/*
 * A file look-up utility to complement updatedb
 *
 * Compile and run updatedb command first to create locate.db file.  Then,
 * compile this program with Visual Studio and run the program in console with
 * a file name argument.  For example, the command
 *
 *     locate autoexec
 *
 * might output something like
 *
 *     c:/AUTOEXEC.BAT
 *     c:/WINDOWS/repair/autoexec.nt
 *     c:/WINDOWS/system32/AUTOEXEC.NT
 *
 * Be ware that this file uses wide-character API which is not compatible
 * with Linux or other major Unixes.
 *
 * Copyright (C) 1998-2019 Toni Ronkko
 * This file is part of dirent.  Dirent may be freely distributed
 * under the MIT license.  For all details and documentation, see
 * https://github.com/tronkko/dirent
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#ifdef WIN32
#   include <io.h>
#   include <fcntl.h>
#endif
#include <dirent.h>

/* File name and location of database file */
#define DB_LOCATION L"locate.db"


/* Forward-decl */
static int db_locate (const wchar_t *pattern);
static int db_match (const wchar_t *fn, const wchar_t *pattern);
static void db_open (void);
static void db_close (void);
static int db_read (wchar_t *buffer, size_t max);


/* Module local variables */
static FILE *db = NULL;


int
main(
    int argc, char *argv[])
{
#ifdef WIN32
    int i;

    /* Prepare for unicode output */
    _setmode (_fileno (stdout), _O_U16TEXT);

    /* For each pattern in command line */
    i = 1;
    while (i < argc) {
        wchar_t buffer[PATH_MAX + 1];
        errno_t error;
        size_t n;
        int count = 0;

        /* Convert ith argument to wide-character string */
        error = mbstowcs_s (&n, buffer, PATH_MAX, argv[i], _TRUNCATE);
        if (!error) {
            /* Find files matching pattern */
            count = db_locate (buffer);

            /* Output warning if string is not found */
            if (count == 0) {
                wprintf (L"%s not found\n", buffer);
            }
        }


        i++;
    }

    if (argc < 2) {
        wprintf (L"Usage: locate pattern\n");
        exit (EXIT_FAILURE);
    }
#else
    printf ("locate only works on Microsoft Windows\n");
#endif

    return EXIT_SUCCESS;
}

/* Match pattern against files in locate.db file */
static int
db_locate(
    const wchar_t *pattern)
{
    int count = 0;

#ifdef WIN32
    wchar_t buffer[PATH_MAX + 1];

    /* Open locate.db for read */
    db_open ();

    /* Read one directory and file name at a time from database file */
    while (db_read (buffer, PATH_MAX + 1)) {
        /* See if file name in buffer matches the search pattern */
        if (db_match (buffer, pattern)) {
            /* Match found => output file name and path */
            wprintf (L"%s\n", buffer);
            count++;
        }

    }

    db_close ();
#endif

    return count;
}

/* Match pattern against file name */
static int
db_match(
    const wchar_t *fn, const wchar_t *pattern)
{
    int found = 0;

#ifdef WIN32
    wchar_t *p;
    wchar_t base[PATH_MAX + 1];
    wchar_t patt[PATH_MAX + 1];
    int i;
    int done = 0;

    /* Locate zero-terminator from fn */
    p = wcschr (fn, '\0');

    /* Find base name from buffer */
    while (fn < p  &&  !done) {
        switch (p[-1]) {
        case ':':
        case '/':
        case '\\':
            /* Final path separator found */
            done = 1;
            break;

        default:
            /* No path separator yet */
            p--;
        }
    }

    /* Convert base name to lower case */
    i = 0;
    while (i < PATH_MAX  &&  p[i] != '\0') {
        base[i] = towlower (p[i]);
        i++;
    }
    base[i] = '\0';

    /* Convert search pattern to lower case */
    i = 0;
    while (i < PATH_MAX  &&  pattern[i] != '\0') {
        patt[i] = towlower (pattern[i]);
        i++;
    }
    patt[i] = '\0';

    /* See if file name matches pattern */
    if (wcsstr (base, patt) != NULL) {
        found = 1;
    } else {
        found = 0;
    }
#endif

    return found;
}

/*
 * Read line from locate.db.  This function is same as fgetws() except
 * that new-line at the end of line is not included.
 */
static int
db_read(
    wchar_t *buffer, size_t max)
{
    int ok = 0;

#ifdef WIN32
    size_t i = 0;
    wchar_t c;
    int done = 0;

    do {
        /* Read wide-character from stream */
        if (db) {
            c = fgetwc (db);
        } else {
            wprintf (L"Database not open\n");
            exit (EXIT_SUCCESS);
        }

        /* Determine how to process character */
        switch (c) {
        case '\r':
            /* Ignore, should be handled by run-time libraries */
            /*NOP*/;
            break;

        case '\n':
            /* End of string => return file name and true */
            done = 1;
            ok = 1;
            break;

        case /*EOF*/WEOF:
            /* End of file */
            done = 1;
            if (i == 0) {
                /* No data in buffer => return false to indicate EOF */
                ok = 0;
            } else {
                /* Data in buffer => return true */
                ok = 1;
            }
            break;

        default:
            /* Store character */
            if (i < max - 1) {
                buffer[i++] = c;
            } else {
                buffer[max - 1] = '\0';
                wprintf (L"Buffer too small: %s", buffer);
                exit (EXIT_FAILURE);
            }
        }
    } while (!done);

    /* Zero-terminate buffer */
    buffer[i] = '\0';
#endif

    return ok;
}

/* Open database file locate.db */
static void
db_open(
    void)
{
#ifdef WIN32
    if (db == NULL) {
        errno_t error;

        /* Open file for writing */
        error = _wfopen_s (&db, DB_LOCATION, L"rt, ccs=UNICODE");
        if (error) {
            wprintf (L"Cannot open %s\n", DB_LOCATION);
            exit (EXIT_FAILURE);
        }
    }
#endif
}

/* Close database file */
static void
db_close(
    void)
{
    if (db) {
        fclose (db);
        db = NULL;
    }
}