package config

import (
	"encoding/json"
	"os"
	"path/filepath"
	"strconv"

	"github.com/joho/godotenv"
)

// Config holds runtime configuration
type Config struct {
	S3Bucket    string `json:"s3Bucket"`
	LocalDest   string `json:"localDest"`
	AWSProfile  string `json:"awsProfile"`
	Concurrency int    `json:"concurrency"`
}

// Path returns the cross-OS config file path
func Path() string {
	dir, _ := os.UserConfigDir()
	return filepath.Join(dir, "field-sync", "config.json")
}

// Save writes config to disk (atomic)
func Save(cfg Config) error {
	p := Path()
	if err := os.MkdirAll(filepath.Dir(p), 0755); err != nil {
		return err
	}
	data, _ := json.MarshalIndent(cfg, "", "  ")
	tmp := p + ".tmp"
	if err := os.WriteFile(tmp, data, 0644); err != nil {
		return err
	}
	return os.Rename(tmp, p)
}

// LoadFromFile reads from JSON config file (no .env)
func LoadFromFile() Config {
	data, err := os.ReadFile(Path())
	if err != nil {
		return Config{AWSProfile: "cosma", Concurrency: 4, LocalDest: defaultLocalDest()}
	}
	var c Config
	json.Unmarshal(data, &c)
	if c.Concurrency == 0 {
		c.Concurrency = 4
	}
	if c.AWSProfile == "" {
		c.AWSProfile = "cosma"
	}
	if c.LocalDest == "" {
		c.LocalDest = defaultLocalDest()
	}
	return c
}

func defaultLocalDest() string {
	home, _ := os.UserHomeDir()
	return filepath.Join(home, "field-sync-data")
}

// Load reads config from ENV (with optional .env file) — kept for compat
func Load(envFile string) Config {
	_ = godotenv.Load(envFile) // ignore if missing

	concurrency := 4
	if v := os.Getenv("FIELD_SYNC_CONCURRENCY"); v != "" {
		if n, err := strconv.Atoi(v); err == nil && n > 0 {
			concurrency = n
		}
	}

	return Config{
		S3Bucket:    getenv("FIELD_SYNC_S3_BUCKET", ""),
		LocalDest:   getenv("FIELD_SYNC_LOCAL_DEST", os.TempDir()),
		AWSProfile:  getenv("AWS_PROFILE", "cosma"),
		Concurrency: concurrency,
	}
}

func getenv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}