add i3status applet, initially with a clock only

4 files changed, 145 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 55e4a22..e2767b3 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,7 @@
 PKG    = github.com/majewsky/gofu
 PREFIX = /usr
 
-APPLETS = rtree prettyprompt
+APPLETS = i3status rtree prettyprompt
 
 all: build/gofu $(addprefix build/,$(APPLETS))
 
diff --git a/README.md b/README.md
index 469ca2c..ea04307 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,10 @@ $ make && make install
 
 # List of applets
 
+## `i3status`
+
+My own variant of [`i3status`](https://i3wm.org/i3status/).
+
 ## `prettyprompt`
 
 This renders my shell prompt. Among other things, it identifies the current
diff --git a/main.go b/main.go
index 1942c8e..4a79ed9 100644
--- a/main.go
+++ b/main.go
@@ -23,6 +23,7 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/majewsky/gofu/pkg/i3status"
 	"github.com/majewsky/gofu/pkg/prompt"
 	"github.com/majewsky/gofu/pkg/rtree"
 )
@@ -46,6 +47,8 @@ func execApplet(applet string, args []string, allowGofu bool) int {
 		return prompt.Exec(args)
 	case "rtree":
 		return rtree.Exec(args)
+	case "i3status":
+		return i3status.Exec(args)
 	default:
 		fmt.Fprintln(os.Stderr, "ERROR: unknown applet: "+applet)
 		return 255
diff --git a/pkg/i3status/main.go b/pkg/i3status/main.go
new file mode 100644
index 0000000..1b16f21
--- /dev/null
+++ b/pkg/i3status/main.go
@@ -0,0 +1,137 @@
+/*******************************************************************************
+*
+* Copyright 2017 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package i3status
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+	"time"
+)
+
+//Exec executes the i3status applet and returns an exit code (0 for
+//success, >0 for error).
+func Exec(args []string) int {
+	//start protocol (we handle errors here for once because if stdout is
+	//working, we have nothing left to do)
+	_, err := os.Stdout.Write([]byte("{\"version\":1}\n[\n"))
+	if err != nil {
+		fmt.Fprintf(os.Stderr, err.Error())
+		return 1
+	}
+
+	//main loop
+	currentBlocks := make(map[string][]Block)
+	for {
+		//prepare clock (this is inline instead of split into a separate function
+		//because the wallclock also drives the main loop's clock, see below)
+		now := time.Now()
+		currentBlocks["clock"] = []Block{
+			{
+				Name:      "clock",
+				Instance:  "date",
+				Position:  PositionClock,
+				FullText:  now.Format("2006-01-02"),
+				ShortText: " ",
+				Color:     "#AAAAAA",
+			},
+			{
+				Name:     "clock",
+				Instance: "time",
+				Position: PositionClock,
+				FullText: now.Format("15:04:05"),
+			},
+		}
+
+		//put blocks in rendering order
+		var allBlocks []Block
+		for _, blocks := range currentBlocks {
+			allBlocks = append(allBlocks, blocks...)
+		}
+		sort.Sort(byPositionAndInstance(allBlocks))
+
+		//write output
+		buf, err := json.Marshal(allBlocks)
+		if err == nil {
+			os.Stdout.Write(append(buf, ',', '\n'))
+		} else {
+			//this should not happen, but if it does, fall back to just encoding the
+			//error string (which always works, otherwise wtf)
+			buf, _ = json.Marshal(err.Error())
+			fmt.Printf(
+				`[{"name":"error","urgent":true,"color":"#FF0000","full_text":%s}],`,
+				string(buf),
+			)
+		}
+
+		//sleep until the next second starts, so that the clock is always on time
+		nsec := 1000000000 - now.Nanosecond()
+		time.Sleep(time.Duration(nsec) * time.Nanosecond)
+	}
+
+	return 0
+}
+
+//Block is a block of text as used in the i3status protocol.
+//(Not all attributes are represented.)
+type Block struct {
+	Position            Position  `json:"-"`
+	Name                string    `json:"name"` //REQUIRED
+	Instance            string    `json:"instance,omitempty"`
+	FullText            string    `json:"full_text"` //REQUIRED
+	ShortText           string    `json:"short_text"`
+	Color               string    `json:"color,omitempty"` //CSS hex syntax, e.g. #123456
+	BackgroundColor     string    `json:"background,omitempty"`
+	MinWidth            uint      `json:"min_width,omitempty"`
+	Alignment           Alignment `json:"align,omitempty"` //only plausible with MinWidth
+	Urgent              bool      `json:"urgent,omitempty"`
+	Separator           bool      `json:"separator"`
+	SeparatorBlockWidth int       `json:"separator_block_width,omitempty"`
+}
+
+type byPositionAndInstance []Block
+
+func (b byPositionAndInstance) Len() int      { return len(b) }
+func (b byPositionAndInstance) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
+func (b byPositionAndInstance) Less(i, j int) bool {
+	if b[i].Position == b[j].Position {
+		return b[i].Instance < b[j].Instance
+	}
+	return b[i].Position < b[j].Position
+}
+
+//Alignment is the alignment of a Block.
+type Alignment string
+
+//Acceptable values for Alignment.
+const (
+	AlignmentLeft   Alignment = "left"
+	AlignmentCenter Alignment = "center"
+	AlignmentRight  Alignment = "right"
+)
+
+//Position defines how blocks are ordered.
+type Position int
+
+//Acceptable values for Position, from left to right.
+const (
+	PositionNone Position = iota
+	PositionClock
+)