package appview

import (
	"embed"
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"time"
)

//go:embed templates/**/*.html
var templatesFS embed.FS

//go:embed static
var staticFS embed.FS

// Templates returns parsed templates with helper functions
func Templates() (*template.Template, error) {
	funcMap := template.FuncMap{
		"timeAgo": func(t time.Time) string {
			duration := time.Since(t)

			if duration < time.Minute {
				return "just now"
			} else if duration < time.Hour {
				mins := int(duration.Minutes())
				if mins == 1 {
					return "1 minute ago"
				}
				return fmt.Sprintf("%d minutes ago", mins)
			} else if duration < 24*time.Hour {
				hours := int(duration.Hours())
				if hours == 1 {
					return "1 hour ago"
				}
				return fmt.Sprintf("%d hours ago", hours)
			} else {
				days := int(duration.Hours() / 24)
				if days == 1 {
					return "1 day ago"
				}
				return fmt.Sprintf("%d days ago", days)
			}
		},

		"humanizeBytes": func(bytes int64) string {
			const unit = 1024
			if bytes < unit {
				return fmt.Sprintf("%d B", bytes)
			}
			div, exp := int64(unit), 0
			for n := bytes / unit; n >= unit; n /= unit {
				div *= unit
				exp++
			}
			return fmt.Sprintf("%.1f %cB", float64(bytes)/float64(div), "KMGTPE"[exp])
		},

		"truncateDigest": func(digest string, length int) string {
			if len(digest) <= length {
				return digest
			}
			return digest[:length] + "..."
		},

		"firstChar": func(s string) string {
			if len(s) == 0 {
				return "?"
			}
			return string([]rune(s)[0])
		},

		"trimPrefix": func(prefix, s string) string {
			if len(s) >= len(prefix) && s[:len(prefix)] == prefix {
				return s[len(prefix):]
			}
			return s
		},
	}

	tmpl := template.New("").Funcs(funcMap)
	tmpl, err := tmpl.ParseFS(templatesFS, "templates/**/*.html")
	if err != nil {
		return nil, err
	}

	return tmpl, nil
}

// StaticHandler returns HTTP handler for static files
func StaticHandler() http.Handler {
	sub, err := fs.Sub(staticFS, "static")
	if err != nil {
		panic(err)
	}
	return http.FileServer(http.FS(sub))
}