init: rapid_dashboards app from fn_registry

query_engine.go

@@ -0,0 +1,156 @@
+package main
+
+import (
+	"database/sql"
+	"fmt"
+	"regexp"
+	"strings"
+
+	"fn-registry/functions/infra"
+)
+
+var namedParamRe = regexp.MustCompile(`:([a-zA-Z_][a-zA-Z0-9_]*)`)
+
+// QueryEngine executes queries with parameter resolution.
+type QueryEngine struct {
+	config *DashboardConfig
+	pool   map[string]*sql.DB
+}
+
+func NewQueryEngine(cfg *DashboardConfig, pool map[string]*sql.DB) *QueryEngine {
+	return &QueryEngine{config: cfg, pool: pool}
+}
+
+// Execute runs the query for a widget, resolving filter references and named params.
+func (qe *QueryEngine) Execute(widgetID string, filters map[string]any) ([]map[string]any, error) {
+	// Find the widget and its query.
+	widget, err := qe.findWidget(widgetID)
+	if err != nil {
+		return nil, err
+	}
+
+	qdef, ok := qe.config.Queries[widget.Query]
+	if !ok {
+		return nil, fmt.Errorf("query %q not found", widget.Query)
+	}
+
+	db, ok := qe.pool[qdef.Connection]
+	if !ok {
+		return nil, fmt.Errorf("connection %q not found", qdef.Connection)
+	}
+
+	// Resolve parameter values: static or $filter.xxx references.
+	resolvedParams := qe.resolveParams(qdef.Params, filters)
+
+	// Convert :name placeholders to driver-appropriate positional params.
+	driver := qe.config.Connections[qdef.Connection].Driver
+	query, args := convertNamedParams(qdef.SQL, resolvedParams, driver)
+
+	return infra.DBQuery(db, query, args...)
+}
+
+func (qe *QueryEngine) findWidget(id string) (*WidgetDef, error) {
+	for _, sec := range qe.config.Sections {
+		for i := range sec.Widgets {
+			if sec.Widgets[i].ID == id {
+				return &sec.Widgets[i], nil
+			}
+		}
+	}
+	return nil, fmt.Errorf("widget %q not found", id)
+}
+
+// resolveParams replaces $filter.xxx references with actual filter values
+// and resolves relative dates.
+func (qe *QueryEngine) resolveParams(params map[string]string, filters map[string]any) map[string]string {
+	resolved := make(map[string]string, len(params))
+
+	for name, ref := range params {
+		val := ref
+
+		// $filter.date_range.from → filters["date_range"]["from"]
+		if strings.HasPrefix(ref, "$filter.") {
+			val = resolveFilterRef(ref, filters)
+		}
+
+		// Resolve relative dates (now-7d, etc.)
+		if resolved, ok := ResolveRelativeDate(val); ok {
+			val = resolved
+		}
+
+		resolved[name] = val
+	}
+
+	return resolved
+}
+
+// resolveFilterRef extracts a value from the filters map using dot notation.
+// "$filter.date_range.from" → filters["date_range"] → map["from"]
+func resolveFilterRef(ref string, filters map[string]any) string {
+	// Strip "$filter." prefix.
+	path := strings.TrimPrefix(ref, "$filter.")
+	parts := strings.SplitN(path, ".", 2)
+
+	v, ok := filters[parts[0]]
+	if !ok {
+		return ""
+	}
+
+	// Simple value (e.g. $filter.category).
+	if len(parts) == 1 {
+		return fmt.Sprint(v)
+	}
+
+	// Nested value (e.g. $filter.date_range.from).
+	if m, ok := v.(map[string]any); ok {
+		if val, ok := m[parts[1]]; ok {
+			return fmt.Sprint(val)
+		}
+	}
+
+	return ""
+}
+
+// convertNamedParams replaces :name placeholders with positional params ($1, ?, etc.)
+// and builds the args slice in the correct order.
+func convertNamedParams(query string, params map[string]string, driver string) (string, []any) {
+	matches := namedParamRe.FindAllStringSubmatch(query, -1)
+	if len(matches) == 0 {
+		return query, nil
+	}
+
+	// Deduplicate and order params as they appear.
+	seen := make(map[string]int)
+	var ordered []string
+	for _, m := range matches {
+		name := m[1]
+		if _, ok := seen[name]; !ok {
+			seen[name] = len(ordered)
+			ordered = append(ordered, name)
+		}
+	}
+
+	// Build args slice.
+	args := make([]any, len(ordered))
+	for i, name := range ordered {
+		args[i] = params[name]
+	}
+
+	// Replace :name with positional placeholder.
+	result := namedParamRe.ReplaceAllStringFunc(query, func(match string) string {
+		name := match[1:] // strip leading ':'
+		idx := seen[name]
+		return placeholder(driver, idx)
+	})
+
+	return result, args
+}
+
+func placeholder(driver string, idx int) string {
+	switch driver {
+	case "postgres":
+		return fmt.Sprintf("$%d", idx+1)
+	default:
+		return "?"
+	}
+}