package markdown

import (
	"bytes"
	"context"
	"fmt"
	"strings"

	"github.com/yuin/goldmark"

	"gitea.maximumdirect.net/eric/distributor/internal/bundle"
	"gitea.maximumdirect.net/eric/distributor/internal/storage"
	"gitea.maximumdirect.net/eric/distributor/internal/transform"
)

type Transformer struct {
	renderer goldmark.Markdown
}

func New() *Transformer {
	return &Transformer{renderer: goldmark.New()}
}

func (t *Transformer) Generate(ctx context.Context, req transform.Request) ([]transform.Output, error) {
	if t.renderer == nil {
		t.renderer = goldmark.New()
	}
	var outputs []transform.Output
	for _, file := range req.SourceBundle.Manifest.Files {
		if !strings.HasSuffix(file.Path, ".md") {
			continue
		}
		sourcePath, err := storage.Join(req.SourceBundle.RootRelativePath, file.Path)
		if err != nil {
			return nil, err
		}
		data, err := req.SourceBackend.ReadFile(ctx, sourcePath)
		if err != nil {
			return nil, fmt.Errorf("read markdown source %q: %w", file.Path, err)
		}
		var rendered bytes.Buffer
		if err := t.renderer.Convert(data, &rendered); err != nil {
			return nil, fmt.Errorf("render markdown source %q: %w", file.Path, err)
		}
		html := wrapHTML(rendered.Bytes())
		outputPath := strings.TrimSuffix(file.Path, ".md") + ".html"
		outputs = append(outputs, transform.Output{
			Path:       outputPath,
			SourcePath: file.Path,
			Transform:  transform.MarkdownToHTML,
			Data:       html,
			SHA256:     bundle.FileDigest(html),
			Size:       int64(len(html)),
		})
	}
	return outputs, nil
}