package file

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"time"

	"git.andreafazzi.eu/andrea/probo/models"
	"git.andreafazzi.eu/andrea/probo/store"
	"gopkg.in/yaml.v2"
)

type QuizFileStore = FileStore[*models.Quiz, *store.QuizStore]

func NewQuizFileStore(config *FileStoreConfig[*models.Quiz, *store.QuizStore]) (*QuizFileStore, error) {
	return NewFileStore[*models.Quiz, *store.QuizStore](config, store.NewQuizStore())
}

func NewDefaultQuizFileStore() (*QuizFileStore, error) {
	return NewQuizFileStore(
		&FileStoreConfig[*models.Quiz, *store.QuizStore]{
			FilePathConfig: FilePathConfig{GetDefaultQuizzesDir(), "quiz", ".md"},
			IndexDirFunc:   DefaultQuizIndexDirFunc,
		},
	)

}

func DefaultQuizIndexDirFunc(s *QuizFileStore) error {
	files, err := os.ReadDir(s.Dir)
	if err != nil {
		return err
	}

	entityFiles := make([]fs.DirEntry, 0)

	for _, file := range files {
		filename := file.Name()
		if !file.IsDir() && strings.HasSuffix(filename, s.FileSuffix) {
			entityFiles = append(entityFiles, file)
		}
	}

	for _, file := range entityFiles {
		filename := file.Name()
		fullPath := filepath.Join(s.Dir, filename)

		content, err := os.ReadFile(fullPath)
		if err != nil {
			return err
		}

		var entity = new(models.Quiz)

		err = entity.Unmarshal(content)
		if err != nil {
			return err
		}

		var errQuizAlreadyPresent *store.ErrQuizAlreadyPresent

		mEntity, err := s.Create(entity)
		if err != nil && !errors.As(err, &errQuizAlreadyPresent) {
			return err
		}

		if entity.ID == "" {
			writeQuizHeader(fullPath, &models.Meta{
				ID:        mEntity.ID,
				CreatedAt: time.Now(),
			})
		}

		s.SetPath(mEntity, fullPath)
	}

	return nil

}

func writeQuizHeader(path string, meta *models.Meta) (*models.Meta, error) {
	readMeta, err := readQuizHeader(path)
	if err != nil {
		return nil, err
	}
	if readMeta == nil {
		file, err := os.Open(path)
		if err != nil {
			return nil, err
		}
		defer file.Close()

		var buffer bytes.Buffer

		header, err := yaml.Marshal(meta)
		if err != nil {
			return nil, err
		}

		_, err = buffer.WriteString("---\n" + string(header) + "---\n")
		if err != nil {
			return nil, err
		}

		_, err = io.Copy(&buffer, file)
		if err != nil {
			return nil, err
		}

		file, err = os.Create(path)
		if err != nil {
			return nil, err
		}
		defer file.Close()

		_, err = io.Copy(file, &buffer)
		if err != nil {
			return nil, err
		}
	}

	return meta, nil
}

func readQuizHeader(path string) (*models.Meta, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	meta, _, err := models.ParseMetaHeaderFromMarkdown(string(data))
	if err != nil {
		return nil, err
	}
	return meta, nil
}

func addMetaHeaderToMarkdown(content string, meta *models.Meta) (string, error) {
	var buffer bytes.Buffer

	header, err := yaml.Marshal(meta)
	if err != nil {
		return "", err
	}
	_, err = buffer.WriteString("---\n" + string(header) + "---\n")
	if err != nil {
		return "", err
	}

	_, err = buffer.WriteString(content)
	if err != nil {
		return "", err
	}

	return buffer.String(), nil
}

func removeQuizHeader(path string) (*models.Meta, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var buffer bytes.Buffer

	reader := bufio.NewReader(file)

	var meta models.Meta
	var line string
	var sb strings.Builder
	for {
		line, err = reader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return nil, err
		}

		if strings.TrimSpace(line) == "---" {
			break
		}
	}

	for {
		line, err = reader.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break
			}
			return nil, err
		}

		if strings.TrimSpace(line) == "---" {
			break
		}

		sb.WriteString(line)
	}

	err = yaml.Unmarshal([]byte(sb.String()), &meta)
	if err != nil {
		return nil, err
	}

	_, err = io.Copy(&buffer, reader)
	if err != nil {
		return nil, err
	}

	file, err = os.Create(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	_, err = io.Copy(file, &buffer)
	if err != nil {
		return nil, err
	}

	return &meta, nil
}