package item

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

	"gopkg.in/yaml.v3"
	"thehouseoficarus/internal/behavior"
)

type ItemStore struct {
	mu        sync.Mutex
	dataDir   string
	pathIndex map[string]string
	cache     map[string]*ItemDef
}

func NewItemStore(dataDir string) *ItemStore {
	s := &ItemStore{
		dataDir:   dataDir,
		pathIndex: behavior.BuildPathIndex(filepath.Join(dataDir, "items")),
		cache:     make(map[string]*ItemDef),
	}
	return s
}

func (s *ItemStore) Load(id string) (*ItemDef, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if def, ok := s.cache[id]; ok {
		return def, nil
	}
	path, ok := s.pathIndex[id]
	if !ok {
		return nil, fmt.Errorf("read item %s: no such item", id)
	}
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read item %s: %w", id, err)
	}
	var def ItemDef
	if err := yaml.Unmarshal(data, &def); err != nil {
		return nil, fmt.Errorf("parse item %s: %w", id, err)
	}
	warnDeclaredIDMismatch("item", path, id, def.ID)
	def.ID = id
	s.cache[id] = &def
	return &def, nil
}

func (s *ItemStore) LoadAll() ([]*ItemDef, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	dir := filepath.Join(s.dataDir, "items")
	var defs []*ItemDef
	err := behavior.WalkYAMLDir(dir, func(path, id string, data []byte) error {
		if def, ok := s.cache[id]; ok {
			defs = append(defs, def)
			return nil
		}
		var def ItemDef
		if err := yaml.Unmarshal(data, &def); err != nil {
			return fmt.Errorf("parse item %s: %w", id, err)
		}
		warnDeclaredIDMismatch("item", path, id, def.ID)
		def.ID = id
		s.cache[id] = &def
		defs = append(defs, &def)
		return nil
	})
	return defs, err
}

// warnDeclaredIDMismatch logs when a data file declares an id: that disagrees
// with its filename. IDs come from the filename (def.ID = id above), so the
// declared value is silently ignored at runtime; without this warning an author
// sees no sign that the id they wrote is dead.
func warnDeclaredIDMismatch(kind, path, filenameID, declaredID string) {
	if declaredID != "" && declaredID != filenameID {
		log.Printf("%s %s: file declares id %q but is loaded as %q; the filename is authoritative and the declared id is ignored",
			kind, path, declaredID, filenameID)
	}
}

// PathIndex returns a copy of the id→path index, safe to iterate concurrently.
func (s *ItemStore) PathIndex() map[string]string {
	s.mu.Lock()
	defer s.mu.Unlock()
	out := make(map[string]string, len(s.pathIndex))
	for id, p := range s.pathIndex {
		out[id] = p
	}
	return out
}

func (s *ItemStore) IDSet() map[string]bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	ids := make(map[string]bool, len(s.pathIndex))
	for id := range s.pathIndex {
		ids[id] = true
	}
	return ids
}

func (s *ItemStore) Reload(dataDir string) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.dataDir = dataDir
	s.cache = make(map[string]*ItemDef)
	s.pathIndex = behavior.BuildPathIndex(filepath.Join(dataDir, "items"))
}