/*
 * Conky, a system monitor, based on torsmo
 *
 * This program is licensed under BSD license, read COPYING
 *
 *  $Id$
 */

#include "top.h"

static regex_t *exclusion_expression = 0;
static unsigned int g_time = 0;
static unsigned long previous_total = 0;
static struct process *first_process = 0;

static struct process *find_process(pid_t pid)
{
	struct process *p = first_process;
	while (p) {
		if (p->pid == pid)
			return p;
		p = p->next;
	}
	return 0;
}

/*
* Create a new process object and insert it into the process list
*/
static struct process *new_process(int p)
{
	struct process *process;
	process = (struct process*)malloc(sizeof(struct process));

	// clean up memory first
	memset(process, 0, sizeof(struct process));

	/*
	 * Do stitching necessary for doubly linked list
	 */
	process->name = 0;
	process->previous = 0;
	process->next = first_process;
	if (process->next)
		process->next->previous = process;
	first_process = process;

	process->pid = p;
	process->time_stamp = 0;
	process->previous_user_time = INT_MAX;
	process->previous_kernel_time = INT_MAX;
	process->counted = 1;

	
	/*    process_find_name(process); */

	return process;
}

/******************************************/
/* Functions                              */
/******************************************/

static int process_parse_stat(struct process *);
static int update_process_table(void);
static int calculate_cpu(struct process *);
static void process_cleanup(void);
static void delete_process(struct process *);
/*inline void draw_processes(void);*/
static unsigned long calc_cpu_total(void);
static void calc_cpu_each(unsigned long);


/******************************************/
/* Extract information from /proc         */
/******************************************/

/*
* These are the guts that extract information out of /proc.
* Anyone hoping to port wmtop should look here first.
*/
static int process_parse_stat(struct process *process)
{
	struct information *cur;
	cur = &info;
	char line[BUFFER_LEN], filename[BUFFER_LEN], procname[BUFFER_LEN];
	int ps;
	unsigned long user_time = 0;
	unsigned long kernel_time = 0;
	int rc;
	char *r, *q;
	char deparenthesised_name[BUFFER_LEN];
	int endl;
	int nice_val;

	snprintf(filename, sizeof(filename), PROCFS_TEMPLATE,
		 process->pid);

	ps = open(filename, O_RDONLY);
	if (ps < 0)
		/*
		 * The process must have finished in the last few jiffies!
		 */
		return 1;

	/*
	 * Mark process as up-to-date.
	 */
	process->time_stamp = g_time;

	rc = read(ps, line, sizeof(line));
	close(ps);
	if (rc < 0)
		return 1;

	/*
	 * Extract cpu times from data in /proc filesystem
	 */
	rc = sscanf(line,
		    "%*s %s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %*s %lu %lu %*s %*s %*s %d %*s %*s %*s %d %d",
		    procname, &process->user_time, &process->kernel_time,
		    &nice_val, &process->vsize, &process->rss);
	if (rc < 5)
		return 1;
	/*
	 * Remove parentheses from the process name stored in /proc/ under Linux...
	 */
	r = procname + 1;
	/* remove any "kdeinit: " */
	if (r == strstr(r, "kdeinit")) {
		snprintf(filename, sizeof(filename),
			 PROCFS_CMDLINE_TEMPLATE, process->pid);

		ps = open(filename, O_RDONLY);
		if (ps < 0)
			/*
			 * The process must have finished in the last few jiffies!
			 */
			return 1;

		endl = read(ps, line, sizeof(line));
		close(ps);

		/* null terminate the input */
		line[endl] = 0;
		/* account for "kdeinit: " */
		if ((char *) line == strstr(line, "kdeinit: "))
			r = ((char *) line) + 9;
		else
			r = (char *) line;

		q = deparenthesised_name;
		/* stop at space */
		while (*r && *r != ' ')
			*q++ = *r++;
		*q = 0;
	} else {
		q = deparenthesised_name;
		while (*r && *r != ')')
			*q++ = *r++;
		*q = 0;
	}

	if (process->name)
		free(process->name);
	process->name = strdup(deparenthesised_name);
	process->rss *= getpagesize();

	if (!cur->memmax)
		update_total_processes();

	process->totalmem = ((float) process->rss / cur->memmax) / 10;

	if (process->previous_user_time == ULONG_MAX)
		process->previous_user_time = process->user_time;
	if (process->previous_kernel_time == ULONG_MAX)
		process->previous_kernel_time = process->kernel_time;

	/* store the difference of the user_time */
	user_time = process->user_time - process->previous_user_time;
	kernel_time = process->kernel_time - process->previous_kernel_time;

	/* backup the process->user_time for next time around */
	process->previous_user_time = process->user_time;
	process->previous_kernel_time = process->kernel_time;

	/* store only the difference of the user_time here... */
	process->user_time = user_time;
	process->kernel_time = kernel_time;


	return 0;
}

/******************************************/
/* Update process table                   */
/******************************************/

static int update_process_table()
{
	DIR *dir;
	struct dirent *entry;

	if (!(dir = opendir("/proc")))
		return 1;

	++g_time;

	/*
	 * Get list of processes from /proc directory
	 */
	while ((entry = readdir(dir))) {
		pid_t pid;

		if (!entry) {
			/*
			 * Problem reading list of processes
			 */
			closedir(dir);
			return 1;
		}

		if (sscanf(entry->d_name, "%d", &pid) > 0) {
			struct process *p;
			p = find_process(pid);
			if (!p)
				p = new_process(pid);

			/* compute each process cpu usage */
			calculate_cpu(p);
		}
	}

	closedir(dir);

	return 0;
}

/******************************************/
/* Get process structure for process pid  */
/******************************************/

/*
* This function seems to hog all of the CPU time. I can't figure out why - it
* doesn't do much.
*/
static int calculate_cpu(struct process *process)
{
	int rc;

	/* compute each process cpu usage by reading /proc/<proc#>/stat */
	rc = process_parse_stat(process);
	if (rc)
		return 1;
	/*rc = process_parse_statm(process);
	   if (rc)
	   return 1; */

	/*
	 * Check name against the exclusion list
	 */
	if (process->counted && exclusion_expression
	    && !regexec(exclusion_expression, process->name, 0, 0, 0))
		process->counted = 0;

	return 0;
}

/******************************************/
/* Strip dead process entries             */
/******************************************/

static void process_cleanup()
{

	struct process *p = first_process;
	while (p) {
		struct process *current = p;

#if defined(PARANOID)
		assert(p->id == 0x0badfeed);
#endif				/* defined(PARANOID) */

		p = p->next;
		/*
		 * Delete processes that have died
		 */
		if (current->time_stamp != g_time)
			delete_process(current);
	}
}

/******************************************/
/* Destroy and remove a process           */
/******************************************/

static void delete_process(struct process *p)
{
#if defined(PARANOID)
	assert(p->id == 0x0badfeed);

	/*
	 * Ensure that deleted processes aren't reused.
	 */
	p->id = 0x007babe;
#endif				/* defined(PARANOID) */

	/*
	 * Maintain doubly linked list.
	 */
	if (p->next)
		p->next->previous = p->previous;
	if (p->previous)
		p->previous->next = p->next;
	else
		first_process = p->next;

	if (p->name)
		free(p->name);
	free(p);
}

/******************************************/
/* Calculate cpu total                    */
/******************************************/

static unsigned long calc_cpu_total()
{
	unsigned long total = 0;
	unsigned long t = 0;
	int rc;
	int ps;
	char line[BUFFER_LEN];
	unsigned long cpu = 0;
	unsigned long nice = 0;
	unsigned long system = 0;
	unsigned long idle = 0;

	ps = open("/proc/stat", O_RDONLY);
	rc = read(ps, line, sizeof(line));
	close(ps);
	if (rc < 0)
		return 0;
	sscanf(line, "%*s %lu %lu %lu %lu", &cpu, &nice, &system, &idle);
	total = cpu + nice + system + idle;

	t = total - previous_total;
	previous_total = total;


	return t;
}

/******************************************/
/* Calculate each processes cpu           */
/******************************************/

inline static void calc_cpu_each(unsigned long total)
{
	struct process *p = first_process;
	while (p) {
		/*p->amount = total ?
		   (100.0 * (float) (p->user_time + p->kernel_time) /
		   total) : 0; */
		p->amount =
		    (100.0 * (p->user_time + p->kernel_time) / total);

/*		if (p->amount > 100)
		p->amount = 0;*/
		p = p->next;
	}
}

/******************************************/
/* Find the top processes                 */
/******************************************/

/*
* Result is stored in decreasing order in best[0-9].
*/
#define MAX_TOP_SIZE 400 /* this is plenty big */
static struct process **sorttmp;
static size_t sorttmp_size = 1;

int comparecpu(const void * a, const void * b)
{
	if ((*(struct process **)a)->amount > (*(struct process **)b)->amount) {
		return -1;
	}
	if ((*(struct process **)a)->amount < (*(struct process **)b)->amount) {
		return 1;
	}
	return 0;
}

int comparemem(const void * a, const void * b)
{
	if ((*(struct process **)a)->totalmem > (*(struct process **)b)->totalmem) {
		return -1;
	}
	if ((*(struct process **)a)->totalmem < (*(struct process **)b)->totalmem) {
		return 1;
	}
	return 0;
}

inline void process_find_top(struct process **cpu, struct process **mem)
{
	struct process *pr;
	if (sorttmp == NULL) {
		sorttmp = malloc(sizeof(struct process) * sorttmp_size);
		assert(sorttmp != NULL);
	}
	unsigned long total = 0;
	unsigned long i, j;

	total = calc_cpu_total();	/* calculate the total of the processor */

	update_process_table();	/* update the table with process list */
	calc_cpu_each(total);	/* and then the percentage for each task */
	process_cleanup();	/* cleanup list from exited processes */

	/*
	 * this is really ugly,
	 * not to mention probably not too efficient.
	 * the main problem is that there could be any number of processes,
	 * however we have to use a fixed size for the "best" array.
	 * right now i can't think of a better way to do this,
	 * although i'm sure there is one.
	 * Perhaps just using a linked list would be more effecient?
	 * I'm too fucking lazy to do that right now.
	 */
	if (top_cpu) {
		pr = first_process;
		i = 0;
		while (pr) {
			if (i < sorttmp_size && pr->counted) {
				sorttmp[i] = pr;
				i++;
			} else if (i == sorttmp_size && pr->counted && sorttmp_size < MAX_TOP_SIZE) {
				sorttmp_size++;
				sorttmp =
				    realloc(sorttmp,
					    sizeof(struct process) *
					    sorttmp_size);
				sorttmp[i] = pr;
				i++;
			}
			pr = pr->next;
		}
		if (i + 1 < sorttmp_size) {
			sorttmp_size--;
			sorttmp =
			    realloc(sorttmp,
				    sizeof(struct process) * sorttmp_size);
		}
		qsort(sorttmp, i, sizeof(struct process *), comparecpu);
		for (i = 0; i < 10; i++) {
			cpu[i] = sorttmp[i];
		}
	}
	if (top_mem) {
		pr = first_process;
		i = 0;
		while (pr) {
			if (i < sorttmp_size && pr->counted) {
				sorttmp[i] = pr;
				i++;
			} else if (i == sorttmp_size && pr->counted && sorttmp_size < MAX_TOP_SIZE) {
				sorttmp_size++;
				sorttmp =
				    realloc(sorttmp,
					    sizeof(struct process) *
					    sorttmp_size);
				sorttmp[i] = pr;
				i++;
			}
			pr = pr->next;
		}
		if (i + 1 < sorttmp_size) {
			sorttmp_size--;
			sorttmp =
			    realloc(sorttmp,
				    sizeof(struct process) * sorttmp_size);
		}
		qsort(sorttmp, i, sizeof(struct process *), comparemem);
		sorttmp_size = i;
		for (i = 0, j = 0; i < sorttmp_size && j < 10; i++) {
			if (j == 0 || sorttmp[i]->totalmem != mem[j-1]->totalmem
					|| strncmp(sorttmp[i]->name, mem[j-1]->name,128)) {
				mem[j++] = sorttmp[i];
			}
		}
	}
}