#include "cache.h"
#include "pkt-line.h"

static const char *packet_trace_prefix = "git";
static const char trace_key[] = "GIT_TRACE_PACKET";

void packet_trace_identity(const char *prog)
{
        packet_trace_prefix = xstrdup(prog);
}

static void packet_trace(const char *buf, unsigned int len, int write)
{
        int i;
        struct strbuf out;

        if (!trace_want(trace_key))
                return;

        /* +32 is just a guess for header + quoting */
        strbuf_init(&out, len+32);

        strbuf_addf(&out, "packet: %12s%c ",
                    packet_trace_prefix, write ? '>' : '<');

        if ((len >= 4 && !prefixcmp(buf, "PACK")) ||
            (len >= 5 && !prefixcmp(buf+1, "PACK"))) {
                strbuf_addstr(&out, "PACK ...");
                unsetenv(trace_key);
        }
        else {
                /* XXX we should really handle printable utf8 */
                for (i = 0; i < len; i++) {
                        /* suppress newlines */
                        if (buf[i] == '\n')
                                continue;
                        if (buf[i] >= 0x20 && buf[i] <= 0x7e)
                                strbuf_addch(&out, buf[i]);
                        else
                                strbuf_addf(&out, "\\%o", buf[i]);
                }
        }

        strbuf_addch(&out, '\n');
        trace_strbuf(trace_key, &out);
        strbuf_release(&out);
}

/*
 * Write a packetized stream, where each line is preceded by
 * its length (including the header) as a 4-byte hex number.
 * A length of 'zero' means end of stream (and a length of 1-3
 * would be an error).
 *
 * This is all pretty stupid, but we use this packetized line
 * format to make a streaming format possible without ever
 * over-running the read buffers. That way we'll never read
 * into what might be the pack data (which should go to another
 * process entirely).
 *
 * The writing side could use stdio, but since the reading
 * side can't, we stay with pure read/write interfaces.
 */
ssize_t safe_write(int fd, const void *buf, ssize_t n)
{
        ssize_t nn = n;
        while (n) {
                int ret = xwrite(fd, buf, n);
                if (ret > 0) {
                        buf = (char *) buf + ret;
                        n -= ret;
                        continue;
                }
                if (!ret)
                        die("write error (disk full?)");
                die_errno("write error");
        }
        return nn;
}

/*
 * If we buffered things up above (we don't, but we should),
 * we'd flush it here
 */
void packet_flush(int fd)
{
        packet_trace("0000", 4, 1);
        safe_write(fd, "0000", 4);
}

void packet_buf_flush(struct strbuf *buf)
{
        packet_trace("0000", 4, 1);
        strbuf_add(buf, "0000", 4);
}

#define hex(a) (hexchar[(a) & 15])
static char buffer[1000];
static unsigned format_packet(const char *fmt, va_list args)
{
        static char hexchar[] = "0123456789abcdef";
        unsigned n;

        n = vsnprintf(buffer + 4, sizeof(buffer) - 4, fmt, args);
        if (n >= sizeof(buffer)-4)
                die("protocol error: impossibly long line");
        n += 4;
        buffer[0] = hex(n >> 12);
        buffer[1] = hex(n >> 8);
        buffer[2] = hex(n >> 4);
        buffer[3] = hex(n);
        packet_trace(buffer+4, n-4, 1);
        return n;
}

void packet_write(int fd, const char *fmt, ...)
{
        va_list args;
        unsigned n;

        va_start(args, fmt);
        n = format_packet(fmt, args);
        va_end(args);
        safe_write(fd, buffer, n);
}

void packet_buf_write(struct strbuf *buf, const char *fmt, ...)
{
        va_list args;
        unsigned n;

        va_start(args, fmt);
        n = format_packet(fmt, args);
        va_end(args);
        strbuf_add(buf, buffer, n);
}

static void safe_read(int fd, void *buffer, unsigned size)
{
        ssize_t ret = read_in_full(fd, buffer, size);
        if (ret < 0)
                die_errno("read error");
        else if (ret < size)
                die("The remote end hung up unexpectedly");
}

static int packet_length(const char *linelen)
{
        int n;
        int len = 0;

        for (n = 0; n < 4; n++) {
                unsigned char c = linelen[n];
                len <<= 4;
                if (c >= '0' && c <= '9') {
                        len += c - '0';
                        continue;
                }
                if (c >= 'a' && c <= 'f') {
                        len += c - 'a' + 10;
                        continue;
                }
                if (c >= 'A' && c <= 'F') {
                        len += c - 'A' + 10;
                        continue;
                }
                return -1;
        }
        return len;
}

int packet_read_line(int fd, char *buffer, unsigned size)
{
        int len;
        char linelen[4];

        safe_read(fd, linelen, 4);
        len = packet_length(linelen);
        if (len < 0)
                die("protocol error: bad line length character: %.4s", linelen);
        if (!len) {
                packet_trace("0000", 4, 0);
                return 0;
        }
        len -= 4;
        if (len >= size)
                die("protocol error: bad line length %d", len);
        safe_read(fd, buffer, len);
        buffer[len] = 0;
        packet_trace(buffer, len, 0);
        return len;
}

int packet_get_line(struct strbuf *out,
        char **src_buf, size_t *src_len)
{
        int len;

        if (*src_len < 4)
                return -1;
        len = packet_length(*src_buf);
        if (len < 0)
                return -1;
        if (!len) {
                *src_buf += 4;
                *src_len -= 4;
                packet_trace("0000", 4, 0);
                return 0;
        }
        if (*src_len < len)
                return -2;

        *src_buf += 4;
        *src_len -= 4;
        len -= 4;

        strbuf_add(out, *src_buf, len);
        *src_buf += len;
        *src_len -= len;
        packet_trace(out->buf, out->len, 0);
        return len;
}