/* $Id$ */

/***
  This file is part of ivam2.

  ivam2 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.
  
  ivam2 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 ivam2; if not, write to the Free Software Foundation,
  Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/types.h>

#include <oop.h>

#include <libdaemon/dlog.h>
#include <libdaemon/dnonblock.h>

#include "buffio.h"
#include "main.h"
#include "timevalarith.h"

//#define IODEBUG 1
#define BUFSIZE PIPE_BUF

static void* buffio_timeout_cb(oop_source *source, struct timeval tv, void *user);
static void* buffio_read_cb(oop_source *source, int fd, oop_event event, void *user);
static void* buffio_write_cb(oop_source *source, int fd, oop_event event, void *user);

static void buffio_set_writable(struct buffio *b, int v);
static void buffio_set_readable(struct buffio *b, int v);

struct buffio* buffio_new(int ifd, int ofd) {
    struct buffio *b;
    assert(b >= 0);
    
    b = malloc(sizeof(struct buffio));
    assert(b);
    memset(b, 0, sizeof(struct buffio));

    daemon_nonblock(b->ifd = ifd, 1);
    daemon_nonblock(b->ofd = ofd, 1);
    
    b->input_buf = malloc(b->input_max_length = BUFSIZE);
    assert(b->input_buf);
    b->input_length = b->input_index = 0;
    b->input_range = b->input_max_length;
    
    b->output_buf = malloc(b->output_max_length = BUFSIZE);
    assert(b->output_buf);
    b->output_length = b->output_index = 0;
    b->output_range = b->output_max_length;

    buffio_set_readable(b, 0);
    buffio_set_writable(b, 0);
    
    return b;   
}

void buffio_close_input_fd(struct buffio *b) {
    assert(b);

    if (b->b_read_cb) {
        event_source->cancel_fd(event_source, b->ifd, OOP_READ);
        b->b_read_cb = 0;
    }
    
    if (b->ifd >= 0) {

        if (b->ofd != b->ifd)
            close(b->ifd);

        b->ifd = -1;
    }
}

void buffio_close_output_fd(struct buffio *b) {
    assert(b);

    if (b->b_write_cb) {
        event_source->cancel_fd(event_source, b->ofd, OOP_WRITE);
        b->b_write_cb = 0;
    }

    if (b->ofd >= 0) {

        if (b->ofd != b->ifd)
            close(b->ofd);
            
        b->ofd = -1;
    }
}

void buffio_free(struct buffio *b) {
    buffio_close_input_fd(b);
    buffio_close_output_fd(b);

    if (b->delaying)
        event_source->cancel_time(event_source, b->timeout_tv, buffio_timeout_cb, b);
    
    free(b->output_buf);
    free(b->input_buf);
    free(b);
}

static void* buffio_user_cb(oop_source *source, struct timeval tv, void *user) {
    struct buffio *b = user;
    enum buffio_sched_cb s;
    
    int r = 0;
    assert(b && source && source == event_source);
    
    s = b->sched_cb;
    b->sched_cb = BUFFIO_SCHED_CB_IDLE;
    
    if (s & BUFFIO_SCHED_CB_INPUT_READY && b->input_ready_cb && b->input_length)
        r |= b->input_ready_cb(b, b->user);
    if (s & BUFFIO_SCHED_CB_OUTPUT_EMPTY && b->output_empty_cb && !b->output_length)
        r |= b->output_empty_cb(b, b->user);
    if (s & BUFFIO_SCHED_CB_OUTPUT_REQUEST && b->output_request_cb && b->output_length < b->output_range)
        r |= b->output_request_cb(b, b->user);
    if (s & BUFFIO_SCHED_CB_EOF && b->eof_cb)
        r |= b->eof_cb(b, b->user);
    if (s & BUFFIO_SCHED_CB_EPIPE && b->epipe_cb)
        r |= b->epipe_cb(b, b->user);
    if (s & BUFFIO_SCHED_CB_ERROR && b->error_cb)
        r |= b->error_cb(b, b->user);
    
    return r == 0 ? OOP_CONTINUE : OOP_HALT;
}

static void buffio_sched_cb(struct buffio *b, enum buffio_sched_cb s) {
    if (s & BUFFIO_SCHED_CB_INPUT_READY && !b->input_ready_cb) s &= ~BUFFIO_SCHED_CB_INPUT_READY;
    if (s & BUFFIO_SCHED_CB_OUTPUT_REQUEST && !b->output_request_cb) s &= ~BUFFIO_SCHED_CB_OUTPUT_REQUEST;
    if (s & BUFFIO_SCHED_CB_OUTPUT_EMPTY && !b->output_empty_cb) s &= ~BUFFIO_SCHED_CB_OUTPUT_EMPTY;
    if (s & BUFFIO_SCHED_CB_EOF && !b->eof_cb) s &= ~BUFFIO_SCHED_CB_EOF;
    if (s & BUFFIO_SCHED_CB_EPIPE && !b->epipe_cb) s = ~BUFFIO_SCHED_CB_EPIPE;
    if (s & BUFFIO_SCHED_CB_ERROR && !b->error_cb) s = ~BUFFIO_SCHED_CB_ERROR;
    
    if (s == BUFFIO_SCHED_CB_IDLE)
        return;

    if (!b->sched_cb) {
        assert(event_source);
        event_source->on_time(event_source, OOP_TIME_NOW, buffio_user_cb, b);
    }
    
    b->sched_cb |= s;
}

#ifdef IODEBUG
static void esc_print(struct buffio *bio, const char*c, const uint8_t *b, size_t l) {
    size_t i;
    fprintf(stderr, "[%p] %s", bio, c);
    for (i = 0; i < l; i++, b++)
        fputc(*b < 32 ? '.' : *b, stderr);

    fprintf(stderr, "\n");
};
#endif

inline static void buffio_normalize(struct buffio *b) {
    assert(b);

    assert(b->input_index < b->input_max_length);
    assert(b->input_length <= b->input_max_length);

    if (!b->input_length) /* This will optimize throughput a bit */
        b->input_index = 0;

    assert(b->output_index < b->output_max_length);
    assert(b->output_length <= b->output_max_length);

    if (!b->output_length) /* This will optimize throughput a bit */
        b->output_index = 0;
}

static void buffio_set_readable(struct buffio *b, int v) {
    assert(b && event_source);

    if (b->ifd == -1)
        return;
    
    if (!(b->readable = v)) {
        if (!b->b_read_cb) { /* Enable the callback */
            event_source->on_fd(event_source, b->ifd, OOP_READ, buffio_read_cb, b);
            b->b_read_cb = 1;
        }
    } else {
        if (b->b_read_cb) { /* Disable the callback */
            event_source->cancel_fd(event_source, b->ifd, OOP_READ);
            b->b_read_cb = 0;
        }
    }
}

static void buffio_set_writable(struct buffio *b, int v) {
    assert(b && event_source);
        
    if (b->ofd == -1)
        return;

    if (!(b->writable = v)) {
        if (!b->b_write_cb) { /* Enable the callback */
            event_source->on_fd(event_source, b->ofd, OOP_WRITE, buffio_write_cb, b);
            b->b_write_cb = 1;
        }
    } else {
        if (b->b_write_cb) { /* Disable the callback */
            event_source->cancel_fd(event_source, b->ofd, OOP_WRITE);
            b->b_write_cb = 0;
        }
    }
}

static void buffio_delay(struct buffio *b, unsigned bytes) {
    assert(event_source && event_source->on_time);

    if (b->delaying) {
        event_source->cancel_time(event_source, b->timeout_tv, buffio_timeout_cb, b);
        b->delaying = 0;
    }

    if (bytes && b->output_delay_usec) {
        struct timeval now;

        gettimeofday(&now, NULL);

        /* Time when the last write operation is complete */
        b->finish_tv = timeval_add(timeval_max(b->finish_tv, now), (uint64_t) bytes * b->output_delay_usec);

        /* Time when we want to write the next data to the device */
        b->timeout_tv = timeval_sub(b->finish_tv, b->output_latency_usec); 
        
        assert(event_source && event_source->on_time);
        event_source->on_time(event_source, b->timeout_tv, buffio_timeout_cb, b);
        b->delaying = 1;

//        daemon_log(LOG_INFO, "%u bytes, now = %lu|%lu; finish = %lu|%lu; timeout = %lu|%lu", bytes, now.tv_sec, now.tv_usec, b->finish_tv.tv_sec, b->finish_tv.tv_usec, b->timeout_tv.tv_sec, b->timeout_tv.tv_usec);
    }
}

void buffio_set_delay_usec(struct buffio *b, unsigned long delay, unsigned long latency) {
    assert(b);

    b->output_delay_usec = delay;
    b->output_latency_usec = latency;
}

static void do_read(struct buffio *b) {
    ssize_t s;
    size_t m, i;
        
    assert(b);
    
    if (!b->readable || b->input_length >= b->input_range || b->ifd == -1)
        return;
    
    i = (b->input_index + b->input_length) % b->input_max_length;

    m = b->input_range-b->input_length;
    if (m > b->input_max_length-i)
        m = b->input_max_length-i;
    
    s = read(b->ifd, b->input_buf+i, m);
    buffio_set_readable(b, 0);
    //daemon_log(LOG_INFO, "%p: Read %u (%u) bytes.", b, s, m);
    
    if (s < 0) {

        if (errno == EAGAIN)
            return;
        
        daemon_log(LOG_ERR, "Failed to read from file descriptor: %s", strerror(errno));
        buffio_close_input_fd(b);
        buffio_sched_cb(b, BUFFIO_SCHED_CB_ERROR);
        return;
        
    } else if (!s) {
        buffio_close_input_fd(b);
        buffio_sched_cb(b, BUFFIO_SCHED_CB_EOF);
        return;
        
    }
    
#ifdef IODEBUG
    esc_print(b, "INPUT:  ", b->input_buf+i, s);
#endif
    
    assert(s <= m);
    b->input_length += s;
    buffio_normalize(b);
    
    if (b->input_length) 
        buffio_sched_cb(b, BUFFIO_SCHED_CB_INPUT_READY);
}

static void do_write(struct buffio *b) {
    ssize_t s;
    size_t m;

    assert(b);

    if (b->delaying || !b->writable || !b->output_length || b->ofd == -1)
        return;

    if (b->prebuf && b->output_length >= b->output_range)
        b->prebuf = 0;

    if (b->prebuf)
        return;
    
    m = b->output_length;
    if (m > b->output_max_length-b->output_index)
        m = b->output_max_length-b->output_index;
    
    s = write(b->ofd, b->output_buf+b->output_index, m);
    buffio_set_writable(b, 0);
    
    //daemon_log(LOG_INFO, "%p: Wrote %u (%u) bytes.", b, s, m);
    
    if (s < 0) {
        if (errno == EAGAIN)
            return;
        
        buffio_close_output_fd(b);
        
        if (errno == EPIPE) {
            buffio_sched_cb(b, BUFFIO_SCHED_CB_EPIPE);
            return;
            
        } else {
            daemon_log(LOG_ERR, "Failed to write to file descriptor: %s", strerror(errno));
            buffio_sched_cb(b, BUFFIO_SCHED_CB_ERROR);
            return;
        }
    }

#ifdef IODEBUG
    esc_print(b, "OUTPUT: ", b->output_buf+b->output_index, s);
#endif
    
    assert(s > 0 && s <= m);
    b->output_index = (b->output_index + s) % b->output_max_length;
    b->output_length -= s;
    buffio_normalize(b);
    
    buffio_delay(b, s);

    if (b->output_length < b->output_range)
        buffio_sched_cb(b, BUFFIO_SCHED_CB_OUTPUT_REQUEST);
    if (!b->output_length)
        buffio_sched_cb(b, BUFFIO_SCHED_CB_OUTPUT_EMPTY);
}

static void* buffio_read_cb(oop_source *source, int fd, oop_event event, void *user) {
    struct buffio *b = user;
    assert(source && b && b->ifd == fd && event == OOP_READ);

    buffio_set_readable(b, 1);
    do_read(b);
    
    return OOP_CONTINUE;
}

static void* buffio_write_cb(oop_source *source, int fd, oop_event event, void *user) {
    struct buffio *b = user;
    assert(source && b && b->ofd == fd && event == OOP_WRITE);

    buffio_set_writable(b, 1);
    do_write(b);
    
    return OOP_CONTINUE;
}

static void* buffio_timeout_cb(oop_source *source, struct timeval tv, void *user) {
    struct buffio *b = user;
    assert(source && b && b->delaying);

    b->delaying = 0;
    do_write(b);
    
    return OOP_CONTINUE;
}

void buffio_write(struct buffio *b, const uint8_t *d, size_t l) {
    assert(b && d && l);
    
    if (b->output_length > b->output_range || l > b->output_range - b->output_length) {
        daemon_log(LOG_ERR, "buffio_write() with too much data called");
        return;
    }

    while (l > 0) {
        size_t m, i;

        i = (b->output_index + b->output_length) % b->output_max_length;

        m = l;
        if (m > b->output_max_length-i)
            m = b->output_max_length-i;
    
        memcpy(b->output_buf+i, d, m);

        l -= m;
        b->output_length += m;
    }

    buffio_normalize(b);
    do_write(b);
}

void buffio_print(struct buffio *b, const char *s) {
    assert(b && s);
    buffio_write(b, (uint8_t*) s, strlen(s));
}

void buffio_command(struct buffio *b, const char *c) {
    assert(b && c);

    buffio_flush_input(b);
    buffio_print(b, c);
}

void buffio_flush_input(struct buffio *b) {
    assert(b);

    b->input_length = b->input_index = 0;
    do_read(b);
}

void buffio_flush_output(struct buffio *b) {
    assert(b);

    b->output_length = b->output_index = 0;
}

int buffio_find_input(struct buffio *b, const char *c) {
    size_t l, cl, i;
    assert(b && c && *c);
    
    cl = strlen(c);
    
    for (i = b->input_index, l = b->input_length; l >= cl; i = (i+1) % b->input_max_length, l--) {
        const char *p;
        size_t j;
        
        for (j = i, p = c; *p && *p == b->input_buf[j]; p++, j = (j+1) % b->input_max_length);

        if (!*p) { /* Found! */
            b->input_index = j;
            b->input_length = l-cl;
            buffio_normalize(b);

            do_read(b);
            return 1;
        }
    }

    return 0;
    
}

char* buffio_read_line(struct buffio *b, char *c, size_t l) {
    size_t i;
    assert(b && c && l);

    /* Look for a \n */
    for (i = 0; i < b->input_length && i < l-1; i++) {
        if (b->input_buf[(b->input_index+i) % b->input_max_length] == '\n') {
            size_t j;
            
            /* Once again, now copy */
            for (j = 0;; j++) {
                c[j] = b->input_buf[(b->input_index+j) % b->input_max_length];

                /* Finished? */
                if (c[j] == '\n') {
                    c[j+1] = 0;

                    b->input_index = (b->input_index+j+1) % b->input_max_length;
                    b->input_length -= j+1;
                    buffio_normalize(b);

                    do_read(b);
                    return c;
                }
            }
        }
    }

    return NULL;
}

void buffio_dump(struct buffio *b) {
    size_t i;
    assert(b);

    fprintf(stderr, "%p INPUT_BUFFER:  [", b);
    for (i = 0; i < b->input_length; i++) {
        char c = b->input_buf[(i + b->input_index) % b->input_max_length];
        fputc(c < 32 ? '.' : c, stderr);
    }
    fprintf(stderr, "]\n");

    fprintf(stderr, "%p OUTPUT_BUFFER: [", b);
    for (i = 0; i < b->output_length; i++) {
        char c = b->output_buf[(i + b->output_index) % b->output_max_length];
        fputc(c < 32 ? '.' : c, stderr);
    }
    fprintf(stderr, "]\n");
}

void buffio_set_input_range(struct buffio *b, ssize_t w) {
    assert(b);

    if (w < 0)
        b->input_range = b->input_max_length;
    else
        b->input_range = w;

    assert(b->input_range > 0 && b->input_range <= b->input_max_length);

    do_read(b);
}

void buffio_set_output_range(struct buffio *b, ssize_t w) {
    assert(b);

    if (w < 0)
        b->output_range = b->output_max_length;
    else
        b->output_range = w;

    assert(b->output_range > 0 && b->output_range <= b->output_max_length);

    do_write(b);
}


const uint8_t* buffio_read_ptr(struct buffio *b, size_t *l) {
    assert(b && l);

    if (!b->input_length)
        return NULL;
    
    *l = b->input_length;

    if (*l > b->input_max_length - b->input_index)
        *l = b->input_max_length - b->input_index;

    return b->input_buf + b->input_index;    
}

void buffio_read_ptr_inc(struct buffio *b, size_t l) {
    assert(b);

    if (!l)
        return;

    assert(l <= b->input_length && l <= b->input_max_length - b->input_index);
    b->input_index += l;

    while (b->input_index >= b->input_max_length)
        b->input_index -= b->input_max_length;
    
    b->input_length -= l;
    buffio_normalize(b);    

    do_read(b);
}

uint8_t* buffio_write_ptr(struct buffio *b, size_t *l) {
    size_t j;
    assert(b && l);
    
    if (b->output_length >= b->output_range)
        return NULL;
    
    j = (b->output_index + b->output_length) % b->output_max_length;

    *l = b->output_range - b->output_length;
    if (*l > b->output_max_length - j)
        *l = b->output_max_length - j;

    return b->output_buf + j;
}

void buffio_write_ptr_inc(struct buffio *b, size_t l) {
    int j;
    assert(b);

    if (!l)
        return;

    j = (b->output_index + b->output_length) % b->output_max_length;
    assert(l <= b->output_max_length - b->output_length && l <= b->output_max_length - j);

    b->output_length += l;
    buffio_normalize(b);

    do_write(b);
}

int buffio_output_is_empty(struct buffio *b) {
    assert(b);

    return b->output_length == 0;
}

int buffio_input_is_full(struct buffio *b) {
    assert(b);

    return b->input_length >= b->input_range;
}

void buffio_dump_lines(struct buffio *b) {
    int r, i;
    assert(b);

    r = 0;
    
    for (i = 0; i < b->input_length; i++)
        if (b->input_buf[(b->input_index+i) % b->input_max_length] == '\n')
            r = i+1;

    if (r > 0) {
        b->input_index = (b->input_index+r) % b->input_max_length;
        b->input_length -= r;
        buffio_normalize(b);
        
        do_read(b);
    }
}

void buffio_set_fds(struct buffio *b, int ifd, int ofd) {
    assert(b && b->ifd == -1 && b->ofd == -1);

    daemon_nonblock(b->ifd = ifd, 1);
    daemon_nonblock(b->ofd = ofd, 1);

    buffio_set_readable(b, 0);
    buffio_set_writable(b, 0);
}

int buffio_can_write(struct buffio *b, size_t l) {
    assert(b);

    if (b->output_length >= b->output_range)
        return 0;
    
    return l <= b->output_range - b->output_length;
}

int buffio_write_req(struct buffio *b) {
    assert(b);

    return b->output_length < b->output_range;
}

void buffio_set_prebuf(struct buffio *b, int p) {
    assert(b);

    b->prebuf = p;
    do_write(b);
}