// SPDX-License-Identifier: Unlicense

package bytes_test

import (
	"bytes"
	"errors"
	"strings"
	"testing"

	"git.codemonkeysoftware.net/b/gigaparsec"
	pbytes "git.codemonkeysoftware.net/b/gigaparsec/bytes"
	ptest "git.codemonkeysoftware.net/b/gigaparsec/test"
	pgen "git.codemonkeysoftware.net/b/gigaparsec/test/generator"
	"github.com/shoenig/test"
	"github.com/shoenig/test/must"
	"pgregory.net/rapid"
)

func TestRegexp(t *testing.T) {
	alpha := rapid.SliceOfBytesMatching(`[A-Za-z]{1,100}`)
	t.Run("position and value are correct after match", rapid.MakeCheck(func(t *rapid.T) {
		needle := alpha.Draw(t, "needle")
		input := rapid.Map(alpha, func(suffix []byte) []byte { return append(needle, suffix...) }).
			Draw(t, "input")

		p := pbytes.Regexp(string(needle))
		result, err := p(gigaparsec.MakeState(bytes.NewReader(input)))
		succeeded, val, next := result.Status()

		must.NoError(t, err)
		test.True(t, succeeded)
		test.EqOp(t, string(needle), val)
		ptest.StateIsAt(t, next, uint64(len(needle)))
	}))
	t.Run("only searches the beginning of input", rapid.MakeCheck(func(t *rapid.T) {
		needle := alpha.Draw(t, "needle")
		input := rapid.Map(alpha, func(prefix []byte) []byte { return append(prefix, needle...) }).
			Filter(func(b []byte) bool { return !bytes.HasPrefix(b, needle) }).
			Draw(t, "input")

		p := pbytes.Regexp(string(needle))
		result, err := p(gigaparsec.MakeState(bytes.NewReader(input)))
		succeeded, _, _ := result.Status()

		must.NoError(t, err)
		test.False(t, succeeded)
	}))
	t.Run("fails on unexpected error", func(t *testing.T) {
		expectedErr := errors.New("it broke")
		p := pbytes.Regexp("nope")
		result, err := p(gigaparsec.MakeState(ptest.ErrReaderAt(expectedErr)))
		succeeded, _, _ := result.Status()
		test.ErrorIs(t, err, expectedErr)
		test.False(t, succeeded)
	})
	t.Run("returns a useful Got value", func(t *testing.T) {
		p := pbytes.Regexp("hello")
		result, err := p(gigaparsec.MakeState(strings.NewReader("hellaparsec")))

		must.NoError(t, err)
		test.StrContains(t, result.Message().Got(), "hella")
	})
}

func TestRuneReader(t *testing.T) {
	var s = "abcdefghijklmnopqrstuvwxyz"
	rr := pbytes.NewRuneReader(gigaparsec.MakeState(strings.NewReader(s)))
	for i, b := range s {
		r, n, err := rr.ReadRune()
		test.NoError(t, err)
		test.EqOp(t, 1, n)
		test.EqOp(t, r, rune(b))
		if t.Failed() {
			t.Fatalf("failed at %d", i)
		}
	}
}

func TestMatchString(t *testing.T) {
	t.Run("fails on unexpected error", rapid.MakeCheck(func(t *rapid.T) {
		s := rapid.StringN(-1, -1, 100).Draw(t, "s")
		readErr := pgen.Error().Draw(t, "readErr")
		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(ptest.ErrReaderAt(readErr)))
		test.ErrorIs(t, err, readErr)
		success, _, _ := result.Status()
		test.False(t, success)
		test.False(t, result.Consumed())
	}))
	t.Run("does not succeed or consume on mismatch", rapid.MakeCheck(func(t *rapid.T) {
		bgen := rapid.SliceOfN(rapid.Byte(), 1, 100)
		input := bgen.Draw(t, "input")
		notPrefix := func(b []byte) bool { return !bytes.HasPrefix(input, b) }
		s := string(bgen.Filter(notPrefix).Draw(t, "s"))

		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(bytes.NewReader(input)))
		test.NoError(t, err)
		success, _, _ := result.Status()
		test.False(t, success)
		test.False(t, result.Consumed())
	}))
	t.Run("succeeds with correct value, consumption, and position", rapid.MakeCheck(func(t *rapid.T) {
		input := rapid.SliceOfN(rapid.Byte(), 1, 100).Draw(t, "input")
		slen := rapid.IntRange(0, len(input)).Draw(t, "slen")
		s := string(input[:slen])
		result, err := pbytes.MatchString(s)(gigaparsec.MakeState(bytes.NewReader(input)))
		must.NoError(t, err)
		success, value, next := result.Status()
		must.True(t, success)
		test.True(t, result.Consumed())
		test.EqOp(t, s, value)
		ptest.StateIsAt(t, next, uint64(slen))
	}))
}