment != "" {
		envMap, ok := m.config["environments"].(map[string]interface{})
		if ok {
			if env, ok := envMap[m.environment].(map[string]interface{}); ok {
				if config, ok := env["config"].(map[string]interface{}); ok {
					if val, exists := config[key]; exists {
						rawValue = val
					}
				}
			}
		}
	}

	// Fall back to configDefaults
	if rawValue == nil {
		if defaults, ok := m.config["configDefaults"].(map[string]interface{}); ok {
			if val, exists := defaults[key]; exists {
				rawValue = val
			}
		}
	}

	if rawValue == nil {
		return defaultValue
	}

	// Resolve the value if we have a resolver
	var resolvedValue interface{}
	if m.resolver != nil {
		resolvedValue = m.resolver.Resolve(rawValue)
	} else {
		resolvedValue = rawValue
	}

	// Cache the resolved value
	m.resolvedCache[cacheKey] = resolvedValue

	return resolvedValue
}

// GetSecret retrieves a secret value for the current environment.
func (m *Manager) GetSecret(key string, defaultValue interface{}) interface{} {
	m.mu.RLock()

	// Ensure config is loaded
	if m.config == nil || len(m.config) == 0 {
		// Need to upgrade to write lock to load config
		m.mu.RUnlock()
		m.mu.Lock()
		// Double-check after acquiring write lock
		if m.config == nil || len(m.config) == 0 {
			if err := m.loadConfig(); err != nil {
				// Config file not found is expected when all values
				// come from environment variables.
				_ = err
				m.mu.Unlock()
				return defaultValue
			}
		}
		// Downgrade back to read lock
		m.mu.Unlock()
		m.mu.RLock()
	}
	defer m.mu.RUnlock()

	if m.environment == "" {
		return defaultValue
	}

	// Get the current environment's config
	envMap, ok := m.config["environments"].(map[string]interface{})
	if !ok {
		return defaultValue
	}

	env, ok := envMap[m.environment].(map[string]interface{})
	if !ok {
		return defaultValue
	}

	secrets, ok := env["secrets"].(map[string]interface{})
	if !ok {
		return defaultValue
	}

	secretValue, exists := secrets[key]
	if !exists {
		return defaultValue
	}

	// Resolve the value
	if m.resolver != nil {
		resolved := m.resolver.Resolve(secretValue)
		if resolved == nil {
			return defaultValue
		}
		return resolved
	}

	return secretValue
}

// getConfigValue is an internal helper to get config values without locking.
func (m *Manager) getConfigValue(key string, defaultValue interface{}) interface{} {
	// Try environment-specific config first
	var rawValue interface{}
	if m.environment != "" {
		envMap, ok := m.config["environments"].(map[string]interface{})
		if ok {
			if env, ok := envMap[m.environment].(map[string]interface{}); ok {
				if config, ok := env["config"].(map[string]interface{}); ok {
					if val, exists := config[key]; exists {
						rawValue = val
					}
				}
			}
		}
	}

	// Fall back to configDefaults
	if rawValue == nil {
		if defaults, ok := m.config["configDefaults"].(map[string]interface{}); ok {
			if val, exists := defaults[key]; exists {
				rawValue = val
			}
		}
	}

	if rawValue == nil {
		return defaultValue
	}

	return rawValue
}

// Reload reloads the configuration from file.
func (m *Manager) Reload() error {
	m.mu.Lock()
	defer m.mu.Unlock()

	return m.loadConfig()
}

// GetAllConfig returns all configuration values for the current environment.
func (m *Manager) GetAllConfig() map[string]interface{} {
	m.mu.RLock()
	defer m.mu.RUnlock()

	result := make(map[string]interface{})

	// Start with configDefaults
	if defaults, ok := m.config["configDefaults"].(map[string]interface{}); ok {
		for k, v := range defaults {
			if m.resolver != nil {
				result[k] = m.resolver.Resolve(v)
			} else {
				result[k] = v
			}
		}
	}

	// Override with environment-specific config
	if m.environment != "" {
		envMap, ok := m.config["environments"].(map[string]interface{})
		if ok {
			if env, ok := envMap[m.environment].(map[string]interface{}); ok {
				if config, ok := env["config"].(map[string]interface{}); ok {
					for k, v := range config {
						if m.resolver != nil {
							result[k] = m.resolver.Resolve(v)
						} else {
							result[k] = v
						}
					}
				}
			}
		}
	}

	return result
}

// GetAllSecrets returns all secrets for the current environment.
func (m *Manager) GetAllSecrets() map[string]interface{} {
	m.mu.RLock()
	defer m.mu.RUnlock()

	if m.environment == "" {
		return make(map[string]interface{})
	}

	envMap, ok := m.config["environments"].(map[string]interface{})
	if !ok {
		return make(map[string]interface{})
	}

	env, ok := envMap[m.environment].(map[string]interface{})
	if !ok {
		return make(map[string]interface{})
	}

	secrets, ok := env["secrets"].(map[string]interface{})
	if !ok {
		return make(map[string]interface{})
	}

	// Resolve all secrets
	result := make(map[string]interface{})
	for k, v := range secrets {
		if m.resolver != nil {
			result[k] = m.resolver.Resolve(v)
		} else {
			result[k] = v
		}
	}

	return result
}