package main

import (
	"encoding/json"
	"testing"
	"time"

	"github.com/mattermost/mattermost/server/public/model"
	"github.com/mattermost/mattermost/server/public/plugin/plugintest"
	"github.com/mattermost/mattermost/server/public/pluginapi"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/mock"
	"github.com/stretchr/testify/require"
)

func newTestTaskStore(t *testing.T) (*taskStore, *plugintest.API) {
	t.Helper()
	api := &plugintest.API{}
	client := pluginapi.NewClient(api, nil)
	store := newTaskStore(client, nil)
	return store, api
}

func TestSaveTask_New(t *testing.T) {
	store, api := newTestTaskStore(t)

	task := &DownloadTask{
		ID:        "task1",
		BookTitle: "Test Book",
		Status:    TaskStatusPending,
		CreatedAt: time.Now(),
	}

	// pluginapi.KV.Set -> KVSetWithOptions
	api.On("KVSetWithOptions", mock.AnythingOfType("string"), mock.AnythingOfType("[]uint8"), mock.Anything).Return(true, nil)
	// pluginapi.KV.Get -> KVGet (returns []byte, *AppError)
	api.On("KVGet", "dl_task_index").Return([]byte(nil), (*model.AppError)(nil))

	err := store.SaveTask(task)
	require.NoError(t, err)
	assert.False(t, task.UpdatedAt.IsZero())
}

func TestSaveTask_Existing(t *testing.T) {
	store, api := newTestTaskStore(t)

	task := &DownloadTask{
		ID:        "task1",
		BookTitle: "Test Book",
		Status:    TaskStatusQueued,
	}

	api.On("KVSetWithOptions", "dl_task_task1", mock.AnythingOfType("[]uint8"), mock.Anything).Return(true, nil)
	indexData, _ := json.Marshal([]string{"task1"})
	api.On("KVGet", "dl_task_index").Return(indexData, (*model.AppError)(nil))

	err := store.SaveTask(task)
	require.NoError(t, err)
	// Index should NOT be re-saved since task1 already in index.
	api.AssertNotCalled(t, "KVSetWithOptions", "dl_task_index", mock.Anything, mock.Anything)
}

func TestGetTask_Exists(t *testing.T) {
	store, api := newTestTaskStore(t)

	task := &DownloadTask{
		ID:        "task1",
		BookTitle: "Test Book",
		Status:    TaskStatusPending,
	}
	taskData, _ := json.Marshal(task)

	api.On("KVGet", "dl_task_task1").Return(taskData, (*model.AppError)(nil))

	result, err := store.GetTask("task1")
	require.NoError(t, err)
	require.NotNil(t, result)
	assert.Equal(t, "task1", result.ID)
	assert.Equal(t, "Test Book", result.BookTitle)
}

func TestGetTask_NotFound(t *testing.T) {
	store, api := newTestTaskStore(t)

	api.On("KVGet", "dl_task_nonexistent").Return([]byte(nil), (*model.AppError)(nil))

	result, err := store.GetTask("nonexistent")
	require.NoError(t, err)
	assert.Nil(t, result)
}

func TestDeleteTask(t *testing.T) {
	store, api := newTestTaskStore(t)

	// pluginapi.KV.Delete calls KV.Set(key, nil) -> KVSetWithOptions
	api.On("KVSetWithOptions", mock.AnythingOfType("string"), mock.Anything, mock.Anything).Return(true, nil)
	indexData, _ := json.Marshal([]string{"task1", "task2"})
	api.On("KVGet", "dl_task_index").Return(indexData, (*model.AppError)(nil))

	err := store.DeleteTask("task1")
	require.NoError(t, err)
}

func TestListActiveTasks_MixedStatuses(t *testing.T) {
	store, api := newTestTaskStore(t)

	taskMap := map[string]*DownloadTask{
		"pending":     {ID: "pending", Status: TaskStatusPending},
		"queued":      {ID: "queued", Status: TaskStatusQueued},
		"downloading": {ID: "downloading", Status: TaskStatusDownloading},
		"complete":    {ID: "complete", Status: TaskStatusComplete},
		"uploaded":    {ID: "uploaded", Status: TaskStatusUploaded},
		"failed":      {ID: "failed", Status: TaskStatusFailed},
	}

	indexData, _ := json.Marshal([]string{"pending", "queued", "downloading", "complete", "uploaded", "failed"})
	api.On("KVGet", "dl_task_index").Return(indexData, (*model.AppError)(nil))

	for id, task := range taskMap {
		taskData, _ := json.Marshal(task)
		api.On("KVGet", "dl_task_"+id).Return(taskData, (*model.AppError)(nil))
	}

	// For terminal tasks cleanup.
	// pluginapi.KV.Delete calls KV.Set(key,nil) -> KVSetWithOptions
	api.On("KVSetWithOptions", mock.AnythingOfType("string"), mock.Anything, mock.Anything).Return(true, nil)

	result, err := store.ListActiveTasks()
	require.NoError(t, err)

	assert.Len(t, result, 4)
	ids := make([]string, len(result))
	for i, task := range result {
		ids[i] = task.ID
	}
	assert.Contains(t, ids, "pending")
	assert.Contains(t, ids, "queued")
	assert.Contains(t, ids, "downloading")
	assert.Contains(t, ids, "complete")
}

func TestListActiveTasks_OrphanedIndex(t *testing.T) {
	store, api := newTestTaskStore(t)

	indexData, _ := json.Marshal([]string{"orphan"})
	api.On("KVGet", "dl_task_index").Return(indexData, (*model.AppError)(nil))
	api.On("KVGet", "dl_task_orphan").Return([]byte(nil), (*model.AppError)(nil))
	// pluginapi.KV.Delete calls KV.Set(key,nil) -> KVSetWithOptions
	api.On("KVSetWithOptions", mock.AnythingOfType("string"), mock.Anything, mock.Anything).Return(true, nil)

	result, err := store.ListActiveTasks()
	require.NoError(t, err)
	assert.Empty(t, result)
}

func TestListActiveTasks_LogsGetTaskError(t *testing.T) {
	api := &plugintest.API{}
	client := pluginapi.NewClient(api, nil)

	var logged bool
	store := newTaskStore(client, func(msg string, keyvals ...string) {
		logged = true
		assert.Equal(t, "Failed to load task from KV store", msg)
	})

	indexData, _ := json.Marshal([]string{"broken"})
	api.On("KVGet", "dl_task_index").Return(indexData, (*model.AppError)(nil))
	api.On("KVGet", "dl_task_broken").Return([]byte(nil), model.NewAppError("", "", nil, "kv error", 500))

	result, err := store.ListActiveTasks()
	require.NoError(t, err)
	assert.Empty(t, result)
	assert.True(t, logged, "expected logFunc to be called for GetTask error")
}

func TestEffectiveTitle(t *testing.T) {
	t.Run("localized title present", func(t *testing.T) {
		task := &DownloadTask{BookTitle: "Original", LocalizedTitle: "Localized"}
		assert.Equal(t, "Localized", task.EffectiveTitle())
	})

	t.Run("localized title empty", func(t *testing.T) {
		task := &DownloadTask{BookTitle: "Original", LocalizedTitle: ""}
		assert.Equal(t, "Original", task.EffectiveTitle())
	})
}