package cmd

import (
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"text/template"

	"github.com/samber/lo"
	"github.com/spf13/cobra"
	"go.ipao.vip/atomctl/v2/pkg/utils/gomod"
	"go.ipao.vip/atomctl/v2/templates"
)

// CommandNewProvider 注册 new_provider 命令
func CommandNewEvent(root *cobra.Command) {
	cmd := &cobra.Command{
		Use:     "event",
		Aliases: []string{"e"},
		Short:   "创建新的 event publish & subscriber",
		Long: `生成事件的发布者与订阅者模板，并在 app/events/topics.go 中维护事件常量。

行为：
- 根据名称转换：驼峰 -> snake 作为 topic，Pascal 作为导出名
- 生成 publishers/<snake>.go 与 subscribers/<snake>.go（可通过 --only 选择一侧）
- 若 topics.go 不存在会自动创建，并追加 const Topic{Name}="<snake>"（避免重复）
- --dry-run 仅打印渲染与写入动作；--dir 指定输出基目录（默认 .）

示例：
  atomctl new event UserCreated
  atomctl new event UserCreated --only=publisher`,
		Args: cobra.ExactArgs(1),
		RunE: commandNewEventE,
	}

	cmd.Flags().String("only", "", "仅生成: publisher 或 subscriber")

	root.AddCommand(cmd)
}

func commandNewEventE(cmd *cobra.Command, args []string) error {
	snakeName := lo.SnakeCase(args[0])
	camelName := lo.PascalCase(args[0])

	// shared flags
	dryRun, _ := cmd.Flags().GetBool("dry-run")
	baseDir, _ := cmd.Flags().GetString("dir")
	only, _ := cmd.Flags().GetString("only")

	publisherPath := filepath.Join(baseDir, "app/events/publishers")
	subscriberPath := filepath.Join(baseDir, "app/events/subscribers")

	path, err := os.Getwd()
	if err != nil {
		return err
	}

	path, _ = filepath.Abs(path)
	err = gomod.Parse(filepath.Join(path, "go.mod"))
	if err != nil {
		return err
	}

	if dryRun {
		fmt.Printf("[dry-run] mkdir -p %s\n", publisherPath)
		fmt.Printf("[dry-run] mkdir -p %s\n", subscriberPath)
	} else {
		if err := os.MkdirAll(publisherPath, os.ModePerm); err != nil {
			return err
		}
		if err := os.MkdirAll(subscriberPath, os.ModePerm); err != nil {
			return err
		}
	}

	err = fs.WalkDir(templates.Events, "events", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			return nil
		}

		relPath, err := filepath.Rel("events", path)
		if err != nil {
			return err
		}

		var destPath string
		if relPath == "publisher.go.tpl" {
			if only == "subscriber" {
				return nil
			}
			destPath = filepath.Join(publisherPath, snakeName+".go")
		} else if relPath == "subscriber.go.tpl" {
			if only == "publisher" {
				return nil
			}
			destPath = filepath.Join(subscriberPath, snakeName+".go")
		} else {
			return nil
		}

		tmpl, err := template.ParseFS(templates.Events, path)
		if err != nil {
			return err
		}

		if dryRun {
			fmt.Printf("[dry-run] render > %s\n", destPath)
			return nil
		}

		destFile, err := os.Create(destPath)
		if err != nil {
			return err
		}
		defer destFile.Close()

		return tmpl.Execute(destFile, map[string]string{
			"Name":       camelName,
			"ModuleName": gomod.GetModuleName(),
		})
	})

	// 写入或追加 topic 常量，避免重复。
	topicsPath := filepath.Join(baseDir, "app/events/topics.go")
	topicLine := fmt.Sprintf("const Topic%s = %q\n", camelName, "event:"+snakeName)

	if dryRun {
		fmt.Printf("[dry-run] ensure topics file and add constant > %s\n", topicsPath)
	} else {
		// ensure file exists with basic header
		if _, statErr := os.Stat(topicsPath); os.IsNotExist(statErr) {
			if err := os.MkdirAll(filepath.Dir(topicsPath), os.ModePerm); err != nil {
				return err
			}
			header := "package events\n\n// topics generated by atomctl\n\n"
			if err := os.WriteFile(topicsPath, []byte(header), 0o644); err != nil {
				return err
			}
		}
		// check duplicate
		content, _ := os.ReadFile(topicsPath)
		if !strings.Contains(string(content), "Topic"+camelName+" ") && !strings.Contains(string(content), topicLine) {
			f, err := os.OpenFile(topicsPath, os.O_APPEND|os.O_WRONLY, 0o644)
			if err != nil {
				return err
			}
			defer f.Close()
			if _, err := f.WriteString(topicLine); err != nil {
				return err
			}
		}
	}

	fmt.Printf("event 已创建: %s\n", snakeName)
	return nil
}