package internal

import (
	"bytes"
	"text/template"
	htemplate "html/template"
	"strings"

	"tildegit.org/tjp/sliderule/gopher"
	"tildegit.org/tjp/sliderule/internal/types"
)

type renderItem struct {
	Template string
	Object   any
}

type renderRef struct {
	Type     types.Status
	Display  string
	Selector htemplate.URL
	Hostname string
	Port     string
}

func simplifyLinks(items []renderItem, currentHost, currentPort string) {
	for i, item := range items {
		if item.Template != "link" && item.Template != "image" {
			continue
		}

		m := item.Object.(renderRef)
		if m.Hostname == currentHost && m.Port == currentPort {
			m.Hostname = ""
			m.Port = ""
			m.Selector = htemplate.URL(strings.TrimPrefix(string(m.Selector), "URL:"))
			items[i].Object = m
		}
	}
}

func AddOverrides(base *template.Template, overrides *template.Template) (*template.Template, error) {
	if overrides == nil {
		return base, nil
	}

	tmpl := base
	var err error
	for _, override := range overrides.Templates() {
		tmpl, err = tmpl.AddParseTree(override.Name(), override.Tree)
		if err != nil {
			return nil, err
		}
	}

	return tmpl, nil
}

func AddHTMLOverrides(base *htemplate.Template, overrides *htemplate.Template) (*htemplate.Template, error) {
	if overrides == nil {
		return base, nil
	}

	tmpl := base
	var err error
	for _, override := range overrides.Templates() {
		tmpl, err = tmpl.AddParseTree(override.Name(), override.Tree)
		if err != nil {
			return nil, err
		}
	}

	return tmpl, nil
}

func refItem(item gopher.MapItem) renderRef {
	return renderRef{
		Type:     item.Type,
		Display:  item.Display,
		Selector: htemplate.URL(item.Selector),
		Hostname: item.Hostname,
		Port:     item.Port,
	}
}

func RenderItems(doc gopher.MapDocument) []renderItem {
	out := make([]renderItem, 0, len(doc))
	out = append(out, renderItem{
		Template: "header",
		Object:   doc,
	})
	inMsg := false
	msg := &bytes.Buffer{}
	var currentHost, currentPort string

	for _, mapItem := range doc {
		switch mapItem.Type {
		case gopher.InfoMessageType:
			if inMsg {
				_, _ = msg.WriteString("\n")
			} else {
				msg.Reset()
			}
			_, _ = msg.WriteString(mapItem.Display)
			inMsg = true

			if currentHost == "" {
				currentHost = mapItem.Hostname
			}
			if currentPort == "" {
				currentPort = mapItem.Port
			}
		case gopher.GifFileType, gopher.ImageFileType, gopher.BitmapType, gopher.PngImageFileType:
			if inMsg {
				out = append(out, renderItem{
					Template: "message",
					Object:   msg.String(),
				})
				inMsg = false
			}
			out = append(out, renderItem{
				Template: "image",
				Object:   refItem(mapItem),
			})
		default:
			if inMsg {
				out = append(out, renderItem{
					Template: "message",
					Object:   msg.String(),
				})
				inMsg = false
			}
			out = append(out, renderItem{
				Template: "link",
				Object:   refItem(mapItem),
			})
		}
	}

	if inMsg {
		out = append(out, renderItem{
			Template: "message",
			Object:   msg.String(),
		})
	}

	simplifyLinks(out, currentHost, currentPort)

	return append(out, renderItem{
		Template: "footer",
		Object:   doc,
	})
}