package hatmill_test

import (
	"bytes"
	"fmt"
	"html"
	"io"
	"os"
	"reflect"
	"strings"
	"testing"
	"unicode"

	"github.com/leanovate/gopter"
	"github.com/leanovate/gopter/gen"
	"github.com/leanovate/gopter/prop"
	"gitlab.codemonkeysoftware.net/b/hatmill"
	ha "gitlab.codemonkeysoftware.net/b/hatmill/attribute"
	he "gitlab.codemonkeysoftware.net/b/hatmill/element"
)

type NopWriter struct{}

func (NopWriter) Write(p []byte) (n int, err error) {
	return len(p), nil
}

func writeToString(wt io.WriterTo) string {
	var buf bytes.Buffer
	_, err := wt.WriteTo(&buf)
	if err != nil {
		panic(err)
	}
	return buf.String()
}

func checkWrite(wt io.WriterTo, expected string) bool {
	var buf bytes.Buffer
	n, err := wt.WriteTo(&buf)
	return err == nil && n == int64(buf.Len()) && buf.String() == expected
}

var ASCII = &unicode.RangeTable{
	R16: []unicode.Range16{
		{Lo: ' ', Hi: unicode.MaxASCII, Stride: 1},
	},
	LatinOffset: 1,
}

var dangerousASCII = gen.UnicodeString(ASCII).SuchThat(func(v interface{}) bool {
	s := v.(string)
	const specialChars = `&<>'"`
	for _, c := range specialChars {
		if strings.ContainsRune(s, rune(c)) {
			return true
		}
	}
	return false
})

func printableASCII() string {
	const minPrintable rune = 32
	const maxPrintable rune = 126
	var buf bytes.Buffer
	for r := minPrintable; r <= maxPrintable; r++ {
		buf.WriteRune(r)
	}
	return buf.String()
}

func TestText(t *testing.T) {
	properties := gopter.NewProperties(nil)
	properties.Property("WriteTo escapes special chars and outputs all others unchanged", prop.ForAll(
		func(s string) bool {
			expected := html.EscapeString(s)
			return checkWrite(hatmill.Text(s), expected)
		},
		dangerousASCII,
	))
	properties.TestingRun(t)
}

func stringNotEmpty(v interface{}) bool {
	return v.(string) != ""
}

var nonEmptyAlphaString = gen.AlphaString().SuchThat(stringNotEmpty)

func attribGen(value gopter.Gen) gopter.Gen {
	return gen.Struct(reflect.TypeOf(hatmill.Attrib{}), map[string]gopter.Gen{
		"Key":   nonEmptyAlphaString,
		"Value": value,
	})
}

func TestAttrib(t *testing.T) {
	properties := gopter.NewProperties(nil)

	properties.Property("WriteTo only writes key when value is empty", prop.ForAll(
		func(key string) bool {
			attrib := hatmill.Attrib{
				Key: key,
			}
			return checkWrite(attrib, key)
		},
		nonEmptyAlphaString,
	))

	properties.Property("writes key=value when value is not empty", prop.ForAll(
		func(attrib hatmill.Attrib) bool {
			expected := fmt.Sprintf("%s='%s'", attrib.Key, attrib.Value)
			return checkWrite(attrib, expected)
		},
		attribGen(nonEmptyAlphaString),
	))

	properties.Property("WriteTo escapes attribute value", prop.ForAll(
		func(attrib hatmill.Attrib) bool {
			expected := fmt.Sprintf("%s='%s'", attrib.Key, html.EscapeString(attrib.Value))
			return checkWrite(attrib, expected)
		},
		attribGen(dangerousASCII.SuchThat(stringNotEmpty)),
	))

	properties.TestingRun(t)
}

func TestEmptyElement(t *testing.T) {
	properties := gopter.NewProperties(nil)

	properties.Property("WriteTo writes element correctly with no attributes", prop.ForAll(
		func(tagName string) bool {
			elem := &hatmill.VoidElement{
				TagName: tagName,
			}
			expected := "<" + tagName + ">"
			return checkWrite(elem, expected)
		},
		gen.AnyString(),
	))

	properties.Property("WriteTo writes element correctly with attributes", prop.ForAll(
		func(tagName string, attribs []hatmill.Attrib) bool {
			elem := hatmill.VoidElement{
				TagName: tagName,
				Attribs: attribs,
			}

			var attribStrings []string
			for _, attrib := range attribs {
				attribStrings = append(attribStrings, writeToString(attrib))
			}
			if len(attribStrings) > 0 {
				attribStrings[0] = " " + attribStrings[0]
			}

			expected := "<" + tagName + strings.Join(attribStrings, " ") + ">"
			return checkWrite(elem, expected)
		},
		gen.AnyString(),
		gen.SliceOf(attribGen(gen.AlphaString())),
	))

	properties.TestingRun(t)
}

var htmlTextGen = gen.AnyString().Map(func(s string) hatmill.Term {
	return hatmill.Text(s)
})

func TestParentElement(t *testing.T) {
	properties := gopter.NewProperties(nil)

	properties.Property("WriteTo writes element correctly without children", prop.ForAll(
		func(tagName string, attribs []hatmill.Attrib) bool {
			elem := &hatmill.ParentElement{
				VoidElement: hatmill.VoidElement{
					TagName: tagName,
					Attribs: attribs,
				},
			}

			openTag := writeToString(elem.VoidElement)
			expected := openTag + "</" + tagName + ">"
			return checkWrite(elem, expected)
		},
		gen.AnyString(),
		gen.SliceOf(attribGen(gen.AlphaString())),
	))

	properties.Property("WriteTo writes element correctly with children", prop.ForAll(
		func(tagName string, attribs []hatmill.Attrib, children []hatmill.Term) bool {
			elem := &hatmill.ParentElement{
				VoidElement: hatmill.VoidElement{
					TagName: tagName,
					Attribs: attribs,
				},
				Children: children,
			}

			openTag := writeToString(elem.VoidElement)

			var childStrings []string
			for _, child := range children {
				childStrings = append(childStrings, writeToString(child))
			}

			expected := openTag + strings.Join(childStrings, "") + "</" + tagName + ">"
			return checkWrite(elem, expected)
		},
		gen.AnyString(),
		gen.SliceOf(attribGen(gen.AlphaString())),
		gen.SliceOf(htmlTextGen),
	))

	properties.TestingRun(t)
}

func TestTerms(t *testing.T) {
	properties := gopter.NewProperties(nil)

	properties.Property("WriteTo writes the concatenation of calling WriteTo on the slice contents", prop.ForAll(
		func(terms []hatmill.Term) bool {
			var expected string
			for _, term := range terms {
				expected += string(term.(hatmill.Text))
			}
			return checkWrite(hatmill.Terms(terms), expected)
		},
		gen.SliceOf(htmlTextGen),
	))
}

func Example() {
	userInput := "<script>launchMissiles();</script>"

	document := he.Html()(
		he.Body()(
			he.Img(ha.Src("./photo.jpg"), ha.Contenteditable(true)),
			hatmill.Text(userInput),
			he.Div(ha.Disabled(), ha.CustomData("coolness", "awesome"))(),
			he.Textarea(ha.Rows(25))(),
			he.Meter(ha.Min(-1.3), ha.Max(5.5E12))(),
		),
	)
	hatmill.WriteDocument(os.Stdout, document)
	// Output: <!DOCTYPE html><html><body><img src='./photo.jpg' contenteditable='true'>&lt;script&gt;launchMissiles();&lt;/script&gt;<div disabled data-coolness='awesome'></div><textarea rows='25'></textarea><meter min='-1.3' max='5.5E+12'></meter></body></html>
}