package files

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

	"go.alanpearce.eu/homestead/internal/storage"
	"go.alanpearce.eu/x/log"

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

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

func NewReader(path string, log *log.Logger) (*Reader, errors.E) {
	r := &Reader{
		root:  path,
		log:   log,
		files: make(map[string]*storage.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) errors.E {
	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() errors.E {
	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", ".zstd":
			return nil
		}

		r.log.Debug("registering file", "url", urlPath, "filename", relPath)

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

	return nil
}

func (r *Reader) GetFile(urlPath string) (*storage.File, errors.E) {
	return r.files[urlPath], nil
}

func (r *Reader) CanonicalisePath(path string) (cPath string, differs bool) {
	cPath = path
	switch {
	case strings.HasSuffix(path, "/index.html"):
		cPath, differs = strings.CutSuffix(path, "index.html")

	case strings.HasSuffix(path, ".html"):
		cPath, differs = strings.CutSuffix(path, ".html")

	case !strings.HasSuffix(path, "/") && r.files[path+"/"] != nil:
		cPath, differs = path+"/", true

	case strings.HasSuffix(path, "/"):
		if cPath, differs := strings.CutSuffix(path, "/"); differs && r.files[cPath] != nil {
			return cPath, differs
		}
	}

	return cPath, differs
}