tech(influxdb): refactor query builder

trying to reduce the amounts of moving parts for influxdb

pkg/tsdb/influxdb/query.go

@@ -0,0 +1,142 @@
+package influxdb
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"regexp"
+
+	"github.com/grafana/grafana/pkg/tsdb"
+)
+
+var (
+	regexpOperatorPattern *regexp.Regexp = regexp.MustCompile(`^\/.*\/$`)
+)
+
+func (query *Query) Build(queryContext *tsdb.QueryContext) (string, error) {
+	if query.UseRawQuery && query.RawQuery != "" {
+		q := query.RawQuery
+
+		q = strings.Replace(q, "$timeFilter", query.renderTimeFilter(queryContext), 1)
+		q = strings.Replace(q, "$interval", tsdb.CalculateInterval(queryContext.TimeRange), 1)
+
+		return q, nil
+	}
+
+	res := query.renderSelectors(queryContext)
+	res += query.renderMeasurement()
+	res += query.renderWhereClause()
+	res += query.renderTimeFilter(queryContext)
+	res += query.renderGroupBy(queryContext)
+
+	return res, nil
+}
+
+func (query *Query) renderTags() []string {
+	var res []string
+	for i, tag := range query.Tags {
+		str := ""
+
+		if i > 0 {
+			if tag.Condition == "" {
+				str += "AND"
+			} else {
+				str += tag.Condition
+			}
+			str += " "
+		}
+
+		//If the operator is missing we fall back to sensible defaults
+		if tag.Operator == "" {
+			if regexpOperatorPattern.Match([]byte(tag.Value)) {
+				tag.Operator = "=~"
+			} else {
+				tag.Operator = "="
+			}
+		}
+
+		textValue := ""
+		numericValue, err := strconv.ParseFloat(tag.Value, 64)
+
+		// quote value unless regex or number
+		if tag.Operator == "=~" || tag.Operator == "!~" {
+			textValue = tag.Value
+		} else if err == nil {
+			textValue = fmt.Sprintf("%v", numericValue)
+		} else {
+			textValue = fmt.Sprintf("'%s'", tag.Value)
+		}
+
+		res = append(res, fmt.Sprintf(`%s"%s" %s %s`, str, tag.Key, tag.Operator, textValue))
+	}
+
+	return res
+}
+
+func (query *Query) renderTimeFilter(queryContext *tsdb.QueryContext) string {
+	from := "now() - " + queryContext.TimeRange.From
+	to := ""
+
+	if queryContext.TimeRange.To != "now" && queryContext.TimeRange.To != "" {
+		to = " and time < now() - " + strings.Replace(queryContext.TimeRange.To, "now-", "", 1)
+	}
+
+	return fmt.Sprintf("time > %s%s", from, to)
+}
+
+func (query *Query) renderSelectors(queryContext *tsdb.QueryContext) string {
+	res := "SELECT "
+
+	var selectors []string
+	for _, sel := range query.Selects {
+
+		stk := ""
+		for _, s := range *sel {
+			stk = s.Render(query, queryContext, stk)
+		}
+		selectors = append(selectors, stk)
+	}
+
+	return res + strings.Join(selectors, ", ")
+}
+
+func (query *Query) renderMeasurement() string {
+	policy := ""
+	if query.Policy == "" || query.Policy == "default" {
+		policy = ""
+	} else {
+		policy = `"` + query.Policy + `".`
+	}
+	return fmt.Sprintf(` FROM %s"%s"`, policy, query.Measurement)
+}
+
+func (query *Query) renderWhereClause() string {
+	res := " WHERE "
+	conditions := query.renderTags()
+	res += strings.Join(conditions, " ")
+	if len(conditions) > 0 {
+		res += " AND "
+	}
+
+	return res
+}
+
+func (query *Query) renderGroupBy(queryContext *tsdb.QueryContext) string {
+	groupBy := ""
+	for i, group := range query.GroupBy {
+		if i == 0 {
+			groupBy += " GROUP BY"
+		}
+
+		if i > 0 && group.Type != "fill" {
+			groupBy += ", " //fill is so very special. fill is a creep, fill is a weirdo
+		} else {
+			groupBy += " "
+		}
+
+		groupBy += group.Render(query, queryContext, "")
+	}
+
+	return groupBy
+}