Added cache, funcspec and implemented total cache

pkg/cache/query_cache.go

@@ -0,0 +1,127 @@
+package cache
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"strings"
+
+	"github.com/bitechdev/ResolveSpec/pkg/common"
+)
+
+// QueryCacheKey represents the components used to build a cache key for query total count
+type QueryCacheKey struct {
+	TableName      string                 `json:"table_name"`
+	Filters        []common.FilterOption  `json:"filters"`
+	Sort           []common.SortOption    `json:"sort"`
+	CustomSQLWhere string                 `json:"custom_sql_where,omitempty"`
+	CustomSQLOr    string                 `json:"custom_sql_or,omitempty"`
+	Expand         []ExpandOptionKey      `json:"expand,omitempty"`
+	Distinct       bool                   `json:"distinct,omitempty"`
+	CursorForward  string                 `json:"cursor_forward,omitempty"`
+	CursorBackward string                 `json:"cursor_backward,omitempty"`
+}
+
+// ExpandOptionKey represents expand options for cache key
+type ExpandOptionKey struct {
+	Relation string `json:"relation"`
+	Where    string `json:"where,omitempty"`
+}
+
+// BuildQueryCacheKey builds a cache key from query parameters for total count caching
+// This is used to cache the total count of records matching a query
+func BuildQueryCacheKey(tableName string, filters []common.FilterOption, sort []common.SortOption, customWhere, customOr string) string {
+	key := QueryCacheKey{
+		TableName:      tableName,
+		Filters:        filters,
+		Sort:           sort,
+		CustomSQLWhere: customWhere,
+		CustomSQLOr:    customOr,
+	}
+
+	// Serialize to JSON for consistent hashing
+	jsonData, err := json.Marshal(key)
+	if err != nil {
+		// Fallback to simple string concatenation if JSON fails
+		return hashString(fmt.Sprintf("%s_%v_%v_%s_%s", tableName, filters, sort, customWhere, customOr))
+	}
+
+	return hashString(string(jsonData))
+}
+
+// BuildExtendedQueryCacheKey builds a cache key for extended query options (restheadspec)
+// Includes expand, distinct, and cursor pagination options
+func BuildExtendedQueryCacheKey(tableName string, filters []common.FilterOption, sort []common.SortOption,
+	customWhere, customOr string, expandOpts []interface{}, distinct bool, cursorFwd, cursorBwd string) string {
+
+	key := QueryCacheKey{
+		TableName:      tableName,
+		Filters:        filters,
+		Sort:           sort,
+		CustomSQLWhere: customWhere,
+		CustomSQLOr:    customOr,
+		Distinct:       distinct,
+		CursorForward:  cursorFwd,
+		CursorBackward: cursorBwd,
+	}
+
+	// Convert expand options to cache key format
+	if len(expandOpts) > 0 {
+		key.Expand = make([]ExpandOptionKey, 0, len(expandOpts))
+		for _, exp := range expandOpts {
+			// Type assert to get the expand option fields we care about for caching
+			if expMap, ok := exp.(map[string]interface{}); ok {
+				expKey := ExpandOptionKey{}
+				if rel, ok := expMap["relation"].(string); ok {
+					expKey.Relation = rel
+				}
+				if where, ok := expMap["where"].(string); ok {
+					expKey.Where = where
+				}
+				key.Expand = append(key.Expand, expKey)
+			}
+		}
+		// Sort expand options for consistent hashing (already sorted by relation name above)
+	}
+
+	// Serialize to JSON for consistent hashing
+	jsonData, err := json.Marshal(key)
+	if err != nil {
+		// Fallback to simple string concatenation if JSON fails
+		return hashString(fmt.Sprintf("%s_%v_%v_%s_%s_%v_%v_%s_%s",
+			tableName, filters, sort, customWhere, customOr, expandOpts, distinct, cursorFwd, cursorBwd))
+	}
+
+	return hashString(string(jsonData))
+}
+
+// hashString computes SHA256 hash of a string
+func hashString(s string) string {
+	h := sha256.New()
+	h.Write([]byte(s))
+	return hex.EncodeToString(h.Sum(nil))
+}
+
+// GetQueryTotalCacheKey returns a formatted cache key for storing/retrieving total count
+func GetQueryTotalCacheKey(hash string) string {
+	return fmt.Sprintf("query_total:%s", hash)
+}
+
+// CachedTotal represents a cached total count
+type CachedTotal struct {
+	Total int `json:"total"`
+}
+
+// InvalidateCacheForTable removes all cached totals for a specific table
+// This should be called when data in the table changes (insert/update/delete)
+func InvalidateCacheForTable(ctx context.Context, tableName string) error {
+	cache := GetDefaultCache()
+
+	// Build a pattern to match all query totals for this table
+	// Note: This requires pattern matching support in the provider
+	pattern := fmt.Sprintf("query_total:*%s*", strings.ToLower(tableName))
+
+	return cache.DeleteByPattern(ctx, pattern)
+}