module unit_threaded.testcase;

import unit_threaded.should;
import unit_threaded.io;
import unit_threaded.reflection: TestData, TestFunction;

import std.exception;
import std.string;
import std.conv;
import std.algorithm;

/**
 * Class from which other test cases derive
 */
class TestCase {

    /**
     * Returns: the name of the test
     */
    string getPath() const pure nothrow {
        return this.classinfo.name;
    }

    /**
     * Executes the test.
     * Returns: array of failures (child classes may have more than 1)
     */
    string[] opCall() {
        doTest();
        printOutput();
        return _failed ? [getPath()] : [];
    }

    /**
     Certain child classes override this
     */
    ulong numTestsRun() const { return 1; }

package:

    void silence() @safe pure nothrow { _silent = true; }
    string output() @safe const pure nothrow { return _output; }

protected:

    abstract void test();
    void setup() { } ///override to run before test()
    void shutdown() { } ///override to run after test()

private:

    bool _failed;
    string _output;
    bool _silent;

    final auto doTest() {
        print(getPath() ~ ":\n");
        check(setup());
        check(test());
        check(shutdown());
        if(_failed) print("\n\n");
    }

    final bool check(E)(lazy E expression) {
        try {
            expression();
        } catch(UnitTestException ex) {
            fail(ex.toString());
        } catch(Throwable ex) {
            fail("\n    " ~ ex.toString() ~ "\n");
        }

        return !_failed;
    }

    final void fail(in string msg) {
        _failed = true;
        print(msg);
    }

    final void print(in string msg) {
        _output ~= msg;
    }

    final void printOutput() const {
        if(!_silent) utWrite(_output);
    }
}

class CompositeTestCase: TestCase {
    void add(TestCase t) { _tests ~= t;}

    void opOpAssign(string op : "~")(TestCase t) {
        add(t);
    }

    override string[] opCall() {
        return _tests.map!(a => a()).reduce!((a, b) => a ~ b);
    }

    override void test() { assert(false, "CompositeTestCase.test should never be called"); }

    override ulong numTestsRun() const {
        return _tests.length;
    }

    package TestCase[] tests() @safe pure nothrow {
        return _tests;
    }

private:

    TestCase[] _tests;
}

class ShouldFailTestCase: TestCase {
    this(TestCase testCase) {
        this.testCase = testCase;
    }

    override string getPath() const pure nothrow {
        return this.testCase.getPath;
    }

    override void test() {
        const ex = collectException!Throwable(testCase.test());
        if(ex is null) {
            throw new Exception("Test " ~ testCase.getPath() ~ " was expected to fail but did not");
        }
    }

private:

    TestCase testCase;
}

class FunctionTestCase: TestCase {
    this(in TestData data) pure nothrow {
        _name = data.getPath;
        _func = data.testFunction;
    }

    override void test() {
        _func();
    }

    override string getPath() const pure nothrow {
        return _name;
    }

    private string _name;
    private TestFunction _func;
}

class BuiltinTestCase: FunctionTestCase {
    this(in TestData data) pure nothrow {
        super(data);
    }

    override void test() {
        import core.exception: AssertError;

        try
            super.test();
        catch(AssertError e)
            unit_threaded.should.fail(e.msg, e.file, e.line);
    }
}