package templer

import (
	"context"
	"fmt"
	"log/slog"
	"net/http"
	"net/url"
	"strings"
)

type ctxKey int

const (
	pathKey ctxKey = iota
	headerKey
	titleKey
)

func Middleware(next http.Handler) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		ctx := r.Context()

		ctx = context.WithValue(ctx, pathKey, r.URL.Path)

		next.ServeHTTP(w, r.WithContext(ctx))
	}
}

// Path returns the current path with a leading slash
func Path(ctx context.Context) string {
	path, ok := ctx.Value(pathKey).(string)
	if !ok {
		slog.Error("could not extract request path from context")
		return ""
	}
	return path
}

func RelativePath(ctx context.Context, relPath string) (path string, err error) {
	baseStr := Path(ctx)

	if baseStr != "" && !strings.HasSuffix(baseStr, "/") {
		baseStr += "/"
	}

	base, err := url.Parse(baseStr)
	if err != nil {
		err = fmt.Errorf("could not parse base path: %w", err)
		return
	}
	rel, err := url.Parse(relPath)
	if err != nil {
		err = fmt.Errorf("could not parse relative path: %w", err)
		return
	}

	// Resolve the relative path against the base
	path = base.ResolveReference(rel).Path
	if strings.HasSuffix(path, "/") {
		path = path[:len(path)-1]
	}
	return
}