package store

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

	"github.com/google/uuid"
	"printer.backend/internal/model"
	"printer.backend/internal/svgtemplate"
)

// ItemStore manages items (SVG + metadata) in the template directory.
type ItemStore struct {
	dir string
}

// NewItemStore creates a store that scans templateDir for *.meta.json files.
func NewItemStore(templateDir string) *ItemStore {
	if templateDir == "" {
		templateDir = svgtemplate.OutputDir
	}
	return &ItemStore{dir: templateDir}
}

// List returns all items sorted by creation time (newest first).
func (s *ItemStore) List() ([]model.Item, error) {
	return listFromDir(s.dir,
		func(name string) bool { return strings.HasSuffix(name, ".meta.json") },
		"template dir",
		func(it model.Item) time.Time { return it.CreatedAt },
	)
}

// Get returns an item by ID.
func (s *ItemStore) Get(id string) (model.Item, error) {
	list, err := s.List()
	if err != nil {
		return model.Item{}, err
	}
	item, err := findByID(list, id, func(it model.Item) string { return it.ID })
	if err != nil {
		return model.Item{}, fmt.Errorf("item %w", err)
	}
	return item, nil
}

// Create generates SVG + metadata for a new item.
func (s *ItemStore) Create(name string, spec model.ItemSpec) (model.Item, error) {
	if spec.SizeMM <= 0 {
		return model.Item{}, fmt.Errorf("size_mm must be positive")
	}

	basename := svgBasename(name)
	data := svgtemplate.Build(spec.SizeMM, spec.BleedMM, spec.MarginMM, spec.PaddingMM)
	if err := svgtemplate.WriteFile(basename, data); err != nil {
		return model.Item{}, fmt.Errorf("write svg: %w", err)
	}
	displayName := name
	if displayName == "" {
		displayName = strings.TrimSuffix(basename, filepath.Ext(basename))
	}
	return svgtemplate.WriteMeta(basename, spec, displayName)
}

// Update regenerates the SVG and metadata for an existing item (preserves id, svg filename, created_at).
func (s *ItemStore) Update(id string, name string, spec model.ItemSpec) (model.Item, error) {
	if spec.SizeMM <= 0 {
		return model.Item{}, fmt.Errorf("size_mm must be positive")
	}
	item, err := s.Get(id)
	if err != nil {
		return model.Item{}, err
	}
	data := svgtemplate.Build(spec.SizeMM, spec.BleedMM, spec.MarginMM, spec.PaddingMM)
	if err := svgtemplate.WriteFile(item.SVGTemplate, data); err != nil {
		return model.Item{}, fmt.Errorf("write svg: %w", err)
	}
	if name != "" {
		item.Name = name
	}
	item.Spec = spec
	metaPath := filepath.Join(s.dir, model.MetaFilename(item.SVGTemplate))
	if err := writeJSON(metaPath, item); err != nil {
		return model.Item{}, fmt.Errorf("write meta: %w", err)
	}
	return item, nil
}

// Delete removes an item's SVG and metadata by ID.
func (s *ItemStore) Delete(id string) error {
	item, err := s.Get(id)
	if err != nil {
		return err
	}
	for _, path := range []string{
		filepath.Join(s.dir, item.SVGTemplate),
		filepath.Join(s.dir, model.MetaFilename(item.SVGTemplate)),
	} {
		if err := os.Remove(path); err != nil && !os.IsNotExist(err) {
			return err
		}
	}
	return nil
}

// SVGPath returns the path to an item's SVG file.
func (s *ItemStore) SVGPath(id string) (string, error) {
	item, err := s.Get(id)
	if err != nil {
		return "", err
	}
	path := filepath.Join(s.dir, item.SVGTemplate)
	if _, err := os.Stat(path); err != nil {
		return "", fmt.Errorf("svg file missing: %w", err)
	}
	return path, nil
}

func svgBasename(name string) string {
	base := strings.TrimSpace(name)
	if base == "" {
		return uuid.NewString() + ".svg"
	}
	base = strings.ReplaceAll(base, " ", "_")
	if !strings.HasSuffix(strings.ToLower(base), ".svg") {
		base += ".svg"
	}
	return filepath.Base(base)
}