#include "git-compat-util.h"
#include "progress.h"

#define TP_IDX_MAX      8

struct throughput {
        struct timeval prev_tv;
        unsigned long count;
        unsigned long avg_bytes;
        unsigned long last_bytes[TP_IDX_MAX];
        unsigned int avg_misecs;
        unsigned int last_misecs[TP_IDX_MAX];
        unsigned int idx;
        char display[20];
};

struct progress {
        const char *title;
        int last_value;
        unsigned total;
        unsigned last_percent;
        unsigned delay;
        unsigned delayed_percent_treshold;
        struct throughput *throughput;
};

static volatile sig_atomic_t progress_update;

static void progress_interval(int signum)
{
        progress_update = 1;
}

static void set_progress_signal(void)
{
        struct sigaction sa;
        struct itimerval v;

        progress_update = 0;

        memset(&sa, 0, sizeof(sa));
        sa.sa_handler = progress_interval;
        sigemptyset(&sa.sa_mask);
        sa.sa_flags = SA_RESTART;
        sigaction(SIGALRM, &sa, NULL);

        v.it_interval.tv_sec = 1;
        v.it_interval.tv_usec = 0;
        v.it_value = v.it_interval;
        setitimer(ITIMER_REAL, &v, NULL);
}

static void clear_progress_signal(void)
{
        struct itimerval v = {{0,},};
        setitimer(ITIMER_REAL, &v, NULL);
        signal(SIGALRM, SIG_IGN);
        progress_update = 0;
}

static int display(struct progress *progress, unsigned n, int done)
{
        char *eol, *tp;

        if (progress->delay) {
                if (!progress_update || --progress->delay)
                        return 0;
                if (progress->total) {
                        unsigned percent = n * 100 / progress->total;
                        if (percent > progress->delayed_percent_treshold) {
                                /* inhibit this progress report entirely */
                                clear_progress_signal();
                                progress->delay = -1;
                                progress->total = 0;
                                return 0;
                        }
                }
        }

        progress->last_value = n;
        tp = (progress->throughput) ? progress->throughput->display : "";
        eol = done ? ", done.   \n" : "   \r";
        if (progress->total) {
                unsigned percent = n * 100 / progress->total;
                if (percent != progress->last_percent || progress_update) {
                        progress->last_percent = percent;
                        fprintf(stderr, "%s: %3u%% (%u/%u)%s%s",
                                progress->title, percent, n,
                                progress->total, tp, eol);
                        progress_update = 0;
                        return 1;
                }
        } else if (progress_update) {
                fprintf(stderr, "%s: %u%s%s", progress->title, n, tp, eol);
                progress_update = 0;
                return 1;
        }

        return 0;
}

void display_throughput(struct progress *progress, unsigned long n)
{
        struct throughput *tp;
        struct timeval tv;
        unsigned int misecs;

        if (!progress)
                return;
        tp = progress->throughput;

        gettimeofday(&tv, NULL);

        if (!tp) {
                progress->throughput = tp = calloc(1, sizeof(*tp));
                if (tp)
                        tp->prev_tv = tv;
                return;
        }

        tp->count += n;

        /*
         * We have x = bytes and y = microsecs.  We want z = KiB/s:
         *
         *      z = (x / 1024) / (y / 1000000)
         *      z = x / y * 1000000 / 1024
         *      z = x / (y * 1024 / 1000000)
         *      z = x / y'
         *
         * To simplify things we'll keep track of misecs, or 1024th of a sec
         * obtained with:
         *
         *      y' = y * 1024 / 1000000
         *      y' = y / (1000000 / 1024)
         *      y' = y / 977
         */
        misecs = (tv.tv_sec - tp->prev_tv.tv_sec) * 1024;
        misecs += (int)(tv.tv_usec - tp->prev_tv.tv_usec) / 977;

        if (misecs > 512) {
                tp->prev_tv = tv;
                tp->avg_bytes += tp->count;
                tp->avg_misecs += misecs;
                snprintf(tp->display, sizeof(tp->display),
                         ", %lu KiB/s", tp->avg_bytes / tp->avg_misecs);
                tp->avg_bytes -= tp->last_bytes[tp->idx];
                tp->avg_misecs -= tp->last_misecs[tp->idx];
                tp->last_bytes[tp->idx] = tp->count;
                tp->last_misecs[tp->idx] = misecs;
                tp->idx = (tp->idx + 1) % TP_IDX_MAX;
                tp->count = 0;
        }
}

int display_progress(struct progress *progress, unsigned n)
{
        return progress ? display(progress, n, 0) : 0;
}

struct progress *start_progress_delay(const char *title, unsigned total,
                                       unsigned percent_treshold, unsigned delay)
{
        struct progress *progress = malloc(sizeof(*progress));
        if (!progress) {
                /* unlikely, but here's a good fallback */
                fprintf(stderr, "%s...\n", title);
                return NULL;
        }
        progress->title = title;
        progress->total = total;
        progress->last_value = -1;
        progress->last_percent = -1;
        progress->delayed_percent_treshold = percent_treshold;
        progress->delay = delay;
        progress->throughput = NULL;
        set_progress_signal();
        return progress;
}

struct progress *start_progress(const char *title, unsigned total)
{
        return start_progress_delay(title, total, 0, 0);
}

void stop_progress(struct progress **p_progress)
{
        struct progress *progress = *p_progress;
        if (!progress)
                return;
        *p_progress = NULL;
        if (progress->last_value != -1) {
                /* Force the last update */
                progress_update = 1;
                display(progress, progress->last_value, 1);
        }
        clear_progress_signal();
        free(progress->throughput);
        free(progress);
}