package tokenize_test

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

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

func TestCallingPeekRune_PeeksRuneOnInput(t *testing.T) {
	tokenizeAPI := makeTokenizeAPI()
	r, _, _ := tokenizeAPI.Rune.Peek(0)
	AssertEqual(t, 'T', r, "first rune")
}

func TestInputCanAcceptRunesFromReader(t *testing.T) {
	tokenAPI := makeTokenizeAPI()

	r0, _, _ := tokenAPI.Rune.Peek(0)
	tokenAPI.Rune.Accept(r0)

	r1, _, _ := tokenAPI.Rune.Peek(0) // 0, because read offset resets to 0 after Accept* calls.
	r2, _, _ := tokenAPI.Rune.Peek(1)
	tokenAPI.Rune.AcceptMulti(r1, r2)

	AssertEqual(t, "Tes", tokenAPI.Output.String(), "i.String()")
}

// func TestCallingMergeOnTopLevelAPI_Panics(t *testing.T) {
// 	AssertPanic(t, PanicT{
// 		Function: func() {
// 			tokenAPI := makeTokenizeAPI()
// 			tokenAPI.Merge(0)
// 		},
// 		Regexp: true,
// 		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*_test.go:\d+ on the top-level API`})
// }

// func TestCallingMergeOnForkParentAPI_Panics(t *testing.T) {
// 	AssertPanic(t, PanicT{
// 		Function: func() {
// 			tokenAPI := makeTokenizeAPI()
// 			child := tokenAPI.Fork()
// 			tokenAPI.Fork()
// 			tokenAPI.Merge(child)
// 		},
// 		Regexp: true,
// 		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*_test.go:\d+ ` +
// 			`on API stack level 1, but the current stack level is 2 \(forgot to Dispose\(\) a forked child\?\)`})
// }

// func TestCallingDisposeOnTopLevelAPI_Panics(t *testing.T) {
// 	AssertPanic(t, PanicT{
// 		Function: func() {
// 			tokenAPI := makeTokenizeAPI()
// 			tokenAPI.Dispose(0)
// 		},
// 		Regexp: true,
// 		Expect: `tokenize\.API\.Dispose\(\): Dispose\(\) called at /.*_test.go:\d+ on the top-level API`})
// }

// func TestCallingDisposeOnForkParentAPI_Panics(t *testing.T) {
// 	AssertPanic(t, PanicT{
// 		Function: func() {
// 			tokenAPI := makeTokenizeAPI()
// 			child := tokenAPI.Fork()
// 			tokenAPI.Fork()
// 			tokenAPI.Dispose(child)
// 		},
// 		Regexp: true,
// 		Expect: `tokenize\.API\.Dispose\(\): Dispose\(\) called at /.*_test.go:\d+ ` +
// 			`on API stack level 1, but the current stack level is 2 \(forgot to Dispose\(\) a forked child\?\)`})
// }

// func TestCallingForkOnForkedParentAPI_Panics(t *testing.T) {
// 	AssertPanic(t, PanicT{
// 		Function: func() {
// 			tokenAPI := makeTokenizeAPI()
// 			tokenAPI.Fork()
// 			g := tokenAPI.Fork()
// 			tokenAPI.Fork()
// 			tokenAPI.Merge(g)
// 		},
// 		Regexp: true,
// 		Expect: `tokenize\.API\.Merge\(\): Merge\(\) called at /.*_test.go:\d+ ` +
// 			`on API stack level 2, but the current stack level is 3 \(forgot to Dispose\(\) a forked child\?\)`})
// }

func TestAccept_UpdatesCursor(t *testing.T) {
	tokenAPI := tokenize.NewAPI(strings.NewReader("input\r\nwith\r\nnewlines"))
	AssertEqual(t, "start of file", tokenAPI.Input.Cursor(), "cursor 1")
	for j := 0; j < 6; j++ { // read "input\r", cursor end up at "\n"
		r, _, _ := tokenAPI.Rune.Peek(0)
		tokenAPI.Rune.Accept(r)
	}
	AssertEqual(t, "line 1, column 7", tokenAPI.Input.Cursor(), "cursor 2")

	r, _, _ := tokenAPI.Rune.Peek(0) // read "\n", cursor ends up at start of new line
	tokenAPI.Rune.Accept(r)
	AssertEqual(t, "line 2, column 1", tokenAPI.Input.Cursor(), "cursor 3")

	for j := 0; j < 10; j++ { // read "with\r\nnewl", cursor end up at "i"
		b, _ := tokenAPI.Byte.Peek(0)
		tokenAPI.Byte.Accept(b)
	}
	AssertEqual(t, "line 3, column 5", tokenAPI.Input.Cursor(), "cursor 4")
}

func TestWhenCallingPeekruneAtEndOfFile_EOFIsReturned(t *testing.T) {
	tokenAPI := tokenize.NewAPI(strings.NewReader("X"))
	r, _, _ := tokenAPI.Rune.Peek(0)
	tokenAPI.Rune.Accept(r)
	r, _, err := tokenAPI.Rune.Peek(0)

	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"))
// 	child := i.Fork()

// 	// To to the EOF.
// 	r, _, _ := i.Rune.Peek(0)
// 	i.Rune.Accept(r)
// 	r, _, err := i.Rune.Peek(0)
// 	AssertEqual(t, true, r == utf8.RuneError, "returned rune from 2nd NextRune()")
// 	AssertEqual(t, true, err == io.EOF, "returned error from 2nd NextRune()")

// 	// Brings the read offset back to the start.
// 	i.Dispose(child)

// 	// So here we should see the same input data as before.
// 	r, _, err = i.Rune.Peek(0)
// 	AssertEqual(t, 'X', r, "returned rune from 2nd NextRune()")
// 	AssertEqual(t, true, err == nil, "returned error from 2nd NextRune()")
// }

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