Find a Tender API client updates

- Convert OCDS releases to types.Opportunity (internal/types); FetchOnce
  and FetchAll now return opportunities, built from each ocid's latest
  release
- Include each item's main classification as well as its additional ones
- Return ErrUnexpectedStatus for non-200 responses and
  ErrRateLimitExceeded for a repeated 429; close discarded bodies
- Stop fetchAll on a repeated next link and close each page's body once
  read rather than deferring in the loop
- Default a zero Since to 24 hours ago
- Merge date repair and releaseIDs into api.go
- Filter --planning/--opportunities/--awards on each procedure's current
  stage, using OCDS release tags; --opportunities previously matched a
  nonexistent "opportunity" tag and returned nothing
- Reject conflicting filters before fetching (cobra flag group)

internal/cli/fetch/once.go

@@ -9,17 +9,41 @@ import (
 
 	"git.avsdev.uk/Go/job-search/internal/cli"
 	"git.avsdev.uk/Go/job-search/internal/findATender"
-	"git.avsdev.uk/Go/job-search/internal/findATender/ocds"
+	"git.avsdev.uk/Go/job-search/internal/types"
 	"github.com/spf13/cobra"
 )
 
-func filter(reqs []ocds.Release, tag string) []ocds.Release {
-	var resp []ocds.Release
-	for _, req := range reqs {
-		if slices.Contains(req.Tag, tag) {
-			resp = append(resp, req)
+// Release tags for each stage of a procedure, from the OCDS releaseTag
+// codelist. Cancellations are left out, as a cancelled procedure is no longer
+// at any stage.
+var stageTags = map[string][]string{
+	"planning":    {"planning", "planningUpdate"},
+	"opportunity": {"tender", "tenderAmendment", "tenderUpdate"},
+	"award": {
+		"award", "awardUpdate",
+		"contract", "contractUpdate", "contractAmendment",
+		"implementation", "implementationUpdate", "contractTermination",
+	},
+}
+
+// filter keeps the opportunities whose latest release is at stage. Releases
+// are oldest first, so the last one is the procedure's current stage.
+func filter(opps []*types.Opportunity, stage string) []*types.Opportunity {
+	var resp []*types.Opportunity
+
+	for _, opp := range opps {
+		if len(opp.Releases) == 0 {
+			continue
+		}
+		latest := opp.Releases[len(opp.Releases)-1]
+		for _, tag := range latest.Tags {
+			if slices.Contains(stageTags[stage], tag.Tag) {
+				resp = append(resp, opp)
+				break
+			}
 		}
 	}
+
 	return resp
 }
 
@@ -60,14 +84,6 @@ func commandOnce(opts *cli.Options) *cobra.Command {
 			opportunities, _ := cmd.Flags().GetBool("opportunities")
 			awards, _ := cmd.Flags().GetBool("awards")
 
-			if (planning && (opportunities || awards)) ||
-				(opportunities && (planning || awards)) ||
-				(awards && (planning || opportunities)) {
-				return fmt.Errorf(
-					"--planning, --opportunities and --awards are exclusive, only one can be provided",
-				)
-			}
-
 			filterTag := ""
 			if planning {
 				filterTag = "planning"
@@ -112,5 +128,6 @@ func commandOnce(opts *cli.Options) *cobra.Command {
 	cmd.Flags().Bool(
 		"ignore-rate-limit", false, "ignore the rate limit and fail if exceeded",
 	)
+	cmd.MarkFlagsMutuallyExclusive("planning", "opportunities", "awards")
 	return cmd
 }