git-fs-repo load file at path and hash

lookup_file.js

var repo = require('./index')
  , path = require('path')
  , dir = path.resolve(
        __dirname
      , '..'
      , '..'
      , 'personal'
      , 'plate'
      , '.git'
    )

repo(dir, function(err, git) {
  load(git, git.ref('HEAD').hash, 'lib/tags/for.js', function(err, obj) {
    // there'll either be an `err`, an `obj`, or absolutely nothing (if
    // we couldn't find the last object.)
    console.log(err, obj.data() + '')
  })
})

function load(find, hash, filename, ready) {
  var bits = filename.split(path.sep)
    , last

  // load the commit, find the tree hash associated
  // with it, then start iterating the path.
  find(hash, function(err, commit) {
    if(err || commit.looseType !== 'commit') {
      return ready(
          err || new Error('expected commit, got ' + commit.looseType)
      )
    }

    last = hash
    find(commit.tree(), iter)
  })

  // for each bit, find the next member bit.
  // fail if we've either looked something up that's
  // not a tree (we can't recurse any further!) or
  // if the tree doesn't contain the next step.
  function iter(err, tree) {
    if(err || !tree || tree.looseType !== 'tree') {
      return ready(
          err || new Error('could not find ' + last)
      )
    }

    var next = bits.shift()
      , entry

    entry = tree.entries().filter(function(item) {
      return item.name === next
    })[0]

    if(!entry) {
      return ready(
          err || new Error('could not find ' + last)
      )
    }

    last = last + '/' + entry.name

    // if there are no more bits left in the path,
    // we're done! pass whatever comes out of `find`
    // this time to the outer `ready` function.
    find(entry.hash, bits.length ? iter : ready)
  }
}