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

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

// #define WITH_SPEECHD // FIXME Doesn't support audio cues, navigation, or even read the full page.
#ifdef WITH_SPEECHD
#include <speechd_types.h>
#include <libspeechd.h>
#endif

/* 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*);

void c_enableLogging(struct session*);
void c_writeLog(char*, struct session*);

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

/* 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;
}

#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 paragraph_no = 0, section_no = 0;
int tablerow = 0, tablecol = 0, tableno = 0, in_table = 0;
int capture_marks(short *wav, int numsamples, espeak_EVENT *events) {
    while (events->type != 0) {
        if (events->type == espeakEVENT_MARK) {
            in_table = 0;
            if (sscanf(events->id.name, "-rhaps-paragraph%i", &paragraph_no) == 1) {}
            else if (sscanf(events->id.name, "-rhaps-section%i", &section_no) == 1) {}
            else if (sscanf(events->id.name, "-rhaps-tablecell%i:%ix%i",
                    &tableno, &tablerow, &tablecol) == 3) {in_table = 1;}
        }
        events++;
    }
    return 0;
}

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

    while (events->type != 0) {
        if (events->type == espeakEVENT_SAMPLERATE) samplerate = events->id.number;
        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_SetSynthCallback(save_audio);
    } else {
        result = espeak_ng_InitializeOutput(ENOUTPUT_MODE_SPEAK_AUDIO, 0, NULL);
        espeak_SetSynthCallback(capture_marks);
    }
    if (result != ENS_OK) {
        espeak_ng_PrintStatusCodeMessage(result, stderr, context);
        return 3;
    }

    samplerate = espeak_ng_GetSampleRate();
    return 0;
}
void speak(char *ssml, char *mark, char* fallback) {
    int flags = espeakCHARS_AUTO | espeakPHONEMES | espeakENDPAUSE | espeakCHARS_UTF8 | espeakSSML;
    if (mark != NULL && c_ssmlHasMark(mark, ssml))
        espeak_Synth_Mark(ssml, strlen(ssml)+1, mark, 0, flags, NULL, NULL);
    else if (fallback != NULL && c_ssmlHasMark(fallback, ssml))
        espeak_Synth_Mark(ssml, strlen(ssml)+1, fallback, 0, flags, NULL, NULL);
    else espeak_Synth(ssml, strlen(ssml)+1, 0, POS_CHARACTER, 0, flags, NULL, NULL);
}

void speak_text(char *text, espeak_PARAMETER param, int value) {
    if (param != 0) espeak_SetParameter(param, value, /* relative */1);

    int flags = espeakCHARS_AUTO | espeakPHONEMES | espeakENDPAUSE | espeakCHARS_UTF8;
    espeak_Synth(text, strlen(text)+1, 0, POS_CHARACTER, 0, flags, NULL, NULL);

    if (param != 0) espeak_SetParameter(param, espeak_GetParameter(param, /* current */0), /* relative */0);
}

/* Utilities */
#define SWAP(type, a, b) {type temp = a; a = b; b = temp;}
int min(int a, int b) {return a < b ? a : b;}

/* Keyboard input */
int levenshtein_distance(const char *a, const char* b) {
    int a_len = strlen(a);
    int b_len = strlen(b);
    if (a_len < b_len) {
        SWAP(int, a_len, b_len);
        SWAP(const char*, a, b);
    }
    int *v0 = malloc(sizeof(int)*(b_len+1));
    int *v1 = malloc(sizeof(int)*(b_len+1));

    // Initialize v0 for an edit distance of an empty a
    for (int i = 0; i < b_len; i++) v0[i] = i;

    // The core algorithm
    for (int i = 0; i < a_len; i++) {
        // Edit distance from empty string is delete i characters.
        v1[0] = i;

        for (int j = 0; j < b_len; j++) {
            int deletion_cost = v0[j+1] + 1; // above cell + deletion
            int insertion_cost = v1[j] + 1; // left cell + insertion
            // top left cell + maybe substitution
            int substitution_cost = v0[j] + (a[i] == b[j] ? 0 : 1);

            v1[j+1] = min(deletion_cost, min(insertion_cost, substitution_cost));
        }

        // Progress to next row
        SWAP(int*, v0, v1);
    }

    int ret = v0[b_len];
    free(v0); free(v1);
    return ret;
}

int MAX_DIST = 3; // Is this ideal?
char *select_link(char **links, char *command) {
    // Pass 1, min distance
    int score = INT_MAX;
    for (int i = 0; strcmp(links[i], " ") != 0; i++) {
        score = min(score, levenshtein_distance(command, links[i]));
    }

    // Pass 2: Is ambiguous?
    int num_matches = 0;
    for (int i = 0; strcmp(links[i], " ") != 0; i++)
        if (score >= levenshtein_distance(command, links[i]) - MAX_DIST) num_matches++;

    espeak_Cancel();

    // Pass 3: Retrieve answer
    for (int i = 0; strcmp(links[i], " ") != 0; i += 3) {
        if (score < levenshtein_distance(command, links[i]) &&
            score < levenshtein_distance(command, links[i+1]) &&
            score < levenshtein_distance(command, links[i+2])) continue;
        if (num_matches == 1) return links[i+2];

        // Communicate 
        printf("%s\t%s\t%s\n", links[i+2], links[i], links[i+1]);
        speak_text(links[i+2], espeakRATE, 20); // URL, fast
        speak_text(links[i], espeakPITCH, -40); // Label, low
        speak_text(links[i+1], espeakVOLUME, -40); // Title, quite
    }

    return NULL;
}

struct termios stored_settings, no_echo;
int read_keyboard = 0;
int speak_finalize(char *ssml, char **links, char **out_link) {
    while (read_keyboard) {
        if (out_link != NULL && *out_link != NULL) return 0;

        if (getc(stdin) == '\033') {
            char mark[200];
            char fallback[200];
            espeak_Cancel();
            char c = getc(stdin);
            if (c == 0 || c == -1 || c == '\033' || c == 'q') goto close; // skip [
            switch (getc(stdin)) {
            case 'A':
                // 🠕
                if (in_table) {
                    tablerow--;
                    if (tablerow > 0) {
                        sprintf(mark, "-rhaps-tablecell%i:%ix%i", tableno, tablerow, tablecol);
                        speak(ssml, mark, NULL);
                        break;
                    } else in_table = 0;
                }
                section_no--;
                sprintf(mark, "-rhaps-section%i", section_no);
                speak(ssml, section_no > 0 ? mark : NULL, NULL);
                break;
            case 'B':
                // 🠗
                if (in_table) {
                    tablerow++;
                    sprintf(mark, "-rhaps-tablecell%i:%ix%i", tableno, tablerow, tablecol);
                    sprintf(fallback, "-rhaps-section%i", section_no+1);
                    speak(ssml, mark, fallback);
                    break; // FIXME What if that mark doesn't exist?
                }
                section_no++;
                sprintf(mark, "-rhaps-section%i", section_no);
                speak(ssml, section_no > 0 ? mark : NULL, NULL);
                break;
            case 'C':
                // ➔
                if (in_table) {
                    tablecol++;
                    sprintf(mark, "-rhaps-tablecell%i:%ix%i", tableno, tablerow, tablecol);
                    sprintf(fallback, "-rhaps-paragraph%i", paragraph_no+1);
                    speak(ssml, mark, fallback);
                    break; // FIXME What if that mark doesn't exist?
                }
                paragraph_no++;
                sprintf(mark, "-rhaps-paragraph%i", paragraph_no);
                speak(ssml, paragraph_no > 0 ? mark : NULL, NULL);
                break;
            case 'D':
                // 🠔
                if (in_table) {
                    tablecol--;
                    if (tablecol > 0) {
                        sprintf(mark, "-rhaps-tablecell%i:%ix%i", tableno, tablerow, tablecol);
                        speak(ssml, mark, NULL);
                        break;
                    } else in_table = 0;
                }
                paragraph_no--;
                sprintf(mark, "-rhaps-paragraph%i", paragraph_no);
                speak(ssml, paragraph_no > 0 ? mark : NULL, NULL);
                break;
            }
        } else {
            // Read in a line
            tcsetattr(0, TCSANOW, &stored_settings);
            char *line = NULL;
            size_t len = 0;
            if (getline(&line, &len, stdin) < 0)
                fprintf(stderr, "Failed to read stdin line!\n");
            else if (*line == '\n') {
                espeak_Cancel();
                return 0;
            } else if (out_link != NULL)
                *out_link = select_link(links, line);
            tcsetattr(0, TCSANOW, &no_echo);
        }
    }
    espeak_ng_STATUS result = espeak_ng_Synchronize();
    if (result != ENS_OK) {
        espeak_ng_PrintStatusCodeMessage(result, stderr, context);
        return 4;
    }

close:
    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";
    char *logpath = NULL;
    FILE *fd_ssml = NULL;
    FILE *fd_links = NULL;
    int use_espeak = 0;
    tcgetattr(0, &stored_settings);
    #ifdef WITH_SPEECHD
    SPDConnection *spd_conn = NULL;
    #endif

    int c;
    opterr = 0;
    #ifdef WITH_SPEECHD
    while ((c = getopt(argc, argv, "xs::l::L:kw::dh")) != -1) {
    #else
    while ((c = getopt(argc, argv, "xs::l::kw::h")) != -1) {
    #endif
        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 'L':
            logpath = optarg;
            break;
        case 'k':
            read_keyboard = 1;
            // Read input character by character, not line by line.
            no_echo = stored_settings;
            no_echo.c_lflag &= (~ICANON);
            no_echo.c_lflag &= (~ECHO);
            no_echo.c_cc[VTIME] = 0;
            no_echo.c_cc[VMIN] = 1;
            tcsetattr(0, TCSANOW, &no_echo);
            break;
        case 'w':
            use_espeak = 1;
            path_wav = optarg;
            break;
        #ifdef WITH_SPEECHD
        case 'd':
            spd_conn = spd_open("rhapsode", "main", NULL, SPD_MODE_SINGLE);
            if (spd_conn == NULL) fprintf(stderr, "Failed to open SpeechD connection, ignoring\n");
            spd_set_data_mode(spd_conn, SPD_DATA_SSML);
            break;
        #endif
        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-L\tlog\tWrite (append) network request timing to specified filepath.\n");
            fprintf(stderr, "\t-k\tkeyboard\tRead arrow key navigation & links from stdin.\n");
            fprintf(stderr, "\t-w\t.wav\tWrite an audio recording of the webpage, or (DEFAULT) immediately output through speakers.\n");
            #ifdef WITH_SPEECHD
            fprintf(stderr, "\t-d\tSpeechD\tSchedule page read via the SpeechD daemon. (BROKEN)\n");
            #endif
            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;
    #ifdef WITH_SPEECHD
    if (fd_ssml == NULL && fd_links == NULL && spd_conn == NULL && !use_espeak)
    #else
    if (fd_ssml == NULL && fd_links == NULL && !use_espeak)
    #endif
        use_espeak = 1;

#if 0 // Unit-test levenshtein_distance
    int dist = levenshtein_distance("kitten", "kitten");
    printf("kitten => kitten: %i\n", dist);
    if (dist != 0) return 10;
    dist = levenshtein_distance("kitten", "sitting");
    printf("kitten => sitting: %i\n", dist);
    if (dist != 3) return 11;
#endif

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

    if (use_espeak) speak_err = speak_initialize();
    char *ssml, **links, *uri;
    for (int i = optind; i < argc; i++) {
        uri = argv[i];

read_uri:
        if (use_espeak && speak_err == 0) speak_text(uri, espeakRATE, 10);
        #ifdef WITH_SPEECHD
        else if (spd_conn != NULL) spd_say(spd_conn, SPD_MESSAGE, uri);
        #endif
        else printf("%s\n", argv[i]);

        if (logpath != NULL) c_enableLogging(session);

        struct page *page = c_fetchURL(session, mimes, referer, uri);
        ssml = c_renderDoc(session, page, use_espeak);
        links = c_extractLinks(page);

        if (logpath != NULL) c_writeLog(logpath, session);

        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, "main", NULL);
        #ifdef WITH_SPEECHD
        if (spd_conn != NULL) spd_say(spd_conn, SPD_MESSAGE, ssml);
        #endif

        c_freePage(page);
    }

    uri = NULL;
    if (use_espeak & speak_err == 0) speak_err = speak_finalize(ssml, links, &uri);
    if (uri != NULL) goto read_uri;

    #ifdef WITH_SPEECHD
    if (spd_conn != NULL) spd_close(spd_conn);
    #endif

    c_freePage(referer);
    c_freeSession(session);
    hs_exit();
    tcsetattr(0, TCSANOW, &stored_settings);

    return speak_err;
}