From eed10ce514f28e4acf772f76c92ca05eebec105f Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Thu, 5 May 2022 21:20:22 -0600
Subject: Fix various problems with the srv build

---
 srv/src/api/chat.go | 211 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 211 insertions(+)
 create mode 100644 srv/src/api/chat.go

(limited to 'srv/src/api/chat.go')

diff --git a/srv/src/api/chat.go b/srv/src/api/chat.go
new file mode 100644
index 0000000..a1acc5a
--- /dev/null
+++ b/srv/src/api/chat.go
@@ -0,0 +1,211 @@
+package api
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+	"unicode"
+
+	"github.com/gorilla/websocket"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/api/apiutils"
+	"github.com/mediocregopher/blog.mediocregopher.com/srv/chat"
+)
+
+type chatHandler struct {
+	*http.ServeMux
+
+	room       chat.Room
+	userIDCalc *chat.UserIDCalculator
+
+	wsUpgrader websocket.Upgrader
+}
+
+func newChatHandler(
+	room chat.Room, userIDCalc *chat.UserIDCalculator,
+	requirePowMiddleware func(http.Handler) http.Handler,
+) http.Handler {
+	c := &chatHandler{
+		ServeMux:   http.NewServeMux(),
+		room:       room,
+		userIDCalc: userIDCalc,
+
+		wsUpgrader: websocket.Upgrader{},
+	}
+
+	c.Handle("/history", c.historyHandler())
+	c.Handle("/user-id", requirePowMiddleware(c.userIDHandler()))
+	c.Handle("/append", requirePowMiddleware(c.appendHandler()))
+	c.Handle("/listen", c.listenHandler())
+
+	return c
+}
+
+func (c *chatHandler) historyHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		limit, err := apiutils.StrToInt(r.PostFormValue("limit"), 0)
+		if err != nil {
+			apiutils.BadRequest(rw, r, fmt.Errorf("invalid limit parameter: %w", err))
+			return
+		}
+
+		cursor := r.PostFormValue("cursor")
+
+		cursor, msgs, err := c.room.History(r.Context(), chat.HistoryOpts{
+			Limit:  limit,
+			Cursor: cursor,
+		})
+
+		if argErr := (chat.ErrInvalidArg{}); errors.As(err, &argErr) {
+			apiutils.BadRequest(rw, r, argErr.Err)
+			return
+		} else if err != nil {
+			apiutils.InternalServerError(rw, r, err)
+		}
+
+		apiutils.JSONResult(rw, r, struct {
+			Cursor   string         `json:"cursor"`
+			Messages []chat.Message `json:"messages"`
+		}{
+			Cursor:   cursor,
+			Messages: msgs,
+		})
+	})
+}
+
+func (c *chatHandler) userID(r *http.Request) (chat.UserID, error) {
+	name := r.PostFormValue("name")
+	if l := len(name); l == 0 {
+		return chat.UserID{}, errors.New("name is required")
+	} else if l > 16 {
+		return chat.UserID{}, errors.New("name too long")
+	}
+
+	nameClean := strings.Map(func(r rune) rune {
+		if !unicode.IsPrint(r) {
+			return -1
+		}
+		return r
+	}, name)
+
+	if nameClean != name {
+		return chat.UserID{}, errors.New("name contains invalid characters")
+	}
+
+	password := r.PostFormValue("password")
+	if l := len(password); l == 0 {
+		return chat.UserID{}, errors.New("password is required")
+	} else if l > 128 {
+		return chat.UserID{}, errors.New("password too long")
+	}
+
+	return c.userIDCalc.Calculate(name, password), nil
+}
+
+func (c *chatHandler) userIDHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		userID, err := c.userID(r)
+		if err != nil {
+			apiutils.BadRequest(rw, r, err)
+			return
+		}
+
+		apiutils.JSONResult(rw, r, struct {
+			UserID chat.UserID `json:"userID"`
+		}{
+			UserID: userID,
+		})
+	})
+}
+
+func (c *chatHandler) appendHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+		userID, err := c.userID(r)
+		if err != nil {
+			apiutils.BadRequest(rw, r, err)
+			return
+		}
+
+		body := r.PostFormValue("body")
+
+		if l := len(body); l == 0 {
+			apiutils.BadRequest(rw, r, errors.New("body is required"))
+			return
+
+		} else if l > 300 {
+			apiutils.BadRequest(rw, r, errors.New("body too long"))
+			return
+		}
+
+		msg, err := c.room.Append(r.Context(), chat.Message{
+			UserID: userID,
+			Body:   body,
+		})
+
+		if err != nil {
+			apiutils.InternalServerError(rw, r, err)
+			return
+		}
+
+		apiutils.JSONResult(rw, r, struct {
+			MessageID string `json:"messageID"`
+		}{
+			MessageID: msg.ID,
+		})
+	})
+}
+
+func (c *chatHandler) listenHandler() http.Handler {
+	return http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+
+		ctx := r.Context()
+		sinceID := r.FormValue("sinceID")
+
+		conn, err := c.wsUpgrader.Upgrade(rw, r, nil)
+		if err != nil {
+			apiutils.BadRequest(rw, r, err)
+			return
+		}
+		defer conn.Close()
+
+		it, err := c.room.Listen(ctx, sinceID)
+
+		if errors.As(err, new(chat.ErrInvalidArg)) {
+			apiutils.BadRequest(rw, r, err)
+			return
+
+		} else if errors.Is(err, context.Canceled) {
+			return
+
+		} else if err != nil {
+			apiutils.InternalServerError(rw, r, err)
+			return
+		}
+
+		defer it.Close()
+
+		for {
+
+			msg, err := it.Next(ctx)
+			if errors.Is(err, context.Canceled) {
+				return
+
+			} else if err != nil {
+				apiutils.InternalServerError(rw, r, err)
+				return
+			}
+
+			err = conn.WriteJSON(struct {
+				Message chat.Message `json:"message"`
+			}{
+				Message: msg,
+			})
+
+			if err != nil {
+				apiutils.GetRequestLogger(r).Error(ctx, "couldn't write message", err)
+				return
+			}
+		}
+	})
+}
-- 
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