From 9c2d2275a853e0646a02f8de6eb66dcb225a21a0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20Geisendo=CC=88rfer?= <felix@debuggable.com>
Date: Mon, 18 Mar 2013 12:24:44 +0100
Subject: [PATCH] Initial X-Missing work

---
 README.md            |  6 ++---
 src/cmd/tusd/data.go | 61 ++++++++++++++++++++++++++++++++++++++++++++
 src/cmd/tusd/http.go | 26 ++++++++++++++++---
 3 files changed, 87 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 8039a23..75f4671 100644
--- a/README.md
+++ b/README.md
@@ -129,15 +129,15 @@ Host: tus.example.com
 HTTP/1.1 200 Ok
 Content-Length: 100
 Content-Type: image/jpg
-X-Resume: bytes=20-50,60-99
+X-Missing: bytes=20-50,60-99
 ```
 
-The `X-Resume` header holds a [byte
+The `X-Missing` header holds a [byte
 range](http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.35.1) that
 informs the client which parts of the file have not been received yet. It is
 up to the client to choose appropiate `PUT` requests to complete the upload.
 
-The absence of a `X-Resume` header means that the the entire file has been
+The absence of a `X-Missing` header means that the the entire file has been
 received by the server.
 
 ### GET \<fileUrl\>
diff --git a/src/cmd/tusd/data.go b/src/cmd/tusd/data.go
index 9114b65..756761b 100644
--- a/src/cmd/tusd/data.go
+++ b/src/cmd/tusd/data.go
@@ -6,8 +6,11 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 	"path"
+	"strconv"
+	"strings"
 )
 
 var dataDir string
@@ -82,3 +85,61 @@ func putFileChunk(fileId string, start int64, end int64, r io.Reader) error {
 
 	return nil
 }
+
+func getReceivedChunks(fileId string) (chunkSet, error) {
+	l := logPath(fileId)
+	// @TODO stream the file / limit log file size?
+	data, err := ioutil.ReadFile(l)
+	if err != nil {
+		return nil, err
+	}
+	lines := strings.Split(string(data), "\n")
+
+
+	chunks := make(chunkSet, 0, len(lines)-1)
+	for i, line := range lines {
+		// last line is always empty, skip it
+		if lastLine := i+1 == len(lines); lastLine {
+			break
+		}
+
+		parts := strings.Split(line, ",")
+		if len(parts) != 2 {
+			return nil, errors.New("getReceivedChunks: corrupt log line: "+line)
+		}
+
+		start, err := strconv.ParseInt(parts[0], 10, 64)
+		if err != nil {
+			return nil, errors.New("getReceivedChunks: invalid start: "+parts[0])
+		}
+
+		end, err := strconv.ParseInt(parts[1], 10, 64)
+		if err != nil {
+			return nil, errors.New("getReceivedChunks: invalid end: "+parts[1])
+		}
+
+		chunks.Add(chunk{Start: start, End: end})
+	}
+
+	return chunks, nil
+}
+
+func getMissingChunks(fileId string) (chunkSet, error) {
+	d := dataPath(fileId)
+	stat, err := os.Stat(d)
+	if err != nil {
+		return nil, err
+	}
+
+	receivedChunks, err := getReceivedChunks(fileId)
+	if err != nil {
+		return nil, err
+	}
+
+	// @TODO actually calcuate missing chunks instead of received
+	_ = stat
+
+	//chunks := chunkSet{{Start: 0, End: stat.Size()-1}}
+	//chunks := make(chunkSet, 0)
+	return receivedChunks, nil
+}
diff --git a/src/cmd/tusd/http.go b/src/cmd/tusd/http.go
index 6629440..c51b94d 100644
--- a/src/cmd/tusd/http.go
+++ b/src/cmd/tusd/http.go
@@ -30,7 +30,7 @@ func route(w http.ResponseWriter, r *http.Request) {
 		// WIP
 		switch r.Method {
 		case "HEAD":
-			w.Header().Set("X-Resume", "bytes=0-99")
+			headFile(w, r, id)
 		case "GET":
 			reply(w, http.StatusNotImplemented, "File download")
 		case "PUT":
@@ -76,7 +76,7 @@ func postFiles(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	// @TODO: Return X-Resume header
+	// @TODO: Return X-Missing header
 
 	w.Header().Set("Location", "/files/"+id)
 	w.WriteHeader(http.StatusCreated)
@@ -98,5 +98,25 @@ func putFile(w http.ResponseWriter, r *http.Request, fileId string) {
 		return
 	}
 
-	// @TODO: Return X-Resume header
+	// @TODO: Return X-Missing header
+}
+
+func headFile(w http.ResponseWriter, r *http.Request, fileId string) {
+	chunks, err := getMissingChunks(fileId)
+	if err != nil {
+		reply(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	missing := ""
+	for i, chunk := range chunks {
+		missing += fmt.Sprintf("%d-%d", chunk.Start, chunk.End)
+		if i + 1 < len(chunks) {
+			missing += ","
+		}
+	}
+
+	if missing != "" {
+		w.Header().Set("X-Missing", "bytes="+missing)
+	}
 }