package render

import (
	"os"
	"sync"
	"time"
)

type cacheEntry struct {
	html    []byte
	modTime time.Time
}

type Cache struct {
	mu    sync.RWMutex
	items map[string]*cacheEntry
}

func NewCache() *Cache {
	return &Cache{items: make(map[string]*cacheEntry)}
}

func (c *Cache) Get(filePath string) ([]byte, error) {
	info, err := os.Stat(filePath)
	if err != nil {
		return nil, err
	}

	c.mu.RLock()
	entry, ok := c.items[filePath]
	c.mu.RUnlock()

	if ok && entry.modTime.Equal(info.ModTime()) {
		return entry.html, nil
	}

	src, err := os.ReadFile(filePath)
	if err != nil {
		return nil, err
	}

	rendered, err := Markdown(src)
	if err != nil {
		return nil, err
	}

	c.mu.Lock()
	c.items[filePath] = &cacheEntry{html: rendered, modTime: info.ModTime()}
	c.mu.Unlock()

	return rendered, nil
}

func (c *Cache) Invalidate(filePath string) {
	c.mu.Lock()
	delete(c.items, filePath)
	c.mu.Unlock()
}

func (c *Cache) Clear() {
	c.mu.Lock()
	c.items = make(map[string]*cacheEntry)
	c.mu.Unlock()
}