package lib

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
)

// Activity entity as defined by the specification.
type Activity struct {
	ID    string `json:"id"`
	Title string `json:"title"`
}

// GetActivities retrieves all stored activity instances of a project.
func GetActivities(project *Project) ([]*Activity, error) {
	folder, folderErr := getActivitiesFolder(project.ID)
	if folderErr != nil {
		return nil, folderErr
	}

	dirErr := os.MkdirAll(folder, 0o750)
	if dirErr != nil {
		return nil, dirErr
	}

	files, filesErr := os.ReadDir(folder)
	if filesErr != nil {
		return nil, filesErr
	}

	activities := []*Activity{}
	for _, file := range files {
		activity, fileErr := readActivity(filepath.Join(folder, file.Name()))
		if fileErr != nil {
			return nil, fileErr
		}
		activities = append(activities, activity)
	}

	return activities, nil
}

// SetActivity persists an activity.
func SetActivity(project *Project, activity *Activity) error {
	uuid, uuidErr := newUUID()
	if uuidErr != nil {
		return uuidErr
	}

	activity.ID = uuid

	file, fileErr := getActivityFile(project.ID, uuid)
	if fileErr != nil {
		return fileErr
	}

	return writeActivity(file, activity)
}

// readActivity reads an activity from a file and converts it into an entity instance.
func readActivity(filename string) (*Activity, error) {
	file, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	project := Activity{}
	if err := json.NewDecoder(file).Decode(&project); err != nil {
		return nil, err
	}

	return &project, nil
}

// writeActivity writes an activity instance to a file.
func writeActivity(filename string, activity *Activity) error {
	dirErr := os.MkdirAll(filepath.Dir(filename), 0o750)
	if dirErr != nil {
		return dirErr
	}
	fmt.Println("success")

	file, fileErr := os.Create(filename)
	if fileErr != nil {
		return fileErr
	}
	defer file.Close()

	encoder := json.NewEncoder(file)
	encoder.SetIndent("", "    ")

	jsonErr := encoder.Encode(activity)
	if jsonErr != nil {
		return jsonErr
	}

	return nil
}

// getActivitiesFolder returns the folder to store activity entity files in.
func getActivitiesFolder(projectID string) (string, error) {
	folder, err := getDataDir("activities")
	if err != nil {
		return "", err
	}

	return filepath.Join(folder, projectID), nil
}

// getActivityFile returns the file name for an activity entity instance.
func getActivityFile(projectID string, name string) (string, error) {
	folder, err := getActivitiesFolder(projectID)
	if err != nil {
		return "", err
	}

	return filepath.Join(folder, name+".json"), nil
}