chainfee: simplify WebAPIFeeSource interface

This commit removes the interface methods `GenQueryURL` and
`ParseResponse` so the `WebAPIEstimator` can care less about the
implementation details of this interface.

lnwallet/chainfee/estimator.go

@@ -493,16 +493,6 @@ var _ Estimator = (*BitcoindEstimator)(nil)
 // implementation of this interface in order to allow the WebAPIEstimator to
 // be fully generic in its logic.
 type WebAPIFeeSource interface {
-	// GenQueryURL generates the full query URL. The value returned by this
-	// method should be able to be used directly as a path for an HTTP GET
-	// request.
-	GenQueryURL() string
-
-	// ParseResponse attempts to parse the body of the response generated
-	// by the above query URL. Typically this will be JSON, but the
-	// specifics are left to the WebAPIFeeSource implementation.
-	ParseResponse(r io.Reader) (map[uint32]uint32, error)
-
 	// GetFeeMap will query the web API, parse the response and return a
 	// map of confirmation targets to sat/kw fees.
 	GetFeeMap() (map[uint32]uint32, error)
@@ -517,21 +507,12 @@ type SparseConfFeeSource struct {
 	URL string
 }
 
-// GenQueryURL generates the full query URL. The value returned by this
-// method should be able to be used directly as a path for an HTTP GET
-// request.
-//
-// NOTE: Part of the WebAPIFeeSource interface.
-func (s SparseConfFeeSource) GenQueryURL() string {
-	return s.URL
-}
-
-// ParseResponse attempts to parse the body of the response generated by the
+// parseResponse attempts to parse the body of the response generated by the
 // above query URL. Typically this will be JSON, but the specifics are left to
 // the WebAPIFeeSource implementation.
-//
-// NOTE: Part of the WebAPIFeeSource interface.
-func (s SparseConfFeeSource) ParseResponse(r io.Reader) (map[uint32]uint32, error) {
+func (s SparseConfFeeSource) parseResponse(r io.Reader) (
+	map[uint32]uint32, error) {
+
 	type jsonResp struct {
 		FeeByBlockTarget map[uint32]uint32 `json:"fee_by_block_target"`
 	}
@@ -567,7 +548,7 @@ func (s SparseConfFeeSource) GetFeeMap() (map[uint32]uint32, error) {
 
 	// With the client created, we'll query the API source to fetch the URL
 	// that we should use to query for the fee estimation.
-	targetURL := s.GenQueryURL()
+	targetURL := s.URL
 	resp, err := netClient.Get(targetURL)
 	if err != nil {
 		log.Errorf("unable to query web api for fee response: %v",
@@ -578,7 +559,7 @@ func (s SparseConfFeeSource) GetFeeMap() (map[uint32]uint32, error) {
 
 	// Once we've obtained the response, we'll instruct the WebAPIFeeSource
 	// to parse out the body to obtain our final result.
-	feesByBlockTarget, err := s.ParseResponse(resp.Body)
+	feesByBlockTarget, err := s.parseResponse(resp.Body)
 	if err != nil {
 		log.Errorf("unable to parse fee api response: %v", err)