#ifndef PROFILER_H
#define PROFILER_H

#ifndef PROFILER
#define PROFILER 1
#endif

#if PROFILER

#include <stdlib.h> /* malloc */
#include <string.h> /* memset */
#include <time.h> /* clock_gettime */
#include <stdio.h>

unsigned long long profiler_get_time()
{
    struct timespec ts;
    
    if(clock_gettime(CLOCK_MONOTONIC_RAW, &ts) == 0) {
        return (unsigned long long)ts.tv_sec * 1000000000ULL +
               (unsigned long long)ts.tv_nsec;
    }

    return 0ULL;
}

struct profiler_block {
    const char *name;

    unsigned long long start;
    unsigned long long end;
};

struct profiler_tree_node {
    struct profiler_block data;

    struct profiler_tree_node *parent; /* null for root node */

    struct profiler_tree_node *prev_sibling; /* doubly-linked list */
    struct profiler_tree_node *next_sibling;

    int children_count;
    struct profiler_tree_node *first_child;
    struct profiler_tree_node *last_child;
};

struct profiler_tree_node *profiler_root_node = 0;
struct profiler_tree_node *profiler_last_node = 0;

static struct profiler_tree_node *profiler_tree_node(const char *name)
{
    struct profiler_tree_node *node =
        malloc(sizeof(struct profiler_tree_node));
    memset(node, 0, sizeof(struct profiler_tree_node));
    node->data.name = name;
    return node;
}

void profiler_begin(const char *name)
{
    if(!profiler_root_node) { /* create root node */
        profiler_root_node = profiler_tree_node("TOTAL");
        profiler_last_node = profiler_root_node;
    }

    struct profiler_tree_node *node = profiler_tree_node(name);
    node->data.start = profiler_get_time();
    node->parent = profiler_last_node;

    if(!profiler_last_node->last_child) {
        profiler_last_node->first_child = node;
        profiler_last_node->last_child = node;
    } else {
        profiler_last_node->last_child->next_sibling = node;
        node->prev_sibling = profiler_last_node->last_child;
        profiler_last_node->last_child = node;
    }
    profiler_last_node->children_count++;

    profiler_last_node = node;
}

static void profiler_do_print(struct profiler_tree_node *node,
                              int indent_level)
{
    if(node) {
        unsigned long long difference;

        int i;
        for(i = 0; i < indent_level; i++)
            fprintf(stderr, "    ");

        difference = node->data.end - node->data.start;

        fprintf(stderr, "[%s] %lld ns (%.6f ms)\n",
                node->data.name,
                difference,
                (double)(difference) / 1000000.0);

        if(node->first_child) {
            profiler_do_print(node->first_child, indent_level+1);
        }
        if(node->next_sibling) {
            profiler_do_print(node->next_sibling, indent_level);
        }
    }
}

void profiler_print()
{
    profiler_do_print(profiler_root_node->first_child, 0);
}

void profiler_end()
{
    profiler_last_node->data.end = profiler_get_time();
    profiler_last_node = profiler_last_node->parent;
}

#else

#define profiler_begin(...)
#define profiler_end(...)
#define profiler_print(...)

#endif

#endif /* profiler_h */