package lib

import (
	"encoding/csv"
	"os"
	"strings"
)

type Cache struct {
	filePath string
	seen     map[string]bool
}

func NewCache(filePath string) (*Cache, error) {
	c := &Cache{
		filePath: filePath,
		seen:     make(map[string]bool),
	}
	if err := c.load(); err != nil {
		return nil, err
	}
	return c, nil
}

func (c *Cache) load() error {
	f, err := os.Open(c.filePath)
	if os.IsNotExist(err) {
		return nil
	}
	if err != nil {
		return err
	}
	defer f.Close()

	records, err := csv.NewReader(f).ReadAll()
	if err != nil {
		return err
	}
	for _, record := range records {
		if len(record) > 0 {
			c.seen[strings.TrimSpace(record[0])] = true
		}
	}
	return nil
}

func (c *Cache) Has(id string) bool {
	return c.seen[id]
}

func (c *Cache) Add(id string) error {
	c.seen[id] = true

	f, err := os.OpenFile(c.filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	defer f.Close()

	w := csv.NewWriter(f)
	defer w.Flush()
	return w.Write([]string{id})
}