package gemtext

import (
    "fmt"
    "path/filepath"
    "strings"
    "html"
)

// addPrefix adds the prefix "pref" to a path if it is absolute
// this is to allow protocol-independent absolute links.
func addPrefix(pref string, link string) string {
	if filepath.IsAbs(link) {
		return filepath.Join(pref, link)
	} else {
		return link
	}
}

// RenderLink takes a GemtextObject and returns a gemini link as a string or an error if the object is not a link.
func RenderLink(obj GemtextObject) (string, error) {
	if obj.Type != LINK  {
		return "", fmt.Errorf("Invalid Link")
	} else if obj.Path == "" {
		return "", fmt.Errorf("Invalid Link")
	} 
	str := fmt.Sprintf("=> %s %s",obj.Path, obj.Text)
	return str,nil
}

// RenderHeading takes a GemtextObject and returns a gemini heading as a string or an error if the object is not a heading.
func RenderHeading(obj GemtextObject) (string, error) {
	if obj.Type != HEADING {
		return "", fmt.Errorf("Invalid Heading (Not a Heading)")
	} else if obj.Level > 3 {
		return "", fmt.Errorf("Invalid Heading (Invalid level)")
	}
	return strings.Repeat("#", obj.Level) + " " + obj.Text, nil
}

// RenderGemtext takes a *GemtextPage and renders it into Gemtext.
func RenderGemtext(p *GemtextPage) (string, error) {
	str := ""
	for _, o := range *p {
		switch {
			case o.Type == TEXT:
				str += o.Text + "\n"
			case o.Type == LINK:
				l, err := RenderLink(o)
				if err != nil {
					return "", err
				}
				str += l + "\n"
			case o.Type == PREFORMATTED_TOGGLE:
				str += "```" + o.Text + "\n"
			case o.Type == PREFORMATTED_TEXT: 
				str += o.Text + "\n"
			case o.Type == HEADING:
				l, err := RenderHeading(o)
				if err != nil {
					return "", err
				}
				str += l + "\n"
			case o.Type == LIST: 
				str += "* " + o.Text + "\n"
			case o.Type == QUOTE:
				str += ">" + o.Text + "\n"
		}
	}
	return str, nil
}

// RenderHTML renders a *GemtextPage p to a string containing html.
func RenderHTML(p *GemtextPage) (string, error) {
	escape := html.EscapeString // for brevity
	listmode := false
	quotemode := false
	premode := false
	var s string
	for _, item := range *p {
		if listmode {
			if item.Type != LIST {
				s += "</ul>"
				listmode = false
			}
		}
		if quotemode {
			if item.Type != QUOTE {
				s += "</blockquote>"
				quotemode = false
			}}
		switch {
			case item.Type == TEXT:
				s += fmt.Sprintf("<p>%s</p>", escape(item.Text))
			case item.Type == LINK:
				s += fmt.Sprintf("<a href=\"%s\">%s</a><br />", escape(item.Path), escape(item.Text))
			case item.Type == PREFORMATTED_TOGGLE:
				if premode {
					s += "</pre>"
					premode = false
				} else {
					s += "<pre>"
					premode = true
				}
			case item.Type == PREFORMATTED_TEXT:
				s += escape(item.Text) + "\n"
			case item.Type == HEADING:
				s += fmt.Sprintf("<h%d>%s</h%d>", item.Level, escape(item.Text), item.Level)
			case item.Type == LIST:
				if !listmode {
					s += "<ul>"
					listmode = true
				}
				s += fmt.Sprintf("<li>%s</li>", escape(item.Text))
			case item.Type == QUOTE:
				if !quotemode {
					s += "<blockquote>"
					quotemode = true
				}
				s += escape(item.Text) + "\n"
		}
	}
	if listmode {
		s += "</ul>"
	}
	if quotemode {
		s += "</blockquote>"
	}
	if premode {
		s += "</pre>"
	}
	return s, nil
}