/* This is a simple program which uses libstemmer to provide a command
 * line interface for stemming using any of the algorithms provided.
 */

#include <stdio.h>
#include <stdlib.h> /* for malloc, free */
#include <string.h> /* for memmove */
#include <ctype.h>  /* for isupper, tolower */

#include "libstemmer.h"

const char * progname;
static int pretty = 1;

static void
stem_file(struct sb_stemmer * stemmer, FILE * f_in, FILE * f_out)
{
#define INC 10
    int lim = INC;
    sb_symbol * b = (sb_symbol *) malloc(lim * sizeof(sb_symbol));

    while (1) {
        int ch = getc(f_in);
        if (ch == EOF) {
            free(b); return;
        }
        {
            int i = 0;
            int inlen = 0;
            while (ch != '\n' && ch != EOF) {
                if (i == lim) {
                    sb_symbol * newb;
                    newb = (sb_symbol *)
                            realloc(b, (lim + INC) * sizeof(sb_symbol));
                    if (newb == NULL) goto error;
                    b = newb;
                    lim = lim + INC;
                }
                /* Update count of utf-8 characters. */
                if (ch < 0x80 || ch > 0xBF) inlen += 1;
                /* force lower case: */
                ch = tolower(ch);

                b[i] = ch;
                i++;
                ch = getc(f_in);
            }

            {
                const sb_symbol * stemmed = sb_stemmer_stem(stemmer, b, i);
                if (stemmed == NULL)
                {
                    fprintf(stderr, "Out of memory or internal error\n");
                    exit(1);
                }

                if (pretty == 1) {
                    fwrite(b, i, 1, f_out);
                    fputs(" -> ", f_out);
                } else if (pretty == 2) {
                    fwrite(b, i, 1, f_out);
                    if (sb_stemmer_length(stemmer) > 0) {
                        int j;
                        if (inlen < 30) {
                            for (j = 30 - inlen; j > 0; j--)
                                fputs(" ", f_out);
                        } else {
                            fputs("\n", f_out);
                            for (j = 30; j > 0; j--)
                                fputs(" ", f_out);
                        }
                    }
                }

                fputs((const char *)stemmed, f_out);
                putc('\n', f_out);
            }
        }
    }
error:
    free(b);
    return;
}

/** Display the command line syntax, and then exit.
 *  @param n The value to exit with.
 */
static void
usage(int n)
{
    printf("usage: %s [-l <language>] [-i <input file>] [-o <output file>] [-c <character encoding>] [-p[2]] [-h]\n"
          "\n"
          "The input file consists of a list of words to be stemmed, one per\n"
          "line. Words should be in lower case, but (for English) A-Z letters\n"
          "are mapped to their a-z equivalents anyway. If omitted, stdin is\n"
          "used.\n"
          "\n"
          "If -c is given, the argument is the character encoding of the input\n"
          "and output files.  If it is omitted, the UTF-8 encoding is used.\n"
          "\n"
          "If -p is given the output file consists of each word of the input\n"
          "file followed by \"->\" followed by its stemmed equivalent.\n"
          "If -p2 is given the output file is a two column layout containing\n"
          "the input words in the first column and the stemmed equivalents in\n"
          "the second column.\n"
          "Otherwise, the output file consists of the stemmed words, one per\n"
          "line.\n"
          "\n"
          "-h displays this help\n",
          progname);
    exit(n);
}

int
main(int argc, char * argv[])
{
    const char * in = NULL;
    const char * out = NULL;
    FILE * f_in;
    FILE * f_out;
    struct sb_stemmer * stemmer;

    const char * language = "english";
    const char * charenc = NULL;

    int i = 1;
    pretty = 0;

    progname = argv[0];

    while (i < argc) {
        const char * s = argv[i++];
        if (s[0] == '-') {
            if (strcmp(s, "-o") == 0) {
                if (i >= argc) {
                    fprintf(stderr, "%s requires an argument\n", s);
                    exit(1);
                }
                out = argv[i++];
            } else if (strcmp(s, "-i") == 0) {
                if (i >= argc) {
                    fprintf(stderr, "%s requires an argument\n", s);
                    exit(1);
                }
                in = argv[i++];
            } else if (strcmp(s, "-l") == 0) {
                if (i >= argc) {
                    fprintf(stderr, "%s requires an argument\n", s);
                    exit(1);
                }
                language = argv[i++];
            } else if (strcmp(s, "-c") == 0) {
                if (i >= argc) {
                    fprintf(stderr, "%s requires an argument\n", s);
                    exit(1);
                }
                charenc = argv[i++];
            } else if (strcmp(s, "-p2") == 0) {
                pretty = 2;
            } else if (strcmp(s, "-p") == 0) {
                pretty = 1;
            } else if (strcmp(s, "-h") == 0) {
                usage(0);
            } else {
                fprintf(stderr, "option %s unknown\n", s);
                usage(1);
            }
        } else {
            fprintf(stderr, "unexpected parameter %s\n", s);
            usage(1);
        }
    }

    /* prepare the files */
    f_in = (in == NULL) ? stdin : fopen(in, "r");
    if (f_in == NULL) {
        fprintf(stderr, "file %s not found\n", in);
        exit(1);
    }
    f_out = (out == NULL) ? stdout : fopen(out, "w");
    if (f_out == NULL) {
        fprintf(stderr, "file %s cannot be opened\n", out);
        exit(1);
    }

    /* do the stemming process: */
    stemmer = sb_stemmer_new(language, charenc);
    if (stemmer == NULL) {
        if (charenc == NULL) {
            fprintf(stderr, "language `%s' not available for stemming\n", language);
            exit(1);
        } else {
            fprintf(stderr, "language `%s' not available for stemming in encoding `%s'\n", language, charenc);
            exit(1);
        }
    }
    stem_file(stemmer, f_in, f_out);
    sb_stemmer_delete(stemmer);

    if (in != NULL) (void) fclose(f_in);
    if (out != NULL) (void) fclose(f_out);

    return 0;
}
