From bf7da8522cf05df21c77a6b3d2c5e0c5ad560069 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Thu, 14 Apr 2016 13:06:51 -0700
Subject: [PATCH 1/4] basic implementation of object diff

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>
---
 core/commands/object/diff.go       | 85 ++++++++++++++++++++++++++++++
 core/commands/object/object.go     | 16 +++---
 merkledag/utils/diff.go            | 35 +++++++++---
 test/sharness/t0052-object-diff.sh | 71 +++++++++++++++++++++++++
 4 files changed, 192 insertions(+), 15 deletions(-)
 create mode 100644 core/commands/object/diff.go
 create mode 100755 test/sharness/t0052-object-diff.sh

diff --git a/core/commands/object/diff.go b/core/commands/object/diff.go
new file mode 100644
index 000000000..72626ad8d
--- /dev/null
+++ b/core/commands/object/diff.go
@@ -0,0 +1,85 @@
+package objectcmd
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+
+	cmds "github.com/ipfs/go-ipfs/commands"
+	dagutils "github.com/ipfs/go-ipfs/merkledag/utils"
+	path "github.com/ipfs/go-ipfs/path"
+)
+
+var ObjectDiffCmd = &cmds.Command{
+	Helptext: cmds.HelpText{
+		Tagline: "takes a diff of the two given objects",
+		ShortDescription: `
+`,
+	},
+	Arguments: []cmds.Argument{
+		cmds.StringArg("obj_a", true, false, "object to diff against"),
+		cmds.StringArg("obj_b", true, false, "object to diff"),
+	},
+	Run: func(req cmds.Request, res cmds.Response) {
+		node, err := req.InvocContext().GetNode()
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		a := req.Arguments()[0]
+		b := req.Arguments()[1]
+
+		pa, err := path.ParsePath(a)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		pb, err := path.ParsePath(b)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		ctx := req.Context()
+
+		obj_a, err := node.Resolver.ResolvePath(ctx, pa)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		obj_b, err := node.Resolver.ResolvePath(ctx, pb)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		changes, err := dagutils.Diff(ctx, node.DAG, obj_a, obj_b)
+		if err != nil {
+			res.SetError(err, cmds.ErrNormal)
+			return
+		}
+
+		res.SetOutput(changes)
+	},
+	Type: []*dagutils.Change{},
+	Marshalers: cmds.MarshalerMap{
+		cmds.Text: func(res cmds.Response) (io.Reader, error) {
+			changes := res.Output().([]*dagutils.Change)
+			buf := new(bytes.Buffer)
+			for _, change := range changes {
+				switch change.Type {
+				case dagutils.Add:
+					fmt.Fprintf(buf, "added new link %q pointing to %s\n", change.Path, change.After)
+				case dagutils.Mod:
+					fmt.Fprintf(buf, "changed %q from %s to %s\n", change.Path, change.Before, change.After)
+				case dagutils.Remove:
+					fmt.Fprintf(buf, "removed link %q (was %s)\n", change.Path, change.Before)
+				}
+			}
+			return buf, nil
+		},
+	},
+}
diff --git a/core/commands/object/object.go b/core/commands/object/object.go
index 68869119d..f39b35d09 100644
--- a/core/commands/object/object.go
+++ b/core/commands/object/object.go
@@ -48,13 +48,14 @@ var ObjectCmd = &cmds.Command{
 'ipfs object' is a plumbing command used to manipulate DAG objects
 directly.`,
 		Synopsis: `
-ipfs object data <key>      - Outputs raw bytes in an object
-ipfs object get <key>       - Get the DAG node named by <key>
-ipfs object links <key>     - Outputs links pointed to by object
-ipfs object new <template>  - Create new ipfs objects
-ipfs object patch <args>    - Create new object from old ones
-ipfs object put <data>      - Stores input, outputs its key
-ipfs object stat <key>      - Outputs statistics of object
+ipfs object data <key>           - Outputs raw bytes in an object
+ipfs object get <key>            - Get the DAG node named by <key>
+ipfs object links <key>          - Outputs links pointed to by object
+ipfs object new <template>       - Create new ipfs objects
+ipfs object patch <args>         - Create new object from old ones
+ipfs object put <data>           - Stores input, outputs its key
+ipfs object stat <key>           - Outputs statistics of object
+ipfs object diff <key1> <key2>   - Diffs two given objects
 `,
 	},
 
@@ -66,6 +67,7 @@ ipfs object stat <key>      - Outputs statistics of object
 		"patch": ObjectPatchCmd,
 		"put":   ObjectPutCmd,
 		"stat":  ObjectStatCmd,
+		"diff":  ObjectDiffCmd,
 	},
 }
 
diff --git a/merkledag/utils/diff.go b/merkledag/utils/diff.go
index 3237ad913..493394437 100644
--- a/merkledag/utils/diff.go
+++ b/merkledag/utils/diff.go
@@ -75,17 +75,25 @@ func ApplyChange(ctx context.Context, ds dag.DAGService, nd *dag.Node, cs []*Cha
 	return e.Finalize(ds)
 }
 
-func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.Node) []*Change {
+func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.Node) ([]*Change, error) {
 	if len(a.Links) == 0 && len(b.Links) == 0 {
-		ak, _ := a.Key()
-		bk, _ := b.Key()
+		ak, err := a.Key()
+		if err != nil {
+			return nil, err
+		}
+
+		bk, err := b.Key()
+		if err != nil {
+			return nil, err
+		}
+
 		return []*Change{
 			&Change{
 				Type:   Mod,
 				Before: ak,
 				After:  bk,
 			},
-		}
+		}, nil
 	}
 
 	var out []*Change
@@ -99,9 +107,20 @@ func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.Node) []*Change {
 			if bytes.Equal(l.Hash, lnk.Hash) {
 				// no change... ignore it
 			} else {
-				anode, _ := lnk.GetNode(ctx, ds)
-				bnode, _ := l.GetNode(ctx, ds)
-				sub := Diff(ctx, ds, anode, bnode)
+				anode, err := lnk.GetNode(ctx, ds)
+				if err != nil {
+					return nil, err
+				}
+
+				bnode, err := l.GetNode(ctx, ds)
+				if err != nil {
+					return nil, err
+				}
+
+				sub, err := Diff(ctx, ds, anode, bnode)
+				if err != nil {
+					return nil, err
+				}
 
 				for _, subc := range sub {
 					subc.Path = path.Join(lnk.Name, subc.Path)
@@ -128,7 +147,7 @@ func Diff(ctx context.Context, ds dag.DAGService, a, b *dag.Node) []*Change {
 		})
 	}
 
-	return out
+	return out, nil
 }
 
 type Conflict struct {
diff --git a/test/sharness/t0052-object-diff.sh b/test/sharness/t0052-object-diff.sh
new file mode 100755
index 000000000..534f8f110
--- /dev/null
+++ b/test/sharness/t0052-object-diff.sh
@@ -0,0 +1,71 @@
+#!/bin/sh
+#
+# Copyright (c) 2016 Jeromy Johnson
+# MIT Licensed; see the LICENSE file in this repository.
+#
+
+test_description="Test object diff command"
+
+. lib/test-lib.sh
+
+test_init_ipfs
+
+test_expect_success "create some objects for testing diffs" '
+	mkdir foo &&
+	echo "stuff" > foo/bar &&
+	mkdir foo/baz &&
+	A=$(ipfs add -r -q foo | tail -n1) &&
+	echo "more things" > foo/cat &&
+	B=$(ipfs add -r -q foo | tail -n1) &&
+	echo "nested" > foo/baz/dog &&
+	C=$(ipfs add -r -q foo | tail -n1)
+	echo "changed" > foo/bar &&
+	D=$(ipfs add -r -q foo | tail -n1)
+'
+
+test_expect_success "diff against self is empty" '
+	ipfs object diff $A $A > diff_out
+'
+
+test_expect_success "identity diff output looks good" '
+	printf "" > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_expect_success "diff added link works" '
+	ipfs object diff $A $B > diff_out
+'
+
+test_expect_success "diff added link looks right" '
+	echo added new link \"cat\" pointing to QmUSvcqzhdfYM1KLDbM76eLPdS9ANFtkJvFuPYeZt73d7A > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_expect_success "diff removed link works" '
+	ipfs object diff $B $A > diff_out
+'
+
+test_expect_success "diff removed link looks right" '
+	echo removed link \"cat\" \(was QmUSvcqzhdfYM1KLDbM76eLPdS9ANFtkJvFuPYeZt73d7A\) > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_expect_success "diff nested add works" '
+	ipfs object diff $B $C > diff_out
+'
+
+test_expect_success "diff looks right" '
+	echo added new link \"baz/dog\" pointing to QmdNJQUTZuDpsUcec7YDuCfRfvw1w4J13DCm7YcU4VMZdS > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_expect_success "diff changed link works" '
+	ipfs object diff $C $D > diff_out
+'
+
+test_expect_success "diff looks right" '
+	echo changed \"bar\" from QmNgd5cz2jNftnAHBhcRUGdtiaMzb5Rhjqd4etondHHST8 to QmRfFVsjSXkhFxrfWnLpMae2M4GBVsry6VAuYYcji5MiZb > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_done

From 73a2f80c76438a69c6bd48ca0e3c20feb20f0813 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Thu, 14 Apr 2016 13:13:54 -0700
Subject: [PATCH 2/4] Add some help text

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>
---
 core/commands/object/diff.go | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/core/commands/object/diff.go b/core/commands/object/diff.go
index 72626ad8d..d2b72ca20 100644
--- a/core/commands/object/diff.go
+++ b/core/commands/object/diff.go
@@ -14,6 +14,24 @@ var ObjectDiffCmd = &cmds.Command{
 	Helptext: cmds.HelpText{
 		Tagline: "takes a diff of the two given objects",
 		ShortDescription: `
+ipfs object diff is a command used to show the differences between
+two ipfs objects.
+
+Example:
+
+   $ ls foo
+   bar baz/ giraffe
+   $ ipfs add -r foo
+   ...
+   added QmegHcnrPgMwC7tBiMxChD54fgQMBUecNw9nE9UUU4x1bz foo
+   $ OBJ_A=QmegHcnrPgMwC7tBiMxChD54fgQMBUecNw9nE9UUU4x1bz
+   $ echo "different content" > foo/bar
+   $ ipfs add -r foo
+   ...
+   added QmcmRptkSPWhptCttgHg27QNDmnV33wAJyUkCnAvqD3eCD foo
+   $ OBJ_B=QmcmRptkSPWhptCttgHg27QNDmnV33wAJyUkCnAvqD3eCD
+   $ ipfs object diff $OBJ_A $OBJ_B
+   changed "bar" from QmNgd5cz2jNftnAHBhcRUGdtiaMzb5Rhjqd4etondHHST8 to QmRfFVsjSXkhFxrfWnLpMae2M4GBVsry6VAuYYcji5MiZb
 `,
 	},
 	Arguments: []cmds.Argument{

From 7e7fcb35eaffe88718660b9fac5fbd5aeee5f03e Mon Sep 17 00:00:00 2001
From: Jeromy <why@ipfs.io>
Date: Sat, 16 Apr 2016 12:23:34 -0700
Subject: [PATCH 3/4] changes from CR feedback

License: MIT
Signed-off-by: Jeromy <why@ipfs.io>
---
 core/commands/object/diff.go       | 32 +++++++++++++++++++++++-------
 core/commands/object/object.go     |  4 ++--
 test/sharness/t0052-object-diff.sh | 15 +++++++++++---
 3 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/core/commands/object/diff.go b/core/commands/object/diff.go
index d2b72ca20..83dc04e59 100644
--- a/core/commands/object/diff.go
+++ b/core/commands/object/diff.go
@@ -15,6 +15,9 @@ var ObjectDiffCmd = &cmds.Command{
 		Tagline: "takes a diff of the two given objects",
 		ShortDescription: `
 ipfs object diff is a command used to show the differences between
+two ipfs objects.`,
+		LongDescription: `
+ipfs object diff is a command used to show the differences between
 two ipfs objects.
 
 Example:
@@ -38,6 +41,9 @@ Example:
 		cmds.StringArg("obj_a", true, false, "object to diff against"),
 		cmds.StringArg("obj_b", true, false, "object to diff"),
 	},
+	Options: []cmds.Option{
+		cmds.BoolOption("verbose", "v", "Produce verbose output"),
+	},
 	Run: func(req cmds.Request, res cmds.Response) {
 		node, err := req.InvocContext().GetNode()
 		if err != nil {
@@ -85,16 +91,28 @@ Example:
 	Type: []*dagutils.Change{},
 	Marshalers: cmds.MarshalerMap{
 		cmds.Text: func(res cmds.Response) (io.Reader, error) {
+			verbose, _, _ := res.Request().Option("v").Bool()
 			changes := res.Output().([]*dagutils.Change)
 			buf := new(bytes.Buffer)
 			for _, change := range changes {
-				switch change.Type {
-				case dagutils.Add:
-					fmt.Fprintf(buf, "added new link %q pointing to %s\n", change.Path, change.After)
-				case dagutils.Mod:
-					fmt.Fprintf(buf, "changed %q from %s to %s\n", change.Path, change.Before, change.After)
-				case dagutils.Remove:
-					fmt.Fprintf(buf, "removed link %q (was %s)\n", change.Path, change.Before)
+				if verbose {
+					switch change.Type {
+					case dagutils.Add:
+						fmt.Fprintf(buf, "added new link %q pointing to %s\n", change.Path, change.After)
+					case dagutils.Mod:
+						fmt.Fprintf(buf, "changed %q from %s to %s\n", change.Path, change.Before, change.After)
+					case dagutils.Remove:
+						fmt.Fprintf(buf, "removed link %q (was %s)\n", change.Path, change.Before)
+					}
+				} else {
+					switch change.Type {
+					case dagutils.Add:
+						fmt.Fprintf(buf, "+ %s %q\n", change.After, change.Path)
+					case dagutils.Mod:
+						fmt.Fprintf(buf, "~ %s %s %q\n", change.Before, change.After, change.Path)
+					case dagutils.Remove:
+						fmt.Fprintf(buf, "- %s %q\n", change.Before, change.Path)
+					}
 				}
 			}
 			return buf, nil
diff --git a/core/commands/object/object.go b/core/commands/object/object.go
index f39b35d09..7ab8bf949 100644
--- a/core/commands/object/object.go
+++ b/core/commands/object/object.go
@@ -49,25 +49,25 @@ var ObjectCmd = &cmds.Command{
 directly.`,
 		Synopsis: `
 ipfs object data <key>           - Outputs raw bytes in an object
+ipfs object diff <key1> <key2>   - Diffs two given objects
 ipfs object get <key>            - Get the DAG node named by <key>
 ipfs object links <key>          - Outputs links pointed to by object
 ipfs object new <template>       - Create new ipfs objects
 ipfs object patch <args>         - Create new object from old ones
 ipfs object put <data>           - Stores input, outputs its key
 ipfs object stat <key>           - Outputs statistics of object
-ipfs object diff <key1> <key2>   - Diffs two given objects
 `,
 	},
 
 	Subcommands: map[string]*cmds.Command{
 		"data":  ObjectDataCmd,
+		"diff":  ObjectDiffCmd,
 		"get":   ObjectGetCmd,
 		"links": ObjectLinksCmd,
 		"new":   ObjectNewCmd,
 		"patch": ObjectPatchCmd,
 		"put":   ObjectPutCmd,
 		"stat":  ObjectStatCmd,
-		"diff":  ObjectDiffCmd,
 	},
 }
 
diff --git a/test/sharness/t0052-object-diff.sh b/test/sharness/t0052-object-diff.sh
index 534f8f110..3769b803e 100755
--- a/test/sharness/t0052-object-diff.sh
+++ b/test/sharness/t0052-object-diff.sh
@@ -37,12 +37,21 @@ test_expect_success "diff added link works" '
 '
 
 test_expect_success "diff added link looks right" '
+	echo + QmUSvcqzhdfYM1KLDbM76eLPdS9ANFtkJvFuPYeZt73d7A \"cat\" > diff_exp &&
+	test_cmp diff_exp diff_out
+'
+
+test_expect_success "verbose diff added link works" '
+	ipfs object diff -v $A $B > diff_out
+'
+
+test_expect_success "verbose diff added link looks right" '
 	echo added new link \"cat\" pointing to QmUSvcqzhdfYM1KLDbM76eLPdS9ANFtkJvFuPYeZt73d7A > diff_exp &&
 	test_cmp diff_exp diff_out
 '
 
 test_expect_success "diff removed link works" '
-	ipfs object diff $B $A > diff_out
+	ipfs object diff -v $B $A > diff_out
 '
 
 test_expect_success "diff removed link looks right" '
@@ -51,7 +60,7 @@ test_expect_success "diff removed link looks right" '
 '
 
 test_expect_success "diff nested add works" '
-	ipfs object diff $B $C > diff_out
+	ipfs object diff -v $B $C > diff_out
 '
 
 test_expect_success "diff looks right" '
@@ -60,7 +69,7 @@ test_expect_success "diff looks right" '
 '
 
 test_expect_success "diff changed link works" '
-	ipfs object diff $C $D > diff_out
+	ipfs object diff -v $C $D > diff_out
 '
 
 test_expect_success "diff looks right" '

From fa8de1bfd50589add34f055e3bde7dccc41694a8 Mon Sep 17 00:00:00 2001
From: Jeromy <jeromyj@gmail.com>
Date: Mon, 18 Apr 2016 08:41:54 -0700
Subject: [PATCH 4/4] minor correction in help text

License: MIT
Signed-off-by: Jeromy <jeromyj@gmail.com>
---
 core/commands/object/diff.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/commands/object/diff.go b/core/commands/object/diff.go
index 83dc04e59..75dadc341 100644
--- a/core/commands/object/diff.go
+++ b/core/commands/object/diff.go
@@ -33,7 +33,7 @@ Example:
    ...
    added QmcmRptkSPWhptCttgHg27QNDmnV33wAJyUkCnAvqD3eCD foo
    $ OBJ_B=QmcmRptkSPWhptCttgHg27QNDmnV33wAJyUkCnAvqD3eCD
-   $ ipfs object diff $OBJ_A $OBJ_B
+   $ ipfs object diff -v $OBJ_A $OBJ_B
    changed "bar" from QmNgd5cz2jNftnAHBhcRUGdtiaMzb5Rhjqd4etondHHST8 to QmRfFVsjSXkhFxrfWnLpMae2M4GBVsry6VAuYYcji5MiZb
 `,
 	},