package storage

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/google/uuid"

	"mengyastore-backend/internal/models"
)

const defaultCoverURL = "https://img.shumengya.top/i/2026/01/04/695a55058c37f.png"

type JSONStore struct {
	path string
	mu   sync.Mutex
}

func NewJSONStore(path string) (*JSONStore, error) {
	if err := ensureFile(path); err != nil {
		return nil, err
	}
	return &JSONStore{path: path}, nil
}

func ensureFile(path string) error {
	dir := filepath.Dir(path)
	if err := os.MkdirAll(dir, 0o755); err != nil {
		return fmt.Errorf("mkdir data dir: %w", err)
	}
	if _, err := os.Stat(path); err == nil {
		return nil
	} else if !os.IsNotExist(err) {
		return fmt.Errorf("stat data file: %w", err)
	}

	initial := []models.Product{}
	bytes, err := json.MarshalIndent(initial, "", "  ")
	if err != nil {
		return fmt.Errorf("init json: %w", err)
	}
	if err := os.WriteFile(path, bytes, 0o644); err != nil {
		return fmt.Errorf("write init json: %w", err)
	}
	return nil
}

func (s *JSONStore) ListAll() ([]models.Product, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.readAll()
}

func (s *JSONStore) ListActive() ([]models.Product, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	items, err := s.readAll()
	if err != nil {
		return nil, err
	}
	active := make([]models.Product, 0, len(items))
	for _, item := range items {
		if item.Active {
			active = append(active, item)
		}
	}
	return active, nil
}

func (s *JSONStore) Create(p models.Product) (models.Product, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	items, err := s.readAll()
	if err != nil {
		return models.Product{}, err
	}
	p = normalizeProduct(p)
	p.ID = uuid.NewString()
	now := time.Now()
	p.CreatedAt = now
	p.UpdatedAt = now
	items = append(items, p)
	if err := s.writeAll(items); err != nil {
		return models.Product{}, err
	}
	return p, nil
}

func (s *JSONStore) Update(id string, patch models.Product) (models.Product, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	items, err := s.readAll()
	if err != nil {
		return models.Product{}, err
	}
	for i, item := range items {
		if item.ID == id {
			item.Name = patch.Name
			item.Price = patch.Price
			item.Quantity = patch.Quantity
			item.CoverURL = patch.CoverURL
			item.ScreenshotURLs = normalizeProduct(patch).ScreenshotURLs
			item.Description = patch.Description
			item.Active = patch.Active
			item.UpdatedAt = time.Now()
			items[i] = item
			if err := s.writeAll(items); err != nil {
				return models.Product{}, err
			}
			return item, nil
		}
	}
	return models.Product{}, fmt.Errorf("product not found")
}

func (s *JSONStore) Toggle(id string, active bool) (models.Product, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	items, err := s.readAll()
	if err != nil {
		return models.Product{}, err
	}
	for i, item := range items {
		if item.ID == id {
			item.Active = active
			item.UpdatedAt = time.Now()
			items[i] = item
			if err := s.writeAll(items); err != nil {
				return models.Product{}, err
			}
			return item, nil
		}
	}
	return models.Product{}, fmt.Errorf("product not found")
}

func (s *JSONStore) Delete(id string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	items, err := s.readAll()
	if err != nil {
		return err
	}
	filtered := make([]models.Product, 0, len(items))
	for _, item := range items {
		if item.ID != id {
			filtered = append(filtered, item)
		}
	}
	if err := s.writeAll(filtered); err != nil {
		return err
	}
	return nil
}

func (s *JSONStore) readAll() ([]models.Product, error) {
	bytes, err := os.ReadFile(s.path)
	if err != nil {
		return nil, fmt.Errorf("read products: %w", err)
	}
	var items []models.Product
	if err := json.Unmarshal(bytes, &items); err != nil {
		return nil, fmt.Errorf("parse products: %w", err)
	}
	for i, item := range items {
		items[i] = normalizeProduct(item)
	}
	return items, nil
}

func (s *JSONStore) writeAll(items []models.Product) error {
	for i, item := range items {
		items[i] = normalizeProduct(item)
	}
	bytes, err := json.MarshalIndent(items, "", "  ")
	if err != nil {
		return fmt.Errorf("encode products: %w", err)
	}
	if err := os.WriteFile(s.path, bytes, 0o644); err != nil {
		return fmt.Errorf("write products: %w", err)
	}
	return nil
}

func normalizeProduct(item models.Product) models.Product {
	item.CoverURL = strings.TrimSpace(item.CoverURL)
	if item.CoverURL == "" {
		item.CoverURL = defaultCoverURL
	}
	if item.ScreenshotURLs == nil {
		item.ScreenshotURLs = []string{}
	}
	return item
}