package main

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

	"github.com/google/uuid"
	"github.com/jfraeys/fetch_ml/internal/auth"
	"github.com/jfraeys/fetch_ml/internal/config"
	"gopkg.in/yaml.v3"
)

const (
	defaultMetricsFlushInterval = 500 * time.Millisecond
	datasetCacheDefaultTTL      = 30 * time.Minute
)

// Config holds worker configuration
type Config struct {
	Host          string `yaml:"host"`
	User          string `yaml:"user"`
	SSHKey        string `yaml:"ssh_key"`
	Port          int    `yaml:"port"`
	BasePath      string `yaml:"base_path"`
	TrainScript   string `yaml:"train_script"`
	RedisAddr     string `yaml:"redis_addr"`
	RedisPassword string `yaml:"redis_password"`
	RedisDB       int    `yaml:"redis_db"`
	KnownHosts    string `yaml:"known_hosts"`
	WorkerID      string `yaml:"worker_id"`
	MaxWorkers    int    `yaml:"max_workers"`
	PollInterval  int    `yaml:"poll_interval_seconds"`

	// Authentication
	Auth auth.AuthConfig `yaml:"auth"`

	// Metrics exporter
	Metrics MetricsConfig `yaml:"metrics"`
	// Metrics buffering
	MetricsFlushInterval time.Duration `yaml:"metrics_flush_interval"`

	// Data management
	DataManagerPath string        `yaml:"data_manager_path"`
	AutoFetchData   bool          `yaml:"auto_fetch_data"`
	DataDir         string        `yaml:"data_dir"`
	DatasetCacheTTL time.Duration `yaml:"dataset_cache_ttl"`

	// Podman execution
	PodmanImage        string `yaml:"podman_image"`
	ContainerWorkspace string `yaml:"container_workspace"`
	ContainerResults   string `yaml:"container_results"`
	GPUAccess          bool   `yaml:"gpu_access"`

	// Task lease and retry settings
	TaskLeaseDuration time.Duration `yaml:"task_lease_duration"` // How long worker holds lease (default: 30min)
	HeartbeatInterval time.Duration `yaml:"heartbeat_interval"`  // How often to renew lease (default: 1min)
	MaxRetries        int           `yaml:"max_retries"`         // Maximum retry attempts (default: 3)
	GracefulTimeout   time.Duration `yaml:"graceful_timeout"`    // Graceful shutdown timeout (default: 5min)
}

// MetricsConfig controls the Prometheus exporter.
type MetricsConfig struct {
	Enabled    bool   `yaml:"enabled"`
	ListenAddr string `yaml:"listen_addr"`
}

func LoadConfig(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}

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

	// Get smart defaults for current environment
	smart := config.GetSmartDefaults()

	if cfg.Port == 0 {
		cfg.Port = config.DefaultSSHPort
	}
	if cfg.Host == "" {
		cfg.Host = smart.Host()
	}
	if cfg.BasePath == "" {
		cfg.BasePath = smart.BasePath()
	}
	if cfg.RedisAddr == "" {
		cfg.RedisAddr = smart.RedisAddr()
	}
	if cfg.KnownHosts == "" {
		cfg.KnownHosts = smart.KnownHostsPath()
	}
	if cfg.WorkerID == "" {
		cfg.WorkerID = fmt.Sprintf("worker-%s", uuid.New().String()[:8])
	}
	if cfg.MaxWorkers == 0 {
		cfg.MaxWorkers = smart.MaxWorkers()
	}
	if cfg.PollInterval == 0 {
		cfg.PollInterval = smart.PollInterval()
	}
	if cfg.DataManagerPath == "" {
		cfg.DataManagerPath = "./data_manager"
	}
	if cfg.DataDir == "" {
		if cfg.Host == "" || !cfg.AutoFetchData {
			cfg.DataDir = config.DefaultLocalDataDir
		} else {
			cfg.DataDir = smart.DataDir()
		}
	}
	if cfg.Metrics.ListenAddr == "" {
		cfg.Metrics.ListenAddr = ":9100"
	}
	if cfg.MetricsFlushInterval == 0 {
		cfg.MetricsFlushInterval = defaultMetricsFlushInterval
	}
	if cfg.DatasetCacheTTL == 0 {
		cfg.DatasetCacheTTL = datasetCacheDefaultTTL
	}

	// Set lease and retry defaults
	if cfg.TaskLeaseDuration == 0 {
		cfg.TaskLeaseDuration = 30 * time.Minute
	}
	if cfg.HeartbeatInterval == 0 {
		cfg.HeartbeatInterval = 1 * time.Minute
	}
	if cfg.MaxRetries == 0 {
		cfg.MaxRetries = 3
	}
	if cfg.GracefulTimeout == 0 {
		cfg.GracefulTimeout = 5 * time.Minute
	}

	return &cfg, nil
}

// Validate implements config.Validator interface
func (c *Config) Validate() error {
	if c.Port != 0 {
		if err := config.ValidatePort(c.Port); err != nil {
			return fmt.Errorf("invalid SSH port: %w", err)
		}
	}

	if c.BasePath != "" {
		// Convert relative paths to absolute
		c.BasePath = config.ExpandPath(c.BasePath)
		if !filepath.IsAbs(c.BasePath) {
			c.BasePath = filepath.Join(config.DefaultBasePath, c.BasePath)
		}
	}

	if c.RedisAddr != "" {
		if err := config.ValidateRedisAddr(c.RedisAddr); err != nil {
			return fmt.Errorf("invalid Redis configuration: %w", err)
		}
	}

	if c.MaxWorkers < 1 {
		return fmt.Errorf("max_workers must be at least 1, got %d", c.MaxWorkers)
	}

	return nil
}

// Task struct and Redis constants moved to internal/queue