add vcs support

7 files changed, 500 insertions, 6 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 04bd256..2d1cd08 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -23,10 +23,20 @@ dependencies = [
 
 [[package]]
 name = "bitflags"
+version = "0.9.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "bitflags"
 version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "cc"
+version = "1.0.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "chrono"
 version = "0.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -50,11 +60,34 @@ dependencies = [
 ]
 
 [[package]]
+name = "cmake"
+version = "0.1.29"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "curl-sys"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libz-sys 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "openssl-sys 0.9.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "fancy-prompt"
 version = "0.1.0"
 dependencies = [
  "chrono 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "clap 2.30.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "git2 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)",
  "hostname 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
  "term 0.4.6 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -64,6 +97,19 @@ dependencies = [
 ]
 
 [[package]]
+name = "git2"
+version = "0.6.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "bitflags 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libgit2-sys 0.6.19 (registry+https://github.com/rust-lang/crates.io-index)",
+ "openssl-probe 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "openssl-sys 0.9.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "url 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "hostname"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -73,6 +119,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "idna"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-normalization 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "kernel32-sys"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -92,6 +148,49 @@ version = "0.2.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "libgit2-sys"
+version = "0.6.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "curl-sys 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libssh2-sys 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libz-sys 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "openssl-sys 0.9.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libssh2-sys"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libz-sys 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)",
+ "openssl-sys 0.9.26 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "libz-sys"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "matches"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "memchr"
 version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -132,6 +231,32 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "openssl-probe"
+version = "0.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "openssl-sys"
+version = "0.9.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)",
+ "pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "percent-encoding"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "pkg-config"
+version = "0.3.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "redox_syscall"
 version = "0.1.37"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -231,6 +356,19 @@ dependencies = [
 ]
 
 [[package]]
+name = "unicode-bidi"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "unicode-normalization"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "unicode-width"
 version = "0.1.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -244,6 +382,16 @@ dependencies = [
 ]
 
 [[package]]
+name = "url"
+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "idna 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)",
+ "matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
 name = "users"
 version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -257,6 +405,11 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
 [[package]]
+name = "vcpkg"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
 name = "vec_map"
 version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
@@ -316,18 +469,32 @@ dependencies = [
 "checksum aho-corasick 0.6.4 (registry+https://github.com/rust-lang/crates.io-index)" = "d6531d44de723825aa81398a6415283229725a00fa30713812ab9323faa82fc4"
 "checksum ansi_term 0.10.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6b3568b48b7cefa6b8ce125f9bb4989e52fbcc29ebea88df04cc7c5f12f70455"
 "checksum atty 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "8352656fd42c30a0c3c89d26dea01e3b77c0ab2af18230835c15e2e13cd51859"
+"checksum bitflags 0.9.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4efd02e230a02e18f92fc2735f44597385ed02ad8f831e7c1c1156ee5e1ab3a5"
 "checksum bitflags 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "b3c30d3802dfb7281680d6285f2ccdaa8c2d8fee41f93805dba5c4cf50dc23cf"
+"checksum cc 1.0.4 (registry+https://github.com/rust-lang/crates.io-index)" = "deaf9ec656256bb25b404c51ef50097207b9cbb29c933d31f92cae5a8a0ffee0"
 "checksum chrono 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7c20ebe0b2b08b0aeddba49c609fe7957ba2e33449882cb186a180bc60682fa9"
 "checksum clap 2.30.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1c07b9257a00f3fc93b7f3c417fc15607ec7a56823bc2c37ec744e266387de5b"
+"checksum cmake 0.1.29 (registry+https://github.com/rust-lang/crates.io-index)" = "56d741ea7a69e577f6d06b36b7dff4738f680593dc27a701ffa8506b73ce28bb"
+"checksum curl-sys 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)" = "f46e49c7125131f5afaded06944d6888b55cbdf8eba05dae73c954019b907961"
+"checksum git2 0.6.11 (registry+https://github.com/rust-lang/crates.io-index)" = "ee5b4bb7cd2a44e6e5ee3a26ba6a9ca10d4ce2771cdc3839bbc54b47b7d1be84"
 "checksum hostname 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "58fab6e177434b0bb4cd344a4dabaa5bd6d7a8d792b1885aebcae7af1091d1cb"
+"checksum idna 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "014b298351066f1512874135335d62a789ffe78a9974f94b43ed5621951eaf7d"
 "checksum kernel32-sys 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7507624b29483431c0ba2d82aece8ca6cdba9382bff4ddd0f7490560c056098d"
 "checksum lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c8f31047daa365f19be14b47c29df4f7c3b581832407daabe6ae77397619237d"
 "checksum libc 0.2.36 (registry+https://github.com/rust-lang/crates.io-index)" = "1e5d97d6708edaa407429faa671b942dc0f2727222fb6b6539bf1db936e4b121"
+"checksum libgit2-sys 0.6.19 (registry+https://github.com/rust-lang/crates.io-index)" = "6eeae66e7b1c995de45cb4e65c5ab438a96a7b4077e448645d4048dc753ad357"
+"checksum libssh2-sys 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "0db4ec23611747ef772db1c4d650f8bd762f07b461727ec998f953c614024b75"
+"checksum libz-sys 1.0.18 (registry+https://github.com/rust-lang/crates.io-index)" = "87f737ad6cc6fd6eefe3d9dc5412f1573865bded441300904d2f42269e140f16"
+"checksum matches 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)" = "100aabe6b8ff4e4a7e32c1c13523379802df0772b82466207ac25b013f193376"
 "checksum memchr 2.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "796fba70e76612589ed2ce7f45282f5af869e0fdd7cc6199fa1aa1f1d591ba9d"
 "checksum num 0.1.42 (registry+https://github.com/rust-lang/crates.io-index)" = "4703ad64153382334aa8db57c637364c322d3372e097840c72000dabdcf6156e"
 "checksum num-integer 0.1.36 (registry+https://github.com/rust-lang/crates.io-index)" = "f8d26da319fb45674985c78f1d1caf99aa4941f785d384a2ae36d0740bc3e2fe"
 "checksum num-iter 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)" = "4b226df12c5a59b63569dd57fafb926d91b385dfce33d8074a412411b689d593"
 "checksum num-traits 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e7de20f146db9d920c45ee8ed8f71681fd9ade71909b48c3acbd766aa504cf10"
+"checksum openssl-probe 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)" = "77af24da69f9d9341038eba93a073b1fdaaa1b788221b00a69bce9e762cb32de"
+"checksum openssl-sys 0.9.26 (registry+https://github.com/rust-lang/crates.io-index)" = "a5a41ce2f5f2d939c80decde8fcfcf5837c203ca6c06a553510a2fcb84fa3ef1"
+"checksum percent-encoding 1.0.1 (registry+https://github.com/rust-lang/crates.io-index)" = "31010dd2e1ac33d5b46a5b413495239882813e0369f8ed8a5e266f173602f831"
+"checksum pkg-config 0.3.9 (registry+https://github.com/rust-lang/crates.io-index)" = "3a8b4c6b8165cd1a1cd4b9b120978131389f64bdaf456435caa41e630edba903"
 "checksum redox_syscall 0.1.37 (registry+https://github.com/rust-lang/crates.io-index)" = "0d92eecebad22b767915e4d529f89f28ee96dbbf5a4810d2b844373f136417fd"
 "checksum redox_termios 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "7e891cfe48e9100a70a3b6eb652fef28920c117d366339687bd5576160db0f76"
 "checksum regex 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)" = "5be5347bde0c48cfd8c3fdc0766cdfe9d8a755ef84d620d6794c778c91de8b2b"
@@ -340,10 +507,14 @@ dependencies = [
 "checksum textwrap 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c0b59b6b4b44d867f1370ef1bd91bfb262bf07bf0ae65c202ea2fbc16153b693"
 "checksum thread_local 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)" = "279ef31c19ededf577bfd12dfae728040a21f635b06a24cd670ff510edd38963"
 "checksum time 0.1.39 (registry+https://github.com/rust-lang/crates.io-index)" = "a15375f1df02096fb3317256ce2cee6a1f42fc84ea5ad5fc8c421cfe40c73098"
+"checksum unicode-bidi 0.3.4 (registry+https://github.com/rust-lang/crates.io-index)" = "49f2bd0c6468a8230e1db229cff8029217cf623c767ea5d60bfbd42729ea54d5"
+"checksum unicode-normalization 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "51ccda9ef9efa3f7ef5d91e8f9b83bbe6955f9bf86aec89d5cce2c874625920f"
 "checksum unicode-width 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "bf3a113775714a22dcb774d8ea3655c53a32debae63a063acc00a91cc586245f"
 "checksum unreachable 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "382810877fe448991dfc7f0dd6e3ae5d58088fd0ea5e35189655f84e6814fa56"
+"checksum url 1.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fa35e768d4daf1d85733418a49fb42e10d7f633e394fccab4ab7aba897053fe2"
 "checksum users 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)" = "99ab1b53affc9f75f57da4a8b051a188e84d20d43bea0dd9bd8db71eebbca6da"
 "checksum utf8-ranges 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "662fab6525a98beff2921d7f61a39e7d59e0b425ebc7d0d9e66d316e55124122"
+"checksum vcpkg 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "9e0a7d8bed3178a8fb112199d466eeca9ed09a14ba8ad67718179b4fd5487d0b"
 "checksum vec_map 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "887b5b631c2ad01628bbbaa7dd4c869f80d3186688f8d0b6f58774fbe324988c"
 "checksum void 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "6a02e4885ed3bc0f2de90ea6dd45ebcbb66dacffe03547fadbb0eeae2770887d"
 "checksum walkdir 2.1.3 (registry+https://github.com/rust-lang/crates.io-index)" = "b167e9a4420d8dddb260e70c90a4a375a1e5691f21f70e715553da87b6c2503a"
diff --git a/Cargo.toml b/Cargo.toml
index 0040bae..b875d9b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,6 +6,7 @@ authors = ["Jesse Luehrs <doy@tozt.net>"]
 [dependencies]
 chrono = "0.4"
 clap = "2.30"
+git2 = "0.6"
 hostname = "0.1"
 regex = "0.2"
 term = "0.4"
diff --git a/src/main.rs b/src/main.rs
index 471a3a2..85b4627 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 extern crate chrono;
 extern crate clap;
+extern crate git2;
 extern crate hostname;
 extern crate regex;
 extern crate term;
@@ -11,6 +12,7 @@ mod colors;
 mod power;
 mod prompt;
 mod system_info;
+mod vcs;
 
 fn collect_data() -> prompt::PromptData {
     let matches = clap::App::new("fancy-prompt")
@@ -45,6 +47,7 @@ fn collect_data() -> prompt::PromptData {
         is_root: system_info::is_root(),
         time: system_info::time(),
         power_info: system_info::power_info(),
+        vcs_info: system_info::vcs_info(),
     }
 }
 
diff --git a/src/prompt.rs b/src/prompt.rs
index 2679bc9..12a7ee5 100644
--- a/src/prompt.rs
+++ b/src/prompt.rs
@@ -2,15 +2,17 @@ use chrono;
 use regex;
 use std;
 
+use std::fmt::Write;
+
 use colors;
 use power;
+use vcs;
 
 pub struct Prompt {
     colors: colors::Colors,
     data: PromptData,
 }
 
-#[derive(Debug)]
 pub struct PromptData {
     pub shell: colors::ShellType,
     pub error_code: u8,
@@ -22,6 +24,7 @@ pub struct PromptData {
     pub is_root: bool,
     pub time: chrono::DateTime<chrono::Local>,
     pub power_info: power::PowerInfo,
+    pub vcs_info: Option<Box<vcs::VcsInfo>>,
 }
 
 impl Prompt {
@@ -36,13 +39,22 @@ impl Prompt {
         let user = self.data.user.clone().unwrap_or(String::from("???"));
         let host = self.data.hostname.clone().unwrap_or(String::from("???"));
 
+        let max_vcs_len = 20; // "g*+?:mybr...nch:+1-1"
+        let (vcs, vcs_err) = self.format_vcs();
+        let vcs = vcs.map(|vcs| {
+            compress_vcs(&vcs, max_vcs_len)
+        });
+
         let battery_len = 10;
         let cols = self.data.terminal_cols.unwrap_or(80);
 
-        // " (~/a/...cde) ---- {--<=======} doy@lance [19:40:50] "
+        // " (~/a/...cde|g*+?:mybr:+1-1) -- {--<=======} doy@lance [19:40:50] "
         let max_path_len = cols
             - 1                            // " "
-            - 2                            // "()"
+            - vcs
+                .as_ref()
+                .map(|vcs| vcs.len() + 1)  // "|g*+?:mybr:+1-1"
+                .unwrap_or(0) - 2          // "()"
             - 1                            // " "
             - 1                            // "-"
             - 1                            // " "
@@ -65,9 +77,10 @@ impl Prompt {
             &self.data.home,
             max_path_len
         );
+        let path_err = false; // XXX
 
         self.colors.pad(1);
-        self.display_path(&path);
+        self.display_path(&path, path_err, &vcs, vcs_err);
 
         self.colors.pad(1);
         self.display_border(max_path_len - path.len() + 1);
@@ -91,9 +104,19 @@ impl Prompt {
         self.colors.pad(1);
     }
 
-    fn display_path(&self, path: &str) {
+    fn display_path(
+        &self,
+        path: &str,
+        path_err: bool,
+        vcs: &Option<String>,
+        vcs_err: bool
+    ) {
         self.colors.print_host(&self.data.hostname, "(");
-        self.colors.print("default", path);
+        self.colors.print(if path_err { "error" } else { "default" }, path);
+        if let &Some(ref vcs) = vcs {
+            self.colors.print_host(&self.data.hostname, "|");
+            self.colors.print(if vcs_err { "error" } else { "default" }, &vcs);
+        }
         self.colors.print_host(&self.data.hostname, ")");
     }
 
@@ -159,6 +182,64 @@ impl Prompt {
         let prompt = if self.data.is_root { "#" } else { "$" };
         self.colors.print_user(&self.data.user, prompt);
     }
+
+    fn format_vcs(&self) -> (Option<String>, bool) {
+        (self.data.vcs_info.as_ref().map(|vcs_info| {
+            let mut vcs = String::new();
+
+            write!(vcs, "{}", vcs_id(vcs_info.vcs())).unwrap();
+
+            if vcs_info.has_modified_files() {
+                write!(vcs, "*").unwrap();
+            }
+            if vcs_info.has_staged_files() {
+                write!(vcs, "+").unwrap();
+            }
+            if vcs_info.has_new_files() {
+                write!(vcs, "?").unwrap();
+            }
+            if !vcs_info.has_commits() {
+                write!(vcs, "!").unwrap();
+            }
+
+            let branch = vcs_info.branch().map(|branch| {
+                if branch == "master" {
+                    String::new()
+                }
+                else {
+                    branch
+                }
+            }).unwrap_or(String::from("???"));
+            if branch != "" {
+                write!(vcs, ":").unwrap();
+            }
+            write!(vcs, "{}", branch).unwrap();
+
+            if let Some((local, remote)) = vcs_info.remote_branch_diff() {
+                if local > 0 || remote > 0 {
+                    write!(vcs, ":").unwrap();
+                }
+                if local > 0 {
+                    write!(vcs, "+{}", local).unwrap();
+                }
+                if remote > 0 {
+                    write!(vcs, "-{}", remote).unwrap();
+                }
+            }
+            else {
+                write!(vcs, ":-").unwrap();
+            }
+
+            match vcs_info.active_operation() {
+                vcs::ActiveOperation::None => {},
+                op => {
+                    write!(vcs, "({})", active_operation_id(op)).unwrap();
+                }
+            }
+
+            vcs
+        }), false) // XXX
+    }
 }
 
 fn battery_discharge_color(usage: f64, charging: bool) -> &'static str {
@@ -226,3 +307,25 @@ fn compress_path<T, U>(
         String::from("???")
     }
 }
+
+fn compress_vcs(vcs: &str, _len: usize) -> String {
+    // XXX
+    String::from(vcs)
+}
+
+fn vcs_id(vcs: vcs::VcsType) -> String {
+    match vcs {
+        vcs::VcsType::Git => String::from("g"),
+    }
+}
+
+fn active_operation_id(op: vcs::ActiveOperation) -> String {
+    match op {
+        vcs::ActiveOperation::None => String::new(),
+        vcs::ActiveOperation::Merge => String::from("m"),
+        vcs::ActiveOperation::Revert => String::from("v"),
+        vcs::ActiveOperation::CherryPick => String::from("c"),
+        vcs::ActiveOperation::Bisect => String::from("b"),
+        vcs::ActiveOperation::Rebase => String::from("r"),
+    }
+}
diff --git a/src/system_info.rs b/src/system_info.rs
index 2079ea7..47ed0f9 100644
--- a/src/system_info.rs
+++ b/src/system_info.rs
@@ -5,6 +5,7 @@ use std;
 use users;
 
 use power;
+use vcs;
 
 pub fn hostname() -> Option<String> {
     hostname::get_hostname()
@@ -44,3 +45,7 @@ pub fn time() -> chrono::DateTime<chrono::Local> {
 pub fn power_info() -> power::PowerInfo {
     power::PowerInfo::new()
 }
+
+pub fn vcs_info() -> Option<Box<vcs::VcsInfo>> {
+    vcs::detect()
+}
diff --git a/src/vcs/git.rs b/src/vcs/git.rs
new file mode 100644
index 0000000..749d498
--- /dev/null
+++ b/src/vcs/git.rs
@@ -0,0 +1,176 @@
+use git2;
+use std;
+
+use std::fmt::Write;
+
+#[derive(Debug)]
+pub struct GitInfo {
+    modified_files: bool,
+    staged_files: bool,
+    new_files: bool,
+    commits: bool,
+    active_operation: super::ActiveOperation,
+    branch: Option<String>,
+    remote_branch_diff: Option<(usize, usize)>,
+}
+
+impl GitInfo {
+    pub fn new(git: git2::Repository) -> GitInfo {
+        let mut modified_statuses = git2::Status::empty();
+        modified_statuses.insert(git2::STATUS_WT_DELETED);
+        modified_statuses.insert(git2::STATUS_WT_MODIFIED);
+        modified_statuses.insert(git2::STATUS_WT_RENAMED);
+        modified_statuses.insert(git2::STATUS_WT_TYPECHANGE);
+        let mut staged_statuses = git2::Status::empty();
+        staged_statuses.insert(git2::STATUS_INDEX_DELETED);
+        staged_statuses.insert(git2::STATUS_INDEX_MODIFIED);
+        staged_statuses.insert(git2::STATUS_INDEX_NEW);
+        staged_statuses.insert(git2::STATUS_INDEX_RENAMED);
+        staged_statuses.insert(git2::STATUS_INDEX_TYPECHANGE);
+        let mut new_statuses = git2::Status::empty();
+        new_statuses.insert(git2::STATUS_WT_NEW);
+
+        let mut status_options = git2::StatusOptions::new();
+        status_options.include_untracked(true);
+        if true { // XXX
+            status_options.update_index(true);
+        }
+        else {
+            status_options.update_index(false);
+            status_options.no_refresh(true);
+        }
+        let status = git.statuses(Some(&mut status_options));
+        let mut modified_files = false;
+        let mut staged_files = false;
+        let mut new_files = false;
+        for status in status.iter() {
+            for file in status.iter() {
+                if file.status().intersects(modified_statuses) {
+                    modified_files = true;
+                }
+                if file.status().intersects(staged_statuses) {
+                    staged_files = true;
+                }
+                if file.status().intersects(new_statuses) {
+                    new_files = true;
+                }
+            }
+        }
+
+        let head = git.head();
+        let commits = head.is_ok();
+        let branch = head.ok()
+            .and_then(|head| {
+                if head.is_branch() {
+                    head.shorthand().map(|s| s.to_string())
+                }
+                else {
+                    head.resolve().ok()
+                        .and_then(|head| head.target())
+                        .map(|oid| {
+                            let mut sha = String::new();
+                            for b in oid.as_bytes().iter() {
+                                write!(sha, "{:02x}", b).unwrap();
+                            }
+                            sha.truncate(7);
+                            sha
+                        })
+                }
+            });
+
+        let active_operation = match git.state() {
+            git2::RepositoryState::Merge
+                => super::ActiveOperation::Merge,
+            git2::RepositoryState::Revert
+                | git2::RepositoryState::RevertSequence
+                => super::ActiveOperation::Revert,
+            git2::RepositoryState::CherryPick
+                | git2::RepositoryState::CherryPickSequence
+                => super::ActiveOperation::CherryPick,
+            git2::RepositoryState::Bisect
+                => super::ActiveOperation::Bisect,
+            git2::RepositoryState::Rebase
+                | git2::RepositoryState::RebaseInteractive
+                | git2::RepositoryState::RebaseMerge
+                => super::ActiveOperation::Rebase,
+            _ => super::ActiveOperation::None,
+        };
+
+        let remote_branch_diff = git.head().ok()
+            .and_then(|head| if head.is_branch() { Some(head) } else { None })
+            .and_then(|head| {
+                head.resolve().ok()
+            })
+            .map(|head| {
+                (head.target(), head.shorthand().map(|s| s.to_string()))
+            })
+            .and_then(|(head_id, name)| {
+                head_id.and_then(|head_id| {
+                    name.and_then(|name| {
+                        git.refname_to_id(
+                            &(String::from("refs/remotes/origin/") + &name)
+                        ).ok().and_then(|remote_id| {
+                            git.graph_ahead_behind(head_id, remote_id).ok()
+                        })
+                    })
+                })
+            });
+
+        GitInfo {
+            modified_files: modified_files,
+            staged_files: staged_files,
+            new_files: new_files,
+            commits: commits,
+            active_operation: active_operation,
+            branch: branch,
+            remote_branch_diff: remote_branch_diff,
+        }
+    }
+}
+
+impl super::VcsInfo for GitInfo {
+    fn vcs(&self) -> super::VcsType {
+        super::VcsType::Git
+    }
+
+    fn has_modified_files(&self) -> bool {
+        self.modified_files
+    }
+
+    fn has_staged_files(&self) -> bool {
+        self.staged_files
+    }
+
+    fn has_new_files(&self) -> bool {
+        self.new_files
+    }
+
+    fn has_commits(&self) -> bool {
+        self.commits
+    }
+
+    fn active_operation(&self) -> super::ActiveOperation {
+        self.active_operation
+    }
+
+    fn branch(&self) -> Option<String> {
+        self.branch.clone()
+    }
+
+    fn remote_branch_diff(&self) -> Option<(usize, usize)> {
+        self.remote_branch_diff
+    }
+}
+
+pub fn detect() -> Option<Box<super::VcsInfo>> {
+    let git = std::env::current_dir().ok().and_then(|pwd| {
+        git2::Repository::discover(pwd).ok()
+    });
+
+    if let Some(git) = git {
+        Some(Box::new(GitInfo::new(git)))
+    }
+    else {
+        None
+    }
+}
diff --git a/src/vcs/mod.rs b/src/vcs/mod.rs
new file mode 100644
index 0000000..02c2eb7
--- /dev/null
+++ b/src/vcs/mod.rs
@@ -0,0 +1,35 @@
+mod git;
+
+pub enum VcsType {
+    Git,
+}
+
+#[derive(Debug,Copy,Clone)]
+pub enum ActiveOperation {
+    None,
+    Merge,
+    Revert,
+    CherryPick,
+    Bisect,
+    Rebase,
+}
+
+pub trait VcsInfo {
+    fn vcs(&self) -> VcsType;
+    fn has_modified_files(&self) -> bool;
+    fn has_staged_files(&self) -> bool;
+    fn has_new_files(&self) -> bool;
+    fn has_commits(&self) -> bool;
+    fn active_operation(&self) -> ActiveOperation;
+    fn branch(&self) -> Option<String>;
+    fn remote_branch_diff(&self) -> Option<(usize, usize)>;
+}
+
+pub fn detect() -> Option<Box<VcsInfo>> {
+    if let Some(git) = git::detect() {
+        Some(git)
+    }
+    else {
+        None
+    }
+}