package modules

import (
	"html/template"
	"strings"

	"gsg/internal/core"
)

type Readme struct {
	Name string
	HTML template.HTML
}

var readmeNames = []string{"README.md", "readme.md", "README.markdown", "README", "readme"}

func init() { core.Register("readme", readmeMod) }

// readme: first README found at Ctx.Path, rendered.
// Returns nil (not an error) when absent, so `with` in a template just skips it.
func readmeMod(c *core.Ctx, args ...string) (any, error) {
	rev := c.Commit
	if rev == "" {
		rev = c.Ref
	}
	// Same (rev, path) listing the `tree` module already computes for this
	// page -- go through it instead of forking a second identical ls-tree.
	v, err := c.Mod("tree")
	if err != nil {
		return nil, nil
	}
	t, ok := v.(Tree)
	if !ok {
		return nil, nil
	}
	present := map[string]bool{}
	for _, e := range t.Entries {
		if e.Type == "blob" {
			present[e.Name] = true
		}
	}
	for _, name := range readmeNames {
		if !present[name] {
			continue
		}
		full := strings.TrimPrefix(c.Path+"/"+name, "/")
		src, err := c.Repo.Blob(rev, full)
		if err != nil {
			continue
		}
		out, err := Markdown(src, "/"+c.Info.Slug, c.Ref, c.Path)
		if err != nil {
			return nil, err
		}
		return Readme{Name: name, HTML: out}, nil
	}
	return nil, nil
}