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+/* handlekeys.c - Generic terminal input handler.
+ *
+ * Copyright 2012 David Seikel <won_fang@yahoo.com.au>
+ */
+ 
+#include "toys.h"
+#include "handlekeys.h"
+
+struct key
+{
+  char *code;
+  char *name;
+};
+
+// This table includes some variations I have found on some terminals, and the MC "Esc digit" versions.
+// http://rtfm.etla.org/xterm/ctlseq.html has a useful guide.
+// TODO - Don't think I got all the linux console variations.
+// TODO - Add more shift variations, plus Ctrl & Alt variations when needed.
+// TODO - tmux messes with the shift function keys somehow.
+// TODO - Add other miscelany that does not use an escape sequence.
+
+// This is sorted by type, though there is some overlap.
+// Human typing speeds wont need binary searching speeds on this small table.
+// So simple wins out over speed, and sorting by terminal type wins the simple test.
+static struct key keys[] =
+{
+  // Control characters.
+//  {"\x00",            "^@"},          // NUL Commented out coz it's the C string terminator, and may confuse things.
+  {"\x01",              "^A"},          // SOH Apparently sometimes sent as Home
+  {"\x02",              "^B"},          // STX
+  {"\x03",              "^C"},          // ETX SIGINT  Emacs and vi.
+  {"\x04",              "^D"},          // EOT EOF     Emacs, joe, and nano.
+  {"\x05",              "^E"},          // ENQ Apparently sometimes sent as End
+  {"\x06",              "^F"},          // ACK
+  {"\x07",              "^G"},          // BEL
+  {"\x08",              "Del"},         // BS  Delete key, usually.
+  {"\x09",              "Tab"},         // HT  Tab key.
+  {"\x0A",              "Return"},      // LF  Return key.  Roxterm at least is translating both Ctrl-J and Ctrl-M into this.
+  {"\x0B",              "^K"},          // VT
+  {"\x0C",              "^L"},          // FF
+  {"\x0D",              "^M"},          // CR  Other Return key, usually.
+  {"\x0E",              "^N"},          // SO
+  {"\x0F",              "^O"},          // SI  DISCARD
+  {"\x10",              "^P"},          // DLE
+  {"\x11",              "^Q"},          // DC1 SIGCONT  Vi, and made up commands in MC, which seem to work anyway.
+  {"\x12",              "^R"},          // DC2
+  {"\x13",              "^S"},          // DC3 SIGSTOP can't be caught.  Emacs and vi, so much for "can't be caught".
+  {"\x14",              "^T"},          // DC4 SIGINFO STATUS
+  {"\x15",              "^U"},          // NAK KILL character
+  {"\x16",              "^V"},          // SYN LNEXT
+  {"\x17",              "^W"},          // ETB WERASE
+  {"\x18",              "^X"},          // CAN KILL character
+  {"\x19",              "^Y"},          // EM  DSUSP SIGTSTP
+  {"\x1A",              "^Z"},          // SUB SIGTSTP
+//  {"\x1B",            "^["},          // ESC Esc key.  Commented out coz it's the ANSI start byte in the below multibyte keys.  Handled in the code with a timeout.
+  {"\x1C",              "^\\"},         // FS SIGQUIT  Some say ^D is SIGQUIT, but my tests say it's this.
+  {"\x1D",              "^]"},          // GS
+  {"\x1E",              "^^"},          // RS
+  {"\x1F",              "^_"},          // US
+  {"\x7F",              "BS"},          // Backspace key, usually.  Ctrl-? perhaps?
+//  {"\x9B",            "CSI"},         // CSI The eight bit encoding of "Esc [".  Commented out for the same reason Esc is.
+
+  // "Usual" xterm CSI sequences, with ";1" omitted for no modifiers.
+  // Even though we have a proper CSI parser, these should still be in this table.
+  // Coz we would need a table anyway in the CSI parser, so might as well keep them with the others.
+  // Also, less code, no need to have a separate scanner for that other table.
+  {"\x9B\x31~",         "Home"},        // Duplicate, think I've seen this somewhere.
+  {"\x9B\x32~",         "Ins"},
+  {"\x9B\x33~",         "Del"},
+  {"\x9B\x34~",         "End"},         // Duplicate, think I've seen this somewhere.
+  {"\x9B\x35~",         "PgUp"},
+  {"\x9B\x36~",         "PgDn"},
+  {"\x9B\x37~",         "Home"},
+  {"\x9B\x38~",         "End"},
+  {"\x9B\x31\x31~",             "F1"},
+  {"\x9B\x31\x32~",             "F2"},
+  {"\x9B\x31\x33~",             "F3"},
+  {"\x9B\x31\x34~",             "F4"},
+  {"\x9B\x31\x35~",             "F5"},
+  {"\x9B\x31\x37~",             "F6"},
+  {"\x9B\x31\x38~",             "F7"},
+  {"\x9B\x31\x39~",             "F8"},
+  {"\x9B\x32\x30~",             "F9"},
+  {"\x9B\x32\x31~",             "F10"},
+  {"\x9B\x32\x33~",             "F11"},
+  {"\x9B\x32\x34~",             "F12"},
+
+  // As above, ";2" means shift modifier.
+  {"\x9B\x31;2~",               "Shift Home"},
+  {"\x9B\x32;2~",               "Shift Ins"},
+  {"\x9B\x33;2~",               "Shift Del"},
+  {"\x9B\x34;2~",               "Shift End"},
+  {"\x9B\x35;2~",               "Shift PgUp"},
+  {"\x9B\x36;2~",               "Shift PgDn"},
+  {"\x9B\x37;2~",               "Shift Home"},
+  {"\x9B\x38;2~",               "Shift End"},
+  {"\x9B\x31\x31;2~",   "Shift F1"},
+  {"\x9B\x31\x32;2~",   "Shift F2"},
+  {"\x9B\x31\x33;2~",   "Shift F3"},
+  {"\x9B\x31\x34;2~",   "Shift F4"},
+  {"\x9B\x31\x35;2~",   "Shift F5"},
+  {"\x9B\x31\x37;2~",   "Shift F6"},
+  {"\x9B\x31\x38;2~",   "Shift F7"},
+  {"\x9B\x31\x39;2~",   "Shift F8"},
+  {"\x9B\x32\x30;2~",   "Shift F9"},
+  {"\x9B\x32\x31;2~",   "Shift F10"},
+  {"\x9B\x32\x33;2~",   "Shift F11"},
+  {"\x9B\x32\x34;2~",   "Shift F12"},
+
+  // "Normal" Some terminals are special, and it seems they only have four function keys.
+  {"\x9B\x41",          "Up"},
+  {"\x9B\x42",          "Down"},
+  {"\x9B\x43",          "Right"},
+  {"\x9B\x44",          "Left"},
+  {"\x9B\x46",          "End"},
+  {"\x9BH",             "Home"},
+  {"\x9BP",             "F1"},
+  {"\x9BQ",             "F2"},
+  {"\x9BR",             "F3"},
+  {"\x9BS",             "F4"},
+  {"\x9B\x31;2P",               "Shift F1"},
+  {"\x9B\x31;2Q",               "Shift F2"},
+  {"\x9B\x31;2R",               "Shift F3"},
+  {"\x9B\x31;2S",               "Shift F4"},
+
+  // "Application"  Esc O is known as SS3
+  {"\x1BOA",            "Up"},
+  {"\x1BOB",            "Down"},
+  {"\x1BOC",            "Right"},
+  {"\x1BOD",            "Left"},
+  {"\x1BOF",            "End"},
+  {"\x1BOH",            "Home"},
+  {"\x1BOn",            "Del"},
+  {"\x1BOp",            "Ins"},
+  {"\x1BOq",            "End"},
+  {"\x1BOw",            "Home"},
+  {"\x1BOP",            "F1"},
+  {"\x1BOO",            "F2"},
+  {"\x1BOR",            "F3"},
+  {"\x1BOS",            "F4"},
+  {"\x1BOT",            "F5"},
+  // These two conflict with the above four function key variations.
+  {"\x9BR",             "F6"},
+  {"\x9BS",             "F7"},
+  {"\x9BT",             "F8"},
+  {"\x9BU",             "F9"},
+  {"\x9BV",             "F10"},
+  {"\x9BW",             "F11"},
+  {"\x9BX",             "F12"},
+
+  // Can't remember, but saw them somewhere.
+  {"\x1BO1;2P",         "Shift F1"},
+  {"\x1BO1;2Q",         "Shift F2"},
+  {"\x1BO1;2R",         "Shift F3"},
+  {"\x1BO1;2S",         "Shift F4"},
+
+  // MC "Esc digit" specials.
+  // NOTE - The MC Esc variations might not be such a good idea, other programs want the Esc key for other things.
+  //          Notably seems that "Esc somekey" is used in place of "Alt somekey" AKA "Meta somekey" coz apparently some OSes swallow those.
+  //            Conversely, some terminals send "Esc somekey" when you do "Alt somekey".
+  //          MC Esc variants might be used on Macs for other things?
+  {"\x1B\x31",          "F1"},
+  {"\x1B\x32",          "F2"},
+  {"\x1B\x33",          "F3"},
+  {"\x1B\x34",          "F4"},
+  {"\x1B\x35",          "F5"},
+  {"\x1B\x36",          "F6"},
+  {"\x1B\x37",          "F7"},
+  {"\x1B\x38",          "F8"},
+  {"\x1B\x39",          "F9"},
+  {"\x1B\x30",          "F10"},
+
+/* TODO - Rob says -
+...you don't need a NULL terminator for  
+an array, you can do sizeof(table)/sizeof(*table). Divide the size of  
+the table (in bytes) by the size of a member of the table (in bytes) to  
+get the number of entries.
+
+I should try that trick.  Seems to work, let's do that everywhere.
+*/
+
+  {NULL, NULL}
+};
+
+static volatile sig_atomic_t sigWinch;
+static int stillRunning;
+
+static void handleSignals(int signo)
+{
+    sigWinch = 1;
+}
+
+// TODO - Unhandled complications -
+//   Less and more have the "ZZ" command, but nothing else seems to have multi ordinary character commands.
+void handle_keys(long extra, int (*handle_sequence)(long extra, char *sequence), void (*handle_CSI)(long extra, char *command, int *params, int count))
+{
+  fd_set selectFds;
+  struct timespec timeout;
+  struct sigaction sigAction, oldSigAction;
+  sigset_t signalMask;
+  char buffer[20], sequence[20];
+  int buffIndex = 0;
+
+  buffer[0] = 0;
+  sequence[0] = 0;
+
+  // Terminals send the SIGWINCH signal when they resize.
+  memset(&sigAction, 0, sizeof(sigAction));
+  sigAction.sa_handler = handleSignals;
+  sigAction.sa_flags = SA_RESTART;// Useless if we are using poll.
+  if (sigaction(SIGWINCH, &sigAction, &oldSigAction))  perror_exit("can't set signal handler SIGWINCH");
+  sigemptyset(&signalMask);
+  sigaddset(&signalMask, SIGWINCH);
+
+  // TODO - OS buffered keys might be a problem, but we can't do the usual timestamp filter for now.
+  stillRunning = 1;
+  while (stillRunning)
+  {
+    int j, p, csi = 0;
+
+    // Apparently it's more portable to reset these each time.
+    FD_ZERO(&selectFds);
+    FD_SET(0, &selectFds);
+    timeout.tv_sec = 0;  timeout.tv_nsec = 100000000; // One tenth of a second.
+
+// TODO - A bit unstable at the moment, something makes it go into a horrid CPU eating edit line flicker mode sometimes.  And / or vi mode can crash on exit (stack smash).
+//          This might be fixed now.
+
+    // We got a "terminal size changed" signal, ask the terminal how big it is now.
+    if (sigWinch)
+    {
+      // Send - save cursor position, down 999, right 999, request cursor position, restore cursor position.
+      fputs("\x1B[s\x1B[999C\x1B[999B\x1B[6n\x1B[u", stdout);
+      fflush(stdout);
+      sigWinch = 0;
+    }
+
+    // TODO - Should only ask for a time out after we get an Escape, or the user requested time ticks.
+    // I wanted to use poll, but that would mean using ppoll, which is Linux only, and involves defining swear words to get it.
+    p = pselect(0 + 1, &selectFds, NULL, NULL, &timeout, &signalMask);
+    if (0 > p)
+    {
+      if (EINTR == errno)
+        continue;
+      perror_exit("poll");
+    }
+    else if (0 == p)          // A timeout, trigger a time event.
+    {
+      if ((0 == buffer[1]) && ('\x1B' == buffer[0]))
+      {
+        // After a short delay to check, this is a real Escape key, not part of an escape sequence, so deal with it.
+        // TODO - so far the only uses of this have the escape at the start, but maybe a strcat is needed instead later?
+        strcpy(sequence, "^[");
+        buffer[0] = buffIndex = 0;
+      }
+      // TODO - Call some sort of timer tick callback.  This wont be a precise timed event, but don't think we need one.
+    }
+    else if ((0 < p) && FD_ISSET(0, &selectFds))
+    {
+      // I am assuming that we get the input atomically, each multibyte key fits neatly into one read.
+      // If that's not true (which is entirely likely), then we have to get complicated with circular buffers and stuff, or just one byte at a time.
+      j = read(0, &buffer[buffIndex], sizeof(buffer) - (buffIndex + 1));
+      if (j < 0)      // An error happened.
+      {
+        // For now, just ignore errors.
+        fprintf(stderr, "input error on %d\n", p);
+        fflush(stderr);
+      }
+      else if (j == 0)    // End of file.
+      {
+        stillRunning = 0;
+        fprintf(stderr, "EOF\n");
+        for (j = 0; buffer[j + 1]; j++)
+          fprintf(stderr, "(%x), ", (int) buffer[j]);
+        fflush(stderr);
+      }
+      else
+      {
+        buffIndex += j;
+        if (sizeof(buffer) < (buffIndex + 1))  // Ran out of buffer.
+        {
+          fprintf(stderr, "Full buffer - %s  ->  %s\n", buffer, sequence);
+          for (j = 0; buffer[j + 1]; j++)
+            fprintf(stderr, "(%x) %c, ", (int) buffer[j], buffer[j]);
+          fflush(stderr);
+          buffIndex = 0;
+        }
+        buffer[buffIndex] = 0;
+      }
+    }
+
+    // Check if it's a CSI before we check for the known key sequences.
+    if ('\x9B' == buffer[0])
+      csi = 1;
+    if (('\x1B' == buffer[0]) && ('[' == buffer[1]))
+      csi = 2;
+    if (('\xC2' == buffer[0]) && ('\x9B' == buffer[1]))
+      csi = 2;
+    if (2 == csi)
+    {
+      buffer[0] = '\x9B';
+      for (j = 1; buffer[j]; j++)
+        buffer[j] = buffer[j + 1];
+      buffIndex--;
+      csi = 1;
+    }
+
+    // Check for known key sequences.
+    // For a real timeout checked Esc, buffer is now empty, so this for loop wont find it anyway.
+    // While it's true we could avoid it by checking, the user already had to wait for a time out, and this loop wont take THAT long.
+    for (j = 0; keys[j].code; j++)    // Search for multibyte keys and control keys.
+    {
+      if (strcmp(keys[j].code, buffer) == 0)
+      {
+        strcat(sequence, keys[j].name);
+        buffer[0] = buffIndex = 0;
+        csi = 0;
+        break;
+      }
+    }
+
+    // Find out if it's a CSI sequence that's not in the known key sequences.
+    if (csi)
+    {
+      /* ECMA-048 section 5.2 defines this, and is unreadable.
+        General CSI format - CSI [private] n1 ; n2 [extra] final
+            private     0x3c to 0x3f  "<=>?" if first byte is one of these, this is a private command, if it's one of the other n1 ones, it's not private.
+            n1          0x30 to 0x3f  "01234567890:;<=>?" ASCII digits forming a "number"
+                        0x3a [:] used for floats, not expecting any.  Could also be used as some other sort of inter digit separator.
+                        0x3b [;] separates the parameters
+            extra       0x20 to 0x2f  [ !"#$%&'()*+,-./]  Can be multiple, likely isn't.
+            final       0x40 to 0x7e  "@A .. Z[\]^_`a .. z{|}~" it's private if 0x70 to 0x7e "p .. z{|}~"
+                Though the "private" ~ is used for key codes.
+                    We also have SS3 "\x1BO" for other keys, but that's not a CSI.
+          C0 controls, DEL (0x7f), or high characters are undefined.
+TODO        So abort the current CSI and start from scratch.
+      */
+
+      char *t, csFinal[8];
+      int csIndex = 1, csParams[8];
+
+      csFinal[0] = 0;
+      p = 0;
+      // Unspecified params default to a value that is command dependant.
+      // However, they will never be negative, so we can use -1 to flag a default value.
+      for (j = 0; j < (sizeof(csParams) / sizeof(*csParams)); j++)
+        csParams[j] = -1;
+
+      if ('M' == buffer[1])
+      {
+        // TODO - We have a mouse report, which is CSI M ..., where the rest is binary encoded, more or less.  Not fitting into the CSI format.
+      }
+      else
+      {
+        // Check for the private bit.
+        if (index("<=>?", buffer[1]))
+        {
+          csFinal[0] = buffer[1];
+          csFinal[1] = 0;
+          csIndex++;
+        }
+
+        // Decode parameters.
+        j = csIndex;
+        do
+        {
+          // So we know when we get to the end of parameter space.
+          t = index("01234567890:;<=>?", buffer[j + 1]);
+          // See if we passed a paremeter.
+          if ((';' == buffer[j]) || (!t))
+          {
+            // Only stomp on the ; if it's really the ;.
+            if (t)
+              buffer[j] = 0;
+            // Empty parameters are default parameters, so only deal with non defaults.
+            if (';' != buffer[csIndex] || (!t))
+            {
+              // TODO - Might be ":" in the number somewhere, but we are not expecting any in anything we do.
+              csParams[p] = atoi(&buffer[csIndex]);
+            }
+            p++;
+            csIndex = j + 1;
+          }
+          j++;
+        }
+        while (t);
+
+        // Get the final command sequence, and pass it to the callback.
+        strcat(csFinal, &buffer[csIndex]);
+        if (handle_CSI)
+          handle_CSI(extra, csFinal, csParams, p);
+      }
+
+      csi = 0;
+      // Wether or not it's a CSI we understand, it's been handled either here or in the key sequence scanning above.
+      buffer[0] = buffIndex = 0;
+    }
+
+    // Pass the result to the callback.
+    if ((handle_sequence) && (sequence[0] || buffer[0]))
+    {
+      char b[strlen(sequence) + strlen(buffer) + 1];
+
+      sprintf(b, "%s%s", sequence, buffer);
+      if (handle_sequence(extra, b))
+      {
+        sequence[0] = 0;
+        buffer[0] = buffIndex = 0;
+      }
+    }
+  }
+
+  sigaction(SIGWINCH, &oldSigAction, NULL);
+}
+
+void handle_keys_quit()
+{
+  stillRunning = 0;
+}