// Authorize user u to execute query q on database.
// database can be "" for queries that do not require a database.
// If no user is provided it will return an error unless the query's first statement is to create
// a root user.
func (q *QueryExecutor) Authorize(u *meta.UserInfo, query *influxql.Query, database string) error {
	// Special case if no users exist.
	if n := q.MetaClient.UserCount(); n == 0 {
		// Ensure there is at least one statement.
		if len(query.Statements) > 0 {
			// First statement in the query must create a user with admin privilege.
			cu, ok := query.Statements[0].(*influxql.CreateUserStatement)
			if ok && cu.Admin == true {
				return nil
			}
		}
		return NewErrAuthorize(q, query, "", database, "create admin user first or disable authentication")
	}

	if u == nil {
		return NewErrAuthorize(q, query, "", database, "no user provided")
	}

	// Admin privilege allows the user to execute all statements.
	if u.Admin {
		return nil
	}

	// Check each statement in the query.
	for _, stmt := range query.Statements {
		// Get the privileges required to execute the statement.
		privs := stmt.RequiredPrivileges()

		// Make sure the user has the privileges required to execute
		// each statement.
		for _, p := range privs {
			if p.Admin {
				// Admin privilege already checked so statement requiring admin
				// privilege cannot be run.
				msg := fmt.Sprintf("statement '%s', requires admin privilege", stmt)
				return NewErrAuthorize(q, query, u.Name, database, msg)
			}

			// Use the db name specified by the statement or the db
			// name passed by the caller if one wasn't specified by
			// the statement.
			db := p.Name
			if db == "" {
				db = database
			}
			if !u.Authorize(p.Privilege, db) {
				msg := fmt.Sprintf("statement '%s', requires %s on %s", stmt, p.Privilege.String(), db)
				return NewErrAuthorize(q, query, u.Name, database, msg)
			}
		}
	}
	return nil
}

// serveWrite receives incoming series data in line protocol format and writes it to the database.
func (h *Handler) serveWrite(w http.ResponseWriter, r *http.Request, user *meta.UserInfo) {
	h.statMap.Add(statWriteRequest, 1)
	defer func(start time.Time) {
		h.statMap.Add(statWriteRequestDuration, time.Since(start).Nanoseconds())
	}(time.Now())

	database := r.FormValue("db")
	if database == "" {
		resultError(w, influxql.Result{Err: fmt.Errorf("database is required")}, http.StatusBadRequest)
		return
	}

	if di, err := h.MetaClient.Database(database); err != nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("metastore database error: %s", err)}, http.StatusInternalServerError)
		return
	} else if di == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("database not found: %q", database)}, http.StatusNotFound)
		return
	}

	if h.requireAuthentication && user == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("user is required to write to database %q", database)}, http.StatusUnauthorized)
		return
	}

	if h.requireAuthentication && !user.Authorize(influxql.WritePrivilege, database) {
		resultError(w, influxql.Result{Err: fmt.Errorf("%q user is not authorized to write to database %q", user.Name, database)}, http.StatusUnauthorized)
		return
	}

	// Handle gzip decoding of the body
	body := r.Body
	if r.Header.Get("Content-encoding") == "gzip" {
		b, err := gzip.NewReader(r.Body)
		if err != nil {
			resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
			return
		}
		defer b.Close()
		body = b
	}

	var bs []byte
	if clStr := r.Header.Get("Content-Length"); clStr != "" {
		if length, err := strconv.Atoi(clStr); err == nil {
			// This will just be an initial hint for the gzip reader, as the
			// bytes.Buffer will grow as needed when ReadFrom is called
			bs = make([]byte, 0, length)
		}
	}
	buf := bytes.NewBuffer(bs)

	_, err := buf.ReadFrom(body)
	if err != nil {
		if h.WriteTrace {
			h.Logger.Print("write handler unable to read bytes from request body")
		}
		resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		return
	}
	h.statMap.Add(statWriteRequestBytesReceived, int64(buf.Len()))

	if h.WriteTrace {
		h.Logger.Printf("write body received by handler: %s", buf.Bytes())
	}

	points, parseError := models.ParsePointsWithPrecision(buf.Bytes(), time.Now().UTC(), r.FormValue("precision"))
	// Not points parsed correctly so return the error now
	if parseError != nil && len(points) == 0 {
		if parseError.Error() == "EOF" {
			w.WriteHeader(http.StatusOK)
			return
		}
		resultError(w, influxql.Result{Err: parseError}, http.StatusBadRequest)
		return
	}

	// Write points.
	if err := h.PointsWriter.WritePoints(database, r.FormValue("rp"), models.ConsistencyLevelAny, points); influxdb.IsClientError(err) {
		h.statMap.Add(statPointsWrittenFail, int64(len(points)))
		resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		return
	} else if err != nil {
		h.statMap.Add(statPointsWrittenFail, int64(len(points)))
		resultError(w, influxql.Result{Err: err}, http.StatusInternalServerError)
		return
	} else if parseError != nil {
		// We wrote some of the points
		h.statMap.Add(statPointsWrittenOK, int64(len(points)))
		// The other points failed to parse which means the client sent invalid line protocol.  We return a 400
		// response code as well as the lines that failed to parse.
		resultError(w, influxql.Result{Err: fmt.Errorf("partial write:\n%v", parseError)}, http.StatusBadRequest)
		return
	}

	h.statMap.Add(statPointsWrittenOK, int64(len(points)))
	w.WriteHeader(http.StatusNoContent)
}

// serveWriteLine receives incoming series data in line protocol format and writes it to the database.
func (h *Handler) serveWriteLine(w http.ResponseWriter, r *http.Request, body []byte, user *meta.UserInfo) {
	// Some clients may not set the content-type header appropriately and send JSON with a non-json
	// content-type.  If the body looks JSON, try to handle it as as JSON instead
	if len(body) > 0 {
		var i int
		for {
			// JSON requests must start w/ an opening bracket
			if body[i] == '{' {
				h.serveWriteJSON(w, r, body, user)
				return
			}

			// check that the byte is in the standard ascii code range
			if body[i] > 32 || i >= len(body)-1 {
				break
			}
			i++
		}
	}

	precision := r.FormValue("precision")
	if precision == "" {
		precision = "n"
	}

	points, parseError := models.ParsePointsWithPrecision(body, time.Now().UTC(), precision)
	// Not points parsed correctly so return the error now
	if parseError != nil && len(points) == 0 {
		if parseError.Error() == "EOF" {
			w.WriteHeader(http.StatusOK)
			return
		}
		resultError(w, influxql.Result{Err: parseError}, http.StatusBadRequest)
		return
	}

	database := r.FormValue("db")
	if database == "" {
		resultError(w, influxql.Result{Err: fmt.Errorf("database is required")}, http.StatusBadRequest)
		return
	}

	if di, err := h.MetaClient.Database(database); err != nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("metastore database error: %s", err)}, http.StatusInternalServerError)
		return
	} else if di == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("database not found: %q", database)}, http.StatusNotFound)
		return
	}

	if h.requireAuthentication && user == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("user is required to write to database %q", database)}, http.StatusUnauthorized)
		return
	}

	if h.requireAuthentication && !user.Authorize(influxql.WritePrivilege, database) {
		resultError(w, influxql.Result{Err: fmt.Errorf("%q user is not authorized to write to database %q", user.Name, database)}, http.StatusUnauthorized)
		return
	}

	// Write points.
	if err := h.PointsWriter.WritePoints(database, r.FormValue("rp"), models.ConsistencyLevelAny, points); influxdb.IsClientError(err) {
		h.statMap.Add(statPointsWrittenFail, int64(len(points)))
		resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		return
	} else if err != nil {
		h.statMap.Add(statPointsWrittenFail, int64(len(points)))
		resultError(w, influxql.Result{Err: err}, http.StatusInternalServerError)
		return
	} else if parseError != nil {
		// We wrote some of the points
		h.statMap.Add(statPointsWrittenOK, int64(len(points)))
		// The other points failed to parse which means the client sent invalid line protocol.  We return a 400
		// response code as well as the lines that failed to parse.
		resultError(w, influxql.Result{Err: fmt.Errorf("partial write:\n%v", parseError)}, http.StatusBadRequest)
		return
	}

	h.statMap.Add(statPointsWrittenOK, int64(len(points)))
	w.WriteHeader(http.StatusNoContent)
}

// serveWriteJSON receives incoming series data in JSON and writes it to the database.
func (h *Handler) serveWriteJSON(w http.ResponseWriter, r *http.Request, body []byte, user *meta.UserInfo) {
	if !h.JSONWriteEnabled {
		resultError(w, influxql.Result{Err: fmt.Errorf("JSON write protocol has been deprecated")}, http.StatusBadRequest)
		return
	}

	var bp client.BatchPoints
	var dec *json.Decoder

	dec = json.NewDecoder(bytes.NewReader(body))

	if err := dec.Decode(&bp); err != nil {
		if err.Error() == "EOF" {
			w.WriteHeader(http.StatusOK)
			return
		}
		resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		return
	}

	if bp.Database == "" {
		resultError(w, influxql.Result{Err: fmt.Errorf("database is required")}, http.StatusBadRequest)
		return
	}

	if di, err := h.MetaClient.Database(bp.Database); err != nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("metastore database error: %s", err)}, http.StatusInternalServerError)
		return
	} else if di == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("database not found: %q", bp.Database)}, http.StatusNotFound)
		return
	}

	if h.requireAuthentication && user == nil {
		resultError(w, influxql.Result{Err: fmt.Errorf("user is required to write to database %q", bp.Database)}, http.StatusUnauthorized)
		return
	}

	if h.requireAuthentication && !user.Authorize(influxql.WritePrivilege, bp.Database) {
		resultError(w, influxql.Result{Err: fmt.Errorf("%q user is not authorized to write to database %q", user.Name, bp.Database)}, http.StatusUnauthorized)
		return
	}

	points, err := NormalizeBatchPoints(bp)
	if err != nil {
		resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		return
	}

	// Convert the json batch struct to a points writer struct
	if err := h.PointsWriter.WritePoints(bp.Database, bp.RetentionPolicy, models.ConsistencyLevelAny, points); err != nil {
		h.statMap.Add(statPointsWrittenFail, int64(len(points)))
		if influxdb.IsClientError(err) {
			resultError(w, influxql.Result{Err: err}, http.StatusBadRequest)
		} else {
			resultError(w, influxql.Result{Err: err}, http.StatusInternalServerError)
		}
		return
	}
	h.statMap.Add(statPointsWrittenOK, int64(len(points)))

	w.WriteHeader(http.StatusNoContent)
}