var availableCommands    = {};
var keyToCommandRegistry = {};

function addCommand(command, description, isBackgroundCommand, passCountToFunction) {
  if (availableCommands[command])
  {
    console.log(command, "is already defined! Check commands.js for duplicates.");
    return;
  }

  availableCommands[command] = { description: description,
                                 isBackgroundCommand: isBackgroundCommand,
                                 passCountToFunction: passCountToFunction
                               };
}

function mapKeyToCommand(key, command) {
  if (!availableCommands[command])
  {
    console.log(command, "doesn't exist!");
    return;
  }

  keyToCommandRegistry[key] = { command: command,
                                isBackgroundCommand: availableCommands[command].isBackgroundCommand,
                                passCountToFunction: availableCommands[command].passCountToFunction
                              };
}

function unmapKey(key) { delete keyToCommandRegistry[key]; }

/* Lower-case the appropriate portions of named keys.
 *
 * A key name is one of three forms exemplified by <c-a> <left> or <c-f12>
 * (prefixed normal key, named key, or prefixed named key). Internally, for
 * simplicity, we would like prefixes and key names to be lowercase, though
 * humans may prefer other forms <Left> or <C-a>.
 * On the other hand, <c-a> and <c-A> are different named keys - for one of
 * them you have to press "shift" as well.
 */
function normalizeKey(key) {
    return key.replace(/<[acm]-/ig, function(match){ return match.toLowerCase(); })
              .replace(/<([acm]-)?([a-zA-Z0-9]{2,5})>/g, function(match, optionalPrefix, keyName){
                  return "<" + ( optionalPrefix ? optionalPrefix : "") + keyName.toLowerCase() + ">";
              });
}

function parseCustomKeyMappings(customKeyMappings) {
  lines = customKeyMappings.split("\n");

  for (var i = 0; i < lines.length; i++) {
    if (lines[i][0] == "\"" || lines[i][0] == "#") { continue }
    split_line = lines[i].split(/\s+/);

    var lineCommand = split_line[0];

    if (lineCommand == "map") {
      if (split_line.length != 3) { continue; }
      var key = normalizeKey(split_line[1]);
      var vimiumCommand = split_line[2];

      if (!availableCommands[vimiumCommand]) { continue }

      console.log("Mapping", key, "to", vimiumCommand);
      mapKeyToCommand(key, vimiumCommand);
    }
    else if (lineCommand == "unmap") {
      if (split_line.length != 2) { continue; }

      var key = normalizeKey(split_line[1]);

      console.log("Unmapping", key);
      unmapKey(key);
    }
    else if (lineCommand == "unmapAll") {
      keyToCommandRegistry = {};
    }
  }
}

function clearKeyMappingsAndSetDefaults() {
  keyToCommandRegistry = {};

  var defaultKeyMappings = {
    "?": "showHelp",
    "j": "scrollDown",
    "k": "scrollUp",
    "h": "scrollLeft",
    "l": "scrollRight",
    "gg": "scrollToTop",
    "G": "scrollToBottom",
    "zH": "scrollToLeft",
    "zL": "scrollToRight",
    "<c-e>": "scrollDown",
    "<c-y>": "scrollUp",
    "<c-d>": "scrollPageDown",
    "<c-u>": "scrollPageUp",
    "<c-f>": "scrollFullPageDown",
    "<c-b>": "scrollFullPageUp",
    "r": "reload",
    "gs": "toggleViewSource",

    "i": "enterInsertMode",

    "H": "goBack",
    "L": "goForward",
    "gu": "goUp",

    "zi": "zoomIn",
    "zo": "zoomOut",
    "z0": "zoomReset",

    "gi": "focusInput",

    "f":     "activateLinkHintsMode",
    "F":     "activateLinkHintsModeToOpenInNewTab",
    "<a-f>": "activateLinkHintsModeWithQueue",

    "/": "enterFindMode",
    "n": "performFind",
    "N": "performBackwardsFind",

    "[[": "goPrevious",
    "]]": "goNext",

    "yy": "copyCurrentUrl",

    "K": "nextTab",
    "J": "previousTab",
    "gt": "nextTab",
    "gT": "previousTab",

    "t": "createTab",
    "d": "removeTab",
    "u": "restoreTab",

    "gf": "nextFrame"
  };

  for (var key in defaultKeyMappings)
    mapKeyToCommand(key, defaultKeyMappings[key]);
}

// Navigating the current page:
addCommand("showHelp",            "Show help",  true);
addCommand("scrollDown",          "Scroll down");
addCommand("scrollUp",            "Scroll up");
addCommand("scrollLeft",          "Scroll left");
addCommand("scrollRight",         "Scroll right");
addCommand("scrollToTop",         "Scroll to the top of the page");
addCommand("scrollToBottom",      "Scroll to the bottom of the page");
addCommand("scrollToLeft",        "Scroll to the left of the page");
addCommand("scrollToRight",       "Scroll to the right of the page");
addCommand("scrollPageDown",      "Scroll a page down");
addCommand("scrollPageUp",        "Scroll a page up");
addCommand("scrollFullPageDown",  "Scroll a full page down");
addCommand("scrollFullPageUp",    "Scroll a full page up");

addCommand("reload",              "Reload the page");
addCommand("toggleViewSource",    "View page source");
addCommand("zoomIn",              "Zoom in");
addCommand("zoomOut",             "Zoom out");
addCommand("zoomReset",             "Reset zoom to default value");
addCommand("copyCurrentUrl",      "Copy the current URL to the clipboard");

addCommand("enterInsertMode",     "Enter insert mode");

addCommand("focusInput",          "Focus the first (or n-th) text box on the page", false, true);

addCommand("activateLinkHintsMode",               "Enter link hints mode to open links in current tab");
addCommand("activateLinkHintsModeToOpenInNewTab", "Enter link hints mode to open links in new tab");
addCommand("activateLinkHintsModeWithQueue",      "Enter link hints mode to open multiple links in a new tab");

addCommand("enterFindMode",        "Enter find mode");
addCommand("performFind",          "Cycle forward to the next find match");
addCommand("performBackwardsFind", "Cycle backward to the previous find match");

addCommand("goPrevious",          "Follow the link labeled previous or <");
addCommand("goNext",              "Follow the link labeled next or >");

// Navigating your history:
addCommand("goBack",              "Go back in history");
addCommand("goForward",           "Go forward in history");

// Navigating the URL hierarchy
addCommand("goUp",                "Go up the URL hierarchy", false, true);

// Manipulating tabs:
addCommand("nextTab",             "Go one tab right",  true);
addCommand("previousTab",         "Go one tab left",   true);
addCommand("createTab",           "Create new tab",    true);
addCommand("removeTab",           "Close current tab", true);
addCommand("restoreTab",          "Restore closed tab", true);

addCommand("nextFrame",           "Cycle forward to the next frame on the page", true);


// An ordered listing of all available commands, grouped by type. This is the order they will
// be shown in the help page.
var commandGroups = {
  pageNavigation:
    ["scrollDown", "scrollUp", "scrollLeft", "scrollRight",
     "scrollToTop", "scrollToBottom", "scrollToLeft", "scrollToRight", "scrollPageDown",
     "scrollPageUp", "scrollFullPageUp", "scrollFullPageDown",
     "reload", "toggleViewSource", "zoomIn", "zoomOut", "zoomReset", "copyCurrentUrl", "goUp",
     "enterInsertMode", "focusInput",
     "activateLinkHintsMode", "activateLinkHintsModeToOpenInNewTab", "activateLinkHintsModeWithQueue",
     "goPrevious", "goNext",
     "enterFindMode", "performFind", "performBackwardsFind", "nextFrame"],
  historyNavigation:
    ["goBack", "goForward"],
  tabManipulation:
    ["nextTab", "previousTab", "createTab", "removeTab", "restoreTab"],
  misc:
    ["showHelp"]
};