From 685889d195e4362eea6d226ea155255d3d77f39c Mon Sep 17 00:00:00 2001
From: Volker Mische <volker.mische@gmail.com>
Date: Fri, 12 Jan 2018 17:02:25 +0000
Subject: [PATCH] feat: Add tree() method

---
 src/resolver.js       | 93 +++++++++++++++++++++++++++----------------
 test/resolver.spec.js | 27 +++++++++++++
 2 files changed, 85 insertions(+), 35 deletions(-)

diff --git a/src/resolver.js b/src/resolver.js
index a4b245b..2605d1a 100644
--- a/src/resolver.js
+++ b/src/resolver.js
@@ -24,38 +24,19 @@ const resolve = (binaryBlob, path, callback) => {
     const pathArray = path.split('/')
     // `/` is the first element
     pathArray.shift()
-
-    // The values that can directly be resolved
-    let value
-    // Links to other blocks
-    let link
-    switch (pathArray[0]) {
-      case 'version':
-        value = dagNode.version
-        break
-      case 'timestamp':
-        value = dagNode.timestamp
-        break
-      case 'difficulty':
-        value = dagNode.bits
-        break
-      case 'nonce':
-        value = dagNode.nonce
-        break
-      case 'parent':
-        link = dagNode.prevHash
-        break
-      case 'tx':
-        link = dagNode.merkleRoot
-        break
-      default:
-        return callback(new Error('No such path'), null)
+    const value = resolveField(dagNode, pathArray[0])
+    if (value === null) {
+      return callback(new Error('No such path'), null)
     }
 
     let remainderPath = pathArray.slice(1).join('/')
-    // Bitcoin has only top-level fields, every deeper nesting needs to
-    // be a link
-    if (value !== undefined) {
+    // It is a link, hence it may have a remainder
+    if (value['/'] !== undefined) {
+      return callback(null, {
+        value: value,
+        remainderPath: remainderPath
+      })
+    } else {
       if (remainderPath.length > 0) {
         return callback(new Error('No such path'), null)
       } else {
@@ -64,16 +45,58 @@ const resolve = (binaryBlob, path, callback) => {
           remainderPath: ''
         })
       }
+    }
+  })
+}
+
+const tree = (binaryBlob, options, callback) => {
+  if (typeof options === 'function') {
+    callback = options
+    options = undefined
+  }
+  options = options || {}
+
+  util.deserialize(binaryBlob, (err, dagNode) => {
+    if (err) {
+      return callback(err)
+    }
+
+    const paths = ['/version', '/timestamp', '/difficulty', '/nonce',
+      '/parent', '/tx']
+
+    if (options.value === true) {
+      const pathValues = {}
+      for (let path of paths) {
+        pathValues[path] = resolveField(dagNode, path.substr(1))
+      }
+      return callback(null, pathValues)
     } else {
-      // It's a link
-      return callback(null, {
-        value: {'/': util.hashToCid(link)},
-        remainderPath: remainderPath
-      })
+      return callback(null, paths)
     }
   })
 }
 
+// Return top-level fields. Returns `null` if field doesn't exist
+const resolveField = (dagNode, field) => {
+  switch (field) {
+    case 'version':
+      return dagNode.version
+    case 'timestamp':
+      return dagNode.timestamp
+    case 'difficulty':
+      return dagNode.bits
+    case 'nonce':
+      return dagNode.nonce
+    case 'parent':
+      return {'/': util.hashToCid(dagNode.prevHash)}
+    case 'tx':
+      return {'/': util.hashToCid(dagNode.merkleRoot)}
+    default:
+      return null
+  }
+}
+
 module.exports = {
-  resolve: resolve
+  resolve: resolve,
+  tree: tree
 }
diff --git a/test/resolver.spec.js b/test/resolver.spec.js
index a522654..9b54ce9 100644
--- a/test/resolver.spec.js
+++ b/test/resolver.spec.js
@@ -90,6 +90,33 @@ describe('IPLD format resolver API resolve()', () => {
   })
 })
 
+describe('IPLD format resolver API tree()', () => {
+  it('should return only paths by default', (done) => {
+    IpldBitcoin.resolver.tree(fixtureBlock, (err, value) => {
+      expect(err).to.not.exist()
+      expect(value).to.deep.equal(['/version', '/timestamp', '/difficulty',
+        '/nonce', '/parent', '/tx'])
+      done()
+    })
+  })
+
+  it('should be able to return paths and values', (done) => {
+    IpldBitcoin.resolver.tree(fixtureBlock, {value: true}, (err, value) => {
+      expect(err).to.not.exist()
+      expect(value).to.deep.equal({
+        '/version': 2,
+        '/timestamp': 1386981279,
+        '/difficulty': 419740270,
+        '/nonce': 3159344128,
+        '/parent': {
+          '/': new CID('z4HFzdHLxSgJvCMJrsDtV7MgqiGALZdbbxgcTLVUUXQGBkGYjLb')},
+        '/tx': {
+          '/': new CID('z4HFzdHD15kVvtmVzeD7z9sisZ7acSC88wXS3KJGwGrnr2DwcVQ')}})
+      done()
+    })
+  })
+})
+
 const verifyPath = (block, path, expected, done) => {
   IpldBitcoin.resolver.resolve(block, path, (err, value) => {
     expect(err).to.not.exist()