package web

import (
	"fmt"
	"html/template"
	"net/url"
	"strconv"
	"strings"

	"gitbay.org/cmc/gallery/internal/library"
	"gitbay.org/cmc/gallery/internal/render"
)

var funcs = template.FuncMap{
	"albumURL":      albumURL,
	"photoURL":      photoURL,
	"imgURL":        imgURL,
	"srcset":        srcset,
	"preloadSrcset": preloadSrcset,
	"ar":            aspect,
	"exif":          exifLine,
	"add":           func(a, b int) int { return a + b },
}

func albumURL(a *library.Album) string {
	return "/" + url.PathEscape(a.Slug) + "/"
}

func photoURL(it *library.Item) string {
	return "/" + url.PathEscape(it.Album) + "/" + url.PathEscape(it.Name) + "/"
}

func imgURL(it *library.Item, w int) string {
	return fmt.Sprintf("/img/%s/%s/%d.jpg?v=%d", url.PathEscape(it.Album), url.PathEscape(it.Name), w, it.ModTime.UnixNano())
}

// srcset lists allowed widths up to the first one that reaches the source width.
func srcset(it *library.Item) string {
	var parts []string
	for _, w := range render.Widths {
		actual := w
		reached := it.Meta.Width > 0 && w >= it.Meta.Width
		if reached {
			actual = it.Meta.Width
		}
		parts = append(parts, fmt.Sprintf("%s %dw", imgURL(it, w), actual))
		if reached {
			break
		}
	}
	return strings.Join(parts, ", ")
}

// preloadSrcset renders the whole imagesrcset attribute: html/template treats
// any unknown attribute containing "src" as a single URL and would escape the
// spaces and commas a srcset list needs.
func preloadSrcset(it *library.Item) template.HTMLAttr {
	return template.HTMLAttr(`imagesrcset="` + template.HTMLEscapeString(srcset(it)) + `"`)
}

func aspect(it *library.Item) string {
	if it.Meta.Height == 0 {
		return "1"
	}
	return strconv.FormatFloat(float64(it.Meta.Width)/float64(it.Meta.Height), 'f', 4, 64)
}

func exifLine(it *library.Item) string {
	m := it.Meta
	var parts []string
	for _, s := range []string{m.Camera, m.Lens, m.Aperture, m.Shutter} {
		if s != "" {
			parts = append(parts, s)
		}
	}
	if m.ISO > 0 {
		parts = append(parts, "ISO "+strconv.Itoa(m.ISO))
	}
	if !m.Taken.IsZero() {
		parts = append(parts, m.Taken.Format("2006-01-02"))
	}
	return strings.Join(parts, " · ")
}