File size: 1,745 Bytes
8059bf0 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 | //go:build embed
package web
import (
"crypto/sha256"
"encoding/hex"
"sync"
)
// HTMLCache manages the cached index.html with injected settings
type HTMLCache struct {
mu sync.RWMutex
cachedHTML []byte
etag string
baseHTMLHash string // Hash of the original index.html (immutable after build)
settingsVersion uint64 // Incremented when settings change
}
// CachedHTML represents the cache state
type CachedHTML struct {
Content []byte
ETag string
}
// NewHTMLCache creates a new HTML cache instance
func NewHTMLCache() *HTMLCache {
return &HTMLCache{}
}
// SetBaseHTML initializes the cache with the base HTML template
func (c *HTMLCache) SetBaseHTML(baseHTML []byte) {
c.mu.Lock()
defer c.mu.Unlock()
hash := sha256.Sum256(baseHTML)
c.baseHTMLHash = hex.EncodeToString(hash[:8]) // First 8 bytes for brevity
}
// Invalidate marks the cache as stale
func (c *HTMLCache) Invalidate() {
c.mu.Lock()
defer c.mu.Unlock()
c.settingsVersion++
c.cachedHTML = nil
c.etag = ""
}
// Get returns the cached HTML or nil if cache is stale
func (c *HTMLCache) Get() *CachedHTML {
c.mu.RLock()
defer c.mu.RUnlock()
if c.cachedHTML == nil {
return nil
}
return &CachedHTML{
Content: c.cachedHTML,
ETag: c.etag,
}
}
// Set updates the cache with new rendered HTML
func (c *HTMLCache) Set(html []byte, settingsJSON []byte) {
c.mu.Lock()
defer c.mu.Unlock()
c.cachedHTML = html
c.etag = c.generateETag(settingsJSON)
}
// generateETag creates an ETag from base HTML hash + settings hash
func (c *HTMLCache) generateETag(settingsJSON []byte) string {
settingsHash := sha256.Sum256(settingsJSON)
return `"` + c.baseHTMLHash + "-" + hex.EncodeToString(settingsHash[:8]) + `"`
}
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