package service

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"sync"

	"github.com/Tencent/WeKnora/internal/agent/skills"
	"github.com/Tencent/WeKnora/internal/logger"
	"github.com/Tencent/WeKnora/internal/types/interfaces"
)

// DefaultPreloadedSkillsDir is the default directory for preloaded skills
const DefaultPreloadedSkillsDir = "skills/preloaded"

// skillService implements SkillService interface
type skillService struct {
	loader       *skills.Loader
	preloadedDir string
	mu           sync.RWMutex
	initialized  bool
}

// NewSkillService creates a new skill service
func NewSkillService() interfaces.SkillService {
	// Determine the preloaded skills directory
	preloadedDir := getPreloadedSkillsDir()

	return &skillService{
		preloadedDir: preloadedDir,
		initialized:  false,
	}
}

// getPreloadedSkillsDir returns the path to the preloaded skills directory
func getPreloadedSkillsDir() string {
	// Check if SKILLS_DIR environment variable is set
	if dir := os.Getenv("WEKNORA_SKILLS_DIR"); dir != "" {
		return dir
	}

	// Try to find the skills directory relative to the executable
	execPath, err := os.Executable()
	if err == nil {
		execDir := filepath.Dir(execPath)
		skillsDir := filepath.Join(execDir, DefaultPreloadedSkillsDir)
		if _, err := os.Stat(skillsDir); err == nil {
			return skillsDir
		}
	}

	// Try current working directory
	cwd, err := os.Getwd()
	if err == nil {
		skillsDir := filepath.Join(cwd, DefaultPreloadedSkillsDir)
		if _, err := os.Stat(skillsDir); err == nil {
			return skillsDir
		}
	}

	// Default to relative path (will be created if needed)
	return DefaultPreloadedSkillsDir
}

// ensureInitialized initializes the loader if not already done
func (s *skillService) ensureInitialized(ctx context.Context) error {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.initialized {
		return nil
	}

	// Check if preloaded directory exists
	if _, err := os.Stat(s.preloadedDir); os.IsNotExist(err) {
		logger.Warnf(ctx, "Preloaded skills directory does not exist: %s", s.preloadedDir)
		// Create the directory to avoid repeated warnings
		if err := os.MkdirAll(s.preloadedDir, 0755); err != nil {
			logger.Warnf(ctx, "Failed to create preloaded skills directory: %v", err)
		}
	}

	// Create loader with preloaded directory
	s.loader = skills.NewLoader([]string{s.preloadedDir})
	s.initialized = true

	logger.Infof(ctx, "Skill service initialized with preloaded directory: %s", s.preloadedDir)

	return nil
}

// ListPreloadedSkills returns metadata for all preloaded skills
func (s *skillService) ListPreloadedSkills(ctx context.Context) ([]*skills.SkillMetadata, error) {
	if err := s.ensureInitialized(ctx); err != nil {
		return nil, fmt.Errorf("failed to initialize skill service: %w", err)
	}

	s.mu.RLock()
	defer s.mu.RUnlock()

	metadata, err := s.loader.DiscoverSkills()
	if err != nil {
		logger.Errorf(ctx, "Failed to discover preloaded skills: %v", err)
		return nil, fmt.Errorf("failed to discover skills: %w", err)
	}

	logger.Infof(ctx, "Discovered %d preloaded skills", len(metadata))

	return metadata, nil
}

// GetSkillByName retrieves a skill by its name
func (s *skillService) GetSkillByName(ctx context.Context, name string) (*skills.Skill, error) {
	if err := s.ensureInitialized(ctx); err != nil {
		return nil, fmt.Errorf("failed to initialize skill service: %w", err)
	}

	s.mu.RLock()
	defer s.mu.RUnlock()

	skill, err := s.loader.LoadSkillInstructions(name)
	if err != nil {
		logger.Errorf(ctx, "Failed to load skill %s: %v", name, err)
		return nil, fmt.Errorf("failed to load skill: %w", err)
	}

	return skill, nil
}

// GetPreloadedDir returns the configured preloaded skills directory
func (s *skillService) GetPreloadedDir() string {
	return s.preloadedDir
}