package web

import (
	"fmt"
	"html/template"
	"net/http"
	"strings"
	"time"
)

var funcMap = template.FuncMap{
	"join": func(items []string, sep string) string { return strings.Join(items, sep) },
	"fmtTime": func(t time.Time) string {
		if t.IsZero() {
			return "-"
		}
		return t.Format("2006-01-02 15:04:05")
	},
	"timeAgo": timeAgo,
	"deref": func(t *time.Time) time.Time {
		if t == nil {
			return time.Time{}
		}
		return *t
	},
	"deref64": func(v *int64) int64 {
		if v == nil {
			return 0
		}
		return *v
	},
	"slice": func(items ...int) []int { return items },
	"add":   func(a, b int) int { return a + b },
	"sub":   func(a, b int) int { return a - b },
	"mul":   func(a, b int) int { return a * b },
	"iterate": func(n int) []int {
		out := make([]int, n)
		for i := range out {
			out[i] = i
		}
		return out
	},
	"statusClass": func(status int) string {
		switch {
		case status >= 500:
			return "text-danger"
		case status >= 400:
			return "text-warning"
		case status >= 300:
			return "text-info"
		default:
			return "text-success"
		}
	},
}

func timeAgo(t time.Time) string {
	if t.IsZero() {
		return "never"
	}
	d := time.Since(t)
	switch {
	case d < time.Minute:
		return "just now"
	case d < time.Hour:
		return fmt.Sprintf("%dm ago", int(d.Minutes()))
	case d < 24*time.Hour:
		return fmt.Sprintf("%dh ago", int(d.Hours()))
	default:
		return fmt.Sprintf("%dd ago", int(d.Hours()/24))
	}
}

var templates *template.Template

func init() {
	t, err := template.New("").Funcs(funcMap).ParseFS(templatesFS, "templates/*.html", "templates/partials/*.html")
	if err != nil {
		panic(err)
	}
	templates = t
}

// PageData is the common envelope passed to every page template.
type PageData struct {
	Active    string // nav item key for sidebar highlighting
	Title     string
	CSRFToken string
	Flash     string
	FlashKind string // success|danger|warning
	Data      any
}

func render(w http.ResponseWriter, name string, data PageData) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := templates.ExecuteTemplate(w, name, data); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}