// Copyright 2024 Matthew Rich <matthewrich.conf@gmail.com>. All rights reserved.

package config

import (
_	"context"
_	"encoding/json"
_	"fmt"
_	"gopkg.in/yaml.v3"
	"net/url"
	"path/filepath"
	"decl/internal/codec"
	"os"
	"io"
	"errors"
	"io/fs"
	"log/slog"
)


type ConfigFS struct {
	Path string `yaml:"path" json:"path"`
	subDirsStack []fs.FS `yaml:"-" json:"-"`
	fsys fs.FS `yaml:"-" json:"-"`
}

func NewConfigFS(fsys fs.FS) *ConfigFS {
	return &ConfigFS{
		subDirsStack: make([]fs.FS, 0, 100),
		fsys: fsys,
	}
}

func init() {
	ConfigSourceTypes.Register([]string{"fs"}, func(u *url.URL) ConfigSource {

		t := NewConfigFS(nil)
		t.Path,_ = filepath.Abs(filepath.Join(u.Hostname(), u.RequestURI()))
		t.fsys = os.DirFS(t.Path)
		return t
	})

}

func (c *ConfigFS) Type() string { return "fs" }

func (c *ConfigFS) ExtractDirectory(fsys fs.FS) ([]*Document, error) {
	documents := make([]*Document, 0, 100)

	files, err := fs.ReadDir(fsys, ".")
	if err != nil {
		return nil, err
	}

	for _,file := range files {

		slog.Info("ConfigFS.ExtractDirectory", "file", file)
		if file.IsDir() {
			dir, subErr := fs.Sub(fsys, file.Name())
			if subErr != nil {
				return nil, subErr
			}
			c.subDirsStack = append(c.subDirsStack, dir)
		} else {
			fileHandle, fileErr := fsys.Open(file.Name())
			if fileErr != nil {
				return nil, fileErr
			}
			decoder := codec.NewYAMLDecoder(fileHandle)
			doc := NewDocument()
			e := decoder.Decode(doc)
			if errors.Is(e, io.EOF) {
				break
			}
			if e != nil {
				return documents, e
			}
			slog.Info("ConfigFS.ExtractDirectory", "doc", doc)
			if validationErr := doc.Validate(); validationErr != nil {
				return documents, validationErr
			}
			documents = append(documents, doc)
		}
	}
	return documents, nil
}

func (c *ConfigFS) Extract(filter ConfigurationSelector) ([]*Document, error) {
	documents := make([]*Document, 0, 100)

	path := c.fsys
	c.subDirsStack = append(c.subDirsStack, path)

	for {
		if len(c.subDirsStack) == 0 {
			break
		}
		var dirPath fs.FS
		dirPath, c.subDirsStack = c.subDirsStack[len(c.subDirsStack) - 1], c.subDirsStack[:len(c.subDirsStack) - 1]
		docs, dirErr := c.ExtractDirectory(dirPath)
		if dirErr != nil {
			return documents, dirErr
		}
                
		documents = append(documents, docs...)
	}
	return documents, nil
}