/*
 * Copyright (c) 2000-2009, 2013-2015, 2019-2020 Paul Mattes.
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of Paul Mattes nor his contributors may be used
 *       to endorse or promote products derived from this software without
 *       specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY PAUL MATTES "AS IS" AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL PAUL MATTES BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*
 *	keymap.c
 *		A Windows Console-based 3270 Terminal Emulator
 *		Keyboard mapping
 */

#include "globals.h"
#include <errno.h>
#include "appres.h"
#include "resources.h"

#include "actions.h"
#include "glue.h"
#include "host.h"
#include "keymap.h"
#include "lazya.h"
#include "names.h"
#include "popups.h"
#include "screen.h"
#include "status.h"
#include "task.h"
#include "trace.h"
#include "utils.h"
#include "varbuf.h"

#define ISREALLYSPACE(c) ((((c) & 0xff) <= ' ') && isspace(c))

#define WC3270KM_SUFFIX	"wc3270km"
#define SUFFIX_LEN	sizeof(WC3270KM_SUFFIX)

#define KM_3270_ONLY	0x0100	/* used in 3270 mode only */
#define KM_NVT_ONLY	0x0200	/* used in NVT mode only */
#define KM_INACTIVE	0x0400	/* wrong NVT/3270 mode, or overridden */

#define KM_KEYMAP	0x8000
#define KM_HINTS	(KM_SHIFT | KM_CTRL | KM_ALT | KM_ENHANCED)

struct keymap {
    struct keymap *next;	/* next element in the keymap */
    struct keymap *successor;	/* mapping that overrules this one */
    int ncodes;			/* number of key codes */
    int *codes;			/* key codes (ASCII or vkey symbols) */
    int *hints;			/* hints (modifiers and restrictions) */
    char *name;			/* keymap name */
    char *file;			/* file path or resource name */
    int line;			/* keymap line number */
    bool temp;
    char *action;		/* action(s) to perform */
};

#define IS_INACTIVE(k)	((k)->hints[0] & KM_INACTIVE)

static struct keymap *master_keymap = NULL;

static bool last_3270 = false;
static bool last_nvt = false;

static int lookup_ccode(const char *s);
static void keymap_3270_mode(bool);

static void read_one_keymap(const char *name, const char *fn, bool temp,
	const char *r0, int flags);
static void clear_keymap(void);
static void set_inactive(void);

/*
 * Parse a key definition.
 * Returns <0 for error, 1 for key found and parsed, 0 for nothing found.
 * Returns the balance of the string and the character code.
 * Is destructive.
 */

enum {
    PKE_MKEY = -1,
    PKE_UMOD = -2,
    PKE_MSYM = -3,
    PKE_USYM = -4
} pk_error;

static char *pk_errmsg[] = {
    "Missing <Key>",
    "Unknown modifier",
    "Missing key",
    "Unknown key"
};

static int
parse_keydef(char **str, int *ccode, int *hint)
{
    char *s = *str;
    char *t;
    char *ks;
    int flags = 0;
    ks_t Ks;
    int xccode;

    /* Check for nothing. */
    while (ISREALLYSPACE(*s)) {
	s++;
    }
    if (!*s) {
	return 0;
    }
    *str = s;

    s = strstr(s, "<Key>");
    if (s == NULL) {
	return PKE_MKEY;
    }
    ks = s + 5;
    *s = '\0';
    s = *str;
    while (*s) {
	while (ISREALLYSPACE(*s)) {
	    s++;
	}
	if (!*s) {
	    break;
	}
	if (!strncasecmp(s, "Shift", 5)) {
	    flags |= KM_SHIFT;
	    s += 5;
	} else if (!strncasecmp(s, "Ctrl", 4)) {
	    flags |= KM_CTRL;
	    s += 4;
	} else if (!strncasecmp(s, "LeftCtrl", 8)) {
	    flags |= KM_LCTRL;
	    s += 8;
	} else if (!strncasecmp(s, "RightCtrl", 9)) {
	    flags |= KM_RCTRL;
	    s += 9;
	} else if (!strncasecmp(s, "Alt", 3)) {
	    flags |= KM_ALT;
	    s += 3;
	} else if (!strncasecmp(s, "LeftAlt", 7)) {
	    flags |= KM_LALT;
	    s += 7;
	} else if (!strncasecmp(s, "RightAlt", 8)) {
	    flags |= KM_RALT;
	    s += 8;
	} else if (!strncasecmp(s, "Enhanced", 8)) {
	    flags |= KM_ENHANCED;
	    s += 8;
	} else {
	    return PKE_UMOD;
	}
    }
    s = ks;
    while (ISREALLYSPACE(*s)) {
	s++;
    }
    if (!*s) {
	return PKE_MSYM;
    }

    t = s;
    while (*t && !ISREALLYSPACE(*t)) {
	t++;
    }
    if (*t) {
	*t++ = '\0';
    }
    xccode = lookup_ccode(s);
    if (xccode != -1) {
	*ccode = xccode;
    } else {
	if (!strncasecmp(s, "U+", 2) || !strncasecmp(s, "0x", 2)) {
	    unsigned long l;
	    char *ptr;

	    /*
	     * Explicit Unicode.
	     * We limit ourselves to UCS-2 for now, becuase of how
	     * we represent keymaps and keys (VK_xxx in upper 16
	     * bits, Unicode in lower 16 bits).
	     */
	    l = strtoul(s, &ptr, 16);
	    if (!((l == 0) || (l & ~0xffff) || *ptr != '\0')) {
		*ccode = (int)l;
	    } else {
		return PKE_USYM;
	    }
	} else if (strlen(s) == 1) {
	    int nc;
	    WCHAR w;

	    /* Single (ANSI CP) character. */
	    nc = MultiByteToWideChar(CP_ACP, 0, s, 1, &w, 1);
	    if (nc == 1) {
		*ccode = (int)w;
	    } else {
		return PKE_USYM;
	    }
	} else {
	    /* Try for a Latin-1 name. */
	    Ks = string_to_key(s);
	    if (Ks != KS_NONE) {
		*ccode = (int)Ks;
	    } else {
		return PKE_USYM;
	    }
	}
    }

    /* Canonicalize Ctrl. */
    if ((flags & KM_CTRL) && *ccode >= '@' && *ccode <= '~') {
	*ccode &= 0x1f;
	flags &= ~KM_CTRL;
    }

    /* Return the remaining string, and success. */
    *str = t;
    *hint = flags;
    return 1;
}

/*
 * Locate a keymap resource or file.
 * Returns 0 for do-nothing, 1 for success, -1 for error.
 * On success, returns the full name of the resource or file (which must be
 *  freed) in '*fullname'.
 * On success, returns a resource string (which must be closed) or NULL
 *  (indicating a file name to open is in *fullname) in '*r'.
 */
static int
locate_keymap(const char *name, char **fullname, char **r)
{
    char *rs;			/* resource value */
    char *fnx;			/* expanded file name */
    char *fny;
    char *fnp;
    int a;

    /* Return nothing, to begin with. */
    *fullname = NULL;
    *r = NULL;

    /* See if it's a resource. */
    rs = get_fresource(ResKeymap ".%s", name);

    /* If there's a plain version, return it. */
    if (rs != NULL) {
	*fullname = NewString(name);
	*r = NewString(rs);
	return 1;
    }

    /* See if it's a file. */
    fnx = do_subst(name, DS_VARS | DS_TILDE);
    fny = xs_buffer("%s.%s", fnx, WC3270KM_SUFFIX);

    /* My Documents\wc3270\foo.wc3270km? */
    if (mydocs3270 != NULL) {
	fnp = xs_buffer("%s%s", mydocs3270, fny);
	a = access(fnp, R_OK);
	if (a == 0) {
	    *fullname = fnp;
	    Free(fny);
	    Free(fnx);
	    return 1;
	}
	Free(fnp);
    }

    /* Public Documents\wc3270\foo.wc3270km? */
    if (commondocs3270 != NULL) {
	fnp = xs_buffer("%s%s", commondocs3270, fny);
	a = access(fnp, R_OK);
	if (a == 0) {
	    *fullname = fnp;
	    Free(fny);
	    Free(fnx);
	    return 1;
	}
	Free(fnp);
    }

    /* InstDir\foo.wc3270km? */
    fnp = xs_buffer("%s%s", instdir, fny);
    a = access(fnp, R_OK);
    if (a == 0) {
	Free(fny);
	Free(fnx);
	*fullname = fnp;
	return 1;
    }
    Free(fnp);

    /* foo.wc3270km? */
    a = access(fny, R_OK);
    if (a == 0) {
	Free(fnx);
	*fullname = fny;
	return 1;
    }
    Free(fny);

    /* foo? */
    a = access(fnx, R_OK);
    if (a == 0) {
	*fullname = fnx;
	return 1;
    }
    Free(fnx);

    /* No dice. */
    return -1;
}

/*
 * Compare a pair of keymaps for compatablity (could k2 match k1).
 * N.B.: This functon may need to be further parameterized for equality versus
 * (ambiguous) matching.
 */
static int
codecmp(struct keymap *k1, struct keymap *k2, int len)
{
    int r;
    int i;

    /* Compare the raw codes first. */
    r = memcmp(k1->codes, k2->codes, len * sizeof(int));
    if (r) {
	return r;
    }

    /* The codes agree, now try the modifiers. */
    for (i = 0; i < len; i++) {
	if ((k1->hints[i] & KM_HINTS) != (k2->hints[i] & KM_HINTS)) {
	    return -1;
	}
    }

    /* Same same. */
    return 0;
}

/* Add a keymap entry. */
static void
add_keymap_entry(int ncodes, int *codes, int *hints, const char *name,
	const char *file, int line, bool temp, const char *action,
	struct keymap ***nextkp)
{
    struct keymap *k;

    /* Allocate a new node. */
    k = Malloc(sizeof(struct keymap));
    k->next = NULL;
    k->successor = NULL;
    k->ncodes = ncodes;
    k->codes = Malloc(ncodes * sizeof(int));
    memcpy(k->codes, codes, ncodes * sizeof(int));
    k->hints = Malloc(ncodes * sizeof(int));
    memcpy(k->hints, hints, ncodes * sizeof(int));
    k->name = NewString(name);
    k->file = NewString(file);
    k->line = line;
    k->temp = temp;
    k->action = NewString(action);

    /* Link it in. */
    **nextkp = k;
    *nextkp = &k->next;
}

/*
 * Read a keymap from a file.
 * Returns true for success, false for an error.
 *
 * Keymap files look suspiciously like x3270 keymaps, but aren't.
 */
static bool
read_keymap(const char *name, bool temp)
{
    char *name_3270 = xs_buffer("%s.3270", name);
    char *name_nvt = xs_buffer("%s.nvt", name);
    int rc, rc_3270, rc_nvt;
    char *fn, *fn_3270, *fn_nvt;
    char *r0, *r0_3270, *r0_nvt;

    if (master_keymap != NULL && !strcmp(name, master_keymap->name)) {
	popup_an_error("Duplicate keymap: %s", name);
	return false;
    }

    rc = locate_keymap(name, &fn, &r0);
    rc_3270 = locate_keymap(name_3270, &fn_3270, &r0_3270);
    rc_nvt = locate_keymap(name_nvt, &fn_nvt, &r0_nvt);
    if (rc < 0 && rc_3270 < 0 && rc_nvt < 0) {
	popup_an_error("No such keymap resource or file: %s", name);
	Free(name_3270);
	Free(name_nvt);
	return false;
    }

    if (rc >= 0) {
	read_one_keymap(name, fn, temp, r0, 0);
	Free(fn);
	Free(r0);
    }
    if (rc_3270 >= 0) {
	read_one_keymap(name_3270, fn_3270, temp, r0_3270, KM_3270_ONLY);
	Free(fn_3270);
	Free(r0_3270);
    }
    if (rc_nvt >= 0) {
	read_one_keymap(name_nvt, fn_nvt, temp, r0_nvt, KM_NVT_ONLY);
	Free(fn_nvt);
	Free(r0_nvt);
    }
    Free(name_3270);
    Free(name_nvt);
    return true;
}

/*
 * Read a keymap from a file.
 * Accumulates the keymap onto the list pointed to by nextkp.
 * Returns 0 for success, -1 for an error.
 *
 * Keymap files look suspiciously like x3270 keymaps, but aren't.
 */
static void
read_one_keymap_internal(const char *name, const char *fn, bool temp,
	const char *r0, int flags, struct keymap ***nextkp)
{
    char *r = NULL;		/* resource value */
    char *r_copy = NULL;	/* initial value of r */
    FILE *f = NULL;		/* resource file */
    char buf[1024];		/* file read buffer */
    int line = 0;		/* line number */
    char *left, *right;		/* chunks of line */
    static int ncodes = 0;
    static int maxcodes = 0;
    static int *codes = NULL, *hints = NULL;
    int rc = 0;
    char *xfn = NULL;

    /* Find the resource or file. */
    if (r0 != NULL) {
	r = r_copy = NewString(r0);
	xfn = (char *)fn;
    } else {
	size_t sl;

	f = fopen(fn, "r");
	if (f == NULL) {
	    popup_an_error("File '%s' exists but cannot open: %s", fn,
		    strerror(errno));
	    return;
	}
	sl = strlen(fn);
	if (sl > SUFFIX_LEN &&
	    !strcmp(fn + sl - SUFFIX_LEN, "." WC3270KM_SUFFIX)) {

	    xfn = NewString(fn);
	    xfn[sl - SUFFIX_LEN] = '\0';
	} else {
	    xfn = (char *)fn;
	}
    }

    while ((r != NULL)? (rc = split_dresource(&r, &left, &right)):
		        fgets(buf, sizeof(buf), f) != NULL) {
	char *s;
	int ccode;
	int pkr;
	int hint;

	line++;

	/* Skip empty lines and comments. */
	if (r == NULL) {
	    s = buf;
	    while (ISREALLYSPACE(*s)) {
		s++;
	    }
	    if (!*s || *s == '!' || *s == '#') {
		continue;
	    }
	}

	/* Split. */
	if (rc < 0 || (r == NULL && split_dresource(&s, &left, &right) < 0)) {
	    popup_an_error("Keymap %s, line %d: syntax error", name, line);
	    goto done;
	}

	pkr = parse_keydef(&left, &ccode, &hint);
	if (pkr == 0) {
	    popup_an_error("Keymap %s, line %d: Missing <Key>", name, line);
	    goto done;
	}
	if (pkr < 0) {
	    popup_an_error("Keymap %s, line %d: %s", name, line,
		    pk_errmsg[-1 - pkr]);
	    goto done;
	}

	/* Accumulate keycodes. */
	ncodes = 0;
	do {
	    if (++ncodes > maxcodes) {
		maxcodes = ncodes;
		codes = Realloc(codes, maxcodes * sizeof(int));
		hints = Realloc(hints, maxcodes * sizeof(int));
	    }
	    codes[ncodes - 1] = ccode;
	    hints[ncodes - 1] = hint;
	    pkr = parse_keydef(&left, &ccode, &hint);
	    if (pkr < 0) {
		popup_an_error("Keymap %s, line %d: %s", name, line,
			pk_errmsg[-1 - pkr]);
		goto done;
	    }
	} while (pkr != 0);

	/* Add it to the list. */
	hints[0] |= flags;
	add_keymap_entry(ncodes, codes, hints, name, name, line, temp,
		right, nextkp);
    }

done:
    Free(r_copy);
    if (f != NULL) {
	fclose(f);
    }
    if (xfn != fn) {
	Free(xfn);
    }
}

/*
 * Read a keymap from a file.
 * Adds the keymap to the front of the 'master_keymap' list.
 * Returns 0 for success, -1 for an error.
 */
static void
read_one_keymap(const char *name, const char *fn, bool temp, const char *r0,
	int flags)
{
    struct keymap *one_master;
    struct keymap **one_nextk;

    /* Read in the keymap. */
    one_master = NULL;
    one_nextk = &one_master;
    read_one_keymap_internal(name, fn, temp, r0, flags, &one_nextk);

    if (one_master == NULL) {
	/* Nothing added. */
	return;
    }
    if (master_keymap == NULL) {
	/* Something added, nothing there before. */
	master_keymap = one_master;
	return;
    }

    /* Insert this keymap ahead of the previous ones. */
    *one_nextk = master_keymap;
    master_keymap = one_master;
}

/* Multi-key keymap support. */
static struct keymap *current_match = NULL;
static int consumed = 0;
static char *ignore = "[ignore]";

/* Find the shortest keymap with a longer match than k. */
static struct keymap *
longer_match(struct keymap *k, int nc)
{
    struct keymap *j;
    struct keymap *shortest = NULL;

    for (j = master_keymap; j != NULL; j = j->next) {
	if (IS_INACTIVE(j)) {
	    continue;
	}
	if (j != k && j->ncodes > nc && !codecmp(j, k, nc)) {
	    if (j->ncodes == nc+1) {
		return j;
	    }
	    if (shortest == NULL || j->ncodes < shortest->ncodes) {
		shortest = j;
	    }
	}
    }
    return shortest;
}

/*
 * Helper function that returns a keymap action, sets the status line, and
 * traces the result.  
 *
 * If s is NULL, then this is a failed initial lookup.
 * If s is 'ignore', then this is a lookup in progress (k non-NULL) or a
 *  failed multi-key lookup (k NULL).
 * Otherwise, this is a successful lookup.
 */
static char *
status_ret(char *s, struct keymap *k)
{
    /* Set the compose indicator based on the new value of current_match. */
    if (k != NULL) {
	status_compose(true, ' ', KT_STD);
    } else {
	status_compose(false, 0, KT_STD);
    }

    if (s != NULL && s != ignore) {
	vtrace(" %s:%d -> %s\n", current_match->file, current_match->line, s);
    }
    if ((current_match = k) == NULL) {
	consumed = 0;
    }
    return s;
}

/* Timeout for ambiguous keymaps. */
static struct keymap *timeout_match = NULL;
static ioid_t kto = NULL_IOID;

static void
key_timeout(ioid_t id _is_unused)
{
    vtrace("Timeout, using shortest keymap match\n");
    kto = NULL_IOID;
    current_match = timeout_match;
    push_keymap_action(status_ret(timeout_match->action, NULL));
    timeout_match = NULL;
}

static struct keymap *
ambiguous(struct keymap *k, int nc)
{
    struct keymap *j;

    if ((j = longer_match(k, nc)) != NULL) {
	vtrace(" ambiguous keymap match, shortest is %s:%d, setting timeout\n",
		j->file, j->line);
	timeout_match = k;
	kto = AddTimeOut(500L, key_timeout);
    }
    return j;
}

/*
 * Check for compatability between a keymap and a key's modifier state.
 * Returns 1 for success, 0 for failure.
 */
static int
compatible_hint(int hint, int state)
{
    int h = hint & KM_HINTS;
    int s = state & KM_HINTS;

    if (!h) {
	return 1;
    }

    /*
     * This used to be fairly straightforward, but it got murky when
     * we split the left and right ctrl and alt keys.
     *
     * Basically, what we want is if both left and right Alt or Ctrl
     * are set in 'hint', then either left or right Alt or Ctrl set in
     * 'state' would be a match.  If only left or right is set in 'hint',
     * then the match in 'state' has to be exact.
     *
     * We do this by checking for both being set in 'hint' and either
     * being set in 'state'.  If this is the case, we set both in 'state'
     * and try for an exact match.
     */
    if ((h & KM_CTRL) == KM_CTRL) {
	if (s & KM_CTRL) {
	    s |= KM_CTRL;
	}
    }
    if ((h & KM_ALT) == KM_ALT) {
	if (s & KM_ALT) {
	    s |= KM_ALT;
	}
    }

    return (h & s) == h;
}

/*
 * Look up an key in the keymap, return the matching action if there is one.
 *
 * This code implements the mutli-key lookup, by returning dummy actions for
 * partial matches.
 */
char *
lookup_key(unsigned long code, unsigned long state)
{
    struct keymap *j, *k;
    int n_shortest = 0;
    int state_match = 0;

    vtrace("lookup_key(0x%08lx, 0x%lx)\n", code, state);

    /* If there's a timeout pending, cancel it. */
    if (kto != NULL_IOID) {
	RemoveTimeOut(kto);
	kto = NULL_IOID;
	timeout_match = NULL;
    }

    /* Translate the Windows state to KM flags. */
    if (state & SHIFT_PRESSED) {
	state_match |= KM_SHIFT;
    }
    if (state & LEFT_ALT_PRESSED) {
	state_match |= KM_LALT;
    }
    if (state & RIGHT_ALT_PRESSED) {
	state_match |= KM_RALT;
    }
    if (state & LEFT_CTRL_PRESSED) {
	state_match |= KM_LCTRL;
    }
    if (state & RIGHT_CTRL_PRESSED) {
	state_match |= KM_RCTRL;
    }
    if (state & ENHANCED_KEY) {
	state_match |= KM_ENHANCED;
    }

    /* If there's no match pending, find the shortest one. */
    if (current_match == NULL) {
	struct keymap *shortest = NULL;

	for (k = master_keymap; k != NULL; k = k->next) {
	    if (IS_INACTIVE(k)) {
		continue;
	    }
	    if (code == k->codes[0] &&
		    compatible_hint(k->hints[0], state_match)) {
		if (k->ncodes == 1) {
		    shortest = k;
		    break;
		}
		if (shortest == NULL || k->ncodes < shortest->ncodes) {
		    shortest = k;
		    n_shortest++;
		}
	    }
	}
	if (shortest != NULL) {
	    current_match = shortest;
	    consumed = 0;
	} else {
	    return NULL;
	}
    }

    /* See if this character matches the next one we want. */
    if (code == current_match->codes[consumed] &&
	    compatible_hint(current_match->hints[consumed], state_match)) {
	consumed++;
	if (consumed == current_match->ncodes) {
	    /* Final match. */
	    j = ambiguous(current_match, consumed);
	    if (j == NULL) {
		return status_ret(current_match->action, NULL);
	    } else {
		return status_ret(ignore, j);
	    }
	} else {
	    /* Keep looking. */
	    vtrace(" partial keymap match in %s:%d %s\n",
		current_match->file, current_match->line,
		(n_shortest > 1)? " and other(s)": "");
	    return status_ret(ignore, current_match);
	}
    }

    /* It doesn't.  Try for a better candidate. */
    for (k = master_keymap; k != NULL; k = k->next) {
	if (IS_INACTIVE(k))
	    continue;
	if (k == current_match)
	    continue;
	if (k->ncodes > consumed && !codecmp(k, current_match, consumed) &&
		k->codes[consumed] == code &&
		compatible_hint(k->hints[consumed], state_match)) {
	    consumed++;
	    if (k->ncodes == consumed) {
		j = ambiguous(k, consumed);
		if (j == NULL) {
		    current_match = k;
		    return status_ret(k->action, NULL);
		} else {
		    return status_ret(ignore, j);
		}
	    } else {
		return status_ret(ignore, k);
	    }
	}
    }

    /* Complain. */
    Beep(750, 150);
    vtrace(" keymap lookup failure after partial match\n");
    return status_ret(ignore, NULL);
}

static struct {
    const char *name;
    unsigned long code;
} vk_key[] = {
    { "SHIFT",		VK_SHIFT << 16 },
    { "CTRL",		VK_CONTROL << 16 },
    { "ALT",		0x12 << 16 },
    { "CAPSLOCK",	0x14 << 16 },
    { "BACK",		VK_BACK << 16 },
    { "RETURN",		VK_RETURN << 16 },
    { "TAB",		VK_TAB << 16 },
    { "ESCAPE",		VK_ESCAPE << 16 },
    { "CLEAR",		VK_CLEAR << 16 },
    { "PAUSE",		VK_PAUSE << 16 },
    { "PRIOR",		VK_PRIOR << 16 },
    { "NEXT",		VK_NEXT << 16 },
    { "END",		VK_END << 16 },
    { "HOME",		VK_HOME << 16 },
    { "LEFT",		VK_LEFT << 16 },
    { "UP",		VK_UP << 16 },
    { "RIGHT",		VK_RIGHT << 16 },
    { "DOWN",		VK_DOWN << 16 },
    { "SELECT",		VK_SELECT << 16 },
    { "PRINT",		VK_PRINT << 16 },
    { "EXECUTE",	VK_EXECUTE << 16 },
    { "SNAPSHOT",	VK_SNAPSHOT << 16 },
    { "INSERT",		VK_INSERT << 16 },
    { "DELETE",		VK_DELETE << 16 },
    { "HELP",		VK_HELP << 16 },
    { "LWIN",		VK_LWIN << 16 },
    { "RWIN",		VK_RWIN << 16 },
    { "APPS",		VK_APPS << 16 },
    { "SLEEP",		VK_SLEEP << 16 },
    { "NUMPAD0",	VK_NUMPAD0 << 16 },
    { "NUMPAD1",	VK_NUMPAD1 << 16 },
    { "NUMPAD2",	VK_NUMPAD2 << 16 },
    { "NUMPAD3",	VK_NUMPAD3 << 16 },
    { "NUMPAD4",	VK_NUMPAD4 << 16 },
    { "NUMPAD5",	VK_NUMPAD5 << 16 },
    { "NUMPAD6",	VK_NUMPAD6 << 16 },
    { "NUMPAD7",	VK_NUMPAD7 << 16 },
    { "NUMPAD8",	VK_NUMPAD8 << 16 },
    { "NUMPAD9",	VK_NUMPAD9 << 16 },
    { "MULTIPLY",	VK_MULTIPLY << 16 },
    { "ADD",		VK_ADD << 16 },
    { "SEPARATOR",	VK_SEPARATOR << 16 },
    { "SUBTRACT",	VK_SUBTRACT << 16 },
    { "DECIMAL",	VK_DECIMAL << 16 },
    { "DIVIDE",		VK_DIVIDE << 16 },
    { "F1",		VK_F1 << 16 },
    { "F2",		VK_F2 << 16 },
    { "F3",		VK_F3 << 16 },
    { "F4",		VK_F4 << 16 },
    { "F5",		VK_F5 << 16 },
    { "F6",		VK_F6 << 16 },
    { "F7",		VK_F7 << 16 },
    { "F8",		VK_F8 << 16 },
    { "F9",		VK_F9 << 16 },
    { "F10",		VK_F10 << 16 },
    { "F11",		VK_F11 << 16 },
    { "F12",		VK_F12 << 16 },
    { "F13",		VK_F13 << 16 },
    { "F14",		VK_F14 << 16 },
    { "F15",		VK_F15 << 16 },
    { "F16",		VK_F16 << 16 },
    { "F17",		VK_F17 << 16 },
    { "F18",		VK_F18 << 16 },
    { "F19",		VK_F19 << 16 },
    { "F20",		VK_F20 << 16 },
    { "F21",		VK_F21 << 16 },
    { "F22",		VK_F22 << 16 },
    { "F23",		VK_F23 << 16 },
    { "F24",		VK_F24 << 16 },
    { "NUMLOCK",	VK_NUMLOCK << 16 },
    { "SCROLL",		VK_SCROLL << 16 },
    { "LMENU",		VK_LMENU << 16 },
    { "RMENU",		VK_RMENU << 16 },

    /* Some handy aliases */
    { "BackSpace",	VK_BACK << 16 },
    { "Enter",		VK_RETURN << 16 },
    { "PageUp",		VK_PRIOR << 16 },
    { "PageDown",	VK_NEXT << 16 },
    { "Esc",		VK_ESCAPE << 16 },

    { NULL, 0 }
};

/* Look up a symbolic vkey name and return its code. */
static int
lookup_ccode(const char *s)
{
    int i;

    /* Look it up in the table. */
    for (i = 0; vk_key[i].name != NULL; i++) {
	if (!strcasecmp(s, vk_key[i].name)) {
	    return vk_key[i].code;
	}
    }

    /* Check for a numeric encoding: VKEY-nnn or VKEY-0xnnn. */
    if (!strncasecmp(s, "VKEY-", 5)) {
	const char *t;
	int base;
	unsigned long u;
	char *ptr;

	if (!strncasecmp(s + 5, "0x", 2)) {
	    t = s + 7;
	    base = 16;
	} else {
	    t = s + 5;
	    base = 10;
	}

	u = strtoul(t, &ptr, base);
	if (ptr != t && *ptr == '\0' && u > 0 && u <= 0xfe) {
	    return (int)(u << 16);
	}
    }

    return -1;
}

/* Look up a vkey code and return its name. */
const char *
lookup_cname(unsigned long ccode)
{
    int i;

    for (i = 0; vk_key[i].name != NULL; i++) {
	if (ccode == vk_key[i].code) {
	    return vk_key[i].name;
	}
    }

    if (ccode >= (' ' << 16) && ccode <= ('~' << 16)) {
	static char cbuf[2];

	cbuf[0] = (char)(ccode >> 16);
	cbuf[1] = '\0';
	return cbuf;
    }

    if (ccode >= (1 << 16) && ccode <= (0xfe << 16)) {
	return lazyaf("VKEY-0x%02x", ccode >> 16);
    }

    return NULL;
}

/**
 * Free a temporary keymap entry.
 */
static void
free_keymap(struct keymap *k)
{
    Free(k->codes);
    Free(k->hints);
    Free(k->name);
    Free(k->file);
    Free(k->action);
    Free(k);
}

/**
 * Push or pop a temporary keymap.
 */
static bool
Keymap_action(ia_t ia, unsigned argc, const char **argv)
{
    action_debug(AnKeymap, ia, argc, argv);
    if (check_argc(AnKeymap, argc, 0, 1) < 0) {
	return false;
    }

    if (argc > 0) {
	/* Push this keymap. */
	if (!read_keymap(argv[0], true)) {
	    return false;
	}

	/* Set the inactive flags. */
	set_inactive();
    } else {
	struct keymap *k;
	char *km_name = NULL;

	if (master_keymap == NULL || !master_keymap->temp) {
	    return true;
	}
	km_name = NewString(master_keymap->name);

	/* Pop the top keymap. */
	while ((k = master_keymap) != NULL) {
	    if (!k->temp || strcmp(k->name, km_name)) {
		break;
	    }
	    master_keymap = k->next;
	    free_keymap(k);
	}
	Free(km_name);

	/* Set the inactive flags. */
	set_inactive();
    }

    return true;
}

/**
 * Keymap module registration.
 */
void
keymap_register(void)
{
    static action_table_t keymap_actions[] = {
	{ AnKeymap,		Keymap_action, ACTION_KE },
	{ AnTemporaryKeymap,	Keymap_action, ACTION_KE }
    };

    /* Register for state changes. */
    register_schange(ST_3270_MODE, keymap_3270_mode);
    register_schange(ST_CONNECT, keymap_3270_mode);

    /* Register the actions. */
    register_actions(keymap_actions, array_count(keymap_actions));
}

/* Read each of the keymaps specified by the keymap resource. */
void
keymap_init(void)
{
    char *s0, *s;
    char *comma;

    /* In case this is a subsequent call, wipe out the current keymap. */
    clear_keymap();

    /* Read the base keymap. */
    read_keymap("base", false);

    /* Read the user-defined keymaps. */
    if (appres.interactive.key_map != NULL) {
	s = s0 = NewString(appres.interactive.key_map);
	while ((comma = strchr(s, ',')) != NULL) {
	    *comma = '\0';
	    if (*s) {
		read_keymap(s, false);
	    }
	    s = comma + 1;
	}
	if (*s) {
	    read_keymap(s, false);
	}
	Free(s0);
    }

    last_3270 = IN_3270;
    last_nvt = IN_NVT;
    set_inactive();
}

/* Erase the current keymap. */
static void
clear_keymap(void)
{
    struct keymap *k, *next;

    for (k = master_keymap; k != NULL; k = next) {
	next = k->next;
	free_keymap(k);
    }
    master_keymap = NULL;
}

/* Set the inactive flags for the current keymap. */
static void
set_inactive(void)
{
    struct keymap *k, *j;

    /* Clear the inactive flags and successors. */
    for (k = master_keymap; k != NULL; k = k->next) {
	k->hints[0] &= ~KM_INACTIVE;
	k->successor = NULL;
    }

    /* Turn off elements which have the wrong mode. */
    for (k = master_keymap; k != NULL; k = k->next) {
	/* If the mode is wrong, turn it off. */
	if ((!last_3270 && (k->hints[0] & KM_3270_ONLY)) ||
	    (!last_nvt  && (k->hints[0] & KM_NVT_ONLY))) {
		k->hints[0] |= KM_INACTIVE;
	}
    }

    /* Compute superceded entries. */
    for (k = master_keymap; k != NULL; k = k->next) {
	if (k->hints[0] & KM_INACTIVE) {
	    continue;
	}
	for (j = k->next; j != NULL; j = j->next) {
	    if (j->hints[0] & KM_INACTIVE) {
		continue;
	    }
	    /* It may supercede other entries. */
	    if (j->ncodes == k->ncodes && !codecmp(j, k, k->ncodes)) {
		j->hints[0] |= KM_INACTIVE;
		j->successor = k;
	    }
	}
    }
}

/* 3270/NVT mode change. */
static void
keymap_3270_mode(bool ignored _is_unused)
{
    if (last_3270 != IN_3270 || last_nvt != IN_NVT) {
	last_3270 = IN_3270;
	last_nvt = IN_NVT;
	set_inactive();
    }
}

/* Decode hints (modifiers). */
static const char *
decode_hint(int hint)
{
    static char buf[128];
    char *s = buf;

    *s = '\0';

    if (hint & KM_SHIFT) {
	s += sprintf(s, "Shift ");
    }

    if ((hint & KM_CTRL) == KM_CTRL) {
	s += sprintf(s, "Ctrl ");
    } else if (hint & KM_LCTRL) {
	s += sprintf(s, "LeftCtrl");
    } else if (hint & KM_RCTRL) {
	s += sprintf(s, "RightCtrl");
    }

    if ((hint & KM_ALT) == KM_ALT) {
	s += sprintf(s, "Alt ");
    } else if (hint & KM_LALT) {
	s += sprintf(s, "LeftAlt");
    } else if (hint & KM_RALT) {
	s += sprintf(s, "RightAlt");
    } else if (hint & KM_ENHANCED) {
	s += sprintf(s, "Enhanced");
    }

    return buf;
}

/*
 * Decode a key.
 * Accepts a hint as to which form was used to specify it, if it came from a
 * keymap definition.
 */
const char *
decode_key(int k, int hint, char *buf)
{
    char *s = buf;

    if (k & 0xffff0000) {
	const char *n;

	/* VK_xxx */
	n = lookup_cname(k);
	sprintf(buf, "%s<Key>%s", decode_hint(hint), n? n: "???");
    } else if (k < ' ') {
	sprintf(s, "%sCtrl <Key>%c", decode_hint(hint & ~KM_CTRL),
		k + '@');
    } else if (k == ':') {
	sprintf(s, "%s<Key>colon", decode_hint(hint));
    } else if (k == ' ') {
	sprintf(s, "%s<Key>space", decode_hint(hint));
    } else {
	wchar_t w = k;
	char c;
	BOOL udc = FALSE;

	/* Try translating to OEM for display on the console. */
	WideCharToMultiByte(CP_OEMCP, 0, &w, 1, &c, 1, "?", &udc);
	if (!udc) {
	    sprintf(s, "%s<Key>%c", decode_hint(hint), c);
	} else {
	    sprintf(s, "%s<Key>U+%04x", decode_hint(hint), k);
	}
    }
    return buf;
}

/* Dump the current keymap. */
const char *
keymap_dump(void)
{
    varbuf_t r;
    struct keymap *k;
    char *s;
    size_t sl;

    vb_init(&r);

    for (k = master_keymap; k != NULL; k = k->next) {
	if (k->successor != NULL) {
	    vb_appendf(&r, "[%s:%d%s] -- superceded by %s:%d --\n",
		    k->file, k->line,
		    k->temp? " temp": "",
		    k->successor->file, k->successor->line);
	} else if (!IS_INACTIVE(k)) {
	    int i;
	    char buf[1024];
	    char *s = buf;
	    char dbuf[128];
	    char *t = safe_string(k->action);

	    for (i = 0; i < k->ncodes; i++) {
		s += sprintf(s, " %s", decode_key(k->codes[i],
			    (k->hints[i] & KM_HINTS) | KM_KEYMAP, dbuf));
	    }
	    vb_appendf(&r, "[%s:%d%s]%s: %s\n", k->file, k->line,
		k->temp? " temp": "", buf, t);
	    Free(t);
	}
    }

    s = vb_consume(&r);
    sl = strlen(s);
    if (sl > 0 && s[sl - 1] == '\n') {
	s[sl - 1] = '\0';
    }

    return lazya(s);
}
