1 files changed, 245 insertions, 0 deletions
diff --git a/devtools/server/actors/webconsole/commands.js b/devtools/server/actors/webconsole/commands.js
new file mode 100644
index 0000000000..4bc415e7ce
--- /dev/null
+++ b/devtools/server/actors/webconsole/commands.js
@@ -0,0 +1,245 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+const validCommands = ["block", "help", "history", "screenshot", "unblock"];
+
+const COMMAND = "command";
+const KEY = "key";
+const ARG = "arg";
+
+const COMMAND_PREFIX = /^:/;
+const KEY_PREFIX = /^--/;
+
+// default value for flags
+const DEFAULT_VALUE = true;
+const COMMAND_DEFAULT_FLAG = {
+  block: "url",
+  screenshot: "filename",
+  unblock: "url",
+};
+
+/**
+ * When given a string that begins with `:` and a unix style string,
+ * format a JS like object.
+ * This is intended to be used by the WebConsole actor only.
+ *
+ * @param String string
+ *        A string to format that begins with `:`.
+ *
+ * @returns String formatted as `command({ ..args })`
+ */
+function formatCommand(string) {
+  if (!isCommand(string)) {
+    throw Error("formatCommand was called without `:`");
+  }
+  const tokens = string
+    .trim()
+    .split(/\s+/)
+    .map(createToken);
+  const { command, args } = parseCommand(tokens);
+  const argsString = formatArgs(args);
+  return `${command}(${argsString})`;
+}
+
+/**
+ * collapses the array of arguments from the parsed command into
+ * a single string
+ *
+ * @param Object tree
+ *               A tree object produced by parseCommand
+ *
+ * @returns String formatted as ` { key: value, ... } ` or an empty string
+ */
+function formatArgs(args) {
+  return Object.keys(args).length ? JSON.stringify(args) : "";
+}
+
+/**
+ * creates a token object depending on a string which as a prefix,
+ * either `:` for a command or `--` for a key, or nothing for an argument
+ *
+ * @param String string
+ *               A string to use as the basis for the token
+ *
+ * @returns Object Token Object, with the following shape
+ *                { type: String, value: String }
+ */
+function createToken(string) {
+  if (isCommand(string)) {
+    const value = string.replace(COMMAND_PREFIX, "");
+    if (!value || !validCommands.includes(value)) {
+      throw Error(`'${value}' is not a valid command`);
+    }
+    return { type: COMMAND, value };
+  }
+  if (isKey(string)) {
+    const value = string.replace(KEY_PREFIX, "");
+    if (!value) {
+      throw Error("invalid flag");
+    }
+    return { type: KEY, value };
+  }
+  return { type: ARG, value: string };
+}
+
+/**
+ * returns a command Tree object for a set of tokens
+ *
+ *
+ * @param Array Tokens tokens
+ *                     An array of Token objects
+ *
+ * @returns Object Tree Object, with the following shape
+ *                 { command: String, args: Array of Strings }
+ */
+function parseCommand(tokens) {
+  let command = null;
+  const args = {};
+
+  for (let i = 0; i < tokens.length; i++) {
+    const token = tokens[i];
+    if (token.type === COMMAND) {
+      if (command) {
+        // we are throwing here because two commands have been passed and it is unclear
+        // what the user's intention was
+        throw Error("Invalid command");
+      }
+      command = token.value;
+    }
+
+    if (token.type === KEY) {
+      const nextTokenIndex = i + 1;
+      const nextToken = tokens[nextTokenIndex];
+      let values = args[token.value] || DEFAULT_VALUE;
+      if (nextToken && nextToken.type === ARG) {
+        const { value, offset } = collectString(
+          nextToken,
+          tokens,
+          nextTokenIndex
+        );
+        // in order for JSON.stringify to correctly output values, they must be correctly
+        // typed
+        // As per the old GCLI documentation, we can only have one value associated with a
+        // flag but multiple flags with the same name can exist and should be combined
+        // into and array.  Here we are associating only the value on the right hand
+        // side if it is of type `arg` as a single value; the second case initializes
+        // an array, and the final case pushes a value to an existing array
+        const typedValue = getTypedValue(value);
+        if (values === DEFAULT_VALUE) {
+          values = typedValue;
+        } else if (!Array.isArray(values)) {
+          values = [values, typedValue];
+        } else {
+          values.push(typedValue);
+        }
+        // skip the next token since we have already consumed it
+        i = nextTokenIndex + offset;
+      }
+      args[token.value] = values;
+    }
+
+    // Since this has only been implemented for screenshot, we can only have one default
+    // value. Eventually we may have more default values. For now, ignore multiple
+    // unflagged args
+    const defaultFlag = COMMAND_DEFAULT_FLAG[command];
+    if (token.type === ARG && !args[defaultFlag]) {
+      const { value, offset } = collectString(token, tokens, i);
+      args[defaultFlag] = getTypedValue(value);
+      i = i + offset;
+    }
+  }
+  return { command, args };
+}
+
+const stringChars = ['"', "'", "`"];
+function isStringChar(testChar) {
+  return stringChars.includes(testChar);
+}
+
+function checkLastChar(string, testChar) {
+  const lastChar = string[string.length - 1];
+  return lastChar === testChar;
+}
+
+function hasUnescapedChar(value, char, rightOffset, leftOffset) {
+  const lastPos = value.length - 1;
+  const string = value.slice(rightOffset, lastPos - leftOffset);
+  const index = string.indexOf(char);
+  if (index === -1) {
+    return false;
+  }
+  const prevChar = index > 0 ? string[index - 1] : null;
+  // return false if the unexpected character is escaped, true if it is not
+  return prevChar !== "\\";
+}
+
+function collectString(token, tokens, index) {
+  const firstChar = token.value[0];
+  const isString = isStringChar(firstChar);
+  const UNESCAPED_CHAR_ERROR = segment =>
+    `String has unescaped \`${firstChar}\` in [${segment}...],` +
+    " may miss a space between arguments";
+  let value = token.value;
+
+  // the test value is not a string, or it is a string but a complete one
+  // i.e. `"test"`, as opposed to `"foo`. In either case, this we can return early
+  if (!isString || checkLastChar(value, firstChar)) {
+    return { value, offset: 0 };
+  }
+
+  if (hasUnescapedChar(value, firstChar, 1, 0)) {
+    throw Error(UNESCAPED_CHAR_ERROR(value));
+  }
+
+  let offset = null;
+  for (let i = index + 1; i <= tokens.length; i++) {
+    if (i === tokens.length) {
+      throw Error("String does not terminate");
+    }
+
+    const nextToken = tokens[i];
+    if (nextToken.type !== ARG) {
+      throw Error(`String does not terminate before flag "${nextToken.value}"`);
+    }
+
+    value = `${value} ${nextToken.value}`;
+
+    if (hasUnescapedChar(nextToken.value, firstChar, 0, 1)) {
+      throw Error(UNESCAPED_CHAR_ERROR(value));
+    }
+
+    if (checkLastChar(nextToken.value, firstChar)) {
+      offset = i - index;
+      break;
+    }
+  }
+  return { value, offset };
+}
+
+function isCommand(string) {
+  return COMMAND_PREFIX.test(string);
+}
+
+function isKey(string) {
+  return KEY_PREFIX.test(string);
+}
+
+function getTypedValue(value) {
+  if (!isNaN(value)) {
+    return Number(value);
+  }
+  if (value === "true" || value === "false") {
+    return Boolean(value);
+  }
+  if (isStringChar(value[0])) {
+    return value.slice(1, value.length - 1);
+  }
+  return value;
+}
+
+exports.formatCommand = formatCommand;
+exports.isCommand = isCommand;
+exports.validCommands = validCommands;