/*
 * GIT - The information manager from hell
 *
 * Copyright (C) 2000-2002 Michael R. Elkins <me@mutt.org>
 * Copyright (C) 2002-2004 Oswald Buddenhagen <ossi@users.sf.net>
 * Copyright (C) 2004 Theodore Y. Ts'o <tytso@mit.edu>
 * Copyright (C) 2006 Mike McCormack
 * Copyright (C) 2006 Christian Couder
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "cache.h"
#include "quote.h"

/* Get a trace file descriptor from "key" env variable. */
static int get_trace_fd(struct trace_key *key)
{
        static struct trace_key trace_default = { "GIT_TRACE" };
        const char *trace;

        /* use default "GIT_TRACE" if NULL */
        if (!key)
                key = &trace_default;

        /* don't open twice */
        if (key->initialized)
                return key->fd;

        trace = getenv(key->key);

        if (!trace || !strcmp(trace, "") ||
            !strcmp(trace, "0") || !strcasecmp(trace, "false"))
                key->fd = 0;
        else if (!strcmp(trace, "1") || !strcasecmp(trace, "true"))
                key->fd = STDERR_FILENO;
        else if (strlen(trace) == 1 && isdigit(*trace))
                key->fd = atoi(trace);
        else if (is_absolute_path(trace)) {
                int fd = open(trace, O_WRONLY | O_APPEND | O_CREAT, 0666);
                if (fd == -1) {
                        fprintf(stderr,
                                "Could not open '%s' for tracing: %s\n"
                                "Defaulting to tracing on stderr...\n",
                                trace, strerror(errno));
                        key->fd = STDERR_FILENO;
                } else {
                        key->fd = fd;
                        key->need_close = 1;
                }
        } else {
                fprintf(stderr, "What does '%s' for %s mean?\n"
                        "If you want to trace into a file, then please set "
                        "%s to an absolute pathname (starting with /).\n"
                        "Defaulting to tracing on stderr...\n",
                        trace, key->key, key->key);
                key->fd = STDERR_FILENO;
        }

        key->initialized = 1;
        return key->fd;
}

void trace_disable(struct trace_key *key)
{
        if (key->need_close)
                close(key->fd);
        key->fd = 0;
        key->initialized = 1;
        key->need_close = 0;
}

static const char err_msg[] = "Could not trace into fd given by "
        "GIT_TRACE environment variable";

static int prepare_trace_line(const char *file, int line,
                              struct trace_key *key, struct strbuf *buf)
{
        static struct trace_key trace_bare = TRACE_KEY_INIT(BARE);
        struct timeval tv;
        struct tm tm;
        time_t secs;

        if (!trace_want(key))
                return 0;

        set_try_to_free_routine(NULL);  /* is never reset */

        /* unit tests may want to disable additional trace output */
        if (trace_want(&trace_bare))
                return 1;

        /* print current timestamp */
        gettimeofday(&tv, NULL);
        secs = tv.tv_sec;
        localtime_r(&secs, &tm);
        strbuf_addf(buf, "%02d:%02d:%02d.%06ld ", tm.tm_hour, tm.tm_min,
                    tm.tm_sec, (long) tv.tv_usec);

#ifdef HAVE_VARIADIC_MACROS
        /* print file:line */
        strbuf_addf(buf, "%s:%d ", file, line);
        /* align trace output (column 40 catches most files names in git) */
        while (buf->len < 40)
                strbuf_addch(buf, ' ');
#endif

        return 1;
}

static void print_trace_line(struct trace_key *key, struct strbuf *buf)
{
        /* append newline if missing */
        if (buf->len && buf->buf[buf->len - 1] != '\n')
                strbuf_addch(buf, '\n');

        write_or_whine_pipe(get_trace_fd(key), buf->buf, buf->len, err_msg);
        strbuf_release(buf);
}

static void trace_vprintf_fl(const char *file, int line, struct trace_key *key,
                             const char *format, va_list ap)
{
        struct strbuf buf = STRBUF_INIT;

        if (!prepare_trace_line(file, line, key, &buf))
                return;

        strbuf_vaddf(&buf, format, ap);
        print_trace_line(key, &buf);
}

static void trace_argv_vprintf_fl(const char *file, int line,
                                  const char **argv, const char *format,
                                  va_list ap)
{
        struct strbuf buf = STRBUF_INIT;

        if (!prepare_trace_line(file, line, NULL, &buf))
                return;

        strbuf_vaddf(&buf, format, ap);

        sq_quote_argv(&buf, argv, 0);
        print_trace_line(NULL, &buf);
}

void trace_strbuf_fl(const char *file, int line, struct trace_key *key,
                     const struct strbuf *data)
{
        struct strbuf buf = STRBUF_INIT;

        if (!prepare_trace_line(file, line, key, &buf))
                return;

        strbuf_addbuf(&buf, data);
        print_trace_line(key, &buf);
}

static struct trace_key trace_perf_key = TRACE_KEY_INIT(PERFORMANCE);

static void trace_performance_vprintf_fl(const char *file, int line,
                                         uint64_t nanos, const char *format,
                                         va_list ap)
{
        struct strbuf buf = STRBUF_INIT;

        if (!prepare_trace_line(file, line, &trace_perf_key, &buf))
                return;

        strbuf_addf(&buf, "performance: %.9f s", (double) nanos / 1000000000);

        if (format && *format) {
                strbuf_addstr(&buf, ": ");
                strbuf_vaddf(&buf, format, ap);
        }

        print_trace_line(&trace_perf_key, &buf);
}

#ifndef HAVE_VARIADIC_MACROS

void trace_printf(const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_vprintf_fl(NULL, 0, NULL, format, ap);
        va_end(ap);
}

void trace_printf_key(struct trace_key *key, const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_vprintf_fl(NULL, 0, key, format, ap);
        va_end(ap);
}

void trace_argv_printf(const char **argv, const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_argv_vprintf_fl(NULL, 0, argv, format, ap);
        va_end(ap);
}

void trace_strbuf(const char *key, const struct strbuf *data)
{
        trace_strbuf_fl(NULL, 0, key, data);
}

void trace_performance(uint64_t nanos, const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_performance_vprintf_fl(NULL, 0, nanos, format, ap);
        va_end(ap);
}

void trace_performance_since(uint64_t start, const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_performance_vprintf_fl(NULL, 0, getnanotime() - start,
                                     format, ap);
        va_end(ap);
}

#else

void trace_printf_key_fl(const char *file, int line, struct trace_key *key,
                         const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_vprintf_fl(file, line, key, format, ap);
        va_end(ap);
}

void trace_argv_printf_fl(const char *file, int line, const char **argv,
                          const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_argv_vprintf_fl(file, line, argv, format, ap);
        va_end(ap);
}

void trace_performance_fl(const char *file, int line, uint64_t nanos,
                              const char *format, ...)
{
        va_list ap;
        va_start(ap, format);
        trace_performance_vprintf_fl(file, line, nanos, format, ap);
        va_end(ap);
}

#endif /* HAVE_VARIADIC_MACROS */


static const char *quote_crnl(const char *path)
{
        static char new_path[PATH_MAX];
        const char *p2 = path;
        char *p1 = new_path;

        if (!path)
                return NULL;

        while (*p2) {
                switch (*p2) {
                case '\\': *p1++ = '\\'; *p1++ = '\\'; break;
                case '\n': *p1++ = '\\'; *p1++ = 'n'; break;
                case '\r': *p1++ = '\\'; *p1++ = 'r'; break;
                default:
                        *p1++ = *p2;
                }
                p2++;
        }
        *p1 = '\0';
        return new_path;
}

/* FIXME: move prefix to startup_info struct and get rid of this arg */
void trace_repo_setup(const char *prefix)
{
        static struct trace_key key = TRACE_KEY_INIT(SETUP);
        const char *git_work_tree;
        char *cwd;

        if (!trace_want(&key))
                return;

        cwd = xgetcwd();

        if (!(git_work_tree = get_git_work_tree()))
                git_work_tree = "(null)";

        if (!prefix)
                prefix = "(null)";

        trace_printf_key(&key, "setup: git_dir: %s\n", quote_crnl(get_git_dir()));
        trace_printf_key(&key, "setup: worktree: %s\n", quote_crnl(git_work_tree));
        trace_printf_key(&key, "setup: cwd: %s\n", quote_crnl(cwd));
        trace_printf_key(&key, "setup: prefix: %s\n", quote_crnl(prefix));

        free(cwd);
}

int trace_want(struct trace_key *key)
{
        return !!get_trace_fd(key);
}

#ifdef HAVE_CLOCK_GETTIME

static inline uint64_t highres_nanos(void)
{
        struct timespec ts;
        if (clock_gettime(CLOCK_MONOTONIC, &ts))
                return 0;
        return (uint64_t) ts.tv_sec * 1000000000 + ts.tv_nsec;
}

#elif defined (GIT_WINDOWS_NATIVE)

static inline uint64_t highres_nanos(void)
{
        static uint64_t high_ns, scaled_low_ns;
        static int scale;
        LARGE_INTEGER cnt;

        if (!scale) {
                if (!QueryPerformanceFrequency(&cnt))
                        return 0;

                /* high_ns = number of ns per cnt.HighPart */
                high_ns = (1000000000LL << 32) / (uint64_t) cnt.QuadPart;

                /*
                 * Number of ns per cnt.LowPart is 10^9 / frequency (or
                 * high_ns >> 32). For maximum precision, we scale this factor
                 * so that it just fits within 32 bit (i.e. won't overflow if
                 * multiplied with cnt.LowPart).
                 */
                scaled_low_ns = high_ns;
                scale = 32;
                while (scaled_low_ns >= 0x100000000LL) {
                        scaled_low_ns >>= 1;
                        scale--;
                }
        }

        /* if QPF worked on initialization, we expect QPC to work as well */
        QueryPerformanceCounter(&cnt);

        return (high_ns * cnt.HighPart) +
               ((scaled_low_ns * cnt.LowPart) >> scale);
}

#else
# define highres_nanos() 0
#endif

static inline uint64_t gettimeofday_nanos(void)
{
        struct timeval tv;
        gettimeofday(&tv, NULL);
        return (uint64_t) tv.tv_sec * 1000000000 + tv.tv_usec * 1000;
}

/*
 * Returns nanoseconds since the epoch (01/01/1970), for performance tracing
 * (i.e. favoring high precision over wall clock time accuracy).
 */
inline uint64_t getnanotime(void)
{
        static uint64_t offset;
        if (offset > 1) {
                /* initialization succeeded, return offset + high res time */
                return offset + highres_nanos();
        } else if (offset == 1) {
                /* initialization failed, fall back to gettimeofday */
                return gettimeofday_nanos();
        } else {
                /* initialize offset if high resolution timer works */
                uint64_t now = gettimeofday_nanos();
                uint64_t highres = highres_nanos();
                if (highres)
                        offset = now - highres;
                else
                        offset = 1;
                return now;
        }
}

static uint64_t command_start_time;
static struct strbuf command_line = STRBUF_INIT;

static void print_command_performance_atexit(void)
{
        trace_performance_since(command_start_time, "git command:%s",
                                command_line.buf);
}

void trace_command_performance(const char **argv)
{
        if (!trace_want(&trace_perf_key))
                return;

        if (!command_start_time)
                atexit(print_command_performance_atexit);

        strbuf_reset(&command_line);
        sq_quote_argv(&command_line, argv, 0);
        command_start_time = getnanotime();
}