From ed17b5eb3e86d018e51565198df33f0ea25ed28c Mon Sep 17 00:00:00 2001
From: Enzo Matsumiya <ematsumiya@suse.de>
Date: Fri, 24 May 2019 17:17:52 -0300
Subject: [PATCH] Limit to max_brightness, some clean up, add some TODOs

- Although I don't know the behaviour if value goes above max_brightness, doesn't
hurt to check.

- Changed some variable names for better understanding :P

- Add some TODOs to README and code
---
 README.md | 12 +++++++++---
 twbl.cpp  | 42 ++++++++++++++++++++++++++++++++----------
 2 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/README.md b/README.md
index d3b44b7..1353d27 100644
--- a/README.md
+++ b/README.md
@@ -4,13 +4,13 @@ Had some trouble getting xbacklight to work on openSUSE Tumbleweed, so I wrote t
 simple program that should work around it. Requires root, a workaround can be found
 at [stackoverflow](https://unix.stackexchange.com/a/248495).
 
-The value of the `fname` variable might need to be changed to the correct path
-to your backlight brightness file.
+The values of the `fname` and `max_fname` variables might need to be changed to the correct path
+to your backlight brightness files.
 
 ### Compilation:
 
 ```
-g++ -std=c++11 twbl.cpp
+g++ -std=c++11 -o twbl twbl.cpp
 ```
 
 ### Usage (i3 config):
@@ -19,3 +19,9 @@ g++ -std=c++11 twbl.cpp
 bindsym XF86MonBrightnessUp exec sudo /home/dzejrou/bin/twbl +100 # increase screen brightness
 bindsym XF86MonBrightnessDown exec sudo /home/dzejrou/bin/twbl -100 # decrease screen brightness
 ```
+
+### TODO
+
+- Create a Makefile
+- Find a way to not need sudo
+- (RFC) Maybe change granularity of increment/decrement (e.g. "./twbl +1" makes no difference at all, up until 1000)
diff --git a/twbl.cpp b/twbl.cpp
index e4b8084..b74dc35 100644
--- a/twbl.cpp
+++ b/twbl.cpp
@@ -7,37 +7,59 @@ int main(int argc, char** argv)
 {
     /**
      * Edit here with the proper path to your backlight.
+	 * TODO: save these strings in a file maybe?
      */
     std::string fname{"/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness"};
+	std::string max_fname{"/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/max_brightness"};
 
     if (argc < 2)
     {
-        std::cerr << "Usage: " << argv[0] << " {,+,-}N\n";
+        std::cerr << "Usage: " << argv[0] << " {,+,-}N\n\n";
         return 1;
     }
 
-    std::istringstream iss{argv[1]};
+    std::istringstream read_val{argv[1]};
     int val{};
 
-    if (!(iss >> val))
+    if (!(read_val >> val))
     {
         std::cerr << "Argument " << argv[1] << " is not a valid number.\n";
         return 1;
     }
 
-    std::ifstream ifs{fname};
+    std::ifstream read_current{fname};
+    int current_value{};
 
-    int curr{};
-    if (!(ifs >> curr))
+    if (!(read_current >> current_value))
     {
         std::cerr << "Could not read current brightness value.\n";
         return 1;
     }
-    ifs.close();
 
-    val += curr;
-    std::ofstream ofs{fname};
-    if (!(ofs << std::to_string(val)))
+    read_current.close();
+
+	std::ifstream read_max{max_fname};
+	int max_value{};
+	
+	if (!(read_max >> max_value))
+	{
+		std::cerr << "Could not read max brightness value.\n";
+		return 1;
+	}
+
+	read_max.close();
+
+	if ((current_value + val) > max_value)
+	{
+		std::cerr << "Invalid input value: " << val << " is greater than max value " << max_value;
+		return 1;
+	}
+
+    val += current_value;
+
+    std::ofstream write_value{fname};
+
+    if (!(write_value << std::to_string(val)))
     {
         std::cerr << "Could not write new brightness value.\n";
         return 1;