"use strict";

Components.utils.import("resource://gre/modules/ExtensionUtils.jsm");
var {
  SingletonEventManager,
} = ExtensionUtils;

/**
 * Checks whether the given error matches the given expectations.
 *
 * @param {*} error
 *        The error to check.
 * @param {string|RegExp|function|null} expectedError
 *        The expectation to check against. If this parameter is:
 *
 *        - a string, the error message must exactly equal the string.
 *        - a regular expression, it must match the error message.
 *        - a function, it is called with the error object and its
 *          return value is returned.
 *        - null, the function always returns true.
 * @param {BaseContext} context
 *
 * @returns {boolean}
 *        True if the error matches the expected error.
 */
function errorMatches(error, expectedError, context) {
  if (expectedError === null) {
    return true;
  }

  if (typeof expectedError === "function") {
    return context.runSafeWithoutClone(expectedError, error);
  }

  if (typeof error !== "object" || error == null ||
      typeof error.message !== "string") {
    return false;
  }

  if (typeof expectedError === "string") {
    return error.message === expectedError;
  }

  try {
    return expectedError.test(error.message);
  } catch (e) {
    Cu.reportError(e);
  }

  return false;
}

/**
 * Calls .toSource() on the given value, but handles null, undefined,
 * and errors.
 *
 * @param {*} value
 * @returns {string}
 */
function toSource(value) {
  if (value === null) {
    return "null";
  }
  if (value === undefined) {
    return "undefined";
  }
  if (typeof value === "string") {
    return JSON.stringify(value);
  }

  try {
    return String(value.toSource());
  } catch (e) {
    return "<unknown>";
  }
}

function makeTestAPI(context) {
  const {extension} = context;

  function getStack() {
    return new context.cloneScope.Error().stack.replace(/^/gm, "    ");
  }

  function assertTrue(value, msg) {
    extension.emit("test-result", Boolean(value), String(msg), getStack());
  }

  return {
    test: {
      sendMessage(...args) {
        extension.emit("test-message", ...args);
      },

      notifyPass(msg) {
        extension.emit("test-done", true, msg, getStack());
      },

      notifyFail(msg) {
        extension.emit("test-done", false, msg, getStack());
      },

      log(msg) {
        extension.emit("test-log", true, msg, getStack());
      },

      fail(msg) {
        assertTrue(false, msg);
      },

      succeed(msg) {
        assertTrue(true, msg);
      },

      assertTrue(value, msg) {
        assertTrue(value, msg);
      },

      assertFalse(value, msg) {
        assertTrue(!value, msg);
      },

      assertEq(expected, actual, msg) {
        let equal = expected === actual;

        expected = String(expected);
        actual = String(actual);

        if (!equal && expected === actual) {
          actual += " (different)";
        }
        extension.emit("test-eq", equal, String(msg), expected, actual, getStack());
      },

      assertRejects(promise, expectedError, msg) {
        // Wrap in a native promise for consistency.
        promise = Promise.resolve(promise);

        if (msg) {
          msg = `: ${msg}`;
        }

        return promise.then(result => {
          assertTrue(false, `Promise resolved, expected rejection${msg}`);
        }, error => {
          let errorMessage = toSource(error && error.message);

          assertTrue(errorMatches(error, expectedError, context),
                     `Promise rejected, expecting rejection to match ${toSource(expectedError)}, ` +
                     `got ${errorMessage}${msg}`);
        });
      },

      assertThrows(func, expectedError, msg) {
        if (msg) {
          msg = `: ${msg}`;
        }

        try {
          func();

          assertTrue(false, `Function did not throw, expected error${msg}`);
        } catch (error) {
          let errorMessage = toSource(error && error.message);

          assertTrue(errorMatches(error, expectedError, context),
                     `Function threw, expecting error to match ${toSource(expectedError)}` +
                     `got ${errorMessage}${msg}`);
        }
      },

      onMessage: new SingletonEventManager(context, "test.onMessage", fire => {
        let handler = (event, ...args) => {
          context.runSafe(fire, ...args);
        };

        extension.on("test-harness-message", handler);
        return () => {
          extension.off("test-harness-message", handler);
        };
      }).api(),
    },
  };
}

extensions.registerSchemaAPI("test", "addon_child", makeTestAPI);
extensions.registerSchemaAPI("test", "content_child", makeTestAPI);