/*
Copyright 2025-2026 linux.do
Modified by Arctel.net, 2026

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package logger

import (
	"testing"

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

func TestLogRingBuffer_WriteAndQuery(t *testing.T) {
	rb := NewLogRingBuffer(5)

	// Write some logs
	_, _ = rb.Write([]byte("line1\nline2\nline3\n"))

	entries, hasMore := rb.Query(0, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 3, len(entries))
	assert.Equal(t, "line1", entries[0].Data)
	assert.Equal(t, "line2", entries[1].Data)
	assert.Equal(t, "line3", entries[2].Data)
	assert.Equal(t, 0, entries[0].Index)
	assert.Equal(t, 1, entries[1].Index)
	assert.Equal(t, 2, entries[2].Index)
}

func TestLogRingBuffer_CapacityOverflow(t *testing.T) {
	rb := NewLogRingBuffer(3)

	_, _ = rb.Write([]byte("a\nb\nc\nd\ne\n"))

	entries, hasMore := rb.Query(0, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 3, len(entries))
	assert.Equal(t, "c", entries[0].Data)
	assert.Equal(t, "d", entries[1].Data)
	assert.Equal(t, "e", entries[2].Data)
}

func TestLogRingBuffer_QueryLatest(t *testing.T) {
	rb := NewLogRingBuffer(10)

	_, _ = rb.Write([]byte("a\nb\nc\nd\ne\n"))

	// Query latest 2
	entries, hasMore := rb.Query(0, 2)
	assert.True(t, hasMore)
	assert.Equal(t, 2, len(entries))
	assert.Equal(t, "d", entries[0].Data)
	assert.Equal(t, "e", entries[1].Data)
}

func TestLogRingBuffer_QueryByCursor(t *testing.T) {
	rb := NewLogRingBuffer(10)

	_, _ = rb.Write([]byte("a\nb\nc\nd\ne\n"))

	// First get all to find indices
	all, _ := rb.Query(0, 10)
	assert.Equal(t, 5, len(all))

	// Query entries before index 3
	entries, hasMore := rb.Query(3, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 3, len(entries))
	assert.Equal(t, "a", entries[0].Data)
	assert.Equal(t, "b", entries[1].Data)
	assert.Equal(t, "c", entries[2].Data)
}

func TestLogRingBuffer_QueryByCursorWithLimit(t *testing.T) {
	rb := NewLogRingBuffer(10)

	_, _ = rb.Write([]byte("a\nb\nc\nd\ne\n"))

	// Query 2 entries before index 4
	entries, hasMore := rb.Query(4, 2)
	assert.True(t, hasMore)
	assert.Equal(t, 2, len(entries))
	assert.Equal(t, "c", entries[0].Data)
	assert.Equal(t, "d", entries[1].Data)
}

func TestLogRingBuffer_QueryEmpty(t *testing.T) {
	rb := NewLogRingBuffer(5)

	entries, hasMore := rb.Query(0, 10)
	assert.False(t, hasMore)
	assert.Nil(t, entries)
}

func TestLogRingBuffer_QueryNonExistentCursor(t *testing.T) {
	rb := NewLogRingBuffer(5)
	_, _ = rb.Write([]byte("a\nb\n"))

	entries, hasMore := rb.Query(999, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 2, len(entries))
	assert.Equal(t, "a", entries[0].Data)
	assert.Equal(t, "b", entries[1].Data)
}

func TestLogRingBuffer_Subscribe(t *testing.T) {
	rb := NewLogRingBuffer(5)

	ch := rb.Subscribe()
	defer rb.Unsubscribe(ch)

	_, _ = rb.Write([]byte("hello\n"))

	entry := <-ch
	assert.Equal(t, "hello", entry.Data)
	assert.Equal(t, 0, entry.Index)
}

func TestLogRingBuffer_SubscribeMultiple(t *testing.T) {
	rb := NewLogRingBuffer(5)

	ch1 := rb.Subscribe()
	defer rb.Unsubscribe(ch1)
	ch2 := rb.Subscribe()
	defer rb.Unsubscribe(ch2)

	_, _ = rb.Write([]byte("msg\n"))

	e1 := <-ch1
	e2 := <-ch2
	assert.Equal(t, "msg", e1.Data)
	assert.Equal(t, "msg", e2.Data)
}

func TestLogRingBuffer_WriteNoNewline(t *testing.T) {
	rb := NewLogRingBuffer(5)

	_, _ = rb.Write([]byte("partial"))

	entries, _ := rb.Query(0, 10)
	assert.Equal(t, 1, len(entries))
	assert.Equal(t, "partial", entries[0].Data)
}

func TestLogRingBuffer_WriteEmpty(t *testing.T) {
	rb := NewLogRingBuffer(5)

	n, err := rb.Write([]byte(""))
	assert.Equal(t, 0, n)
	assert.NoError(t, err)

	entries, _ := rb.Query(0, 10)
	assert.Nil(t, entries)
}

func TestLogRingBuffer_QueryAfterOverflow(t *testing.T) {
	rb := NewLogRingBuffer(3)

	_, _ = rb.Write([]byte("1\n2\n3\n4\n5\n6\n7\n"))

	entries, hasMore := rb.Query(0, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 3, len(entries))
	assert.Equal(t, "5", entries[0].Data)
	assert.Equal(t, "6", entries[1].Data)
	assert.Equal(t, "7", entries[2].Data)

	// Query by cursor - index 4 is "5", so cursor=4 should return index < 4
	older, hasMore2 := rb.Query(4, 10)
	assert.False(t, hasMore2)
	assert.Nil(t, older)
}

func TestLogRingBuffer_NextCursor(t *testing.T) {
	rb := NewLogRingBuffer(10)

	_, _ = rb.Write([]byte("a\nb\nc\nd\ne\n"))

	// Query latest 2, should return next_cursor pointing to first returned entry
	entries, _ := rb.Query(0, 2)
	assert.Equal(t, 2, len(entries))
	// entries[0].Index = 3 ("d"), entries[1].Index = 4 ("e")
	assert.Equal(t, 3, entries[0].Index)

	// Now use that index as cursor to get older entries
	older, hasMore := rb.Query(entries[0].Index, 10)
	assert.False(t, hasMore)
	assert.Equal(t, 3, len(older))
	assert.Equal(t, "a", older[0].Data)
	assert.Equal(t, "b", older[1].Data)
	assert.Equal(t, "c", older[2].Data)
}