package tokenize_test

import (
	"fmt"
	"io"
	"strings"
	"testing"
	"unicode/utf8"

	"git.makaay.nl/mauricem/go-parsekit/tokenize"
)

// TODO For error handling, it would be really cool if for example the
// 10.0.300.1/24 case would return an actual error stating that
// 300 is not a valid octet for an IPv4 address.
// Biggest thing to take care of here, is that errors should not stop
// a Parser flow (since we might be trying to match different cases in
// sequence), but a Parser flow should optionally be able to make use
// of the actual error.
// The same goes for a Tokenizer, since those can also make use of
// optional matching using tokenize.C.Any(...) for example. If matching
// for Any(IPv4, Digits), the example case should simply end up with 10
// after the IPv4 mismatch.
func ExampleNew() {
	// Build the tokenizer for ip/mask.
	var c, a, t = tokenize.C, tokenize.A, tokenize.T
	ip := t.Str("ip", a.IPv4)
	mask := t.Int8("mask", a.IPv4CIDRMask)
	cidr := c.Seq(ip, a.Slash, mask)
	tokenizer := tokenize.New(cidr)

	for _, input := range []string{
		"000.000.000.000/000",
		"192.168.0.1/24",
		"255.255.255.255/32",
		"10.0.300.1/24",
		"not an IPv4 CIDR",
	} {
		// Execute returns a Result and an error, which is nil on success.
		result, err := tokenizer(input)

		if err == nil {
			fmt.Printf("Result: %s\n", result.Tokens())
		} else {
			fmt.Printf("Error: %s\n", err)
		}
	}
	// Output:
	// Result: [ip((string)0.0.0.0) mask((int8)0)]
	// Result: [ip((string)192.168.0.1) mask((int8)24)]
	// Result: [ip((string)255.255.255.255) mask((int8)32)]
	// Error: mismatch at start of file
	// Error: mismatch at start of file
}

func TestCallingNextRune_ReturnsNextRune(t *testing.T) {
	r, _ := mkInput().NextRune()
	AssertEqual(t, 'T', r, "first rune")
}

func TestInputCanAcceptRunesFromReader(t *testing.T) {
	i := mkInput()
	i.NextRune()
	i.Accept()
	i.NextRune()
	i.Accept()
	i.NextRune()
	i.Accept()
	AssertEqual(t, "Tes", i.Result().String(), "i.Result().String()")
}

func TestCallingNextRuneTwice_Panics(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: func() {
			i := mkInput()
			i.NextRune()
			i.NextRune()
		},
		Regexp: true,
		Expect: `tokenize\.API\.NextRune\(\): NextRune\(\) called at /.*/tokenizer_test\.go:\d+ without a prior call to Accept\(\)`,
	})
}

func TestCallingAcceptWithoutCallingNextRune_Panics(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: mkInput().Accept,
		Regexp:   true,
		Expect:   `tokenize\.API\.Accept\(\): Accept\(\) called at /.*/assertions_test\.go:\d+ without first calling NextRune()`,
	})
}

func TestCallingMergeOnNonForkedChild_Panics(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: func() {
			i := mkInput()
			i.Merge()
		},
		Regexp: true,
		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*/tokenizer_test\.go:\d+ on a non-forked API`})
}

func TestCallingNextRuneOnForkedParent_DetachesForkedChild(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: func() {
			i := mkInput()
			f := i.Fork()
			i.NextRune()
			f.Merge()
		},
		Regexp: true,
		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*/tokenizer_test\.go:\d+ on a non-forked API`})
}

func TestCallingForkOnForkedParent_DetachesForkedChild(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: func() {
			i := mkInput()
			f := i.Fork()
			i.Fork()
			f.Merge()
		},
		Regexp: true,
		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*/tokenizer_test\.go:\d+ on a non-forked API`})
}

func TestForkingInput_ClearsLastRune(t *testing.T) {
	AssertPanic(t, PanicT{
		Function: func() {
			i := mkInput()
			i.NextRune()
			i.Fork()
			i.Accept()
		},
		Regexp: true,
		Expect: `tokenize\.API\.Accept\(\): Accept\(\) called at /hom.*/tokenizer_test\.go:\d+ without first calling NextRune\(\)`,
	})
}

func TestAccept_UpdatesCursor(t *testing.T) {
	i := tokenize.NewAPI(strings.NewReader("input\r\nwith\r\nnewlines"))
	AssertEqual(t, "start of file", i.Result().Cursor().String(), "cursor 1")
	for j := 0; j < 6; j++ { // read "input\r", cursor end up at "\n"
		i.NextRune()
		i.Accept()
	}
	AssertEqual(t, "line 1, column 7", i.Result().Cursor().String(), "cursor 2")
	i.NextRune() // read "\n", cursor ends up at start of new line
	i.Accept()
	AssertEqual(t, "line 2, column 1", i.Result().Cursor().String(), "cursor 3")
	for j := 0; j < 10; j++ { // read "with\r\nnewl", cursor end up at "i"
		i.NextRune()
		i.Accept()
	}
	AssertEqual(t, "line 3, column 5", i.Result().Cursor().String(), "cursor 4")
}

func TestWhenCallingNextruneAtEndOfFile_EOFIsReturned(t *testing.T) {
	i := tokenize.NewAPI(strings.NewReader("X"))
	i.NextRune()
	i.Accept()
	r, err := i.NextRune()
	AssertEqual(t, true, r == utf8.RuneError, "returned rune from NextRune()")
	AssertEqual(t, true, err == io.EOF, "returned error from NextRune()")
}
func TestAfterReadingruneAtEndOfFile_EarlierRunesCanStillBeAccessed(t *testing.T) {
	i := tokenize.NewAPI(strings.NewReader("X"))
	f := i.Fork()
	f.NextRune()
	f.Accept()
	r, err := f.NextRune()
	AssertEqual(t, true, r == utf8.RuneError, "returned rune from 2nd NextRune()")
	r, err = i.NextRune()
	AssertEqual(t, 'X', r, "returned rune from 2nd NextRune()")
	AssertEqual(t, true, err == nil, "returned error from 2nd NextRune()")
}

func mkInput() *tokenize.API {
	return tokenize.NewAPI("Testing")
}