// Package data manages the loading, saving, and manipulation of application data
// pertaining to health tracking. It provides an abstraction layer over the storage
// mechanism used for persisting records and offers convenient methods to interact
// with the data.
package data

import (
	"encoding/json"
	"ketotrack/model"
	"os"
)

// AppContext represents the application's data context, encapsulating the storage
// and management of health-related records. It provides mechanisms to load and save
// these records from a persistent storage.
type AppContext struct {
	Records  []model.Record
	dataPath string
}

// NewContext initializes a new application data context with the specified data
// path. It attempts to load existing records from the provided data path, or
// initializes an empty context if the records do not exist.
func NewContext(dataPath string) (AppContext, error) {
	ctx := AppContext{dataPath: dataPath}
	err := ctx.LoadRecords()
	if err != nil {
		return AppContext{}, err
	}
	return ctx, nil
}

// LoadRecords loads the records from the data file specified in the AppContext.
// If the records file does not exist, it initializes an empty record list and
// saves it to create the file.
func (ctx *AppContext) LoadRecords() error {
	data, err := os.ReadFile(ctx.dataPath)

	// Create the records file if it does not exist
	if os.IsNotExist(err) {
		ctx.Records = []model.Record{}
		return ctx.SaveRecords()
	} else if err != nil {
		// Some other type of error has occurred
		return err
	}

	return json.Unmarshal(data, &ctx.Records)
}

// SaveRecords serializes the current records to JSON and writes them to the
// data path specified in the AppContext. It ensures data persistence with
// appropriate access permissions.
func (ctx *AppContext) SaveRecords() error {
	jsonData, err := json.Marshal(ctx.Records)
	if err != nil {
		return err
	}
	return os.WriteFile(ctx.dataPath, jsonData, 0660)
}

// AddReading appends a new Reading record to the AppContext. It updates the
// application context's records with the latest readings data.
func (ctx *AppContext) AddReading(reading model.Reading) {
	ctx.Records = append(ctx.Records, model.Record{Reading: &reading})
}

// AddNote appends a new Note record to the AppContext. It updates the
// application context's records with the newly added note.
func (ctx *AppContext) AddNote(note model.Note) {
	ctx.Records = append(ctx.Records, model.Record{Note: &note})
}