package weather

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

	"git.leaktechnologies.dev/Leak_Technologies/Skyfeed/internal/config"
)

// Cache file path
var cacheFile = filepath.Join(config.DataDir, "last_weather.json")

// CacheTTL defines how long cached weather data is considered "fresh".
// Default: 30 minutes.
const CacheTTL = 30 * time.Minute

// LoadFromCache loads cached weather data if available and still fresh.
// Returns (WeatherData, isFresh, error)
func LoadFromCache() (WeatherData, bool, error) {
	file, err := os.Open(cacheFile)
	if err != nil {
		return WeatherData{}, false, fmt.Errorf("no cache found")
	}
	defer file.Close()

	var data WeatherData
	if err := json.NewDecoder(file).Decode(&data); err != nil {
		return WeatherData{}, false, fmt.Errorf("failed to decode cache: %w", err)
	}

	ts, err := time.Parse(time.RFC3339, data.Timestamp)
	if err != nil {
		// handle legacy or non-RFC timestamps
		return data, false, nil
	}

	age := time.Since(ts)
	if age > CacheTTL {
		fmt.Printf("[weather] Cache is stale (%.0f min old)\n", age.Minutes())
		return data, false, nil
	}

	fmt.Println("[weather] Loaded fresh cache (", int(age.Minutes()), "min old )")
	return data, true, nil
}

// SaveToCache writes a WeatherData object to disk.
func SaveToCache(data WeatherData) error {
	if err := os.MkdirAll(filepath.Dir(cacheFile), 0755); err != nil {
		return fmt.Errorf("failed to create cache dir: %w", err)
	}

	file, err := os.Create(cacheFile)
	if err != nil {
		return fmt.Errorf("failed to write cache: %w", err)
	}
	defer file.Close()

	data.Timestamp = time.Now().UTC().Format(time.RFC3339)

	enc := json.NewEncoder(file)
	enc.SetIndent("", "  ")
	if err := enc.Encode(data); err != nil {
		return fmt.Errorf("failed to encode cache: %w", err)
	}

	fmt.Println("[weather] Cache saved →", cacheFile)
	return nil
}

// ClearCache removes the current cached file if present.
func ClearCache() error {
	if _, err := os.Stat(cacheFile); os.IsNotExist(err) {
		return nil
	}
	if err := os.Remove(cacheFile); err != nil {
		return fmt.Errorf("failed to clear cache: %w", err)
	}
	fmt.Println("[weather] Cache cleared.")
	return nil
}