/*=========================================================================*\
* Input/Output interface for Lua programs
* LuaSocket toolkit
*
* RCS ID: $Id$
\*=========================================================================*/
#include <lua.h>
#include <lauxlib.h>

#include "buffer.h"

/*=========================================================================*\
* Internal function prototypes
\*=========================================================================*/
static int recvraw(p_buf buf, size_t wanted, luaL_Buffer *b);
static int recvline(p_buf buf, luaL_Buffer *b);
static int recvall(p_buf buf, luaL_Buffer *b);
static int buf_get(p_buf buf, const char **data, size_t *count);
static void buf_skip(p_buf buf, size_t count);
static int sendraw(p_buf buf, const char *data, size_t count, size_t *sent);

/* min and max macros */
#ifndef MIN
#define MIN(x, y) ((x) < (y) ? x : y)
#endif
#ifndef MAX
#define MAX(x, y) ((x) > (y) ? x : y)
#endif

/*=========================================================================*\
* Exported functions
\*=========================================================================*/
/*-------------------------------------------------------------------------*\
* Initializes module
\*-------------------------------------------------------------------------*/
int buf_open(lua_State *L) {
    (void) L;
    return 0;
}

/*-------------------------------------------------------------------------*\
* Initializes C structure 
\*-------------------------------------------------------------------------*/
void buf_init(p_buf buf, p_io io, p_tm tm) {
	buf->first = buf->last = 0;
    buf->io = io;
    buf->tm = tm;
}

/*-------------------------------------------------------------------------*\
* object:send() interface
\*-------------------------------------------------------------------------*/
int buf_meth_send(lua_State *L, p_buf buf) {
    int top = lua_gettop(L);
    size_t total = 0;
    int arg, err = IO_DONE;
    p_tm tm = tm_markstart(buf->tm);
    for (arg = 2; arg <= top; arg++) { /* first arg is socket object */
        size_t sent, count;
        const char *data = luaL_optlstring(L, arg, NULL, &count);
        if (!data || err != IO_DONE) break;
        err = sendraw(buf, data, count, &sent);
        total += sent;
    }
    /* check if there was an error */
    if (err != IO_DONE) {
        lua_pushnil(L);
        io_pusherror(L, buf->io, err); 
        lua_pushnumber(L, total);
    } else {
        lua_pushnumber(L, total);
        lua_pushnil(L);
        lua_pushnil(L);
    }
#ifdef LUASOCKET_DEBUG
    /* push time elapsed during operation as the last return value */
    lua_pushnumber(L, tm_gettime() - tm_getstart(tm));
#endif
    return lua_gettop(L) - top;
}

/*-------------------------------------------------------------------------*\
* object:receive() interface
\*-------------------------------------------------------------------------*/
int buf_meth_receive(lua_State *L, p_buf buf) {
    int err = IO_DONE, top = lua_gettop(L);
    p_tm tm = tm_markstart(buf->tm);
    luaL_Buffer b;
    luaL_buffinit(L, &b);
    /* receive all patterns */
    if (!lua_isnumber(L, 2)) {
        static const char *patternnames[] = {"*l", "*a", NULL};
        const char *pattern = luaL_optstring(L, 2, "*l");
        /* get next pattern */
        int p = luaL_findstring(pattern, patternnames);
        if (p == 0) err = recvline(buf, &b);
        else if (p == 1) err = recvall(buf, &b); 
        else luaL_argcheck(L, 0, 2, "invalid receive pattern");
        /* get a fixed number of bytes */
    } else err = recvraw(buf, (size_t) lua_tonumber(L, 2), &b);
    /* check if there was an error */
    if (err != IO_DONE) {
        luaL_pushresult(&b);
        io_pusherror(L, buf->io, err); 
        lua_pushvalue(L, -2); 
        lua_pushnil(L);
        lua_replace(L, -4);
    } else {
        luaL_pushresult(&b);
        lua_pushnil(L);
        lua_pushnil(L);
    }
#ifdef LUASOCKET_DEBUG
    /* push time elapsed during operation as the last return value */
    lua_pushnumber(L, tm_gettime() - tm_getstart(tm));
#endif
    return lua_gettop(L) - top;
}

/*-------------------------------------------------------------------------*\
* Determines if there is any data in the read buffer
\*-------------------------------------------------------------------------*/
int buf_isempty(p_buf buf) {
    return buf->first >= buf->last;
}

/*=========================================================================*\
* Internal functions
\*=========================================================================*/
/*-------------------------------------------------------------------------*\
* Sends a block of data (unbuffered)
\*-------------------------------------------------------------------------*/
static int sendraw(p_buf buf, const char *data, size_t count, size_t *sent) {
    p_io io = buf->io;
    p_tm tm = buf->tm;
    size_t total = 0;
    int err = IO_DONE;
    while (total < count && err == IO_DONE) {
        size_t done;
        err = io->send(io->ctx, data+total, count-total, &done, tm);
        total += done;
    }
    *sent = total;
    return err;
}

/*-------------------------------------------------------------------------*\
* Reads a fixed number of bytes (buffered)
\*-------------------------------------------------------------------------*/
static int recvraw(p_buf buf, size_t wanted, luaL_Buffer *b) {
    int err = IO_DONE;
    size_t total = 0;
    while (total < wanted && err == IO_DONE) {
        size_t count; const char *data;
        err = buf_get(buf, &data, &count);
        count = MIN(count, wanted - total);
        luaL_addlstring(b, data, count);
        buf_skip(buf, count);
        total += count;
    }
    return err;
}

/*-------------------------------------------------------------------------*\
* Reads everything until the connection is closed (buffered)
\*-------------------------------------------------------------------------*/
static int recvall(p_buf buf, luaL_Buffer *b) {
    int err = IO_DONE;
    while (err == IO_DONE) {
        const char *data; size_t count;
        err = buf_get(buf, &data, &count);
        luaL_addlstring(b, data, count);
        buf_skip(buf, count);
    }
    if (err == IO_CLOSED) return IO_DONE;
    else return err;
}

/*-------------------------------------------------------------------------*\
* Reads a line terminated by a CR LF pair or just by a LF. The CR and LF 
* are not returned by the function and are discarded from the buffer
\*-------------------------------------------------------------------------*/
static int recvline(p_buf buf, luaL_Buffer *b) {
    int err = IO_DONE;
    while (err == IO_DONE) {
        size_t count, pos; const char *data;
        err = buf_get(buf, &data, &count);
        pos = 0;
        while (pos < count && data[pos] != '\n') {
            /* we ignore all \r's */
            if (data[pos] != '\r') luaL_putchar(b, data[pos]);
            pos++;
        }
        if (pos < count) { /* found '\n' */
            buf_skip(buf, pos+1); /* skip '\n' too */
            break; /* we are done */
        } else /* reached the end of the buffer */
            buf_skip(buf, pos);
    }
    return err;
}

/*-------------------------------------------------------------------------*\
* Skips a given number of bytes from read buffer. No data is read from the
* transport layer
\*-------------------------------------------------------------------------*/
static void buf_skip(p_buf buf, size_t count) {
    buf->first += count;
    if (buf_isempty(buf)) 
        buf->first = buf->last = 0;
}

/*-------------------------------------------------------------------------*\
* Return any data available in buffer, or get more data from transport layer
* if buffer is empty
\*-------------------------------------------------------------------------*/
static int buf_get(p_buf buf, const char **data, size_t *count) {
    int err = IO_DONE;
    p_io io = buf->io;
    p_tm tm = buf->tm;
    if (buf_isempty(buf)) {
        size_t got;
        err = io->recv(io->ctx, buf->data, BUF_SIZE, &got, tm);
        buf->first = 0;
        buf->last = got;
    }
    *count = buf->last - buf->first;
    *data = buf->data + buf->first;
    return err;
}