// Package file is adapted from go-kratos/kratos config/file.
//
// Upstream: https://github.com/go-kratos/kratos/tree/v2.9.2/config/file
// License: MIT, see ../LICENSE.kratos.
package file

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

	"github.com/geo-platform/tenant-api/internal/shared/config/runtime"
)

type file struct {
	path  string
	names map[string]struct{}
}

func NewSource(path string, names ...string) runtime.Source {
	return &file{path: path, names: namesSet(names)}
}

func (f *file) loadFile(path string) (*runtime.KeyValue, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	data, err := io.ReadAll(file)
	if err != nil {
		return nil, err
	}
	info, err := file.Stat()
	if err != nil {
		return nil, err
	}
	return &runtime.KeyValue{
		Key:    info.Name(),
		Format: format(info.Name()),
		Value:  data,
	}, nil
}

func (f *file) loadDir(path string) ([]*runtime.KeyValue, error) {
	files, err := os.ReadDir(path)
	if err != nil {
		return nil, err
	}
	kvs := make([]*runtime.KeyValue, 0, len(files))
	for _, item := range files {
		if item.IsDir() || strings.HasPrefix(item.Name(), ".") || !f.matchName(item.Name()) {
			continue
		}
		kv, err := f.loadFile(filepath.Join(path, item.Name()))
		if err != nil {
			return nil, err
		}
		kvs = append(kvs, kv)
	}
	return kvs, nil
}

func (f *file) Load() ([]*runtime.KeyValue, error) {
	info, err := os.Stat(f.path)
	if err != nil {
		return nil, err
	}
	if info.IsDir() {
		return f.loadDir(f.path)
	}
	kv, err := f.loadFile(f.path)
	if err != nil {
		return nil, err
	}
	return []*runtime.KeyValue{kv}, nil
}

func (f *file) Watch() (runtime.Watcher, error) {
	return newWatcher(f)
}

func (f *file) match(path string) bool {
	return f.matchName(filepath.Base(path))
}

func (f *file) matchName(name string) bool {
	if len(f.names) == 0 {
		return true
	}
	_, ok := f.names[name]
	return ok
}

func namesSet(names []string) map[string]struct{} {
	if len(names) == 0 {
		return nil
	}
	out := make(map[string]struct{}, len(names))
	for _, name := range names {
		name = strings.TrimSpace(name)
		if name == "" {
			continue
		}
		out[filepath.Base(name)] = struct{}{}
	}
	return out
}