#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

#include "HsFFI.h"
#include <espeak-ng/espeak_ng.h>
#include <sndfile.h>

/* Exported Haskell functions/types */
struct session;
struct session *c_newSession();
void c_freeSession(struct session*);

struct page;
struct page *c_initialReferer();
void *c_fetchURL(struct session*, char*, struct page*, char*);
//struct page **c_fetchURLs(struct session*, struct page*, char**); // FIXME segfaults.
void c_freePage(struct page*);

char *c_renderDoc(struct session*, struct page*, _Bool);
char **c_extractLinks(struct page*);
char **c_docLinksAndRendering(struct session*, struct page*, _Bool); // FIXME segfaults.

/* espeak-ng integration. Based on the espeak-ng command source code. */
SNDFILE *fd_wav = NULL;
char *path_wav = NULL;
static int samplerate;
espeak_ng_ERROR_CONTEXT context;

int choose_format(char *path) {
    SF_FORMAT_INFO	format_info;
    int k, count;

    sf_command(fd_wav, SFC_GET_FORMAT_MAJOR_COUNT, &count, sizeof (int));
    for (k = 0; k < count; k++) {
        format_info.format = k;
        sf_command(fd_wav, SFC_GET_FORMAT_MAJOR, &format_info, sizeof (format_info));
        char *suffix = path + strlen(path) - strlen(format_info.extension);
        if (strcmp(path, format_info.extension) == 0) return format_info.format;
    }
    return SF_FORMAT_WAV;
}

int should_play(int type, const char *uri, const char *base) {
    return strncmp(uri, "file:///", strlen("file:///"));
}
#define		BUFFER_LEN	1024
#define		MAX_CHANNELS	6
// FIXME convert samplerate
int read_mono(SNDFILE *fd, SF_INFO *info, short *out) {
    sf_count_t count = sf_read_short(fd, out, BUFFER_LEN);
    if (info->channels == 1) return count;

    int i = 0;
    for (int j = 0; j < count; j += info->channels) out[i++] = out[j];
    return i;
}

int synth_callback(short *wav, int numsamples, espeak_EVENT *events) {
    if (wav == NULL) return 0;

    while (events->type != 0) {
        if (events->type == espeakEVENT_SAMPLERATE) samplerate = events->id.number;
        if (events->type == espeakEVENT_PLAY) {
            SF_INFO info;
            info.format = 0;
            short buf[BUFFER_LEN];
            int len;
            SNDFILE *fd = sf_open(events->id.name + strlen("file://"), SFM_READ, &info);
            if (fd == NULL || info.channels > MAX_CHANNELS) {
                fprintf(stderr, "Failed to open %s: %s\n", events->id.name + strlen("file://"),
                    sf_strerror(fd));
                events++;
                continue;
            }
            while ((len = read_mono(fd, &info, buf)) != 0)
                sf_write_short(fd_wav, buf, len);
            sf_close(fd);
        }
        events++;
    }

    if (fd_wav == NULL) {
        SF_INFO info;
        info.samplerate = samplerate;
        info.channels = 1;
        info.format = choose_format(path_wav) | SF_FORMAT_PCM_16 | SF_ENDIAN_LITTLE;
        fd_wav = sf_open(path_wav, SFM_WRITE, &info);
    }
    if (numsamples > 0) sf_writef_short(fd_wav, wav, numsamples);
    return 0;
}

int speak_initialize() {
    espeak_ng_InitializePath(NULL);
    context = NULL;
    espeak_ng_STATUS result = espeak_ng_Initialize(&context);
    if (result != ENS_OK) {
        espeak_ng_PrintStatusCodeMessage(result, stderr, context);
		espeak_ng_ClearErrorContext(&context);
		return 2;
    }

    if (path_wav != NULL) {
        result = espeak_ng_InitializeOutput(ENOUTPUT_MODE_SYNCHRONOUS, 0, NULL);
        espeak_SetUriCallback(should_play);
        espeak_SetSynthCallback(synth_callback);
    } else {
        result = espeak_ng_InitializeOutput(ENOUTPUT_MODE_SPEAK_AUDIO, 0, NULL);
    }
    if (result != ENS_OK) {
        espeak_ng_PrintStatusCodeMessage(result, stderr, context);
        return 3;
    }

    samplerate = espeak_ng_GetSampleRate();
    return 0;
}
void speak(char *ssml) {
    int flags = espeakCHARS_AUTO | espeakPHONEMES | espeakENDPAUSE | espeakCHARS_UTF8 | espeakSSML;
    espeak_Synth(ssml, strlen(ssml)+1, 0, POS_CHARACTER, 0, flags, NULL, NULL);
}
int speak_finalize() {
    espeak_ng_STATUS result = espeak_ng_Synchronize();
    if (result != ENS_OK) {
        espeak_ng_PrintStatusCodeMessage(result, stderr, context);
        return 4;
    }

    if (path_wav != NULL) sf_close(fd_wav);
    espeak_ng_Terminate();
    return 0;
}

/* Main driver */
void write_links(FILE *dest, char **links) {
    for (int i = 0; strcmp(links[i], " ") != 0; i++) {
        fprintf(dest, "%s%c", links[i], (i % 3) == 2 ? '\n' : '\t');
    }
}

FILE *parse_opt_file() {
    FILE *ret = optarg != NULL ? fopen(optarg, "w") : stdout;
    if (ret == NULL) {
      fprintf(stderr, "Failed to open file %s\n", optarg);
      hs_exit();
      exit(-1);
    }
    return ret;
}

int main(int argc, char **argv) {
    int speak_err = 0;
    hs_init(&argc, &argv);

    char *mimes = "text/html text/xml application/xml application/xhtml+xml text/plain";
    FILE *fd_ssml = NULL;
    FILE *fd_links = NULL;
    int use_espeak = 0;

    int c;
    opterr = 0;
    while ((c = getopt(argc, argv, "xs::l::w::h")) != -1) {
        switch (c) {
        case 'x':
            mimes = "text/xml application/xml application/xhtml+xml text/html text/plain";
            break;
        case 's':
            fd_ssml = parse_opt_file();
            break;
        case 'l':
            fd_links = parse_opt_file();
            break;
        case 'w':
            use_espeak = 1;
            path_wav = optarg;
            break;
        case '?':
            fprintf(stderr, "Invalid flag %c\n\n", optopt);
        case 'h':
            fprintf(stderr, "USAGE: rhapsode [FLAGS] URL...\n");
            fprintf(stderr, "\t-x\tX(HT)ML\tIndicates to expect an X(HT)ML file.\n");
            fprintf(stderr, "\t-s\tsilent/SSML\tWrites SSML to the specified file or stdout.\n");
            fprintf(stderr, "\t\t\thttps://xkcd.com/1692/\n");
            fprintf(stderr, "\t-l\tlinks\tWrite extracted links to specifed file or stdout as TSV.\n");
            fprintf(stderr, "\t-h\thelp\tOutputs this usage information to stderr.\n");
            fprintf(stderr, "\t\t\tIf both -s & -l are enabled without an argument, writes to stderr instead.\n");

            hs_exit();
            return c == 'h' ? 0 : 1;
        }
    }
    if (fd_ssml == stdout && fd_links == stdout) fd_links = stderr;
    if (fd_ssml == NULL && fd_links == NULL && !use_espeak) use_espeak = 1;

    struct session *session = c_newSession();
    struct page *referer = c_initialReferer();

    if (use_espeak) speak_err = speak_initialize();
    for (int i = optind; i < argc; i++) {
        if (use_espeak && speak_err == 0) speak(argv[i]);
        else printf("%s\n", argv[i]);

        struct page *page = c_fetchURL(session, mimes, referer, argv[i]);
        char *ssml = c_renderDoc(session, page, use_espeak);
        char **links = c_extractLinks(page);

        if (fd_ssml != NULL) fprintf(fd_ssml, "%s\n", ssml);
        if (fd_links != NULL) write_links(fd_links, links);
        if (use_espeak & speak_err == 0) speak(ssml);

        c_freePage(page);
    }
    if (use_espeak & speak_err == 0) speak_err = speak_finalize();

    c_freePage(referer);
    c_freeSession(session);
    hs_exit();

    return speak_err;
}