implement basic chat history endpoint

srv/api/api.go

@@ -12,6 +12,7 @@ import (
 	"os"
 
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/chat"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/mailinglist"
 	"github.com/mediocregopher/blog.mediocregopher.com/srv/pow"
 	"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
@@ -24,6 +25,7 @@ type Params struct {
 	Logger      *mlog.Logger
 	PowManager  pow.Manager
 	MailingList mailinglist.MailingList
+	GlobalRoom  chat.Room
 
 	// ListenProto and ListenAddr are passed into net.Listen to create the
 	// API's listener. Both "tcp" and "unix" protocols are explicitly

srv/api/chat.go

@@ -0,0 +1,41 @@
+package api
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/chat"
+)
+
+func (a *api) chatHistoryHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		limit, err := strToInt(r.FormValue("limit"), 0)
+		if err != nil {
+			badRequest(rw, r, fmt.Errorf("invalid limit parameter: %w", err))
+			return
+		}
+
+		cursor := r.FormValue("cursor")
+
+		cursor, msgs, err := a.params.GlobalRoom.History(r.Context(), chat.HistoryOpts{
+			Limit:  limit,
+			Cursor: cursor,
+		})
+
+		if argErr := (chat.ErrInvalidArg{}); errors.As(err, &argErr) {
+			badRequest(rw, r, argErr.Err)
+			return
+		} else if err != nil {
+			internalServerError(rw, r, err)
+		}
+
+		jsonResult(rw, r, struct {
+			Cursor   string         `json:"cursor"`
+			Messages []chat.Message `json:"messages"`
+		}{
+			Cursor:   cursor,
+			Messages: msgs,
+		})
+	})
+}

srv/api/utils.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"net/http"
+	"strconv"
 
 	"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
 )
@@ -58,3 +59,10 @@ func internalServerError(rw http.ResponseWriter, r *http.Request, err error) {
 		Error: "internal server error",
 	})
 }
+
+func strToInt(str string, defaultVal int) (int, error) {
+	if str == "" {
+		return defaultVal, nil
+	}
+	return strconv.Atoi(str)
+}