package engine

import (
	"bytes"
	"fmt"
	"strings"
	"text/template"
)

type Renderer struct{}

func NewRenderer() *Renderer {
	return &Renderer{}
}

func (r *Renderer) Render(tmplContent string, data map[string]interface{}) (string, error) {
	tmpl, err := template.New("notify").
		Option("missingkey=zero").
		Funcs(template.FuncMap{"line": templateLine}).
		Parse(tmplContent)
	if err != nil {
		return "", fmt.Errorf("parse template: %w", err)
	}
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", fmt.Errorf("execute template: %w", err)
	}
	return buf.String(), nil
}

// templateLine renders "label：value\n" or empty if value is missing/zero.
func templateLine(label string, v any) string {
	if isEmptyValue(v) {
		return ""
	}
	return label + "：" + fmt.Sprint(v) + "\n"
}

func isEmptyValue(v any) bool {
	switch t := v.(type) {
	case nil:
		return true
	case string:
		return strings.TrimSpace(t) == ""
	case bool:
		return !t
	case int:
		return t == 0
	case int32:
		return t == 0
	case int64:
		return t == 0
	case float32:
		return t == 0
	case float64:
		return t == 0
	default:
		return false
	}
}