package files

import (
	"io/fs"
	"path/filepath"
	"strings"

	"go.alanpearce.eu/x/log"

	"gitlab.com/tozd/go/errors"
)

type Reader struct {
	root  string
	log   *log.Logger
	files map[string]*File
}

func NewReader(path string, log *log.Logger) (*Reader, error) {
	r := &Reader{
		root:  path,
		log:   log,
		files: make(map[string]*File),
	}
	if err := r.registerContentFiles(); err != nil {
		return nil, errors.WithMessagef(err, "registering content files")
	}

	return r, nil
}

func (r *Reader) registerFile(urlpath string, filepath string) error {
	file, err := r.OpenFile(urlpath, filepath)
	if err != nil {
		return errors.WithMessagef(err, "could not register file %s", filepath)
	}

	r.files[urlpath] = file

	return nil
}

func (r *Reader) registerContentFiles() error {
	err := filepath.WalkDir(r.root, func(filePath string, f fs.DirEntry, err error) error {
		if err != nil {
			return errors.WithMessagef(err, "failed to access path %s", filePath)
		}
		if f.IsDir() {
			return nil
		}

		relPath, err := filepath.Rel(r.root, filePath)
		if err != nil {
			return errors.WithMessagef(err, "failed to make path relative, path: %s", filePath)
		}
		urlPath := fileNameToPathName("/" + relPath)

		switch filepath.Ext(relPath) {
		case ".br", ".gz":
			return nil
		}

		return r.registerFile(urlPath, filePath)
	})
	if err != nil {
		return errors.WithMessage(err, "could not walk directory")
	}

	return nil
}

func (r *Reader) GetFile(urlPath string) *File {
	return r.files[urlPath]
}

func (r *Reader) CanonicalisePath(path string) (cPath string, differs bool) {
	cPath = path
	if strings.HasSuffix(path, "/index.html") {
		cPath, differs = strings.CutSuffix(path, "index.html")
	} else if !strings.HasSuffix(path, "/") && r.files[path+"/"] != nil {
		cPath, differs = path+"/", true
	}

	return cPath, differs
}