// Constructs an if-and-only-if/then matcher:
//     matcher := IfAndOnlyIf(AntecedentMatcher).Then(ConsequentMatcher)
// that matches when both or neither of the Antecedent and the
// Consequent match.  Note that this is logically equivalent to:
//     Either(Not(AntecedentMatcher)).Xor(ConsequentMatcher)
// But may be more readable in practice.
func (self *IfAndOnlyIfClause) Then(consequent *base.Matcher) *base.Matcher {
	antecedent := self.antecedent
	match := func(actual interface{}) *base.Result {
		result1 := antecedent.Match(actual)
		result2 := consequent.Match(actual)
		if result1.Matched() {
			if result2.Matched() {
				return base.NewResultf(true,
					"Matched because both parts of 'Iff/Then' matched on [%v]", actual).
					WithCauses(result1, result2)
			}
			return base.NewResultf(false,
				"Failed because only the first part of 'Iff/Then' matched on [%v]", actual).
				WithCauses(result1, result2)
		}
		if result2.Matched() {
			return base.NewResultf(false,
				"Failed because only the second part of 'IFf/Then' matched on [%v]", actual).
				WithCauses(result1, result2)
		}
		return base.NewResultf(true,
			"Matched because neither part of 'Iff/Then' matched on [%v]", actual).
			WithCauses(result1, result2)
	}
	return base.NewMatcherf(match, "if and only if [%v] then [%v]", antecedent, consequent)
}

// Returns a matcher that matches on any array or slice input value
// if the given matcher matches every element of that array or slice.
//
// The returned matcher does not match any non-array-or-slice value.
func EachElem(matcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		v := reflect.NewValue(actual)
		var value _ElemAndLen
		var ok bool
		value, ok = v.(*reflect.ArrayValue)
		if !ok {
			value, ok = v.(*reflect.SliceValue)
		}
		if !ok {
			return base.NewResultf(false,
				"Was not array or slice: was type %T", actual)
		}
		n := value.Len()
		for i := 0; i < n; i++ {
			elem := value.Elem(i).Interface()
			result := matcher.Match(elem)
			if !result.Matched() {
				return base.NewResultf(false,
					"Failed to match element %v of %v: %v",
					i+1, n, elem).
					WithCauses(result)
			}
		}
		return base.NewResultf(true,
			"Matched all of the %v elements", n)
	}
	return base.NewMatcherf(match, "EveryElement[%v]", matcher)
}

// Second part of a builder for an either/xor matcher:
//     matcher := Either(matcher1).Xor(matcher2)
// This matcher matches when exactly one of the two matchers matches
// a given value;  if both or neither of the matchers is successful,
// xor fails to match.  Note that this is *never* a short-circuiting
// operation.
func (self *EitherClause) Xor(matcher2 *base.Matcher) *base.Matcher {
	matcher1 := self.matcher
	match := func(actual interface{}) *base.Result {
		result1 := matcher1.Match(actual)
		result2 := matcher2.Match(actual)
		if result1.Matched() {
			if result2.Matched() {
				return base.NewResultf(false,
					"both parts of 'Either/Xor' matched [%v]", actual).
					WithCauses(result1, result2)
			}
			return base.NewResultf(true,
				"only the first part of 'Either/Xor' matched [%v]", actual).
				WithCauses(result1, result2)
		}
		if result2.Matched() {
			return base.NewResultf(true,
				"only the second part of 'Either/Xor' matched [%v]", actual).
				WithCauses(result1, result2)
		}
		return base.NewResultf(false,
			"neither part of 'Either/Xor' matched [%v]", actual).
			WithCauses(result1, result2)
	}
	return base.NewMatcherf(match, "either [%v] xor [%v]", matcher1, matcher2)
}

func logSamples(t *testing.T, matcher *base.Matcher) {
	t.Logf("Sample results for: %v\n", matcher)
	we := asserter.Using(t)
	for index, value := range sampleValues {
		t.Logf("Sample #%v: %T[value: %v]\n", index+1, value, value)
		we.LogResult(matcher.Match(value))
	}
}

// Creates a new matcher that applies the given matcher to the result of
// converting an input string to uppercase (using strings.ToUpper).
// If the input value is not a string, the matcher fails to match.
func ToUpper(matcher *base.Matcher) *base.Matcher {
	match := func(s string) *base.Result {
		upper := strings.ToUpper(s)
		result := matcher.Match(upper)
		return base.NewResultf(result.Matched(),
			"ToUpper is %v", upper).
			WithCauses(result)
	}
	return base.NewMatcherf(match, "ToUpper(%v)", matcher)
}

// Creates a new matcher that applies the given matcher to the result of
// converting an input string its length. (using the `len()` builtin).
// If the input value is not a string, the matcher fails to match.
func ToLen(matcher *base.Matcher) *base.Matcher {
	match := func(s string) *base.Result {
		length := len(s)
		result := matcher.Match(length)
		return base.NewResultf(result.Matched(),
			"length is %v", length).
			WithCauses(result)
	}
	return base.NewMatcherf(match, "ToLen(%v)", matcher)
}

// Returns a new matcher that applies the type of its input
// element to the given matcher.
func ToType(matcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		actualType := reflect.Typeof(actual)
		result := matcher.Match(actualType)
		return base.NewResultf(result.Matched(),
			"reflect.Typeof() returned %v", actualType).
			WithCauses(result)
	}
	return base.NewMatcherf(match, "ToType(%v)", matcher)
}

func safeMatch(value interface{}, matcher *base.Matcher) (result *base.Result) {
	defer func() {
		if x := recover(); x != nil {
			result = base.NewResultf(false, "Panic: %v", x).
				WithMatcherAndValue(matcher, value)
		}
	}()
	result = matcher.Match(value)
	return
}

// Applies the given matcher to the length of the input element.
func ToLen(matcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		value := reflect.NewValue(actual)
		if hasLen, ok := value.(_HasLen); ok {
			length := hasLen.Len()
			result := matcher.Match(length)
			return base.NewResultf(result.Matched(), "Len() returned %v", length)
		}
		return base.NewResultf(false,
			"Can't determine Len() for %T", actual)
	}
	return base.NewMatcherf(match, "ToLen[%v]", matcher)
}

// Returns a new matcher that, on any input that is a *reflect.SliceType,
// extracts the type of element and matches it against the given matcher.
//
// If the given input is not an *reflect.SliceType, this fails to match.
// Note:  this matches slice *types*, not slices.  (See SliceOf.)
func SliceTypeOf(elementTypeMatcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		if sliceType, ok := actual.(*reflect.SliceType); ok {
			elementType := sliceType.Elem()
			result := elementTypeMatcher.Match(elementType)
			return base.NewResultf(
				result.Matched(),
				"was SliceType with elements of type %v", elementType.Name()).
				WithCauses(result)
		}
		return base.NewResultf(false, "was of type %T, not a slice", actual)
	}
	return base.NewMatcherf(match, "SliceTypeOf(%v)", elementTypeMatcher)
}

// Returns a new matcher that, on any input that is an array, extracts
// its type and matches it against the given matcher.
//
// If the given input is not an array, this fails to match.
// Note: this matches *arrays*, not array *types*. (See ArrayTypeOf.)
func ArrayOf(elementTypeMatcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		actualType := reflect.Typeof(actual)
		if arrayType, ok := actualType.(*reflect.ArrayType); ok {
			elementType := arrayType.Elem()
			result := elementTypeMatcher.Match(elementType)
			return base.NewResultf(
				result.Matched(),
				"was array with elements of type %v", elementType).
				WithCauses(result)
		}
		return base.NewResultf(false, "was of type %T, not an array", actual)
	}
	return base.NewMatcherf(match, "ArrayOf(%v)", elementTypeMatcher)
}

// Returns a new matcher that, on any input that is a channel, extracts
// its type and matches it against the given matcher.
//
// If the given input is not a channel, this fails to match.
// Note: this matches *channels*, not channel *types*. (See ChannelTypeOf.)
func ChannelOf(elementTypeMatcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		actualType := reflect.Typeof(actual)
		if channelType, ok := actualType.(*reflect.ChanType); ok {
			elementType := channelType.Elem()
			result := elementTypeMatcher.Match(elementType)
			return base.NewResultf(result.Matched(),
				"was channel with elements of type %v",
				elementType).
				WithCauses(result)
		}
		return base.NewResultf(false, "was of type %T, not a channel", actual)
	}
	return base.NewMatcherf(match, "ChannelOf(%v)", elementTypeMatcher)
}

// Returns a new matcher that, on any input that is a pointer, extracts the
// type of object that it thinks it's pointing to (the "pointee") and
// matches it against the given matcher.
//
// If the given input is not an pointer, this fails to match.
// Note:  this matches *pointers*, not pointer *types*. (See PtrTypeTo.)
func PtrTo(pointeeTypeMatcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		actualType := reflect.Typeof(actual)
		if ptrType, ok := actualType.(*reflect.PtrType); ok {
			elementType := ptrType.Elem()
			result := pointeeTypeMatcher.Match(elementType)
			return base.NewResultf(
				result.Matched(), "was PtrType to type %v", elementType).
				WithCauses(result)
		}
		return base.NewResultf(false,
			"was type %T, not a pointer", actual)
	}
	return base.NewMatcherf(match,
		"PtrTo(%v)", pointeeTypeMatcher)
}

// Applies the given matcher to the result of writing the input object's
// to a string by using fmt.Sprintf("%#v", object).
func ToGoString(matcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		if gostringer, ok := actual.(fmt.GoStringer); ok {
			s := gostringer.GoString()
			result := matcher.Match(s)
			return base.NewResultf(result.Matched(),
				"GoString() returned %v", s).
				WithCauses(result)
		}
		s := fmt.Sprintf("%#v", actual)
		result := matcher.Match(s)
		return base.NewResultf(result.Matched(),
			"Not a fmt.GoStringer, but prints as %v", s).
			WithCauses(result)
	}
	return base.NewMatcherf(match, "ToGoString(%v)", matcher)
}

// Creates a matcher that passes when neither this matcher nor the
// other matcher pass.  This operation is short-circuiting, so that
// if the first matcher matches, the second is not attempted.
//  Note that this is logically equivalent to:
//     Both(Not(matcher1)).And(Not(matcher2))
// But may be more readable in practice.
func (self *NeitherClause) Nor(matcher2 *base.Matcher) *base.Matcher {
	matcher1 := self.matcher
	match := func(actual interface{}) *base.Result {
		result1 := matcher1.Match(actual)
		if result1.Matched() {
			return base.NewResultf(false,
				"first part of 'Nor' matched [%v]", actual).
				WithCauses(result1)
		}
		result2 := matcher2.Match(actual)
		if result2.Matched() {
			return base.NewResultf(false,
				"second part of 'Nor' matched [%v]", actual).
				WithCauses(result2)
		}
		return base.NewResultf(true,
			"neither part of 'Nor' matched [%v]", actual).
			WithCauses(result1, result2)
	}
	return base.NewMatcherf(match, "neither [%v] nor [%v]", matcher1, matcher2)
}

// Second part of a builder for a short-circuiting both/and matcher.
func (self *BothClause) And(matcher2 *base.Matcher) *base.Matcher {
	matcher1 := self.matcher
	match := func(actual interface{}) *base.Result {
		result1 := matcher1.Match(actual)
		if !result1.Matched() {
			return base.NewResultf(false,
				"first part of 'Both/And' did not match [%v]", actual).
				WithCauses(result1)
		}
		result2 := matcher2.Match(actual)
		if !result2.Matched() {
			return base.NewResultf(false,
				"second part of 'Both/And' did not match [%v]", actual).
				WithCauses(result2)
		}
		return base.NewResultf(true,
			"both parts of 'Both/And' matched [%v]", actual).
			WithCauses(result1, result2)
	}
	return base.NewMatcherf(match, "both [%v] and [%v]", matcher1, matcher2)
}

// Returns a matcher that matches on any array or slice input value
// if the given matcher matches at least one element of that array
// or slice.
//
// The returned matcher does not match any non-array-or-slice value.
func AnyElem(matcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		v := reflect.NewValue(actual)
		if value, ok := v.(_ElemAndLen); ok {
			n := value.Len()
			for i := 0; i < n; i++ {
				elem := value.Elem(i).Interface()
				result := matcher.Match(elem)
				if result.Matched() {
					return base.NewResultf(true,
						"Matched element %v of %v: %v", i+1, n, elem).
						WithCauses(result)
				}
			}
			return base.NewResultf(false,
				"Matched none of the %v elements", n)
		}
		return matcher.Match(v)
	}
	return base.NewMatcherf(match, "AnyElement[%v]", matcher)
}

// Returns a new matcher that, on any input that is a *reflect.MapType,
// extracts the type of keys and element and matches them against two
// given matchers.
//
// If the given input is not an *reflect.MapType, this fails to match.
// Note:  this matches map *types*, not maps.  (See MapOf.)
func MapTypeOf(keyTypeMatcher, elementTypeMatcher *base.Matcher) *base.Matcher {
	match := func(actual interface{}) *base.Result {
		if mapType, ok := actual.(*reflect.MapType); ok {
			keyType := mapType.Key()
			elementType := mapType.Elem()
			keyResult := keyTypeMatcher.Match(keyType)
			if !keyResult.Matched() {
				return base.NewResultf(false,
					"was MapType with keys of type %v", keyType).
					WithCauses(keyResult)
			}
			elementResult := elementTypeMatcher.Match(elementType)
			return base.NewResultf(elementResult.Matched(),
				"was MapType with keys/elements of type %v/%v",
				keyType, elementType).
				WithCauses(keyResult, elementResult)
		}
		return base.NewResultf(false, "was of type %T, not a MapType", actual)
	}
	return base.NewMatcherf(match,
		"MapTypeOf(%v, %v)", keyTypeMatcher, elementTypeMatcher)
}

func checkMatcherIsNonMatchingOnNils(t *testing.T, matcher *base.Matcher) {
	checkResultIsNonMatching(t, matcher.Match(nil), "nil")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._pointer), "uninitialized pointer")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._func), "uninitialized func")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._slice), "uninitialized slice")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._chan), "uninitialized chan")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._map), "uninitialized map")
	checkResultIsNonMatching(t, matcher.Match(uninitialized._interface), "uninitialized interface")
}

func logSamples(t *testing.T, matcher *base.Matcher) {
	t.Logf("Sample results for: %v\n", matcher)
	t.Logf("\ton true: %v\n", matcher.Match(true))
	t.Logf("\ton false: %v\n", matcher.Match(false))
	t.Logf("\ton int: %v\n", matcher.Match(42))
	t.Logf("\ton uint: %v\n", matcher.Match(uint(42)))
	t.Logf("\ton float: %v\n", matcher.Match(42.0))
	t.Logf("\ton string: %v\n", matcher.Match("foobar"))
	t.Logf("\ton struct: %v\n", matcher.Match(struct{ Field int }{Field: 42}))
	t.Logf("\ton type: %v\n", matcher.Match(reflect.Typeof(uninitialized)))

	t.Logf("\ton channel: %v\n", matcher.Match(make(chan int, 1)))
	t.Logf("\ton function: %v\n", matcher.Match(func() int { return 1 }))
	t.Logf("\ton function: %v\n", matcher.Match(interface{}(nil)))
	t.Logf("\ton map: %v\n", matcher.Match(map[int]string{1: "one", 2: "two"}))
	t.Logf("\ton pointer: %v\n", matcher.Match(&struct{ Field int }{Field: 42}))
	t.Logf("\ton slice: %v\n", matcher.Match([]int{1}))

	t.Logf("\ton nil: %v\n", matcher.Match(nil))
	t.Logf("\ton nil channel: %v\n", matcher.Match(uninitialized._chan))
	t.Logf("\ton nil function: %v\n", matcher.Match(uninitialized._func))
	t.Logf("\ton nil interface: %v\n", matcher.Match(uninitialized._interface))
	t.Logf("\ton nil map: %v\n", matcher.Match(uninitialized._map))
	t.Logf("\ton nil pointer: %v\n", matcher.Match(uninitialized._pointer))
	t.Logf("\ton nil slice: %v\n", matcher.Match(uninitialized._slice))
}