//
//  ProcessLister.m
//  Top
//
//  Created by Simon Brenner on 2008-01-01.
//  Copyright 2008 __MyCompanyName__. All rights reserved.
//

#import "ProcessLister.h"
#include <sys/sysctl.h>

@implementation ProcessLister

+(NSMutableArray*)allProcesses
{
	    // --- Defining local variables for this function and initializing all to zero --- //
    int mib[6] = {0,0,0,0,0,0}; //used for sysctl call.
    int SuccessfullyGotProcessInformation;
    size_t sizeOfBufferRequired = 0; //set to zero to start with.
    int error = 0;
    long NumberOfRunningProcesses = 0;
    struct kinfo_proc* BSDProcessInformationStructure = NULL;

	NSMutableArray *returnArray = [NSMutableArray new];

    //--- Getting list of process information for all processes --- //
    
    /* Setting up the mib (Management Information Base) which is an array of integers where each
    * integer specifies how the data will be gathered.  Here we are setting the MIB
    * block to lookup the information on all the BSD processes on the system.  Also note that
    * every regular application has a recognized BSD process accociated with it.  We pass
    * CTL_KERN, KERN_PROC, KERN_PROC_ALL to sysctl as the MIB to get back a BSD structure with
    * all BSD process information for all processes in it (including BSD process names)
    */
    mib[0] = CTL_KERN;
    mib[1] = KERN_PROC;
    mib[2] = KERN_PROC_ALL;

    /* Here we have a loop set up where we keep calling sysctl until we finally get an unrecoverable error
    * (and we return) or we finally get a succesful result.  Note with how dynamic the process list can
    * be you can expect to have a failure here and there since the process list can change between
    * getting the size of buffer required and the actually filling that buffer.
    */
    SuccessfullyGotProcessInformation = FALSE;
    
    while (SuccessfullyGotProcessInformation == FALSE)
    {
        /* Now that we have the MIB for looking up process information we will pass it to sysctl to get the 
        * information we want on BSD processes.  However, before we do this we must know the size of the buffer to 
        * allocate to accomidate the return value.  We can get the size of the data to allocate also using the 
        * sysctl command.  In this case we call sysctl with the proper arguments but specify no return buffer 
        * specified (null buffer).  This is a special case which causes sysctl to return the size of buffer required.
        *
        * First Argument: The MIB which is really just an array of integers.  Each integer is a constant
        *     representing what information to gather from the system.  Check out the man page to know what
        *     constants sysctl will work with.  Here of course we pass our MIB block which was passed to us.
        * Second Argument: The number of constants in the MIB (array of integers).  In this case there are three.
        * Third Argument: The output buffer where the return value from sysctl will be stored.  In this case
        *     we don't want anything return yet since we don't yet know the size of buffer needed.  Thus we will
        *     pass null for the buffer to begin with.
        * Forth Argument: The size of the output buffer required.  Since the buffer itself is null we can just
        *     get the buffer size needed back from this call.
        * Fifth Argument: The new value we want the system data to have.  Here we don't want to set any system
        *     information we only want to gather it.  Thus, we pass null as the buffer so sysctl knows that 
        *     we have no desire to set the value.
        * Sixth Argument: The length of the buffer containing new information (argument five).  In this case
        *     argument five was null since we didn't want to set the system value.  Thus, the size of the buffer
        *     is zero or NULL.
        * Return Value: a return value indicating success or failure.  Actually, sysctl will either return
        *     zero on no error and -1 on error.  The errno UNIX variable will be set on error.
        */ 
        error = sysctl(mib, 3, NULL, &sizeOfBufferRequired, NULL, 0);

        /* If an error occurred then return the accociated error.  The error itself actually is stored in the UNIX 
        * errno variable.  We can access the errno value using the errno global variable.  We will return the 
        * errno value as the sysctlError return value from this function.
        */
        if (error) 
        {
			perror("sysctl to get sizeofBufferRequired");
            return NULL;
        }
    
        /* Now we successful obtained the size of the buffer required for the sysctl call.  This is stored in the 
        * SizeOfBufferRequired variable.  We will malloc a buffer of that size to hold the sysctl result.
        */
        BSDProcessInformationStructure = (struct kinfo_proc*) malloc(sizeOfBufferRequired);

        if (BSDProcessInformationStructure == NULL)
        {
			printf("OOM allocating BSDProcessInformationStructure\n");
			return NULL;
        }
    
        /* Now we have the buffer of the correct size to hold the result we can now call sysctl
        * and get the process information.  
        *
        * First Argument: The MIB for gathering information on running BSD processes.  The MIB is really 
        *     just an array of integers.  Each integer is a constant representing what information to 
        *     gather from the system.  Check out the man page to know what constants sysctl will work with.  
        * Second Argument: The number of constants in the MIB (array of integers).  In this case there are three.
        * Third Argument: The output buffer where the return value from sysctl will be stored.  This is the buffer
        *     which we allocated specifically for this purpose.  
        * Forth Argument: The size of the output buffer (argument three).  In this case its the size of the 
        *     buffer we already allocated.  
        * Fifth Argument: The buffer containing the value to set the system value to.  In this case we don't
        *     want to set any system information we only want to gather it.  Thus, we pass null as the buffer
        *     so sysctl knows that we have no desire to set the value.
        * Sixth Argument: The length of the buffer containing new information (argument five).  In this case
        *     argument five was null since we didn't want to set the system value.  Thus, the size of the buffer
        *     is zero or NULL.
        * Return Value: a return value indicating success or failure.  Actually, sysctl will either return 
        *     zero on no error and -1 on error.  The errno UNIX variable will be set on error.
        */ 
        error = sysctl(mib, 3, BSDProcessInformationStructure, &sizeOfBufferRequired, NULL, 0);
    
        //Here we successfully got the process information.  Thus set the variable to end this sysctl calling loop
        if (error == 0)
        {
            SuccessfullyGotProcessInformation = TRUE;
        }
        else 
        {
            /* failed getting process information we will try again next time around the loop.  Note this is caused
            * by the fact the process list changed between getting the size of the buffer and actually filling
            * the buffer (something which will happen from time to time since the process list is dynamic).
            * Anyways, the attempted sysctl call failed.  We will now begin again by freeing up the allocated 
            * buffer and starting again at the beginning of the loop.
            */
            free(BSDProcessInformationStructure); 
        }
    }//end while loop

    // --- Going through process list looking for processes with matching names --- //

    /* Now that we have the BSD structure describing the running processes we will parse it for the desired
     * process name.  First we will the number of running processes.  We can determine
     * the number of processes running because there is a kinfo_proc structure for each process.
     */
    NumberOfRunningProcesses = sizeOfBufferRequired / sizeof(struct kinfo_proc);  
    
    /* Now we will go through each process description checking to see if the process name matches that
     * passed to us.  The BSDProcessInformationStructure has an array of kinfo_procs.  Each kinfo_proc has
     * an extern_proc accociated with it in the kp_proc attribute.  Each extern_proc (kp_proc) has the process name
     * of the process accociated with it in the p_comm attribute and the PID of that process in the p_pid attibute.
     * We test the process name by compairing the process name passed to us with the value in the p_comm value.
     * Note we limit the compairison to MAXCOMLEN which is the maximum length of a BSD process name which is used
     * by the system. 
     */
    for (int i = 0; i < NumberOfRunningProcesses; i++)
    {
        //Getting PID of process we are examining
        pid_t pid = BSDProcessInformationStructure[i].kp_proc.p_pid; 
    
        //Getting name of process we are examining
        const char *name = BSDProcessInformationStructure[i].kp_proc.p_comm; 
		
		fixpt_t	cpuPercent = BSDProcessInformationStructure[i].kp_proc.p_pctcpu;
		u_int estcpu = BSDProcessInformationStructure[i].kp_proc.p_estcpu;
		int ticks = BSDProcessInformationStructure[i].kp_proc.p_cpticks;
		
		u_quad_t uticks = BSDProcessInformationStructure[i].kp_proc.p_uticks;
		u_quad_t sticks = BSDProcessInformationStructure[i].kp_proc.p_sticks;
		u_quad_t iticks = BSDProcessInformationStructure[i].kp_proc.p_iticks;
        
        if (pid > 0)
        {
			printf("%5d: %5lld %5lld %5lld %s\n", pid, uticks, sticks, iticks, name);
			
			if(strcmp(name, "cat") == 0)
				abort();
			
			[returnArray addObject: [NSString stringWithCString: name]];
        }
    }//end looking through process list

    free(BSDProcessInformationStructure); //done with allocated buffer so release.

    return returnArray;
}

+(NSMutableArray*)interestingProcesses:(double)minPercent
{
	return NULL;
}

@end