1 files changed, 181 insertions, 0 deletions
diff --git a/lex-fetch/at/at.go b/lex-fetch/at/at.go
new file mode 100644
index 0000000..44efb27
--- /dev/null
+++ b/lex-fetch/at/at.go
@@ -0,0 +1,181 @@
+package at
+
+import (
+	"encoding/json"
+	"fmt"
+	"log/slog"
+	"maps"
+	"math"
+	"net/http"
+	"net/url"
+	"slices"
+	"strconv"
+	"strings"
+	"sync"
+	"time"
+
+	"push-f.com/lex-surf/internal/lex"
+	"push-f.com/lex-surf/lex-fetch/progress"
+)
+
+type Fetcher struct{}
+
+const concurrentRequests = 4
+
+func (s *Fetcher) Fetch(log *slog.Logger, client *http.Client, progress *progress.Reporter) ([]lex.Law, error) {
+	// The API is documented in https://data.bka.gv.at/ris/ogd/v2.6/Documents/Dokumentation_OGD-RIS_API.pdf.
+
+	// Consolidated laws can only be queried via the Bundesrecht endpoint which returns individual paragraphs.
+	// Since we'll get multiple results for each law, we're saving results into a hash map.
+	lawsMap := make(map[string]lex.Law)
+
+	// TODO: also query laws from the past and future
+	date := time.Now().Format("2006-01-02")
+
+	data, err := fetchPage(client, date, 1)
+	if err != nil {
+		return nil, fmt.Errorf("failed to fetch first page: %w", err)
+	}
+	totalResults, _ := strconv.Atoi(data.Hits.Text)
+	if totalResults == 0 {
+		return nil, fmt.Errorf("API returned 0 results")
+	}
+	totalPages := int(math.Ceil(float64(totalResults) / 100))
+	progress.Total = totalPages
+	assign(lawsMap, data.OgdDocumentReference)
+
+	semaphore := make(chan struct{}, concurrentRequests)
+	var wg sync.WaitGroup
+	var mu sync.Mutex
+	var retErr error
+	var retErrPage int
+	var errOnce sync.Once
+
+	for page := 2; page <= totalPages; page++ {
+		if retErr != nil {
+			return nil, fmt.Errorf("failed to fetch page %d: %w", retErrPage, retErr)
+		}
+		wg.Add(1)
+		semaphore <- struct{}{}
+
+		go func(p int) {
+			defer wg.Done()
+			defer func() { <-semaphore }()
+
+			data, err := fetchPage(client, date, page)
+			progress.ReportProgress(page)
+			if err != nil {
+				errOnce.Do(func() {
+					retErr = err
+					retErrPage = p
+				})
+			}
+			mu.Lock()
+			assign(lawsMap, data.OgdDocumentReference)
+			mu.Unlock()
+		}(page)
+	}
+	laws := slices.SortedFunc(maps.Values(lawsMap), func(a, b lex.Law) int {
+		if a.Title > b.Title {
+			return 1
+		} else if a.Title < b.Title {
+			return -1
+		}
+		return 0
+	})
+	return laws, nil
+}
+
+func fetchPage(client *http.Client, date string, page int) (*ogdDocumentResults, error) {
+	req, err := http.NewRequest("GET", "https://data.bka.gv.at/ris/api/v2.6/Bundesrecht", nil)
+	if err != nil {
+		return nil, fmt.Errorf("build request: %w", err)
+	}
+	req.URL.RawQuery = url.Values{
+		"Appl":              {"BrKons"},      // Bundesrecht konsolidiert
+		"Typ":               {"BG oder BVG"}, // Bundesgesetz or Bundesverfassungsgesetz
+		"DokumenteProSeite": {"OneHundred"},
+		"Seitennummer":      {strconv.Itoa(page)},
+		"FassungVom":        {date},
+	}.Encode()
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("send request: %w", err)
+	}
+
+	if resp.StatusCode != 200 {
+		return nil, fmt.Errorf("unexpected status code %d", resp.StatusCode)
+	}
+
+	var data brKonsResult
+
+	err = json.NewDecoder(resp.Body).Decode(&data)
+	if err != nil {
+		return nil, fmt.Errorf("JSON decode: %w", err)
+	}
+
+	result := data.OgdSearchResult
+
+	if result.Error != nil {
+		return nil, fmt.Errorf("error response: %s", result.Error)
+	}
+
+	return result.OgdDocumentResults, nil
+}
+
+func assign(laws map[string]lex.Law, paraDocs []document) {
+	for _, paraDoc := range paraDocs {
+		para := paraDoc.Data.Metadaten.Bundesrecht
+		law := lex.Law{
+			Title: para.Kurztitel,
+			URL:   para.BrKons.GesamteRechtsvorschriftUrl,
+		}
+		if para.BrKons.Abkuerzung != nil {
+			law.Abbr = *para.BrKons.Abkuerzung
+			redir := strings.ToLower(*para.BrKons.Abkuerzung)
+			redir = strings.ReplaceAll(redir, ")", "")
+			redir = strings.ReplaceAll(redir, "(", "")
+			redir = strings.ReplaceAll(redir, " – ", "-")
+			redir = strings.ReplaceAll(redir, " ", "-")
+			redir = strings.ReplaceAll(redir, "\u00A0", "-")
+			redir = strings.ReplaceAll(redir, "ä", "ae")
+			redir = strings.ReplaceAll(redir, "ü", "ue")
+			redir = strings.ReplaceAll(redir, "ö", "oe")
+			redir = strings.ReplaceAll(redir, "ß", "ss")
+			law.Redir = redir
+		}
+		laws[para.BrKons.Gesetzesnummer] = law
+	}
+}
+
+type brKonsResult struct {
+	OgdSearchResult struct {
+		Error *struct {
+			Applikation string
+			Message     string
+		}
+		OgdDocumentResults *ogdDocumentResults
+	}
+}
+
+type ogdDocumentResults struct {
+	Hits struct {
+		Text string `json:"#text"`
+	}
+	OgdDocumentReference []document
+}
+
+type document struct {
+	Data struct {
+		Metadaten struct {
+			Bundesrecht struct {
+				Kurztitel string
+				BrKons    struct {
+					GesamteRechtsvorschriftUrl string
+					Abkuerzung                 *string
+					Gesetzesnummer             string
+				}
+			}
+		}
+	}
+}