4 files changed, 223 insertions, 0 deletions
diff --git a/plugins/caldav/caldav.go b/plugins/caldav/caldav.go
new file mode 100644
index 0000000..1c043e9
--- /dev/null
+++ b/plugins/caldav/caldav.go
@@ -0,0 +1,61 @@
+package koushincaldav
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"git.sr.ht/~emersion/koushin"
+	"github.com/emersion/go-webdav/caldav"
+)
+
+var errNoCalendar = fmt.Errorf("caldav: no calendar found")
+
+type authRoundTripper struct {
+	upstream http.RoundTripper
+	session  *koushin.Session
+}
+
+func (rt *authRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	rt.session.SetHTTPBasicAuth(req)
+	return rt.upstream.RoundTrip(req)
+}
+
+func newClient(u *url.URL, session *koushin.Session) (*caldav.Client, error) {
+	rt := authRoundTripper{
+		upstream: http.DefaultTransport,
+		session:  session,
+	}
+	c, err := caldav.NewClient(&http.Client{Transport: &rt}, u.String())
+	if err != nil {
+		return nil, fmt.Errorf("failed to create CalDAV client: %v", err)
+	}
+
+	return c, nil
+}
+
+func getCalendar(u *url.URL, session *koushin.Session) (*caldav.Client, *caldav.Calendar, error) {
+	c, err := newClient(u, session)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	principal, err := c.FindCurrentUserPrincipal()
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to query CalDAV principal: %v", err)
+	}
+
+	calendarHomeSet, err := c.FindCalendarHomeSet(principal)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to query CalDAV calendar home set: %v", err)
+	}
+
+	calendars, err := c.FindCalendars(calendarHomeSet)
+	if err != nil {
+		return nil, nil, fmt.Errorf("failed to find calendars: %v", err)
+	}
+	if len(calendars) == 0 {
+		return nil, nil, errNoCalendar
+	}
+	return c, &calendars[0], nil
+}
diff --git a/plugins/caldav/plugin.go b/plugins/caldav/plugin.go
new file mode 100644
index 0000000..1915646
--- /dev/null
+++ b/plugins/caldav/plugin.go
@@ -0,0 +1,71 @@
+package koushincaldav
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"git.sr.ht/~emersion/koushin"
+)
+
+func sanityCheckURL(u *url.URL) error {
+	req, err := http.NewRequest(http.MethodOptions, u.String(), nil)
+	if err != nil {
+		return err
+	}
+
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		return err
+	}
+	resp.Body.Close()
+
+	// Servers might require authentication to perform an OPTIONS request
+	if resp.StatusCode/100 != 2 && resp.StatusCode != http.StatusUnauthorized {
+		return fmt.Errorf("HTTP request failed: %v %v", resp.StatusCode, resp.Status)
+	}
+	return nil
+}
+
+func newPlugin(srv *koushin.Server) (koushin.Plugin, error) {
+	u, err := srv.Upstream("caldavs", "caldav+insecure", "https", "http+insecure")
+	if _, ok := err.(*koushin.NoUpstreamError); ok {
+		return nil, nil
+	} else if err != nil {
+		return nil, fmt.Errorf("caldav: failed to parse upstream caldav server: %v", err)
+	}
+	switch u.Scheme {
+	case "caldavs":
+		u.Scheme = "https"
+	case "caldav+insecure", "http+insecure":
+		u.Scheme = "http"
+	}
+	if u.Scheme == "" {
+		return nil, fmt.Errorf("caldav: discovery not yet implemented") // TODO
+	}
+
+	if err := sanityCheckURL(u); err != nil {
+		return nil, fmt.Errorf("caldav: failed to connect to CalDAV server %q: %v", u, err)
+	}
+
+	srv.Logger().Printf("Configured upstream CalDAV server: %v", u)
+
+	p := koushin.GoPlugin{Name: "caldav"}
+
+	registerRoutes(&p, u)
+
+	return p.Plugin(), nil
+}
+
+func init() {
+	koushin.RegisterPluginLoader(func(s *koushin.Server) ([]koushin.Plugin, error) {
+		p, err := newPlugin(s)
+		if err != nil {
+			return nil, err
+		}
+		if p == nil {
+			return nil, nil
+		}
+		return []koushin.Plugin{p}, err
+	})
+}
diff --git a/plugins/caldav/public/calendar.html b/plugins/caldav/public/calendar.html
new file mode 100644
index 0000000..6011f9e
--- /dev/null
+++ b/plugins/caldav/public/calendar.html
@@ -0,0 +1,25 @@
+{{template "head.html"}}
+
+<h1>koushin</h1>
+
+<p>
+  <a href="/">Back</a>
+</p>
+
+<h2>Calendar: {{.Calendar.Name}}</h2>
+
+{{if .Events}}
+  <ul>
+    {{range .Events}}
+      {{$event := index .Data.Events 0}}
+      <li>
+        <a href="/calendar/{{$event.UID | pathescape}}">{{$event.Summary}}</a>
+        ({{$event.StartDate | formatdate}} — {{$event.EndDate | formatdate}})
+      </li>
+    {{end}}
+  </ul>
+{{else}}
+  <p>No events.</p>
+{{end}}
+
+{{template "foot.html"}}
diff --git a/plugins/caldav/routes.go b/plugins/caldav/routes.go
new file mode 100644
index 0000000..acc879f
--- /dev/null
+++ b/plugins/caldav/routes.go
@@ -0,0 +1,66 @@
+package koushincaldav
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+	"time"
+
+	"git.sr.ht/~emersion/koushin"
+	"github.com/emersion/go-webdav/caldav"
+)
+
+type CalendarRenderData struct {
+	koushin.BaseRenderData
+	Calendar *caldav.Calendar
+	Events   []caldav.CalendarObject
+}
+
+func registerRoutes(p *koushin.GoPlugin, u *url.URL) {
+	p.GET("/calendar", func(ctx *koushin.Context) error {
+		// TODO: multi-calendar support
+		c, calendar, err := getCalendar(u, ctx.Session)
+		if err != nil {
+			return err
+		}
+
+		now := time.Now()
+		start := time.Date(now.Year(), now.Month(), 1, 0, 0, 0, 0, now.Location())
+		end := start.AddDate(0, 1, 0)
+
+		query := caldav.CalendarQuery{
+			CompRequest: caldav.CalendarCompRequest{
+				Name:  "VCALENDAR",
+				Props: []string{"VERSION"},
+				Comps: []caldav.CalendarCompRequest{{
+					Name: "VEVENT",
+					Props: []string{
+						"SUMMARY",
+						"UID",
+						"DTSTART",
+						"DTEND",
+						"DURATION",
+					},
+				}},
+			},
+			CompFilter: caldav.CompFilter{
+				Name: "VCALENDAR",
+				Comps: []caldav.CompFilter{{
+					Name:  "VEVENT",
+					Start: start,
+					End:   end,
+				}},
+			},
+		}
+		events, err := c.QueryCalendar(calendar.Path, &query)
+		if err != nil {
+			return fmt.Errorf("failed to query calendar: %v", err)
+		}
+
+		return ctx.Render(http.StatusOK, "calendar.html", &CalendarRenderData{
+			BaseRenderData: *koushin.NewBaseRenderData(ctx),
+			Calendar:       calendar,
+			Events:         events,
+		})
+	})
+}