common.go

// Copyright (c) 2018 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package prometheus

import (
	"fmt"
	"io"
	"io/ioutil"
	"net/http"
	"time"

	"github.com/m3db/m3/src/query/errors"
	"github.com/m3db/m3/src/query/models"
	xpromql "github.com/m3db/m3/src/query/parser/promql"
	"github.com/m3db/m3/src/query/storage"
	"github.com/m3db/m3/src/query/util"
	"github.com/m3db/m3/src/query/util/json"
	xhttp "github.com/m3db/m3/src/x/net/http"

	"github.com/golang/snappy"
	"github.com/gorilla/mux"
	"github.com/prometheus/prometheus/promql"
)

const (
	// NameReplace is the parameter that gets replaced
	NameReplace         = "name"
	queryParam          = "query"
	filterNameTagsParam = "tag"
	errFormatStr        = "error parsing param: %s, error: %v"

	maxTimeout = 5 * time.Minute
)

var (
	matchValues = []byte(".*")
)

// TimeoutOpts stores options related to various timeout configurations
type TimeoutOpts struct {
	FetchTimeout time.Duration
}

// ParsePromCompressedRequest parses a snappy compressed request from Prometheus
func ParsePromCompressedRequest(r *http.Request) ([]byte, *xhttp.ParseError) {
	body := r.Body
	if r.Body == nil {
		err := fmt.Errorf("empty request body")
		return nil, xhttp.NewParseError(err, http.StatusBadRequest)
	}
	defer body.Close()
	compressed, err := ioutil.ReadAll(body)

	if err != nil {
		return nil, xhttp.NewParseError(err, http.StatusInternalServerError)
	}

	if len(compressed) == 0 {
		return nil, xhttp.NewParseError(fmt.Errorf("empty request body"), http.StatusBadRequest)
	}

	reqBuf, err := snappy.Decode(nil, compressed)
	if err != nil {
		return nil, xhttp.NewParseError(err, http.StatusBadRequest)
	}

	return reqBuf, nil
}

// ParseRequestTimeout parses the input request timeout with a default
func ParseRequestTimeout(r *http.Request, configFetchTimeout time.Duration) (time.Duration, error) {
	timeout := r.Header.Get("timeout")
	if timeout == "" {
		return configFetchTimeout, nil
	}

	duration, err := time.ParseDuration(timeout)
	if err != nil {
		return 0, fmt.Errorf("%s: invalid 'timeout': %v", xhttp.ErrInvalidParams, err)
	}

	if duration > maxTimeout {
		return 0, fmt.Errorf("%s: invalid 'timeout': greater than %v", xhttp.ErrInvalidParams, maxTimeout)
	}

	return duration, nil
}

// ParseTagCompletionParamsToQuery parses all params from the GET request
func ParseTagCompletionParamsToQuery(
	r *http.Request,
) (*storage.CompleteTagsQuery, *xhttp.ParseError) {
	tagQuery := storage.CompleteTagsQuery{}

	query, err := parseTagCompletionQuery(r)
	if err != nil {
		return nil, xhttp.NewParseError(fmt.Errorf(errFormatStr, queryParam, err), http.StatusBadRequest)
	}

	matchers, err := models.MatchersFromString(query)
	if err != nil {
		return nil, xhttp.NewParseError(err, http.StatusBadRequest)
	}

	tagQuery.TagMatchers = matchers
	// If there is a result type field present, parse it and set
	// complete name only parameter appropriately. Otherwise, default
	// to returning both completed tag names and values
	if result := r.FormValue("result"); result != "" {
		switch result {
		case "default":
			tagQuery.CompleteNameOnly = false
		case "tagNamesOnly":
			tagQuery.CompleteNameOnly = true
		default:
			return nil, xhttp.NewParseError(errors.ErrInvalidResultParamError, http.StatusBadRequest)
		}
	}

	filterNameTags := r.Form[filterNameTagsParam]
	tagQuery.FilterNameTags = make([][]byte, len(filterNameTags))
	for i, f := range filterNameTags {
		tagQuery.FilterNameTags[i] = []byte(f)
	}

	return &tagQuery, nil
}

func parseTagCompletionQuery(r *http.Request) (string, error) {
	queries, ok := r.URL.Query()[queryParam]
	if !ok || len(queries) == 0 || queries[0] == "" {
		return "", errors.ErrNoQueryFound
	}

	// TODO: currently, we only support one target at a time
	if len(queries) > 1 {
		return "", errors.ErrBatchQuery
	}

	return queries[0], nil
}

func parseTimeWithDefault(
	r *http.Request,
	key string,
	defaultTime time.Time,
) (time.Time, error) {
	if t := r.FormValue(key); t != "" {
		return util.ParseTimeString(t)
	}

	return defaultTime, nil
}

// ParseSeriesMatchQuery parses all params from the GET request
func ParseSeriesMatchQuery(
	r *http.Request,
	tagOptions models.TagOptions,
) (*storage.SeriesMatchQuery, *xhttp.ParseError) {
	r.ParseForm()
	matcherValues := r.Form["match[]"]
	if len(matcherValues) == 0 {
		return nil, xhttp.NewParseError(errors.ErrInvalidMatchers, http.StatusBadRequest)
	}

	start, err := parseTimeWithDefault(r, "start", time.Now().Add(time.Hour*24*-40))
	if err != nil {
		return nil, xhttp.NewParseError(err, http.StatusBadRequest)
	}

	end, err := parseTimeWithDefault(r, "end", time.Now())
	if err != nil {
		return nil, xhttp.NewParseError(err, http.StatusBadRequest)
	}

	tagMatchers := make([]models.Matchers, len(matcherValues))
	for i, s := range matcherValues {
		promMatchers, err := promql.ParseMetricSelector(s)
		if err != nil {
			return nil, xhttp.NewParseError(err, http.StatusBadRequest)
		}

		matchers, err := xpromql.LabelMatchersToModelMatcher(promMatchers, tagOptions)
		if err != nil {
			return nil, xhttp.NewParseError(err, http.StatusBadRequest)
		}

		tagMatchers[i] = matchers
	}

	return &storage.SeriesMatchQuery{
		TagMatchers: tagMatchers,
		Start:       start,
		End:         end,
	}, nil
}

// ParseTagValuesToQuery parses a tag values request to a complete tags query
func ParseTagValuesToQuery(
	r *http.Request,
) (*storage.CompleteTagsQuery, error) {
	vars := mux.Vars(r)
	name, ok := vars[NameReplace]
	if !ok || len(name) == 0 {
		return nil, errors.ErrNoName
	}

	nameBytes := []byte(name)
	return &storage.CompleteTagsQuery{
		CompleteNameOnly: false,
		FilterNameTags:   [][]byte{nameBytes},
		TagMatchers: models.Matchers{
			models.Matcher{
				Type:  models.MatchRegexp,
				Name:  nameBytes,
				Value: matchValues,
			},
		},
	}, nil
}

func renderNameOnlyTagCompletionResultsJSON(
	w io.Writer,
	results []storage.CompletedTag,
) error {
	jw := json.NewWriter(w)
	jw.BeginArray()

	for _, tag := range results {
		jw.WriteString(string(tag.Name))
	}

	jw.EndArray()

	return jw.Close()
}

func renderDefaultTagCompletionResultsJSON(
	w io.Writer,
	results []storage.CompletedTag,
) error {
	jw := json.NewWriter(w)
	jw.BeginObject()

	jw.BeginObjectField("hits")
	jw.WriteInt(len(results))

	jw.BeginObjectField("tags")
	jw.BeginArray()

	for _, tag := range results {
		jw.BeginObject()

		jw.BeginObjectField("key")
		jw.WriteString(string(tag.Name))

		jw.BeginObjectField("values")
		jw.BeginArray()
		for _, value := range tag.Values {
			jw.WriteString(string(value))
		}
		jw.EndArray()

		jw.EndObject()
	}
	jw.EndArray()

	jw.EndObject()

	return jw.Close()
}

// RenderTagCompletionResultsJSON renders tag completion results to json format
func RenderTagCompletionResultsJSON(
	w io.Writer,
	result *storage.CompleteTagsResult,
) error {
	results := result.CompletedTags
	if result.CompleteNameOnly {
		return renderNameOnlyTagCompletionResultsJSON(w, results)
	}

	return renderDefaultTagCompletionResultsJSON(w, results)
}

// RenderTagValuesResultsJSON renders tag values results to json format
func RenderTagValuesResultsJSON(
	w io.Writer,
	result *storage.CompleteTagsResult,
) error {
	if result.CompleteNameOnly {
		return errors.ErrNamesOnly
	}

	tagCount := len(result.CompletedTags)

	if tagCount > 1 {
		return errors.ErrMultipleResults
	}

	jw := json.NewWriter(w)
	jw.BeginObject()

	jw.BeginObjectField("status")
	jw.WriteString("success")

	jw.BeginObjectField("data")
	jw.BeginArray()

	// if no tags found, return empty array
	if tagCount == 0 {
		jw.EndArray()

		jw.EndObject()

		return jw.Close()
	}

	values := result.CompletedTags[0].Values
	for _, value := range values {
		jw.WriteString(string(value))
	}

	jw.EndArray()

	jw.EndObject()

	return jw.Close()
}

type tag struct {
	name  string
	value string
}

func writeTagsHelper(
	jw *json.Writer,
	completedTags []storage.CompletedTag,
	tags []tag,
) {
	if len(completedTags) == 0 {
		jw.BeginObject()
		for _, tag := range tags {
			jw.BeginObjectField(tag.name)
			jw.WriteString(tag.value)
		}

		jw.EndObject()
		return
	}

	firstResult := completedTags[0]
	name := string(firstResult.Name)

	copiedTags := make([]tag, len(tags)+1)
	copy(copiedTags, tags)
	for _, value := range firstResult.Values {
		copiedTags[len(tags)] = tag{name: name, value: string(value)}
		writeTagsHelper(jw, completedTags[1:], copiedTags)
	}
}

func writeTags(
	jw *json.Writer,
	results []*storage.CompleteTagsResult,
) {
	for _, result := range results {
		jw.BeginArray()
		tags := result.CompletedTags
		if len(tags) > 0 {
			writeTagsHelper(jw, result.CompletedTags, nil)
		}
		jw.EndArray()
	}
}

// RenderSeriesMatchResultsJSON renders series match results to json format
func RenderSeriesMatchResultsJSON(
	w io.Writer,
	results []*storage.CompleteTagsResult,
) error {
	jw := json.NewWriter(w)
	jw.BeginObject()

	jw.BeginObjectField("status")
	jw.WriteString("success")

	jw.BeginObjectField("data")
	writeTags(jw, results)
	jw.EndObject()

	return jw.Close()
}

// PromResp represents Prometheus's query response
type PromResp struct {
	Status string `json:"status"`
	Data   struct {
		ResultType string `json:"resultType"`
		Result     []struct {
			Metric map[string]string `json:"metric"`
			// todo(braskin): use `Datapoints` instead of interface{} in values
			// Values is [float, string]
			Values [][]interface{} `json:"values"`
		} `json:"result"`
	} `json:"data"`
}

// PromDebug represents the input and output that are used in the debug endpoint
type PromDebug struct {
	Input   PromResp `json:"input"`
	Results PromResp `json:"results"`
}