/*
 * Copyright (C) 1984-2012  Mark Nudelman
 * Modified for use with illumos by Garrett D'Amore.
 * Copyright 2014 Garrett D'Amore <garrett@damore.org>
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information, see the README file.
 */

/*
 *      lesskey [-o output] [input]
 *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *
 *      Make a .less file.
 *      If no input file is specified, standard input is used.
 *      If no output file is specified, $HOME/.less is used.
 *
 *      The .less file is used to specify (to "less") user-defined
 *      key bindings.  Basically any sequence of 1 to MAX_CMDLEN
 *      keystrokes may be bound to an existing less function.
 *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *
 *      The input file is an ascii file consisting of a
 *      sequence of lines of the form:
 *              string <whitespace> action [chars] <newline>
 *
 *      "string" is a sequence of command characters which form
 *              the new user-defined command.  The command
 *              characters may be:
 *              1. The actual character itself.
 *              2. A character preceded by ^ to specify a
 *                 control character (e.g. ^X means control-X).
 *              3. A backslash followed by one to three octal digits
 *                 to specify a character by its octal value.
 *              4. A backslash followed by b, e, n, r or t
 *                 to specify \b, ESC, \n, \r or \t, respectively.
 *              5. Any character (other than those mentioned above) preceded
 *                 by a \ to specify the character itself (characters which
 *                 must be preceded by \ include ^, \, and whitespace.
 *      "action" is the name of a "less" action, from the table below.
 *      "chars" is an optional sequence of characters which is treated
 *              as keyboard input after the command is executed.
 *
 *      Blank lines and lines which start with # are ignored,
 *      except for the special control lines:
 *              #command        Signals the beginning of the command
 *                              keys section.
 *              #line-edit      Signals the beginning of the line-editing
 *                              keys section.
 *              #env            Signals the beginning of the environment
 *                              variable section.
 *              #stop           Stops command parsing in less;
 *                              causes all default keys to be disabled.
 *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 *
 *      The output file is a non-ascii file, consisting of a header,
 *      one or more sections, and a trailer.
 *      Each section begins with a section header, a section length word
 *      and the section data.  Normally there are three sections:
 *              CMD_SECTION     Definition of command keys.
 *              EDIT_SECTION    Definition of editing keys.
 *              END_SECTION     A special section header, with no
 *                              length word or section data.
 *
 *      Section data consists of zero or more byte sequences of the form:
 *              string <0> <action>
 *      or
 *              string <0> <action|A_EXTRA> chars <0>
 *
 *      "string" is the command string.
 *      "<0>" is one null byte.
 *      "<action>" is one byte containing the action code (the A_xxx value).
 *      If action is ORed with A_EXTRA, the action byte is followed
 *              by the null-terminated "chars" string.
 *
 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 */

#include <err.h>

#include "cmd.h"
#include "less.h"
#include "lesskey.h"

struct cmdname {
        char *cn_name;
        int cn_action;
};

static void     lkerr(char *);

struct cmdname cmdnames[] = {
        { "back-bracket",               A_B_BRACKET },
        { "back-line",                  A_B_LINE },
        { "back-line-force",            A_BF_LINE },
        { "back-screen",                A_B_SCREEN },
        { "back-scroll",                A_B_SCROLL },
        { "back-search",                A_B_SEARCH },
        { "back-window",                A_B_WINDOW },
        { "debug",                      A_DEBUG },
        { "digit",                      A_DIGIT },
        { "display-flag",               A_DISP_OPTION },
        { "display-option",             A_DISP_OPTION },
        { "end",                        A_GOEND },
        { "examine",                    A_EXAMINE },
        { "filter",                     A_FILTER },
        { "first-cmd",                  A_FIRSTCMD },
        { "firstcmd",                   A_FIRSTCMD },
        { "flush-repaint",              A_FREPAINT },
        { "forw-bracket",               A_F_BRACKET },
        { "forw-forever",               A_F_FOREVER },
        { "forw-until-hilite",          A_F_UNTIL_HILITE },
        { "forw-line",                  A_F_LINE },
        { "forw-line-force",            A_FF_LINE },
        { "forw-screen",                A_F_SCREEN },
        { "forw-screen-force",          A_FF_SCREEN },
        { "forw-scroll",                A_F_SCROLL },
        { "forw-search",                A_F_SEARCH },
        { "forw-skip",                  A_F_SKIP },
        { "forw-window",                A_F_WINDOW },
        { "goto-end",                   A_GOEND },
        { "goto-line",                  A_GOLINE },
        { "goto-mark",                  A_GOMARK },
        { "help",                       A_HELP },
        { "index-file",                 A_INDEX_FILE },
        { "invalid",                    A_UINVALID },
        { "left-scroll",                A_LSHIFT },
        { "next-file",                  A_NEXT_FILE },
        { "next-tag",                   A_NEXT_TAG },
        { "noaction",                   A_NOACTION },
        { "percent",                    A_PERCENT },
        { "pipe",                       A_PIPE },
        { "prev-file",                  A_PREV_FILE },
        { "prev-tag",                   A_PREV_TAG },
        { "quit",                       A_QUIT },
        { "remove-file",                A_REMOVE_FILE },
        { "repaint",                    A_REPAINT },
        { "repaint-flush",              A_FREPAINT },
        { "repeat-search",              A_AGAIN_SEARCH },
        { "repeat-search-all",          A_T_AGAIN_SEARCH },
        { "reverse-search",             A_REVERSE_SEARCH },
        { "reverse-search-all",         A_T_REVERSE_SEARCH },
        { "right-scroll",               A_RSHIFT },
        { "set-mark",                   A_SETMARK },
        { "status",                     A_STAT },
        { "toggle-flag",                A_OPT_TOGGLE },
        { "toggle-option",              A_OPT_TOGGLE },
        { "undo-hilite",                A_UNDO_SEARCH },
        { "version",                    A_VERSION },
        { "visual",                     A_VISUAL },
        { NULL,                         0 }
};

struct cmdname editnames[] = {
        { "back-complete",      EC_B_COMPLETE },
        { "backspace",          EC_BACKSPACE },
        { "delete",             EC_DELETE },
        { "down",               EC_DOWN },
        { "end",                EC_END },
        { "expand",             EC_EXPAND },
        { "forw-complete",      EC_F_COMPLETE },
        { "home",               EC_HOME },
        { "insert",             EC_INSERT },
        { "invalid",            EC_UINVALID },
        { "kill-line",          EC_LINEKILL },
        { "abort",              EC_ABORT },
        { "left",               EC_LEFT },
        { "literal",            EC_LITERAL },
        { "right",              EC_RIGHT },
        { "up",                 EC_UP },
        { "word-backspace",     EC_W_BACKSPACE },
        { "word-delete",        EC_W_DELETE },
        { "word-left",          EC_W_LEFT },
        { "word-right",         EC_W_RIGHT },
        { NULL, 0 }
};

struct table {
        struct cmdname *names;
        char *pbuffer;
        char buffer[MAX_USERCMD];
};

struct table cmdtable;
struct table edittable;
struct table vartable;
struct table *currtable = &cmdtable;

char fileheader[] = {
        C0_LESSKEY_MAGIC,
        C1_LESSKEY_MAGIC,
        C2_LESSKEY_MAGIC,
        C3_LESSKEY_MAGIC
};
char filetrailer[] = {
        C0_END_LESSKEY_MAGIC,
        C1_END_LESSKEY_MAGIC,
        C2_END_LESSKEY_MAGIC
};
char cmdsection[1] =    { CMD_SECTION };
char editsection[1] =   { EDIT_SECTION };
char varsection[1] =    { VAR_SECTION };
char endsection[1] =    { END_SECTION };

char *infile = NULL;
char *outfile = NULL;

int linenum;
int errors;

extern char version[];

static void
usage(void)
{
        (void) fprintf(stderr, "usage: lesskey [-o output] [input]\n");
        exit(1);
}

static char *
mkpathname(char *dirname, char *filename)
{
        char *pathname;
        size_t len;

        len = strlen(dirname) + strlen(filename) + 2;
        pathname = calloc(1, len);
        if (pathname == NULL) {
                fprintf(stderr, "mkpathname: out of memory\n");
                exit(1);
        }
        (void) snprintf(pathname, len, "%s/%s", dirname, filename);
        return (pathname);
}

/*
 * Figure out the name of a default file (in the user's HOME directory).
 */
char *
homefile(char *filename)
{
        char *p;
        char *pathname;

        if ((p = getenv("HOME")) != NULL && *p != '\0') {
                pathname = mkpathname(p, filename);
        } else {
                (void) fprintf(stderr, "cannot find $HOME - "
                    "using current directory\n");
                pathname = mkpathname(".", filename);
        }
        return (pathname);
}

/*
 * Parse command line arguments.
 */
static void
parse_args(int argc, char **argv)
{
        char *arg;

        outfile = NULL;
        while (--argc > 0) {
                arg = *++argv;
                if (arg[0] != '-')
                        /* Arg does not start with "-"; it's not an option. */
                        break;
                if (arg[1] == '\0')
                        /* "-" means standard input. */
                        break;
                if (arg[1] == '-' && arg[2] == '\0') {
                        /* "--" means end of options. */
                        argc--;
                        argv++;
                        break;
                }
                switch (arg[1]) {
                case '-':
                        if (strncmp(arg, "--output", 8) == 0) {
                                if (arg[8] == '\0')
                                        outfile = &arg[8];
                                else if (arg[8] == '=')
                                        outfile = &arg[9];
                                else
                                        usage();
                                goto opt_o;
                        }
                        if (strcmp(arg, "--version") == 0) {
                                goto opt_V;
                        }
                        usage();
                        break;
                case 'o':
                        outfile = &argv[0][2];
                opt_o:
                        if (*outfile == '\0') {
                                if (--argc <= 0)
                                        usage();
                                outfile = *(++argv);
                        }
                        break;
                case 'V':
                opt_V:
                        (void) printf("lesskey  version %s\n", version);
                        exit(0);
                default:
                        usage();
                }
        }
        if (argc > 1)
                usage();
        /*
         * Open the input file, or use DEF_LESSKEYINFILE if none specified.
         */
        if (argc > 0)
                infile = *argv;
        else
                infile = homefile(DEF_LESSKEYINFILE);
}

/*
 * Initialize data structures.
 */
static void
init_tables(void)
{
        cmdtable.names = cmdnames;
        cmdtable.pbuffer = cmdtable.buffer;

        edittable.names = editnames;
        edittable.pbuffer = edittable.buffer;

        vartable.names = NULL;
        vartable.pbuffer = vartable.buffer;
}

/*
 * Parse one character of a string.
 */
static char *
tstr(char **pp, int xlate)
{
        char *p;
        char ch;
        int i;
        static char buf[10];
        static char tstr_control_k[] =
                { SK_SPECIAL_KEY, SK_CONTROL_K, 6, 1, 1, 1, '\0' };

        p = *pp;
        switch (*p) {
        case '\\':
                ++p;
                switch (*p) {
                case '0': case '1': case '2': case '3':
                case '4': case '5': case '6': case '7':
                        /*
                         * Parse an octal number.
                         */
                        ch = 0;
                        i = 0;
                        do
                                ch = 8*ch + (*p - '0');
                        while (*++p >= '0' && *p <= '7' && ++i < 3)
                                ;
                        *pp = p;
                        if (xlate && ch == CONTROL('K'))
                                return (tstr_control_k);
                        buf[0] = ch;
                        buf[1] = '\0';
                        return (buf);
                case 'b':
                        *pp = p+1;
                        return ("\b");
                case 'e':
                        *pp = p+1;
                        buf[0] = ESC;
                        buf[1] = '\0';
                        return (buf);
                case 'n':
                        *pp = p+1;
                        return ("\n");
                case 'r':
                        *pp = p+1;
                        return ("\r");
                case 't':
                        *pp = p+1;
                        return ("\t");
                case 'k':
                        if (xlate) {
                                switch (*++p) {
                                case 'u': ch = SK_UP_ARROW; break;
                                case 'd': ch = SK_DOWN_ARROW; break;
                                case 'r': ch = SK_RIGHT_ARROW; break;
                                case 'l': ch = SK_LEFT_ARROW; break;
                                case 'U': ch = SK_PAGE_UP; break;
                                case 'D': ch = SK_PAGE_DOWN; break;
                                case 'h': ch = SK_HOME; break;
                                case 'e': ch = SK_END; break;
                                case 'x': ch = SK_DELETE; break;
                                default:
                                        lkerr("illegal char after \\k");
                                        *pp = p+1;
                                        return ("");
                                }
                                *pp = p+1;
                                buf[0] = SK_SPECIAL_KEY;
                                buf[1] = ch;
                                buf[2] = 6;
                                buf[3] = 1;
                                buf[4] = 1;
                                buf[5] = 1;
                                buf[6] = '\0';
                                return (buf);
                        }
                        /* FALLTHRU */
                default:
                        /*
                         * Backslash followed by any other char
                         * just means that char.
                         */
                        *pp = p+1;
                        buf[0] = *p;
                        buf[1] = '\0';
                        if (xlate && buf[0] == CONTROL('K'))
                                return (tstr_control_k);
                        return (buf);
                }
        case '^':
                /*
                 * Caret means CONTROL.
                 */
                *pp = p+2;
                buf[0] = CONTROL(p[1]);
                buf[1] = '\0';
                if (buf[0] == CONTROL('K'))
                        return (tstr_control_k);
                return (buf);
        }
        *pp = p+1;
        buf[0] = *p;
        buf[1] = '\0';
        if (xlate && buf[0] == CONTROL('K'))
                return (tstr_control_k);
        return (buf);
}

/*
 * Skip leading spaces in a string.
 */
char *
skipsp(char *s)
{
        while (*s == ' ' || *s == '\t')
                s++;
        return (s);
}

/*
 * Skip non-space characters in a string.
 */
static char *
skipnsp(char *s)
{
        while (*s != '\0' && *s != ' ' && *s != '\t')
                s++;
        return (s);
}

/*
 * Clean up an input line:
 * strip off the trailing newline & any trailing # comment.
 */
static char *
clean_line(char *s)
{
        int i;

        s = skipsp(s);
        for (i = 0; s[i] != '\n' && s[i] != '\r' && s[i] != '\0'; i++)
                if (s[i] == '#' && (i == 0 || s[i-1] != '\\'))
                        break;
        s[i] = '\0';
        return (s);
}

/*
 * Add a byte to the output command table.
 */
static void
add_cmd_char(int c)
{
        if (currtable->pbuffer >= currtable->buffer + MAX_USERCMD) {
                lkerr("too many commands");
                exit(1);
        }
        *(currtable->pbuffer)++ = (char)c;
}

/*
 * Add a string to the output command table.
 */
static void
add_cmd_str(char *s)
{
        for (; *s != '\0'; s++)
                add_cmd_char(*s);
}

/*
 * See if we have a special "control" line.
 */
static int
control_line(char *s)
{
#define PREFIX(str, pat)        (strncmp(str, pat, strlen(pat)) == 0)

        if (PREFIX(s, "#line-edit")) {
                currtable = &edittable;
                return (1);
        }
        if (PREFIX(s, "#command")) {
                currtable = &cmdtable;
                return (1);
        }
        if (PREFIX(s, "#env")) {
                currtable = &vartable;
                return (1);
        }
        if (PREFIX(s, "#stop")) {
                add_cmd_char('\0');
                add_cmd_char(A_END_LIST);
                return (1);
        }
        return (0);
}

/*
 * Output some bytes.
 */
static void
fputbytes(FILE *fd, char *buf, int len)
{
        while (len-- > 0) {
                (void) fwrite(buf, sizeof (char), 1, fd);
                buf++;
        }
}

/*
 * Output an integer, in special KRADIX form.
 */
static void
fputint(FILE *fd, unsigned int val)
{
        char c;

        if (val >= KRADIX*KRADIX) {
                (void) fprintf(stderr, "error: integer too big (%d > %d)\n",
                    val, KRADIX*KRADIX);
                exit(1);
        }
        c = val % KRADIX;
        (void) fwrite(&c, sizeof (char), 1, fd);
        c = val / KRADIX;
        (void) fwrite(&c, sizeof (char), 1, fd);
}

/*
 * Find an action, given the name of the action.
 */
static int
findaction(char *actname)
{
        int i;

        for (i = 0; currtable->names[i].cn_name != NULL; i++)
                if (strcmp(currtable->names[i].cn_name, actname) == 0)
                        return (currtable->names[i].cn_action);
        lkerr("unknown action");
        return (A_INVALID);
}

static void
lkerr(char *s)
{
        (void) fprintf(stderr, "line %d: %s\n", linenum, s);
        errors++;
}


static void
parse_cmdline(char *p)
{
        int cmdlen;
        char *actname;
        int action;
        char *s;
        char c;

        /*
         * Parse the command string and store it in the current table.
         */
        cmdlen = 0;
        do {
                s = tstr(&p, 1);
                cmdlen += strlen(s);
                if (cmdlen > MAX_CMDLEN)
                        lkerr("command too long");
                else
                        add_cmd_str(s);
        } while (*p != ' ' && *p != '\t' && *p != '\0');
        /*
         * Terminate the command string with a null byte.
         */
        add_cmd_char('\0');

        /*
         * Skip white space between the command string
         * and the action name.
         * Terminate the action name with a null byte.
         */
        p = skipsp(p);
        if (*p == '\0') {
                lkerr("missing action");
                return;
        }
        actname = p;
        p = skipnsp(p);
        c = *p;
        *p = '\0';

        /*
         * Parse the action name and store it in the current table.
         */
        action = findaction(actname);

        /*
         * See if an extra string follows the action name.
         */
        *p = c;
        p = skipsp(p);
        if (*p == '\0') {
                add_cmd_char(action);
        } else {
                /*
                 * OR the special value A_EXTRA into the action byte.
                 * Put the extra string after the action byte.
                 */
                add_cmd_char(action | A_EXTRA);
                while (*p != '\0')
                        add_cmd_str(tstr(&p, 0));
                add_cmd_char('\0');
        }
}

static void
parse_varline(char *p)
{
        char *s;

        do {
                s = tstr(&p, 0);
                add_cmd_str(s);
        } while (*p != ' ' && *p != '\t' && *p != '=' && *p != '\0');
        /*
         * Terminate the variable name with a null byte.
         */
        add_cmd_char('\0');

        p = skipsp(p);
        if (*p++ != '=') {
                lkerr("missing =");
                return;
        }

        add_cmd_char(EV_OK|A_EXTRA);

        p = skipsp(p);
        while (*p != '\0') {
                s = tstr(&p, 0);
                add_cmd_str(s);
        }
        add_cmd_char('\0');
}

/*
 * Parse a line from the lesskey file.
 */
static void
parse_line(char *line)
{
        char *p;

        /*
         * See if it is a control line.
         */
        if (control_line(line))
                return;
        /*
         * Skip leading white space.
         * Replace the final newline with a null byte.
         * Ignore blank lines and comments.
         */
        p = clean_line(line);
        if (*p == '\0')
                return;

        if (currtable == &vartable)
                parse_varline(p);
        else
                parse_cmdline(p);
}

int
main(int argc, char **argv)
{
        FILE *desc;
        FILE *out;
        char line[1024];

        if (pledge("stdio rpath wpath cpath", NULL) == -1)
                err(1, "pledge");

        /*
         * Process command line arguments.
         */
        parse_args(argc, argv);
        init_tables();

        /*
         * Open the input file.
         */
        if (strcmp(infile, "-") == 0)
                desc = stdin;
        else if ((desc = fopen(infile, "r")) == NULL) {
                perror(infile);
                usage();
        }

        /*
         * Read and parse the input file, one line at a time.
         */
        errors = 0;
        linenum = 0;
        while (fgets(line, sizeof (line), desc) != NULL) {
                ++linenum;
                parse_line(line);
        }
        fclose(desc);

        /*
         * Write the output file.
         * If no output file was specified, use "$HOME/.less"
         */
        if (errors > 0) {
                (void) fprintf(stderr, "%d errors; no output produced\n",
                    errors);
                exit(1);
        }

        if (outfile == NULL)
                outfile = getenv("LESSKEY");
        if (outfile == NULL)
                outfile = homefile(LESSKEYFILE);
        if ((out = fopen(outfile, "wb")) == NULL) {
                perror(outfile);
                exit(1);
        }

        /* File header */
        fputbytes(out, fileheader, sizeof (fileheader));

        /* Command key section */
        fputbytes(out, cmdsection, sizeof (cmdsection));
        fputint(out, cmdtable.pbuffer - cmdtable.buffer);
        fputbytes(out, (char *)cmdtable.buffer,
            cmdtable.pbuffer-cmdtable.buffer);

        /* Edit key section */
        fputbytes(out, editsection, sizeof (editsection));
        fputint(out, edittable.pbuffer - edittable.buffer);
        fputbytes(out, (char *)edittable.buffer,
            edittable.pbuffer-edittable.buffer);

        /* Environment variable section */
        fputbytes(out, varsection, sizeof (varsection));
        fputint(out, vartable.pbuffer - vartable.buffer);
        fputbytes(out, (char *)vartable.buffer,
            vartable.pbuffer-vartable.buffer);

        /* File trailer */
        fputbytes(out, endsection, sizeof (endsection));
        fputbytes(out, filetrailer, sizeof (filetrailer));
        fclose(out);
        return (0);
}