#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <unistd.h>
#include <termios.h>

using namespace std;

int printusage(int,const char *const *argv,const char *message=NULL){
	if(message)cout<<message<<endl;
	cout<<"Usage: "<<argv[0]<<" [volume]"<<endl;
	cout<<"If [volume] is given, changes volume to that value. (Integer in [0,100].)"<<endl;
	cout<<"Otherwise, it shows a graphical slider, adjustable with the arrow keys or h/j/k/l."<<endl;
	cout<<"In graphical mode, 'm' toggles whether sound is muted."<<endl;
	cout<<"If the output is not a tty, the graphical slider is disabled."<<endl;
	return 1;
}

int setvolume(int vol){
	char *cmd=NULL;
	asprintf(&cmd,"osascript -e 'set volume output volume %d'",vol);
	if(!cmd)return 1;
	int ret=system(cmd);
	free(cmd);
	return ret;
}

int getvolume(void){
	FILE *p=popen("osascript -e 'output volume of (get volume settings)'","r");
	if(!p)return 50;
	int vol;
	fscanf(p,"%d",&vol);
	pclose(p);
	return vol;
}

int setmuted(bool m){
	char *cmd=NULL;
	asprintf(&cmd,"osascript -e 'set volume output muted %s'",m?"true":"false");
	if(!cmd)return 1;
	int ret=system(cmd);
	free(cmd);
	return ret;
}

bool getmuted(void){
	FILE *p=popen("osascript -e 'output muted of (get volume settings)'","r");
	if(!p)return false;
	char s[16];
	fscanf(p,"%15s",s);
	pclose(p);
	if(strcmp(s,"true")==0)return true;
	else if(strcmp(s,"false")==0)return false;
	else return false;
}

void displayslider(bool m,int vol){
	cout<<"\x1B[2K\r0 |"
	    <<string(vol/5,'#')<<string((104-vol)/5,'-')
	    <<"| 100 ("<<vol<<"%)";
	if(m)cout<<"  \x1B[1mMUTED (m)\x1B[0m";
	cout.flush();
}

int incvol(int &vol,int inc){
	if((vol==0&&inc<=0)||(vol==100&&inc>=0))return 0;
	vol+=inc;
	if(vol<0)vol=0;
	if(vol>100)vol=100;
	return setvolume(vol);
}

int interact(bool &m,int &vol){
	char c=cin.get();
	if(c=='q'||c=='Q'||c=='\n'||c=='\r')return 1;
	if(c=='l')return incvol(vol,5);
	if(c=='h')return incvol(vol,-5);
	if(c=='k')return incvol(vol,100);
	if(c=='j')return incvol(vol,-100);
	if(c=='m'){
		m=!m;
		setmuted(m);
		return 0;
	}
	if(c!=27){
		cout<<'\x07'<<flush;
		return 0;
	}
	c=cin.get();
	if(c!='['){
		cout<<'\x07'<<flush;
		return 0;
	}
	c=cin.get();
	if(c=='C')return incvol(vol,5);
	if(c=='D')return incvol(vol,-5);
	if(c=='A')return incvol(vol,100);
	if(c=='B')return incvol(vol,-100);
	cout<<'\x07'<<flush;
	return 0;
}

struct termios tios_bak;

void initscreen(void){
	struct termios tios;
	tcgetattr(0,&tios_bak);
	tios=tios_bak;
	tios.c_lflag&=~(
		ECHO|ECHOE|ECHOKE //no echo of normal characters, erasing and killing
		|ECHOCTL //don't visibly echo control characters (^V etc.)
		|ECHONL //don't even echo a newline
		|ICANON //disable canonical mode
#ifdef NOKERNINFO
		|NOKERNINFO //don't print a status line on ^T
#endif
		|IEXTEN //don't handle things like ^V specially
		//|ISIG //disable ^C ^\ and ^Z
		);
	tios.c_cc[VMIN]=1; //read one char at a time
	tios.c_cc[VTIME]=0; //no timeout on reading, make it a blocking read
	tcsetattr(0,TCSAFLUSH,&tios);
}

void endscreen(void){
	tcsetattr(0,TCSAFLUSH,&tios_bak);
}

int main(int argc,char **argv){
	if(argc>2)return printusage(argc,argv);
	if(argc==2){
		if(argv[1][0]=='\0')return printusage(argc,argv,"Invalid volume format");
		char *endp;
		const int vol=strtol(argv[1],&endp,10);
		if(*endp!='\0')return printusage(argc,argv,"Invalid volume format");
		if(vol<0||vol>100)return printusage(argc,argv,"Volume argument not in range");
		return setvolume(vol);
	}
	if(!isatty(1))return printusage(argc,argv,"Won't display slider if stdout is not a terminal");
	initscreen();
	atexit(endscreen);
	bool m=getmuted();
	int vol=getvolume();
	while(true){
		displayslider(m,vol);
		if(interact(m,vol))break;
	}
	cout<<endl;
}