package handler

import (
	"context"

	"AI-Expert-Sidebar/internal/database"
	"AI-Expert-Sidebar/internal/service"

	"github.com/wailsapp/wails/v2/pkg/runtime"
)

// LibraryHandler exposes library management and CSV import via Wails bindings.
type LibraryHandler struct{ ctx context.Context }

func NewLibraryHandler() *LibraryHandler                 { return &LibraryHandler{} }
func (h *LibraryHandler) SetContext(ctx context.Context) { h.ctx = ctx }

// ListLibraries returns all registered knowledge libraries.
func (h *LibraryHandler) ListLibraries() []LibraryInfo {
	libs, err := service.ListLibraries()
	if err != nil {
		return nil
	}
	out := make([]LibraryInfo, len(libs))
	for i, l := range libs {
		out[i] = LibraryInfo{
			ID: l.ID, Name: l.Name, Description: l.Description,
			EntryCount: l.EntryCount, IsActive: l.Name == database.GetActiveLibName(),
		}
	}
	return out
}

// GetActiveLibrary returns the name of the currently active library.
func (h *LibraryHandler) GetActiveLibrary() string {
	return database.GetActiveLibName()
}

// CreateLibrary registers a new knowledge library.
func (h *LibraryHandler) CreateLibrary(name, description string) string {
	if name == "" {
		return "名称不能为空"
	}
	lib, err := service.CreateLibrary(name, description)
	if err != nil {
		return err.Error()
	}
	// Auto-switch to newly created library
	service.SwitchLibrary(lib.Name) //nolint
	return ""
}

// SwitchLibrary makes the named library active.
func (h *LibraryHandler) SwitchLibrary(name string) string {
	if err := service.SwitchLibrary(name); err != nil {
		return err.Error()
	}
	return ""
}

// DeleteLibrary removes a library from the registry (file is kept).
func (h *LibraryHandler) DeleteLibrary(name string) string {
	if name == database.GetActiveLibName() {
		return "不能删除当前使用中的知识库，请先切换到其他库"
	}
	if err := service.DeleteLibrary(name, false); err != nil {
		return err.Error()
	}
	return ""
}

// ImportCSV opens a native file dialog then imports CSV data into the active library.
func (h *LibraryHandler) ImportCSV() service.ImportResult {
	filePath, err := runtime.OpenFileDialog(h.ctx, runtime.OpenDialogOptions{
		Title: "选择 CSV 文件",
		Filters: []runtime.FileFilter{
			{DisplayName: "CSV 文件", Pattern: "*.csv"},
			{DisplayName: "所有文件", Pattern: "*"},
		},
	})
	if err != nil || filePath == "" {
		return service.ImportResult{Error: "已取消"}
	}
	return service.ImportCSV(filePath)
}

// LibraryInfo is the frontend-facing representation of a library.
type LibraryInfo struct {
	ID          uint   `json:"id"`
	Name        string `json:"name"`
	Description string `json:"description"`
	EntryCount  int    `json:"entry_count"`
	IsActive    bool   `json:"is_active"`
}