package convert

import "C"

import (
	"errors"
	"strings"

	"github.com/alecthomas/chroma/v2"
	"github.com/alecthomas/chroma/v2/formatters/html"
	"github.com/alecthomas/chroma/v2/lexers"
	"github.com/alecthomas/chroma/v2/styles"
	"github.com/niklasfasching/go-org/org"
)

func Render(src, path, format string) (string, error) {
	doc := org.New().Parse(strings.NewReader(src), path)

	write := func(w org.Writer) (string, error) {
		out, wErr := doc.Write(w)
		if pErr := doc.Error; pErr != nil {
			return out, pErr
		}
		return out, wErr
	}

	switch strings.ToLower(format) {
	case "org":
		return write(org.NewOrgWriter())
	case "html":
		return write(org.NewHTMLWriter())
	case "html-chroma":
		w := org.NewHTMLWriter()
		w.HighlightCodeBlock = highlightCodeBlock
		return write(w)
	default:
		return "", errors.New("unknown format")
	}
}

func OrgToHTML(src string) (string, error) {
	return Render(src, "", "html")
}


// --- helpers ---------------------------------------------------------------

func highlightCodeBlock(source, lang string, inline bool,
                        params map[string]string) string {
    var b strings.Builder

    l := lexers.Get(lang)
    if l == nil {
        l = lexers.Fallback
    }
    l = chroma.Coalesce(l)
    it, _ := l.Tokenise(nil, source)

    opts := []html.Option{}
    if hl := params[":hl_lines"]; hl != "" {
        if r := org.ParseRanges(hl); r != nil {
            opts = append(opts, html.HighlightLines(r))
        }
    }

    styleName := params[":style"]
    if styleName == "" {
        styleName = "friendly"
    }
    style := styles.Get(styleName)
    if style == nil {
        style = styles.Fallback
    }

    _ = html.New(opts...).Format(&b, style, it)

    wrap := "highlight"
    if inline {
        wrap = "highlight-inline"
    }
    return `<div class="` + wrap + `">` + "\n" + b.String() + "\n</div>"
}