lib/shared.js: consolidate reusable portions into shared resource

Signed-off-by: Rick Waldron <waldron.rick@gmail.com>

lib/shared.js

@@ -0,0 +1,127 @@
+'use strict';
+
+// System Objects
+const cp = require('child_process');
+
+// Program specific
+const profile = '/etc/profile';
+const installed = {
+  aplay: true,
+  arecord: true,
+  espeak: false,
+  fswebcam: true,
+  ffmpeg: true,
+  madplay: false,
+  'mjpg-streamer': false,
+};
+
+module.exports = {
+
+  killAndCatch(binary) {
+    try {
+      cp.spawnSync(`kill -9 $(pgrep "${binary}")`);
+    } catch (error) {}
+  },
+
+  // toSeconds was adapted from Popcorn.js
+  // https://github.com/mozilla/popcorn-js/blob/master/popcorn.js#L2598-L2648
+  toSeconds(time, framerate) {
+    if (typeof time === 'number') {
+      return time;
+    }
+
+    const pairs = time.split(':');
+    const lastIndex = pairs.length - 1;
+    const last = pairs[lastIndex];
+
+    if (last.includes(';')) {
+      let frameInfo = last.split(';');
+      let frameTime = 0;
+
+      if (framerate && typeof framerate === 'number') {
+        frameTime = parseFloat(frameInfo[1], 10) / framerate;
+      }
+
+      pairs[lastIndex] = parseInt(frameInfo[0], 10) + frameTime;
+    }
+
+    const first = pairs[0];
+
+    return {
+      1: parseFloat(first, 10),
+      2: (parseInt(first, 10) * 60) + parseFloat(pairs[1], 10),
+      3: (parseInt(first, 10) * 3600) + (parseInt(pairs[1], 10) * 60) + parseFloat(pairs[2], 10)
+    }[pairs.length];
+  },
+
+  /*
+    All of the operations in the install function are synchronous
+    because without them, the environment cannot support
+    the features provided by tessel-av and it's best
+    to get it done and out of the way before proceeding
+    with the program's exection.
+
+    Generally speaking, the detection and installation
+    path will never be taken, as it serves to provide a
+    fallback, not a primary execution path.
+
+
+    Average execution times
+
+    | Avg Exec Time    | Operation                                                    |
+    | ---------------- | ------------------------------------------------------------ |
+    | 50ms             | cp.spawnSync('which', [binary])                              |
+    | 601ms            | cp.spawnSync('opkg', ['update'])                             |
+    | 24s !!!!!!!!!!!! | cp.spawnSync('opkg', ['install', binary])                    |
+
+   */
+
+
+  // TODO: this can only work if the Tessel is connected to the network...
+  // const os = require('os');
+  // const wlan0 = os.os.networkInterfaces().wlan0[0];
+
+
+  install(binary) {
+    const env = `AV_INSTALLED_${binary.toUpperCase()}`;
+
+    /* istanbul ignore else */
+    if (global.IS_TEST_ENV || process.arch !== 'mipsel') {
+      return true;
+    }
+    // If this binary is known to be published in the
+    // openwrt build, DO NOT PROCEED.
+    if (installed[binary]) {
+      return true;
+    }
+    // If this binary has already been installed via
+    // tessel-av installation operations, DO NOT PROCEED.
+    if (process.env[env]) {
+      return true;
+    }
+
+    const which = cp.spawnSync('which', [binary]);
+    let install;
+
+    // According to `which`, this binary does not exist
+    if (which.status === 1) {
+      // opkg update will return with a status = 1,
+      // but that's just because it might fail to wget a package list,
+      // which is not fatal.
+      cp.spawnSync('opkg', ['update']);
+
+      console.log(`Install: "${binary}"`);
+
+      install = cp.spawnSync('opkg', ['install', binary]);
+
+      if (install.status === 0) {
+        console.log('Completed.');
+
+        cp.execSync(`echo 'export ${env}=1' >> ${profile}; source ${profile}`);
+        installed[binary] = true;
+      } else {
+        console.log(`Error: install "${binary}" failed.`);
+      }
+    }
+  },
+};