/*
 * Simple text-based progress display module for GIT
 *
 * Copyright (c) 2007 by Nicolas Pitre <nico@fluxnic.net>
 *
 * This code is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include "git-compat-util.h"
#include "gettext.h"
#include "progress.h"
#include "strbuf.h"
#include "trace.h"

#define TP_IDX_MAX      8

struct throughput {
        off_t curr_total;
        off_t prev_total;
        uint64_t prev_ns;
        unsigned int avg_bytes;
        unsigned int avg_misecs;
        unsigned int last_bytes[TP_IDX_MAX];
        unsigned int last_misecs[TP_IDX_MAX];
        unsigned int idx;
        struct strbuf display;
};

struct progress {
        const char *title;
        int last_value;
        unsigned total;
        unsigned last_percent;
        unsigned delay;
        unsigned delayed_percent_threshold;
        struct throughput *throughput;
        uint64_t start_ns;
};

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 is_foreground_fd(int fd)
{
        int tpgrp = tcgetpgrp(fd);
        return tpgrp < 0 || tpgrp == getpgid(0);
}

static int display(struct progress *progress, unsigned n, const char *done)
{
        const 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_threshold) {
                                /* 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.buf : "";
        eol = done ? done : "   \r";
        if (progress->total) {
                unsigned percent = n * 100 / progress->total;
                if (percent != progress->last_percent || progress_update) {
                        progress->last_percent = percent;
                        if (is_foreground_fd(fileno(stderr)) || done) {
                                fprintf(stderr, "%s: %3u%% (%u/%u)%s%s",
                                        progress->title, percent, n,
                                        progress->total, tp, eol);
                                fflush(stderr);
                        }
                        progress_update = 0;
                        return 1;
                }
        } else if (progress_update) {
                if (is_foreground_fd(fileno(stderr)) || done) {
                        fprintf(stderr, "%s: %u%s%s",
                                progress->title, n, tp, eol);
                        fflush(stderr);
                }
                progress_update = 0;
                return 1;
        }

        return 0;
}

static void throughput_string(struct strbuf *buf, off_t total,
                              unsigned int rate)
{
        strbuf_reset(buf);
        strbuf_addstr(buf, ", ");
        strbuf_humanise_bytes(buf, total);
        strbuf_addstr(buf, " | ");
        strbuf_humanise_bytes(buf, rate * 1024);
        strbuf_addstr(buf, "/s");
}

void display_throughput(struct progress *progress, off_t total)
{
        struct throughput *tp;
        uint64_t now_ns;
        unsigned int misecs, count, rate;

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

        now_ns = getnanotime();

        if (!tp) {
                progress->throughput = tp = calloc(1, sizeof(*tp));
                if (tp) {
                        tp->prev_total = tp->curr_total = total;
                        tp->prev_ns = now_ns;
                        strbuf_init(&tp->display, 0);
                }
                return;
        }
        tp->curr_total = total;

        /* only update throughput every 0.5 s */
        if (now_ns - tp->prev_ns <= 500000000)
                return;

        /*
         * We have x = bytes and y = nanosecs.  We want z = KiB/s:
         *
         *      z = (x / 1024) / (y / 1000000000)
         *      z = x / y * 1000000000 / 1024
         *      z = x / (y * 1024 / 1000000000)
         *      z = x / y'
         *
         * To simplify things we'll keep track of misecs, or 1024th of a sec
         * obtained with:
         *
         *      y' = y * 1024 / 1000000000
         *      y' = y * (2^10 / 2^42) * (2^42 / 1000000000)
         *      y' = y / 2^32 * 4398
         *      y' = (y * 4398) >> 32
         */
        misecs = ((now_ns - tp->prev_ns) * 4398) >> 32;

        count = total - tp->prev_total;
        tp->prev_total = total;
        tp->prev_ns = now_ns;
        tp->avg_bytes += count;
        tp->avg_misecs += misecs;
        rate = 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] = count;
        tp->last_misecs[tp->idx] = misecs;
        tp->idx = (tp->idx + 1) % TP_IDX_MAX;

        throughput_string(&tp->display, total, rate);
        if (progress->last_value != -1 && progress_update)
                display(progress, progress->last_value, NULL);
}

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

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

struct progress *start_delayed_progress(const char *title, unsigned total)
{
        return start_progress_delay(title, total, 0, 2);
}

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

void stop_progress(struct progress **p_progress)
{
        stop_progress_msg(p_progress, _("done"));
}

void stop_progress_msg(struct progress **p_progress, const char *msg)
{
        struct progress *progress = *p_progress;
        if (!progress)
                return;
        *p_progress = NULL;
        if (progress->last_value != -1) {
                /* Force the last update */
                char *buf;
                struct throughput *tp = progress->throughput;

                if (tp) {
                        uint64_t now_ns = getnanotime();
                        unsigned int misecs, rate;
                        misecs = ((now_ns - progress->start_ns) * 4398) >> 32;
                        rate = tp->curr_total / (misecs ? misecs : 1);
                        throughput_string(&tp->display, tp->curr_total, rate);
                }
                progress_update = 1;
                buf = xstrfmt(", %s.\n", msg);
                display(progress, progress->last_value, buf);
                free(buf);
        }
        clear_progress_signal();
        if (progress->throughput)
                strbuf_release(&progress->throughput->display);
        free(progress->throughput);
        free(progress);
}