1 79ed446f 2022-05-09 op # amused-monitor
 2 79ed446f 2022-05-09 op 
 3 79ed446f 2022-05-09 op This is a small interface for the amused music player
 4 79ed446f 2022-05-09 op 
 5 79ed446f 2022-05-09 op => https://projects.omarpolo.com/amused.html amused
 6 79ed446f 2022-05-09 op 
 7 79ed446f 2022-05-09 op 	#!/usr/bin/env rc
 8 79ed446f 2022-05-09 op 
 9 79ed446f 2022-05-09 op It's written in rc because I found easier to manage subprocesses in it
10 79ed446f 2022-05-09 op rather than in sh.
11 79ed446f 2022-05-09 op 
12 79ed446f 2022-05-09 op There are two main processes involved: input and ui.  The input
13 79ed446f 2022-05-09 op process handles the keybindings and controls amused, the ui input
14 79ed446f 2022-05-09 op waits for some events and redraws the interface.
15 79ed446f 2022-05-09 op 
16 79ed446f 2022-05-09 op 	fn input {
17 79ed446f 2022-05-09 op 		ifs=()
18 79ed446f 2022-05-09 op 
19 79ed446f 2022-05-09 op $ifs needs to be set to the empty list (or empty string), otherwise
20 79ed446f 2022-05-09 op we're not able to read spaces as keybindings.
21 79ed446f 2022-05-09 op 
22 79ed446f 2022-05-09 op 		run=1
23 79ed446f 2022-05-09 op 		while (~ $run 1) {
24 79ed446f 2022-05-09 op 
25 79ed446f 2022-05-09 op rc lacks a break statement, so I'm using a flag variable to quit
26 79ed446f 2022-05-09 op looping.
27 79ed446f 2022-05-09 op 
28 79ed446f 2022-05-09 op 			stty raw
29 79ed446f 2022-05-09 op 			t=`{dd bs=1 count=1 status=none}
30 79ed446f 2022-05-09 op 			stty cooked
31 79ed446f 2022-05-09 op 
32 79ed446f 2022-05-09 op This is just a trick to read without echoing back the characters.
33 79ed446f 2022-05-09 op 
34 79ed446f 2022-05-09 op 			switch ($"t) {
35 79ed446f 2022-05-09 op 			case n
36 79ed446f 2022-05-09 op 				amused next
37 79ed446f 2022-05-09 op 			case p
38 79ed446f 2022-05-09 op 				amused prev
39 79ed446f 2022-05-09 op 			case ' '
40 79ed446f 2022-05-09 op 				amused toggle
41 79ed446f 2022-05-09 op 			case s
42 79ed446f 2022-05-09 op 				amused stop
43 79ed446f 2022-05-09 op 			case q
44 79ed446f 2022-05-09 op 				run=0
45 79ed446f 2022-05-09 op 			case *
46 0e4b4d70 2022-05-09 op 				printf ' unknown keybinding >'$t'<\r'
47 79ed446f 2022-05-09 op 			}
48 79ed446f 2022-05-09 op 		}
49 79ed446f 2022-05-09 op 	}
50 79ed446f 2022-05-09 op 
51 79ed446f 2022-05-09 op The ui functions render the interface.  I'd like to keep a small xterm
52 79ed446f 2022-05-09 op open, that's why I'm narrowing (with grep -A -B) only to the songs
53 79ed446f 2022-05-09 op around the currently played one.
54 79ed446f 2022-05-09 op 
55 79ed446f 2022-05-09 op 	fn ui {
56 79ed446f 2022-05-09 op 		clear
57 79ed446f 2022-05-09 op 		amused show -p | grep -A3 -B3 '^>' | awk '{printf "%s\r\n", $0}'
58 79ed446f 2022-05-09 op 
59 79ed446f 2022-05-09 op The awk trick deserves an explanation.  Since the input function is
60 79ed446f 2022-05-09 op very likely running, the terminal is in "raw" mode: we need \r to
61 79ed446f 2022-05-09 op reposition the character at the start of the line.
62 79ed446f 2022-05-09 op 
63 79ed446f 2022-05-09 op 	}
64 79ed446f 2022-05-09 op 
65 79ed446f 2022-05-09 op The uiloop function is the driver for the ui process: it listens to
66 79ed446f 2022-05-09 op interesting events and redraws the ui when they happen
67 79ed446f 2022-05-09 op 
68 79ed446f 2022-05-09 op 	fn uiloop {
69 fed82e2b 2022-05-14 op 		amused monitor next,prev,jump | {
70 79ed446f 2022-05-09 op 			while (read) {
71 79ed446f 2022-05-09 op 				ui
72 79ed446f 2022-05-09 op 			}
73 79ed446f 2022-05-09 op 
74 79ed446f 2022-05-09 op A small note of merit: unlike other shells read is not a built in in
75 79ed446f 2022-05-09 op rc bur rather an external command (/usr/local/plan9/bin/read here.)
76 79ed446f 2022-05-09 op 
77 79ed446f 2022-05-09 op 		}
78 79ed446f 2022-05-09 op 	}
79 79ed446f 2022-05-09 op 
80 79ed446f 2022-05-09 op And that's all.  I only need to launch the functions in the correct
81 79ed446f 2022-05-09 op order and do one render at the start and amused-monitor is done!
82 79ed446f 2022-05-09 op 
83 79ed446f 2022-05-09 op 	ui
84 79ed446f 2022-05-09 op 	uiloop &
85 79ed446f 2022-05-09 op 	uipid=$apid
86 79ed446f 2022-05-09 op 	input
87 79ed446f 2022-05-09 op 	kill -INT -$uipid
88 79ed446f 2022-05-09 op 
89 79ed446f 2022-05-09 op 
90 79ed446f 2022-05-09 op 
91 79ed446f 2022-05-09 op