#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sysexits.h>
#include <sys/wait.h>
#include <errno.h>

#include <xas/riff.h>
#include <xas/vox.h>

static int vox_stop(xas_vox *vox) {
    if (vox->stdin >= 0) {
        (void)close(vox->stdin);

        vox->stdin = -1;
    }

    if (vox->stdout >= 0) {
        (void)close(vox->stdout);

        vox->stdout = -1;
    }

    if (vox->in) {
        (void)fclose(vox->in);

        vox->in = NULL;
    }

    if (vox->pid) {
        int status;

        if (waitpid(vox->pid, &status, 0) < 0) {
            goto error_waitpid;
        }

        vox->pid = -1;
    }

    vox->flags &= ~XAS_VOX_ACTIVE;

    return 0;

error_waitpid:
    return -1;
}

static int vox_start(xas_vox *vox) {
    int pipe_stdin[2],
        pipe_stdout[2];

    int pid;

    char sample_rate[40];

    char *args[] = {
        (char *)vox->text2wave_path,
        "-F",
        sample_rate,
        "-",
        "-o",
        "-",
        NULL
    };

    snprintf(sample_rate, sizeof(sample_rate)-1, "%zu", vox->sample_rate);

    (void)vox_stop(vox);

    if (pipe(pipe_stdin) < 0) {
        goto error_pipe_stdin;
    }

    if (pipe(pipe_stdout) < 0) {
        goto error_pipe_stdout;
    }

    if ((pid = fork()) < 0) {
        goto error_fork;
    }

    if (pid == 0) {
        int fd;

        if ((fd = open("/dev/null", O_WRONLY)) < 0) {
            goto error_child;
        }

        close(pipe_stdin[1]);
        close(pipe_stdout[0]);

        if (dup2(pipe_stdin[0], 0) < 0) {
            goto error_child;
        }

        if (dup2(pipe_stdout[1], 1) < 0) {
            goto error_child;
        }

        if (dup2(fd, 2) < 0) {
            goto error_child;
        }

        if (execv(vox->text2wave_path, args) < 0) {
            goto error_child;
        }

error_child:
        exit(EX_OSERR);
    }

    close(pipe_stdin[0]);
    close(pipe_stdout[1]);

    vox->pid    = pid;
    vox->stdin  = pipe_stdin[1];
    vox->stdout = pipe_stdout[0];
    vox->in     = fdopen(pipe_stdin[1], "w");
    vox->flags |= XAS_VOX_ACTIVE;

    return 0;

error_fork:
    (void)close(pipe_stdout[1]);
    (void)close(pipe_stdout[0]);

error_pipe_stdout:
    (void)close(pipe_stdin[1]);
    (void)close(pipe_stdin[0]);

error_pipe_stdin:
    return -1;
}

static void vox_cleanup(xas_vox *vox, xas_audio_stream *stream) {
    (void)vox_stop(vox);
}

static ssize_t vox_fill(xas_vox *vox,
                        int16_t *samples,
                        size_t count,
                        xas_audio_stream *stream) {
    ssize_t readlen,
            readcount;

    size_t i;

    if (!(vox->flags & XAS_VOX_ACTIVE)) {
        memset(samples, '\0', count * vox->sample_size);

        return count;
    }

    if ((readlen = read(vox->stdout,
                        samples,
                        count * vox->sample_size)) < 0) {
        goto error_read;
    }

    if (readlen == 0) {
        vox_stop(vox);
    }

    readcount = readlen / vox->sample_size;

    for (i=readcount; i<count-readcount; i++) {
        samples[i] = 0;
    }

    return count;

error_read:
    return -1;
}

xas_vox *xas_vox_new(const char *text2wave_path,
                         size_t sample_size,
                         size_t sample_rate,
                         size_t buffer_size,
                         void *ctx) {
    xas_vox *vox;

    if ((vox = malloc(sizeof(*vox))) == NULL) {
        goto error_malloc_vox;
    }

    vox->text2wave_path = text2wave_path;
    vox->sample_size    = sample_size;
    vox->sample_rate    = sample_rate;
    vox->buffer_size    = buffer_size;
    vox->ctx            = ctx;
    vox->flags          = XAS_VOX_IDLE;

    vox->pid    = -1;
    vox->stdin  = -1;
    vox->stdout = -1;
    vox->in     = NULL;

    return vox;

error_malloc_vox:
    return NULL;
}

void xas_vox_destroy(xas_vox *vox) {
    free(vox);
}

int xas_vox_stop(xas_vox *vox) {
    return vox_stop(vox);
}

int xas_vox_generate(xas_vox *vox) {
    xas_audio_stream *output;

    (void)fflush(vox->in);
    (void)fclose(vox->in);
    (void)close(vox->stdin);

    vox->stdin = -1;
    vox->in    = NULL;

    if ((output = xas_riff_open_fd(vox->stdout)) == NULL) {
        goto error_riff_open_fd;
    }

    if (output->sample_size != vox->sample_size
     || output->sample_rate != vox->sample_rate) {
        errno = EINVAL;

        goto error_invalid_stream;
    }

    xas_audio_stream_destroy(output);

    return 0;

error_invalid_stream:
error_riff_open_fd:
    return -1;
}

int xas_vox_vsayf(xas_vox *vox, const char *format, va_list args) {
    if (vox_start(vox) < 0) {
        goto error_vox_start;
    }

    return vfprintf(vox->in, format, args);

error_vox_start:
    return -1;
}

int xas_vox_sayf(xas_vox *vox, const char *format, ...) {
    int ret;
    va_list args;

    va_start(args, format);
    ret = xas_vox_vsayf(vox, format, args);
    va_end(args);

    return ret;
}

int xas_vox_say(xas_vox *vox, const char *message) {
    return xas_vox_sayf(vox, "%s", message);
}

int xas_vox_active(xas_vox *vox) {
    return vox->flags & XAS_VOX_ACTIVE;
}

xas_audio_stream *xas_vox_stream_new(xas_vox *vox) {
    return xas_audio_stream_new_source((xas_audio_fill)vox_fill,
                                         (xas_audio_cleanup)vox_cleanup,
                                         vox,
                                         vox->sample_size,
                                         vox->sample_rate,
                                         XAS_AUDIO_STREAM_MONO,
                                         vox->buffer_size);
}