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
 }

internal/findATender/api.go

@@ -1,12 +1,16 @@
 package findATender
 
 import (
+	"bytes"
 	"context"
 	"encoding/json"
 	"errors"
 	"fmt"
+	"io"
 	"log/slog"
+	"regexp"
 	"strconv"
+	"strings"
 	"time"
 
 	"git.avsdev.uk/Go/job-search/internal/findATender/ocds"
@@ -18,6 +22,7 @@ var ErrNoNext = errors.New("no next link")
 var ErrNoReleases = errors.New("no releases")
 var ErrRateLimitExceeded = errors.New("rate limit has been exceeded")
 var ErrFetchCancelled = errors.New("fetch cancelled")
+var ErrUnexpectedStatus = errors.New("unexpected response status")
 
 type RequestOptions struct {
 	Since          time.Time
@@ -25,6 +30,232 @@ type RequestOptions struct {
 	AllowRateLimit bool
 }
 
+// ---------- Utility methods for handling API irregularities -----------
+type safeReleasePackage struct {
+	URI               string                        `json:"uri,omitempty"`
+	Version           string                        `json:"version,omitempty"`
+	Extensions        []string                      `json:"extensions,omitempty"`
+	PublishedDate     *string                       `json:"publishedDate,omitempty"`
+	Releases          []json.RawMessage             `json:"releases,omitempty"`
+	Publisher         *ocds.ReleasePackagePublisher `json:"publisher,omitempty"`
+	License           string                        `json:"license,omitempty"`
+	PublicationPolicy string                        `json:"publicationPolicy,omitempty"`
+	Links             *ocds.ReleasePackageLinks     `json:"links,omitempty"`
+}
+
+// dateOnly matches a calendar date with no time of day: "2006-10-02".
+var dateOnly = regexp.MustCompile(`^\d{4}-\d{2}-\d{2}$`)
+
+// unmarshalLenientDates decodes raw json into v like json.Unmarshal, after
+// repairing date fields that time.Time cannot parse.
+func unmarshalLenientDates(raw json.RawMessage, v any) error {
+	fixed, err := repairDates(raw)
+	if err != nil {
+		return err
+	}
+	return json.Unmarshal(fixed, v)
+}
+
+// repairDates returns a copy of raw in which every date field holding a
+// date-only value ("2006-10-02") is rewritten as midnight UTC
+// ("2006-10-02T00:00:00Z"), and every date field holding an empty string is
+// set to null. Values that already have a time, values in other fields, and
+// dates that appear inside free text are left alone. If nothing needs
+// repairing, raw is returned unchanged.
+//
+// A date field is one whose name is "date" or starts with "date", contains
+// "Date", or ends with "Deadline".
+func repairDates(raw json.RawMessage) (json.RawMessage, error) {
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.UseNumber() // keep numbers exactly as written, not as float64
+
+	var doc any
+	if err := dec.Decode(&doc); err != nil {
+		return nil, fmt.Errorf("repairing dates: %w", err)
+	}
+
+	if _, err := dec.Token(); !errors.Is(err, io.EOF) {
+		return nil, errors.New(
+			"repairing dates: unexpected data after the JSON value",
+		)
+	}
+
+	if !recursiveRepairDates(doc) {
+		return raw, nil
+	}
+
+	return json.Marshal(doc)
+}
+
+// recursiveRepairDates fixes date fields in v in place and reports whether it
+// changed anything.
+func recursiveRepairDates(v any) bool {
+	changed := false
+	switch v := v.(type) {
+	case map[string]any:
+		for key, val := range v {
+			if s, ok := val.(string); ok && isDateField(key) {
+				switch {
+				case dateOnly.MatchString(s):
+					v[key] = s + "T00:00:00Z"
+					changed = true
+				case s == "":
+					v[key] = nil
+					changed = true
+				}
+				continue
+			}
+			if recursiveRepairDates(val) {
+				changed = true
+			}
+		}
+	case []any:
+		for _, el := range v {
+			if recursiveRepairDates(el) {
+				changed = true
+			}
+		}
+	}
+	return changed
+}
+
+func isDateField(name string) bool {
+	return strings.HasPrefix(name, "date") ||
+		strings.Contains(name, "Date") ||
+		strings.HasSuffix(name, "Deadline")
+}
+
+// ReleaseIDs reads just the ocid and the release id from a release, without
+// decoding the rest of it. It reads the top-level fields in order and stops
+// as soon as it has both, so an error later in the release (invalid JSON or a
+// value that wouldn't fit the release struct) doesn't matter. Fields before
+// them only need to be valid JSON.
+func releaseIDs(raw json.RawMessage) (ocid, id string, err error) {
+	dec := json.NewDecoder(bytes.NewReader(raw))
+	dec.UseNumber() // a numeric id keeps its exact digits
+
+	if tok, err := dec.Token(); err != nil {
+		return "", "", fmt.Errorf("reading release: %w", err)
+	} else if tok != json.Delim('{') {
+		return "", "", errors.New("reading release: not a JSON object")
+	}
+
+	var haveOCID, haveID bool
+	for dec.More() {
+		tok, err := dec.Token()
+		if err != nil {
+			return ocid, id, fmt.Errorf("reading release: %w", err)
+		}
+		switch key, _ := tok.(string); key {
+		case "ocid":
+			if err := dec.Decode(&ocid); err != nil {
+				return ocid, id, fmt.Errorf("reading release ocid: %w", err)
+			}
+			haveOCID = true
+		case "id":
+			if id, err = decodeReleaseID(dec); err != nil {
+				return ocid, id, err
+			}
+			haveID = true
+		default:
+			var skip json.RawMessage // must be valid JSON, but is otherwise ignored
+			if err := dec.Decode(&skip); err != nil {
+				return ocid, id, fmt.Errorf("reading release field %q: %w", key, err)
+			}
+		}
+		if haveOCID && haveID {
+			return ocid, id, nil
+		}
+	}
+
+	return ocid, id, missingIDsError(haveOCID, haveID)
+}
+
+// decodeReleaseID decodes a release id. OCDS ids are strings, but a number is
+// tolerated and kept as written.
+func decodeReleaseID(dec *json.Decoder) (string, error) {
+	var v any
+	if err := dec.Decode(&v); err != nil {
+		return "", fmt.Errorf("reading release id: %w", err)
+	}
+	switch v := v.(type) {
+	case string:
+		return v, nil
+	case json.Number:
+		return v.String(), nil
+	default:
+		return "", fmt.Errorf("reading release id: unexpected %T", v)
+	}
+}
+
+// missingIDsError reports which of the ocid and release id were not found.
+func missingIDsError(haveOCID, haveID bool) error {
+	switch {
+	case !haveOCID && !haveID:
+		return errors.New("reading release: no ocid or id")
+	case !haveOCID:
+		return errors.New("reading release: no ocid")
+	default:
+		return errors.New("reading release: no id")
+	}
+}
+
+// Unpacks an API response into an OCDS ReleasePackage. Handles API
+// irregularities (malformed dates, missing fields, invalid releases, etc).
+//
+// This method takes ownership of the response body and closes it when done.
+func safeUnpackReleases(response *resty.Response) (*ocds.ReleasePackage, error) {
+	var pkg safeReleasePackage
+
+	// Take ownership of the response body.
+	defer response.Body.Close()
+
+	decoder := json.NewDecoder(response.Body)
+	if err := decoder.Decode(&pkg); err != nil {
+		return nil, err
+	}
+
+	out := &ocds.ReleasePackage{
+		URI:               pkg.URI,
+		Version:           pkg.Version,
+		Extensions:        pkg.Extensions,
+		Publisher:         pkg.Publisher,
+		License:           pkg.License,
+		PublicationPolicy: pkg.PublicationPolicy,
+		Links:             pkg.Links,
+	}
+
+	// Correct PublishedDate of "" and "2006-01-02"
+	if pkg.PublishedDate != nil && len(*pkg.PublishedDate) > 0 {
+		t, err := time.Parse(time.RFC3339, *pkg.PublishedDate)
+		if err != nil {
+			t, err = time.Parse(time.DateOnly, *pkg.PublishedDate)
+		}
+		if err == nil {
+			out.PublishedDate = &t
+		}
+	}
+
+	for _, rawRel := range pkg.Releases {
+		var release ocds.Release
+		err := unmarshalLenientDates(rawRel, &release)
+		if err != nil {
+			ocid, release_id, _ := releaseIDs(rawRel)
+			slog.Warn(fmt.Sprintf(
+				"Skipping release (%s/%s) due to error: %s", ocid, release_id, err,
+			))
+			continue
+		}
+		out.Releases = append(out.Releases, release)
+	}
+
+	return out, nil
+}
+
+// ---------- API interaction methods -----------
+// Sleep the fetch worker until either the context is cancelled (shutdown) or
+// the duration has expired. The duration is usually provided by the API - a
+// nil duration will return immediately.
 func rateSleep(ctx context.Context, duration time.Duration) error {
 	timer := time.NewTimer(duration)
 	defer timer.Stop()
@@ -37,6 +268,14 @@ func rateSleep(ctx context.Context, duration time.Duration) error {
 	}
 }
 
+// Check and close the response body - avoids double close issues
+func closeBody(res *resty.Response) {
+	if res.Body != nil {
+		res.Body.Close()
+	}
+}
+
+// Actually perform a single fetch against the API
 func fetchURI(ft *FindATender, uri string) (*resty.Response, error) {
 	withTrace := ft.config.Logging.LogLevel() <= slog.LevelDebug
 
@@ -69,6 +308,11 @@ func fetchURI(ft *FindATender, uri string) (*resty.Response, error) {
 	return res, err
 }
 
+// Perform a fetch against the API. If the API returns with a rate limit
+// reached response and allowRateLimit is true, then wait and retry like a good
+// client. If allowRateLimit is false, return to the caller informing them of
+// the rate limit exceeded error. If, after waiting, the API still thinks we
+// have exceeded the rate limit, bail out anyway.
 func (ft *FindATender) fetchURI(
 	uri string,
 	allowRateLimit bool,
@@ -85,6 +329,8 @@ func (ft *FindATender) fetchURI(
 	}
 
 	if res.StatusCode() == 429 {
+		closeBody(res)
+
 		if !allowRateLimit {
 			return nil, ErrRateLimitExceeded
 		}
@@ -106,16 +352,26 @@ func (ft *FindATender) fetchURI(
 		if err != nil {
 			return nil, err
 		}
+		if res.StatusCode() == 429 {
+			closeBody(res)
+			return nil, ErrRateLimitExceeded
+		}
+	}
+
+	if res.StatusCode() != 200 {
+		closeBody(res)
+		return nil, fmt.Errorf("%w: %s", ErrUnexpectedStatus, res.Status())
 	}
 
 	return res, nil
 }
 
+// Perform a fetch against the API with some sanitised default options.
 func (ft *FindATender) fetchWithOpts(
 	opts RequestOptions,
 ) (*resty.Response, error) {
 	if opts.Since.IsZero() {
-		opts.Since = time.Now().AddDate(0, 0, 1)
+		opts.Since = time.Now().AddDate(0, 0, -1)
 	}
 	if opts.Limit == 0 {
 		opts.Limit = 100
@@ -131,8 +387,11 @@ func (ft *FindATender) fetchWithOpts(
 	return ft.fetchURI(uri, opts.AllowRateLimit)
 }
 
+// If the response provided a "Next" link, perform another API call to get the
+// next page. Error if there is no "Next" link - the caller can decide if they
+// have attempted to fetch next in error or not.
 func (ft *FindATender) fetchNext(
-	pkg ocds.ReleasePackage,
+	pkg *ocds.ReleasePackage,
 	allowRateLimit bool,
 ) (*resty.Response, error) {
 	if pkg.Links == nil || len(pkg.Links.Next) == 0 {
@@ -141,26 +400,27 @@ func (ft *FindATender) fetchNext(
 	return ft.fetchURI(pkg.Links.Next, allowRateLimit)
 }
 
+// Make one call on the API. Do not follow any "Next" links.
 func (ft *FindATender) fetchOnce(opts RequestOptions) ([]ocds.Release, error) {
 	res, err := ft.fetchWithOpts(opts)
 	if err != nil {
 		return nil, err
 	}
-	defer res.Body.Close()
 
-	var relPkg ocds.ReleasePackage
-	decoder := json.NewDecoder(NewOCDSStreamCleaner(res.Body))
-	if err := decoder.Decode(&relPkg); err != nil {
+	pkg, err := safeUnpackReleases(res)
+	if err != nil {
 		return nil, err
 	}
 
-	if len(relPkg.Releases) == 0 {
+	if len(pkg.Releases) == 0 {
 		return nil, ErrNoReleases
 	}
 
-	return relPkg.Releases, nil
+	return pkg.Releases, nil
 }
 
+// Make a call on the API. If there are any "Next" links, call them in
+// succession until the end has been reached.
 func (ft *FindATender) fetchAll(opts RequestOptions) ([]ocds.Release, error) {
 	var releases []ocds.Release
 
@@ -168,30 +428,40 @@ func (ft *FindATender) fetchAll(opts RequestOptions) ([]ocds.Release, error) {
 	if err != nil {
 		return nil, err
 	}
-	defer res.Body.Close()
 
-	var relPkg ocds.ReleasePackage
-	decoder := json.NewDecoder(NewOCDSStreamCleaner(res.Body))
-	if err := decoder.Decode(&relPkg); err != nil {
+	pkg, err := safeUnpackReleases(res)
+	if err != nil {
 		return nil, err
 	}
-	releases = append(releases, relPkg.Releases...)
+	releases = append(releases, pkg.Releases...)
 
-	for true {
-		res, err := ft.fetchNext(relPkg, opts.AllowRateLimit)
+	// Next links already followed, so a page that links back to an earlier
+	// one cannot loop forever.
+	seen := make(map[string]bool)
+	for {
+		if pkg.Links != nil && len(pkg.Links.Next) > 0 {
+			if seen[pkg.Links.Next] {
+				slog.Warn(fmt.Sprintf(
+					"Stopping at repeated next link: %s", pkg.Links.Next,
+				))
+				break
+			}
+			seen[pkg.Links.Next] = true
+		}
+
+		res, err := ft.fetchNext(pkg, opts.AllowRateLimit)
 		if err == ErrNoNext {
 			break
 		}
 		if err != nil {
 			return nil, err
 		}
-		defer res.Body.Close()
 
-		decoder := json.NewDecoder(NewOCDSStreamCleaner(res.Body))
-		if err := decoder.Decode(&relPkg); err != nil {
+		pkg, err = safeUnpackReleases(res)
+		if err != nil {
 			return nil, err
 		}
-		releases = append(releases, relPkg.Releases...)
+		releases = append(releases, pkg.Releases...)
 	}
 
 	if len(releases) == 0 {

internal/findATender/dateRepair.go

@@ -1,43 +0,0 @@
-package findATender
-
-import (
-	"bufio"
-	"bytes"
-	"io"
-	"regexp"
-)
-
-// Global regex to identify and catch date-only fields
-var invalidDateRegex = regexp.MustCompile(`:\s*"(\d{4}-\d{2}-\d{2})"\s*([,}\s])`)
-var invalidPublishedDateRegex = regexp.MustCompile(`"publishedDate":\s*""`)
-
-// The UK Government FindATender service doesn't strictly follow OCDS date
-// format. Sometimes it provides dates only, sometimes it sends empty strings
-// instead of nulls.
-type FindATenderStreamCleaner struct {
-	reader *bufio.Reader
-	buffer bytes.Buffer
-}
-
-func NewOCDSStreamCleaner(r io.Reader) *FindATenderStreamCleaner {
-	return &FindATenderStreamCleaner{reader: bufio.NewReader(r)}
-}
-
-func (sc *FindATenderStreamCleaner) Read(p []byte) (int, error) {
-	if sc.buffer.Len() == 0 {
-		line, err := sc.reader.ReadBytes('\n')
-		if len(line) > 0 {
-			// Convert "2026-11-16" -> "2026-11-16T00:00:00Z"
-			line = invalidDateRegex.ReplaceAll(line, []byte(`:"$1T00:00:00Z"`))
-			// Convert {publishedDate:""} -> "{publishedDate:null}"
-			line = invalidPublishedDateRegex.ReplaceAll(line, []byte(`"publishedDate":null`))
-			sc.buffer.Write(line)
-		}
-		if err != nil {
-			if sc.buffer.Len() == 0 {
-				return 0, err
-			}
-		}
-	}
-	return sc.buffer.Read(p)
-}

internal/findATender/findATender.go

@@ -5,7 +5,7 @@ import (
 	"time"
 
 	"git.avsdev.uk/Go/job-search/internal/config"
-	"git.avsdev.uk/Go/job-search/internal/findATender/ocds"
+	"git.avsdev.uk/Go/job-search/internal/types"
 	resty "resty.dev/v3"
 )
 
@@ -29,7 +29,6 @@ func New(conf *config.JobSearchConfig, apiRoot string) FindATender {
 
 func (ft *FindATender) ReloadConfig(conf *config.JobSearchConfig) {
 	ft.config = conf
-	// TODO: any reloading required for configuration change handling
 }
 
 func (ft *FindATender) With(ctx context.Context) *FindATender {
@@ -49,27 +48,27 @@ func (ft *FindATender) Shutdown() {
 func (ft *FindATender) FetchOnce(
 	since time.Time,
 	allowRateLimit bool,
-) ([]ocds.Release, error) {
-	reqs, err := ft.fetchOnce(RequestOptions{
+) ([]*types.Opportunity, error) {
+	releases, err := ft.fetchOnce(RequestOptions{
 		Since:          since,
 		AllowRateLimit: allowRateLimit,
 	})
 	if err != nil {
 		return nil, err
 	}
-	return reqs, nil
+	return Convert(releases), nil
 }
 
 func (ft *FindATender) FetchAll(
 	since time.Time,
 	allowRateLimit bool,
-) ([]ocds.Release, error) {
-	reqs, err := ft.fetchAll(RequestOptions{
+) ([]*types.Opportunity, error) {
+	releases, err := ft.fetchAll(RequestOptions{
 		Since:          since,
 		AllowRateLimit: allowRateLimit,
 	})
 	if err != nil {
 		return nil, err
 	}
-	return reqs, nil
+	return Convert(releases), nil
 }

internal/findATender/typeConvert.go

@@ -0,0 +1,190 @@
+package findATender
+
+import (
+	"encoding/json"
+	"slices"
+	"strings"
+
+	"git.avsdev.uk/Go/job-search/internal/findATender/ocds"
+	"git.avsdev.uk/Go/job-search/internal/types"
+)
+
+func ocdsGetBuyerId(release *ocds.Release) string {
+	if release.Buyer != nil {
+		return string(release.Buyer.ID)
+	}
+	return ""
+}
+func ocdsGetBuyerName(release *ocds.Release) string {
+	if release.Buyer != nil {
+		return release.Buyer.Name
+	}
+	return ""
+}
+
+func ocdsConvertClassification(
+	classif *ocds.Classification,
+) types.ClassificationCode {
+	return types.ClassificationCode{
+		IsCPV:          strings.Compare(classif.Scheme, "CPV") == 0,
+		Code:           string(classif.ID),
+		Classification: classif.Description,
+	}
+}
+
+func ocdsGetClassifications(release *ocds.Release) []types.ClassificationCode {
+	classifications := make([]types.ClassificationCode, 0)
+	if release.Tender == nil {
+		return classifications
+	}
+	add := func(classif *ocds.Classification) {
+		newClassif := ocdsConvertClassification(classif)
+		found := slices.ContainsFunc(
+			classifications, func(r types.ClassificationCode) bool {
+				return r.Code == newClassif.Code
+			},
+		)
+		if !found {
+			classifications = append(classifications, newClassif)
+		}
+	}
+	if release.Tender.Classification != nil {
+		add(release.Tender.Classification)
+	}
+	for _, val := range release.Tender.Items {
+		if val.Classification != nil {
+			add(val.Classification)
+		}
+		for _, classif := range val.AdditionalClassifications {
+			add(&classif)
+		}
+	}
+	return classifications
+}
+
+func ocdsIsSMESuitable(release *ocds.Release) bool {
+	if release.Tender == nil {
+		return false
+	}
+	if len(release.Tender.Lots) == 0 {
+		return false
+	}
+	for _, lot := range release.Tender.Lots {
+		if lot.Suitability != nil {
+			if lot.Suitability.SME != nil && *lot.Suitability.SME {
+				return true
+			}
+		}
+	}
+	return false
+}
+func ocdsIsVCSESuitable(release *ocds.Release) bool {
+	if release.Tender == nil {
+		return false
+	}
+	if len(release.Tender.Lots) == 0 {
+		return false
+	}
+	for _, lot := range release.Tender.Lots {
+		if lot.Suitability != nil {
+			if lot.Suitability.Vcse != nil && *lot.Suitability.Vcse {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+func ocdsRelease(release *ocds.Release) types.OpportunityRelease {
+	tags := make([]types.OpportunityReleaseTag, 0)
+	for _, val := range release.Tag {
+		tags = append(tags, types.OpportunityReleaseTag{
+			UUID:      release.OCID,
+			ReleaseID: release.ID,
+			Tag:       val,
+		})
+	}
+
+	rel := types.OpportunityRelease{
+		UUID:        release.OCID,
+		ReleaseID:   release.ID,
+		Tags:        tags,
+		ReleaseDate: release.Date,
+	}
+
+	reencoded, err := json.Marshal(release)
+	if err == nil {
+		rel.JSON = string(reencoded)
+	}
+
+	return rel
+}
+
+func convertOne(release *ocds.Release) *types.Opportunity {
+	t := &types.Opportunity{
+		UUID:      release.OCID,
+		UUIDType:  "ocid",
+		BuyerId:   ocdsGetBuyerId(release),
+		BuyerName: ocdsGetBuyerName(release),
+	}
+
+	if release.Tender != nil {
+		t.Title = release.Tender.Title
+		t.Status = release.Tender.Status
+		t.Description = release.Tender.Description
+		t.Classifications = ocdsGetClassifications(release)
+		t.MainCategory = release.Tender.MainProcurementCategory
+		t.ProcurementMethod = release.Tender.ProcurementMethod
+		t.SMESuitable = ocdsIsSMESuitable(release)
+		t.VCSESuitable = ocdsIsVCSESuitable(release)
+		if release.Tender.TenderPeriod != nil {
+			t.StartDate = release.Tender.TenderPeriod.StartDate
+			t.EndDate = release.Tender.TenderPeriod.EndDate
+		}
+		if release.Tender.Value != nil && release.Tender.Value.Amount != nil {
+			t.GrossValue = *release.Tender.Value.Amount
+		}
+		t.HasDocuments = len(release.Tender.Documents) > 0
+		t.MultiLot = len(release.Tender.Lots) > 1
+	}
+
+	t.LatestReleaseDate = release.Date
+	t.Releases = append(t.Releases, ocdsRelease(release))
+
+	return t
+}
+
+// Convert groups releases by ocid into opportunities, in the order each ocid
+// first appears. Each opportunity is built from its latest release (by date,
+// or the later one in releases on a tie) and lists all of its releases oldest
+// first.
+func Convert(releases []ocds.Release) []*types.Opportunity {
+	var order []string
+	byOCID := make(map[string][]*ocds.Release)
+
+	for idx := range releases {
+		release := &releases[idx]
+		if _, found := byOCID[release.OCID]; !found {
+			order = append(order, release.OCID)
+		}
+		byOCID[release.OCID] = append(byOCID[release.OCID], release)
+	}
+
+	opportunities := make([]*types.Opportunity, 0, len(order))
+	for _, ocid := range order {
+		group := byOCID[ocid]
+
+		slices.SortStableFunc(group, func(a, b *ocds.Release) int {
+			return a.Date.Compare(b.Date)
+		})
+
+		opportunity := convertOne(group[len(group)-1])
+		opportunity.Releases = make([]types.OpportunityRelease, 0, len(group))
+		for _, release := range group {
+			opportunity.Releases = append(opportunity.Releases, ocdsRelease(release))
+		}
+		opportunities = append(opportunities, opportunity)
+	}
+
+	return opportunities
+}

internal/types/classifications.go

@@ -0,0 +1,8 @@
+package types
+
+type ClassificationCode struct {
+	ID             int64  `db:"id"             json:"id"`
+	IsCPV          bool   `db:"is_cpv"         json:"is_cpv"`
+	Code           string `db:"code"           json:"code"`
+	Classification string `db:"classification" json:"classification"`
+}

internal/types/opportunities.go

@@ -0,0 +1,41 @@
+package types
+
+import (
+	"time"
+)
+
+type Opportunity struct {
+	UUID              string               `db:"uuid"                json:"uuid"`
+	UUIDType          string               `db:"uuid_type"           json:"uuid_type"`
+	Title             string               `db:"title"               json:"title"`
+	Status            string               `db:"status"              json:"status"`
+	Description       string               `db:"description"         json:"description"`
+	BuyerName         string               `db:"buyer_name"          json:"buyer_name"`
+	Classifications   []ClassificationCode `db:"-"                   json:"classifications"`
+	BuyerId           string               `db:"buyer_id"            json:"buyer_id"`
+	MainCategory      string               `db:"main_category"       json:"main_category"`
+	ProcurementMethod string               `db:"procurement_method"  json:"procurement_method"`
+	MultiLot          bool                 `db:"multi_lot"           json:"multi_lot"`
+	SMESuitable       bool                 `db:"sme_suitable"        json:"sme_suitable"`
+	VCSESuitable      bool                 `db:"vcse_suitable"       json:"vcse_suitable"`
+	StartDate         *time.Time           `db:"start_date"          json:"start_date"`
+	EndDate           *time.Time           `db:"end_date"            json:"end_date"`
+	GrossValue        float64              `db:"gross_value"         json:"gross_value"`
+	HasDocuments      bool                 `db:"has_documents"       json:"has_documents"`
+	LatestReleaseDate time.Time            `db:"latest_release_date" json:"latest_release_date"`
+	Releases          []OpportunityRelease `db:"-"                   json:"releases"`
+}
+
+type OpportunityRelease struct {
+	UUID        string                  `db:"uuid"         json:"uuid"`
+	ReleaseID   string                  `db:"release_id"   json:"release_id"`
+	ReleaseDate time.Time               `db:"release_date" json:"release_date"`
+	Tags        []OpportunityReleaseTag `db:"-"            json:"release_tags"`
+	JSON        string                  `db:"data"         json:"data"`
+}
+
+type OpportunityReleaseTag struct {
+	UUID      string `db:"uuid"       json:"uuid"`
+	ReleaseID string `db:"release_id" json:"release_id"`
+	Tag       string `db:"tag"        json:"tag"`
+}