// Copyright (C) 2022-2023  Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later

package lowmemjson

import (
	"bytes"
	"io"
	"strings"
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestDecodeNumber(t *testing.T) {
	t.Parallel()
	r := strings.NewReader(`1{}`)

	var num int
	assert.NoError(t, NewDecoder(r).Decode(&num))
	assert.Equal(t, 1, num)
	assert.Equal(t, 2, r.Len()) // check that it didn't read too far
}

func TestDecodeObject(t *testing.T) {
	t.Parallel()
	err := DecodeObject(strings.NewReader(`{"foo":9}`),
		func(r io.RuneScanner) error {
			return nil
		},
		func(r io.RuneScanner) error {
			var n int
			return NewDecoder(r).Decode(&n)
		})
	assert.ErrorContains(t, err, "did not consume entire")
}

func TestDecodeGrowing(t *testing.T) {
	t.Parallel()
	var buf bytes.Buffer
	dec := NewDecoder(&buf)
	var x any
	assert.ErrorIs(t, dec.Decode(&x), io.EOF)
	buf.WriteString("1\n")
	assert.NoError(t, dec.Decode(&x))
	buf.WriteString("1\n")
	assert.NoError(t, dec.Decode(&x))
	assert.ErrorIs(t, dec.Decode(&x), io.EOF)
}

type testAry []int

func (a *testAry) DecodeJSON(r io.RuneScanner) error {
	return DecodeArray(r, func(r io.RuneScanner) error {
		var x int
		if err := NewDecoder(r).Decode(&x); err != nil {
			return err
		}
		*a = append(*a, x)
		return nil
	})
}

type testObj map[string]int

func (o *testObj) DecodeJSON(r io.RuneScanner) error {
	*o = make(testObj)
	var key string
	return DecodeObject(r,
		func(r io.RuneScanner) error {
			return NewDecoder(r).Decode(&key)
		},
		func(r io.RuneScanner) error {
			var val int
			if err := NewDecoder(r).Decode(&val); err != nil {
				return err
			}
			(*o)[key] = val
			return nil
		},
	)
}

type testStr string

func (s *testStr) DecodeJSON(r io.RuneScanner) error {
	var buf strings.Builder
	if err := DecodeString(r, &buf); err != nil {
		return err
	}
	*s = testStr(buf.String())
	return nil
}

var (
	_ Decodable = (*testAry)(nil)
	_ Decodable = (*testObj)(nil)
	_ Decodable = (*testStr)(nil)
)

func TestDecodeTypeError(t *testing.T) {
	t.Parallel()
	type outType struct {
		First  int
		Second testAry
		Third  testObj
		Fourth testStr
	}
	var out outType
	err := NewDecoder(strings.NewReader(`{"First": 1.2, "Second": [3], "Third": {"a":4}, "Fourth": "foo\u000Abar"}`)).Decode(&out)
	assert.EqualError(t, err,
		`json: v["First"]: cannot decode JSON number 1.2 at input byte 9 into Go int: strconv.ParseInt: parsing "1.2": invalid syntax`)
	assert.Equal(t, outType{First: 0, Second: testAry{3}, Third: testObj{"a": 4}, Fourth: "foo\nbar"}, out)
}