/**
 * This module implements custom assertions via $(D shouldXXX) functions
 * that throw exceptions containing information about why the assertion
 * failed.
 */

module unit_threaded.should;

import std.exception;
import std.conv;
import std.algorithm;
import std.traits;
import std.range;

public import unit_threaded.attrs;

@safe:

/**
 * An exception to signal that a test case has failed.
 */
class UnitTestException : Exception
{
    this(in string[] msgLines, string file = __FILE__,
         size_t line = __LINE__, Throwable next = null)
    {
        super(msgLines.join("\n"), next, file, line);
        this.msgLines = msgLines;
    }

    override string toString() const pure
    {
        return msgLines.map!(a => getOutputPrefix(file, line) ~ a).join("\n");
    }

private:

    const string[] msgLines;

    string getOutputPrefix(in string file, in size_t line) const pure
    {
        return "    " ~ file ~ ":" ~ line.to!string ~ " - ";
    }
}

/**
 * Verify that the condition is `true`.
 * Throws: UnitTestException on failure.
 */
void shouldBeTrue(E)(lazy E condition, in string file = __FILE__, in size_t line = __LINE__)
{
    shouldEqual(condition, true, file, line);
}

///
unittest
{
    shouldBeTrue(true);
}

/**
 * Verify that the condition is `false`.
 * Throws: UnitTestException on failure.
 */
void shouldBeFalse(E)(lazy E condition, in string file = __FILE__, in size_t line = __LINE__)
{
    shouldEqual(condition, false, file, line);
}

///
unittest
{
    shouldBeFalse(false);
}

/**
 * Verify that two values are the same.
 * Floating point values are compared using $(D std.math.approxEqual).
 * Throws: UnitTestException on failure
 */
void shouldEqual(V, E)(V value, E expected, in string file = __FILE__, in size_t line = __LINE__)
{
    if (!isEqual(value, expected))
    {
        const msg = formatValue("Expected: ", expected) ~
                    formatValue("     Got: ", value);
        throw new UnitTestException(msg, file, line);
    }
}

///
unittest {
    shouldEqual(true, true);
    shouldEqual(false, false);
    shouldEqual(1, 1) ;
    shouldEqual("foo", "foo") ;
    shouldEqual(1.0, 1.0) ;
    shouldEqual([2, 3], [2, 3]) ;

    shouldEqual(iota(3), [0, 1, 2]);
    shouldEqual([[0, 1], [0, 1, 2]], [[0, 1], [0, 1, 2]]);
    shouldEqual([[0, 1], [0, 1, 2]], [iota(2), iota(3)]);
    shouldEqual([iota(2), iota(3)], [[0, 1], [0, 1, 2]]);

    shouldEqual(3.0, 3.00001); //approximately equal
}

/**
 * Verify that two values are not the same.
 * Throws: UnitTestException on failure
 */
void shouldNotEqual(V, E)(V value, E expected, in string file = __FILE__, in size_t line = __LINE__)
{
    if (isEqual(value, expected))
    {
        const msg = ["Value:",
                     formatValue("", value).join(""),
                     "is not expected to be equal to:",
                     formatValue("", expected).join("")
            ];
        throw new UnitTestException(msg, file, line);
    }
}

///
unittest
{
    shouldNotEqual(true, false);
    shouldNotEqual(1, 2);
    shouldNotEqual("f", "b");
    shouldNotEqual(1.0, 2.0);
    shouldNotEqual([2, 3], [2, 3, 4]);
}


unittest {
    string getExceptionMsg(E)(lazy E expr) {
        try
        {
            expr();
        }
        catch(UnitTestException ex)
        {
            return ex.toString;
        }
        assert(0, "Expression did not throw UnitTestException");
    }


    void assertExceptionMsg(E)(lazy E expr, string expected,
                               in size_t line = __LINE__)
    {
        import std.string: stripLeft;
        //updating the tests below as line numbers change is tedious.]
        //instead, replace the number there with the actual line number
        expected = expected.replace(":123", ":" ~ line.to!string);
        auto msg = getExceptionMsg(expr);
        auto expLines = expected.split("\n").map!stripLeft;
        auto msgLines = msg.split("\n").map!stripLeft;
        assert(zip(msgLines, expLines).all!(a => a[0].endsWith(a[1])),
               text("\nExpected Exception:\n", expected, "\nGot Exception:\n", msg));
    }

    assertExceptionMsg(3.shouldEqual(5),
                       "    source/unit_threaded/should.d:123 - Expected: 5\n"
                       "    source/unit_threaded/should.d:123 -      Got: 3");

    assertExceptionMsg("foo".shouldEqual("bar"),
                       "    source/unit_threaded/should.d:123 - Expected: \"bar\"\n"
                       "    source/unit_threaded/should.d:123 -      Got: \"foo\"");

    assertExceptionMsg([1, 2, 4].shouldEqual([1, 2, 3]),
                       "    source/unit_threaded/should.d:123 - Expected: [1, 2, 3]\n"
                       "    source/unit_threaded/should.d:123 -      Got: [1, 2, 4]");

    assertExceptionMsg([[0, 1, 2, 3, 4], [1], [2], [3], [4], [5]].shouldEqual([[0], [1], [2]]),
                       "    source/unit_threaded/should.d:123 - Expected: [[0], [1], [2]]\n"
                       "    source/unit_threaded/should.d:123 -      Got: [[0, 1, 2, 3, 4], [1], [2], [3], [4], [5]]");

    assertExceptionMsg([[0, 1, 2, 3, 4, 5], [1], [2], [3]].shouldEqual([[0], [1], [2]]),
                       "    source/unit_threaded/should.d:123 - Expected: [[0], [1], [2]]\n"
                       "    source/unit_threaded/should.d:123 -      Got: [[0, 1, 2, 3, 4, 5], [1], [2], [3]]");


    assertExceptionMsg([[0, 1, 2, 3, 4, 5], [1], [2], [3], [4], [5]].shouldEqual([[0]]),
                       "    source/unit_threaded/should.d:123 - Expected: [[0]]\n"

                       "    source/unit_threaded/should.d:123 -      Got: [\n"
                       "    source/unit_threaded/should.d:123 -               [0, 1, 2, 3, 4, 5],\n"
                       "    source/unit_threaded/should.d:123 -               [1],\n"
                       "    source/unit_threaded/should.d:123 -               [2],\n"
                       "    source/unit_threaded/should.d:123 -               [3],\n"
                       "    source/unit_threaded/should.d:123 -               [4],\n"
                       "    source/unit_threaded/should.d:123 -               [5],\n"
                       "    source/unit_threaded/should.d:123 -           ]");

    assertExceptionMsg(1.shouldNotEqual(1),
                       "    source/unit_threaded/should.d:123 - Value:\n"
                       "    source/unit_threaded/should.d:123 - 1\n"
                       "    source/unit_threaded/should.d:123 - is not expected to be equal to:\n"
                       "    source/unit_threaded/should.d:123 - 1");
}

unittest
{
    ubyte[] arr;
    arr.shouldEqual([]);
}


unittest
{
    int[] ints = [1, 2, 3];
    byte[] bytes = [1, 2, 3];
    byte[] bytes2 = [1, 2, 4];
    shouldEqual(ints, bytes);
    shouldEqual(bytes, ints) ;
    shouldNotEqual(ints, bytes2) ;

    shouldEqual([1 : 2.0, 2 : 4.0], [1 : 2.0, 2 : 4.0]) ;
    shouldNotEqual([1 : 2.0, 2 : 4.0], [1 : 2.2, 2 : 4.0]) ;
    const constIntToInts = [1 : 2, 3 : 7, 9 : 345];
    auto intToInts = [1 : 2, 3 : 7, 9 : 345];
    shouldEqual(intToInts, constIntToInts) ;
    shouldEqual(constIntToInts, intToInts) ;
}

/**
 * Verify that the value is null.
 * Throws: UnitTestException on failure
 */
void shouldBeNull(T)(in T value, in string file = __FILE__, in size_t line = __LINE__)
{
    if (value !is null)
        fail("Value is null", file, line);
}

///
unittest
{
    shouldBeNull(null) ;
}


/**
 * Verify that the value is not null.
 * Throws: UnitTestException on failure
 */
void shouldNotBeNull(T)(in T value, in string file = __FILE__, in size_t line = __LINE__)
{
    if (value is null)
        fail("Value is null", file, line);
}

///
unittest
{
    class Foo
    {
        this(int i) { this.i = i; }
        override string toString() const
        {
            import std.conv: to;
            return i.to!string;
        }
        int i;
    }

    shouldNotBeNull(new Foo(4)) ;
    shouldEqual(new Foo(5), new Foo(5));
    assertFail(shouldEqual(new Foo(5), new Foo(4)));
    shouldNotEqual(new Foo(5), new Foo(4)) ;
    assertFail(shouldNotEqual(new Foo(5), new Foo(5)));
}


/**
 * Verify that the value is in the container.
 * Throws: UnitTestException on failure
*/
void shouldBeIn(T, U)(in T value, in U container, in string file = __FILE__, in size_t line = __LINE__)
if (isAssociativeArray!U)
{
    if (value !in container)
    {
        fail("Value " ~ to!string(value) ~ " not in " ~ to!string(container), file,
            line);
    }
}

/**
 * Verify that the value is in the container.
 * Throws: UnitTestException on failure
 */
void shouldBeIn(T, U)(in T value, U container, in string file = __FILE__, in size_t line = __LINE__)
if (!isAssociativeArray!U && isInputRange!U)
{
    if (find(container, value).empty)
    {
        fail("Value " ~ to!string(value) ~ " not in " ~ to!string(container), file,
            line);
    }
}

///
unittest
{
    shouldBeIn(4, [1, 2, 4]);
    shouldBeIn("foo", ["foo" : 1]);
}


/**
 * Verify that the value is not in the container.
 * Throws: UnitTestException on failure
 */
void shouldNotBeIn(T, U)(in T value, in U container,
                         in string file = __FILE__, in size_t line = __LINE__)
if (isAssociativeArray!U)
{
    if (value in container)
    {
        fail("Value " ~ to!string(value) ~ " is in " ~ to!string(container), file,
            line);
    }
}


/**
 * Verify that the value is not in the container.
 * Throws: UnitTestException on failure
 */
void shouldNotBeIn(T, U)(in T value, U container,
                         in string file = __FILE__, in size_t line = __LINE__)
if (!isAssociativeArray!U && isInputRange!U)
{
    if (find(container, value).length > 0)
    {
        fail("Value " ~ to!string(value) ~ " is in " ~ to!string(container), file,
            line);
    }
}

///
unittest
{
    shouldNotBeIn(3.5, [1.1, 2.2, 4.4]);
    shouldNotBeIn(1.0, [2.0 : 1, 3.0 : 2]);
}

/**
 * Verify that expr throws the templated Exception class.
 * This succeeds if the expression throws a child class of
 * the template parameter.
 * Throws: UnitTestException on failure (when expr does not
 * throw the expected exception)
 */
void shouldThrow(T : Throwable = Exception, E)(lazy E expr,
    in string file = __FILE__, in size_t line = __LINE__)
{
    if (!threw!T(expr))
        fail("Expression did not throw", file, line);
}

/**
 * Verify that expr throws the templated Exception class.
 * This only succeeds if the expression throws an exception of
 * the exact type of the template parameter.
 * Throws: UnitTestException on failure (when expr does not
 * throw the expected exception)
 */
void shouldThrowExactly(T : Throwable = Exception, E)(lazy E expr,
    in string file = __FILE__, in size_t line = __LINE__)
{

    immutable threw = threw!T(expr);
    if (!threw)
        fail("Expression did not throw", file, line);

    //Object.opEquals is @system
    immutable sameType = () @trusted{ return threw.typeInfo == typeid(T); }();
    if (!sameType)
        fail(text("Expression threw wrong type ", threw.typeInfo,
            "instead of expected type ", typeid(T)), file, line);
}

/**
 * Verify that expr does not throw the templated Exception class.
 * Throws: UnitTestException on failure
 */
void shouldNotThrow(T : Throwable = Exception, E)(lazy E expr,
    in string file = __FILE__, in size_t line = __LINE__)
{
    if (threw!T(expr))
        fail("Expression threw", file, line);
}

//@trusted because the user might want to catch a throwable
//that's not derived from Exception, such as RangeError
private auto threw(T : Throwable, E)(lazy E expr) @trusted
{

    struct ThrowResult
    {
        bool threw;
        TypeInfo typeInfo;
        T opCast(T)() const pure if (is(T == bool))
        {
            return threw;
        }
    }

    try
    {
        expr();
    }
    catch (T e)
    {
        return ThrowResult(true, typeid(e));
    }

    return ThrowResult(false);
}

unittest
{
    class CustomException : Exception
    {
        this(string msg = "")
        {
            super(msg);
        }
    }

    class ChildException : CustomException
    {
        this(string msg = "")
        {
            super(msg);
        }
    }

    void throwCustom()
    {
        throw new CustomException();
    }

    throwCustom.shouldThrow;
    throwCustom.shouldThrow!CustomException;

    void throwChild()
    {
        throw new ChildException();
    }

    throwChild.shouldThrow;
    throwChild.shouldThrow!CustomException;
    throwChild.shouldThrow!ChildException;
    throwChild.shouldThrowExactly!ChildException;
    try
    {
        throwChild.shouldThrowExactly!CustomException; //should not succeed
        assert(0, "shouldThrowExactly failed");
    }
    catch (Exception ex)
    {
    }
}

unittest
{
    void throwRangeError()
    {
        ubyte[] bytes;
        bytes = bytes[1 .. $];
    }

    import core.exception : RangeError;

    throwRangeError.shouldThrow!RangeError;
}

package void utFail(in string output, in string file, in size_t line)
{
    fail(output, file, line);
}

private void fail(in string output, in string file, in size_t line)
{
    throw new UnitTestException([output], file, line);
}


private string[] formatValue(T)(in string prefix, T value) {
    static if(isSomeString!T) {
        return [ prefix ~ `"` ~ value ~ `"`];
    } else static if(isInputRange!T) {
        return formatRange(prefix, value);
    } else {
        return [() @trusted{ return prefix ~ value.to!string; }()];
    }
}

private string[] formatRange(T)(in string prefix, T value) @trusted {
    //some versions of `to` are @system
    auto defaultLines = () @trusted{ return [prefix ~ value.to!string]; }();

    static if (!isInputRange!(ElementType!T))
        return defaultLines;
    else
    {
        const maxElementSize = value.empty ? 0 : value.map!(a => a.length).reduce!max;
        const tooBigForOneLine = (value.length > 5 && maxElementSize > 5) || maxElementSize > 10;
        if (!tooBigForOneLine)
            return defaultLines;
        return [prefix ~ "["] ~
            value.map!(a => formatValue("              ", a).join("") ~ ",").array ~
            "          ]";
    }
}

private enum isObject(T) = is(T == class) || is(T == interface);

private bool isEqual(V, E)(in V value, in E expected)
 if (!isObject!V &&
     (!isInputRange!V || !isInputRange!E) &&
     !isFloatingPoint!V && !isFloatingPoint!E &&
     is(typeof(value == expected) == bool))
{
    return value == expected;
}

private bool isEqual(V, E)(in V value, in E expected)
 if (!isObject!V && (isFloatingPoint!V || isFloatingPoint!E) && is(typeof(value == expected) == bool))
{
    import std.math;
    return approxEqual(value, expected);
}

private bool isEqual(V, E)(V value, E expected)
if (!isObject!V && isInputRange!V && isInputRange!E && is(typeof(value.front == expected.front) == bool))
{
    return equal(value, expected);
}

private bool isEqual(V, E)(V value, E expected)
if (!isObject!V &&
    isInputRange!V && isInputRange!E && !is(typeof(value.front == expected.front) == bool) &&
    isInputRange!(ElementType!V) && isInputRange!(ElementType!E))
{
    while (!value.empty && !expected.empty)
    {
        if (!equal(value.front, expected.front))
            return false;

        value.popFront;
        expected.popFront;
    }

    return value.empty && expected.empty;
}

private bool isEqual(V, E)(V value, E expected)
if (isObject!V && isObject!E)
{
    static assert(is(typeof(() { string s1 = value.toString; string s2 = expected.toString;})),
                  "Cannot compare instances of " ~ V.stringof ~
                  " or " ~ E.stringof ~ " unless toString is overridden for both");

    return value.tupleof == expected.tupleof;
}


unittest {
    assert(isEqual(2, 2));
    assert(!isEqual(2, 3));

    assert(isEqual(2.1, 2.1));
    assert(!isEqual(2.1, 2.2));

    assert(isEqual("foo", "foo"));
    assert(!isEqual("foo", "fooo"));

    assert(isEqual([1, 2], [1, 2]));
    assert(!isEqual([1, 2], [1, 2, 3]));

    assert(isEqual(iota(2), [0, 1]));
    assert(!isEqual(iota(2), [1, 2, 3]));

    assert(isEqual([[0, 1], [0, 1, 2]], [iota(2), iota(3)]));
    assert(isEqual([[0, 1], [0, 1, 2]], [[0, 1], [0, 1, 2]]));
    assert(!isEqual([[0, 1], [0, 1, 4]], [iota(2), iota(3)]));
    assert(!isEqual([[0, 1], [0]], [iota(2), iota(3)]));

    assert(isEqual([0: 1], [0: 1]));

    const constIntToInts = [1 : 2, 3 : 7, 9 : 345];
    auto intToInts = [1 : 2, 3 : 7, 9 : 345];

    assert(isEqual(intToInts, constIntToInts));
    assert(isEqual(constIntToInts, intToInts));

    class Foo
    {
        this(int i) { this.i = i; }
        override string toString() const { return i.to!string; }
        int i;
    }

    assert(isEqual(new Foo(5), new Foo(5)));
    assert(!isEqual(new Foo(5), new Foo(4)));

    ubyte[] arr;
    assert(isEqual(arr, []));
}


private void assertFail(E)(lazy E expression)
{
    assertThrown!UnitTestException(expression);
}

/**
 * Verify that rng is empty.
 * Throws: UnitTestException on failure.
 */
void shouldBeEmpty(R)(R rng, in string file = __FILE__, in size_t line = __LINE__)
if (isInputRange!R)
{
    if (!rng.empty)
        fail("Range not empty", file, line);
}

/**
 * Verify that aa is empty.
 * Throws: UnitTestException on failure.
 */
void shouldBeEmpty(T)(in T aa, in string file = __FILE__, in size_t line = __LINE__)
if (isAssociativeArray!T)
{
    //keys is @system
    () @trusted{ if (!aa.keys.empty) fail("AA not empty", file, line); }();
}

///
unittest
{
    int[] ints;
    string[] strings;
    string[string] aa;

    shouldBeEmpty(ints);
    shouldBeEmpty(strings);
    shouldBeEmpty(aa);

    ints ~= 1;
    strings ~= "foo";
    aa["foo"] = "bar";

    assertFail(shouldBeEmpty(ints));
    assertFail(shouldBeEmpty(strings));
    assertFail(shouldBeEmpty(aa));
}


/**
 * Verify that rng is not empty.
 * Throws: UnitTestException on failure.
 */
void shouldNotBeEmpty(R)(R rng, in string file = __FILE__, in size_t line = __LINE__)
if (isInputRange!R)
{
    if (rng.empty)
        fail("Range empty", file, line);
}

/**
 * Verify that aa is not empty.
 * Throws: UnitTestException on failure.
 */
void shouldNotBeEmpty(T)(in T aa, in string file = __FILE__, in size_t line = __LINE__)
if (isAssociativeArray!T)
{
    //keys is @system
    () @trusted{ if (aa.keys.empty)
        fail("AA empty", file, line); }();
}

///
unittest
{
    int[] ints;
    string[] strings;
    string[string] aa;

    assertFail(shouldNotBeEmpty(ints));
    assertFail(shouldNotBeEmpty(strings));
    assertFail(shouldNotBeEmpty(aa));

    ints ~= 1;
    strings ~= "foo";
    aa["foo"] = "bar";

    shouldNotBeEmpty(ints);
    shouldNotBeEmpty(strings);
    shouldNotBeEmpty(aa);
}

/**
 * Verify that t is greater than u.
 * Throws: UnitTestException on failure.
 */
void shouldBeGreaterThan(T, U)(in T t, in U u,
                               in string file = __FILE__, in size_t line = __LINE__)
{
    if (t <= u)
        fail(text(t, " is not > ", u), file, line);
}

///
unittest
{
    shouldBeGreaterThan(7, 5);
    assertFail(shouldBeGreaterThan(5, 7));
    assertFail(shouldBeGreaterThan(7, 7));
}


/**
 * Verify that t is smaller than u.
 * Throws: UnitTestException on failure.
 */
void shouldBeSmallerThan(T, U)(in T t, in U u,
                               in string file = __FILE__, in size_t line = __LINE__)
{
    if (t >= u)
        fail(text(t, " is not < ", u), file, line);
}

///
unittest
{
    shouldBeSmallerThan(5, 7);
    assertFail(shouldBeSmallerThan(7, 5));
    assertFail(shouldBeSmallerThan(7, 7));
}



/**
 * Verify that t and u represent the same set (ordering is not important).
 * Throws: UnitTestException on failure.
 */
void shouldBeSameSetAs(V, E)(V value, E expected, in string file = __FILE__, in size_t line = __LINE__)
if (isInputRange!V && isInputRange!E && is(typeof(value.front != expected.front) == bool))
{
    if (!isSameSet(value, expected))
    {
        const msg = formatValue("Expected: ", expected) ~
                    formatValue("     Got: ", value);
        throw new UnitTestException(msg, file, line);
    }
}

///
unittest
{
    auto inOrder = iota(4);
    auto noOrder = [2, 3, 0, 1];
    auto oops = [2, 3, 4, 5];

    inOrder.shouldBeSameSetAs(noOrder);
    inOrder.shouldBeSameSetAs(oops).shouldThrow!UnitTestException;

    struct Struct
    {
        int i;
    }

    [Struct(1), Struct(4)].shouldBeSameSetAs([Struct(4), Struct(1)]);
}

private bool isSameSet(T, U)(T t, U u) {
    //sort makes the element types have to implement opCmp
    //instead, try one by one
    auto ta = t.array;
    auto ua = u.array;
    if (ta.length != ua.length) return false;
    foreach(element; ta)
    {
        if (!ua.canFind(element)) return false;
    }

    return true;
}

/**
 * Verify that value and expected do not represent the same set (ordering is not important).
 * Throws: UnitTestException on failure.
 */
void shouldNotBeSameSetAs(V, E)(V value, E expected, in string file = __FILE__, in size_t line = __LINE__)
if (isInputRange!V && isInputRange!E && is(typeof(value.front != expected.front) == bool))
{
    if (isSameSet(value, expected))
    {
        const msg = ["Value:",
                     formatValue("", value).join(""),
                     "is not expected to be equal to:",
                     formatValue("", expected).join("")
            ];
        throw new UnitTestException(msg, file, line);
    }
}


///
unittest
{
    auto inOrder = iota(4);
    auto noOrder = [2, 3, 0, 1];
    auto oops = [2, 3, 4, 5];

    inOrder.shouldNotBeSameSetAs(oops);
    inOrder.shouldNotBeSameSetAs(noOrder).shouldThrow!UnitTestException;
}