install.js

var os = require("os");
var fs = require("fs");
var path = require("path");
var zlib = require("zlib");
var exec = require("child_process").exec;
var Q = require("q");
var request = require("request");
var tar = require("tar");
var which = require("which");
var rimraf = require("rimraf");
var NODE_VERSION = Number(process.version.match(/^v(\d+\.\d+)/)[1]);

// If the build only flag is set.
var buildOnly = process.env.BUILD_ONLY;

// This will take in an object and find any matching keys in the environment
// to use as overrides.
//
// ENV variables:
//
// PKG: Location of `package.json` sans `.json`.
// LIBGIT2: Location of libgit2 source.
// BUILD: Location of nodegit build directory.
function envOverride(obj) {
  // Look through all keys.
  return Object.keys(obj).reduce(function(obj, key) {
    var normalize = key.toUpperCase();

    // Check for process environment existence.
    if (normalize in process.env) {
      obj[key] = process.env[normalize];
    }

    return obj;
  }, obj);
}

// Convert to the correct system path.
function systemPath(parts) {
  return parts.join(path.sep);
}

// Will be used near the end to configure `node-gyp`.
var python;

var local = path.join.bind(path, __dirname);

// Common reusable paths that can be overwritten by environment variables.
var paths = envOverride({
  pkg: local("package"),
  libgit2: local("vendor/libgit2/"),
  libssh2: local("vendor/libssh2/"),
  http_parser: local("vendor/http_parser/"),
  sys: {
    include: local("include/sys/"),
    src: local("src/sys/"),
    build: local("build/Release/obj.target/src/sys/")
  },
  release: local("build/Release/")
});

// Load the package.json.
var pkg = require(paths.pkg);

if (NODE_VERSION === 0.1) {
  pkg.http_parser = pkg.http_parser["0.10"];
}

// Attempt to fallback on a prebuilt binary.
function fetchPrebuilt() {
  if (!buildOnly) {
    console.info("[nodegit] Fetching binary from S3.");

    // Using the node-pre-gyp module, attempt to fetch a compatible build.
    return Q.nfcall(exec, "node-pre-gyp install");
  }

  throw new Error("Build only");
}

// Attempt to fetch prebuilt binary.
Q.ninvoke(fs, "mkdir", paths.release).then(fetchPrebuilt, fetchPrebuilt)

.fail(function() {
  if (!buildOnly) {
    console.info("[nodegit] Failed to install prebuilt, attempting compile.");
  }

  // Ensure all dependencies are available.
  return Q.allSettled([
    // This will prioritize `python2` over `python`, because we always want to
    // work with Python 2.* if it"s available.
    Q.nfcall(which, "python2"),
    Q.nfcall(which, "python")
  ])
})

// Determine if all the dependency requirements are met.
.then(function(results) {
  console.info("[nodegit] Determining dependencies.");

  // Assign to reusable variables.
  python = results[0].value || results[1].value;

  // Missing Python.
  if (!python) {
    throw new Error("Python is required to build libgit2.");
  }

  // Now lets check the Python version to ensure it"s < 3.
  return Q.nfcall(exec, python + " --version").then(function(version) {
    if (version[1].indexOf("Python 3") === 0) {
      throw new Error("Incorrect version of Python, gyp requires < 3.");
    }
  });
})

// Successfully found all dependencies.  First step is to detect the vendor
// directory.
.then(function() {
  console.info("[nodegit] Detecting vendor/libgit2.");

  return Q.ninvoke(fs, "stat", paths.libgit2).then(function() {
    return Q.ninvoke(fs, "stat", paths.libgit2 + pkg.libgit2.sha);
  }).fail(function() {
    console.info("[nodegit] Removing outdated vendor/libgit2.");

    // This directory is outdated, remove.
    throw Q.ninvoke(rimraf, null, paths.libgit2);
  });
})

// If the directory already exists, no need to refetch.
.fail(function() {
  // Otherwise fetch the libgit2 source from GitHub.
  console.info("[nodegit] Fetching vendor/libgit2.");

  var url = "https://github.com/libgit2/libgit2/tarball/" + pkg.libgit2.sha;

  var extract = tar.Extract({
    path: paths.libgit2,
    strip: true
  });

  // First extract from Zlib and then extract from Tar.
  var expand = request.get(url).pipe(zlib.createUnzip()).pipe(extract);

  return Q.ninvoke(expand, "on", "end").then(function() {
    // Write out a sha file for testing in the future.
    return Q.ninvoke(fs, "writeFile", paths.libgit2 + pkg.libgit2.sha, "");
  });
})

// Grab libssh2 if needed.
.then(function() {
  console.info("[nodegit] Detecting vendor/libssh2.");

  return Q.ninvoke(fs, "stat", paths.libssh2).then(function() {
    return Q.ninvoke(fs, "stat", paths.libssh2 + pkg.libssh2.version);
  }).fail(function() {
    console.info("[nodegit] Removing outdated vendor/libssh2.");

    // This directory is outdated, remove.
    throw Q.ninvoke(rimraf, null, paths.libssh2);
  });
})

// If the directory already exists, no need to refetch.
.fail(function() {
  // Otherwise fetch the libssh2 source.
  console.info("[nodegit] Fetching vendor/libssh2.");

  var url = pkg.libssh2.url;

  var extract = tar.Extract({
    path: paths.libssh2,
    strip: true
  });

  // First extract from Zlib and then extract from Tar.
  var expand = request.get(url).pipe(zlib.createUnzip()).pipe(extract);

  return Q.ninvoke(expand, "on", "end").then(function() {
    // Write out a sha file for testing in the future.
    return Q.ninvoke(fs, "writeFile", paths.libssh2 + pkg.libssh2.version, "");
  }).then(function() {
    // Only run the configuration script in a BSD-like environment.
    if (process.platform !== "win32") {
      return Q.nfcall(exec, "cd " + paths.libssh2 + " ; " + paths.libssh2 +
        "configure");
    }
  });
})

// Grab http-parser if needed.
.then(function() {
  console.info("[nodegit] Detecting vendor/http_parser.");

  return Q.ninvoke(fs, "stat", paths.http_parser).then(function() {
    return Q.ninvoke(fs, "stat", paths.http_parser + pkg.http_parser.version);
  }).fail(function() {
    console.info("[nodegit] Removing outdated vendor/http_parser.");

    // This directory is outdated, remove.
    throw Q.ninvoke(rimraf, null, paths.http_parser);
  });
})

// If the directory already exists, no need to refetch.
.fail(function() {
  // Otherwise fetch the http_parser source.
  console.info("[nodegit] Fetching vendor/http_parser.");

  var url = pkg.http_parser.url;

  var extract = tar.Extract({
    path: paths.http_parser,
    strip: true
  });

  // First extract from Zlib and then extract from Tar.
  var expand = request.get(url).pipe(zlib.createUnzip()).pipe(extract);

  return Q.ninvoke(expand, "on", "end").then(function() {
    // Write out a sha file for testing in the future.
    return Q.ninvoke(fs, "writeFile", paths.http_parser +
      pkg.http_parser.version, "");
  });
})


// Build the native module using node-gyp.
.then(function() {
  console.info("[nodegit] Building native node module.");
  var pythonFlag = " --python \"" + python + "\"";

  return Q.nfcall(exec, systemPath([
    ".", "node_modules", ".bin", "node-gyp clean configure build" + pythonFlag
  ]), {
    cwd: ".",
    maxBuffer: Number.MAX_VALUE
  });
})

// Display a warning message about failing to build native node module.
.fail(function(message) {
  console.info("[nodegit] Failed to build and install nodegit.");
  console.info(message.message);
  console.info(message.stack);
})

// Display a success message.
.then(function() {
  console.info("[nodegit] Completed installation successfully.");
})

// Display a warning message about failing to build native node module.
.fail(function(message) {
  console.info("[nodegit] Failed to build nodegit.");
  console.info(message.message);
  console.info(message.stack);
});