package config

import (
	"fmt"
	"os"
	"strconv"
	"time"
)

type Postgres struct {
	Host     string
	Port     int
	User     string
	Password string
	Database string
	SSLMode  string
}

func (p Postgres) DSN() string {
	return fmt.Sprintf("postgres://%s:%s@%s:%d/%s?sslmode=%s",
		p.User, p.Password, p.Host, p.Port, p.Database, p.SSLMode)
}

type S3 struct {
	Endpoint     string
	Region       string
	AccessKey    string
	SecretKey    string
	Bucket       string
	UsePathStyle bool
}

type Auth struct {
	AccessTTL  time.Duration
	RefreshTTL time.Duration
}

type Server struct {
	Addr    string
	BaseURL string
}

type SSE struct {
	HeartbeatInterval time.Duration
	ClientBuffer      int
}

type Worker struct {
	Interval   time.Duration
	Batch      int
	PendingTTL time.Duration
}

type Storage struct {
	Backend   string
	FSRoot    string
	URLSecret string
	URLTTL    time.Duration
}

type Database struct {
	Backend    string
	SQLitePath string
}

type Config struct {
	Postgres Postgres
	S3       S3
	Storage  Storage
	Database Database
	Auth     Auth
	Server   Server
	SSE      SSE
	Worker   Worker
}

func Load() (*Config, error) {
	pgPort, err := strconv.Atoi(getEnv("PG_PORT", "5432"))
	if err != nil {
		return nil, fmt.Errorf("invalid PG_PORT: %w", err)
	}

	accessTTL, err := time.ParseDuration(getEnv("JWT_ACCESS_TTL", "15m"))
	if err != nil {
		return nil, fmt.Errorf("invalid JWT_ACCESS_TTL: %w", err)
	}

	refreshTTL, err := time.ParseDuration(getEnv("JWT_REFRESH_TTL", "720h"))
	if err != nil {
		return nil, fmt.Errorf("invalid JWT_REFRESH_TTL: %w", err)
	}

	urlTTL, err := time.ParseDuration(getEnv("OBJECT_URL_TTL", "1h"))
	if err != nil {
		return nil, fmt.Errorf("invalid OBJECT_URL_TTL: %w", err)
	}

	heartbeat, err := time.ParseDuration(getEnv("SSE_HEARTBEAT_INTERVAL", "25s"))
	if err != nil {
		return nil, fmt.Errorf("invalid SSE_HEARTBEAT_INTERVAL: %w", err)
	}

	bufSize, err := strconv.Atoi(getEnv("SSE_CLIENT_BUFFER", "64"))
	if err != nil {
		return nil, fmt.Errorf("invalid SSE_CLIENT_BUFFER: %w", err)
	}

	pathStyle, err := strconv.ParseBool(getEnv("S3_USE_PATH_STYLE", "true"))
	if err != nil {
		return nil, fmt.Errorf("invalid S3_USE_PATH_STYLE: %w", err)
	}

	workerInterval, err := time.ParseDuration(getEnv("WORKER_INTERVAL", "5s"))
	if err != nil {
		return nil, fmt.Errorf("invalid WORKER_INTERVAL: %w", err)
	}

	workerBatch, err := strconv.Atoi(getEnv("WORKER_BATCH", "10"))
	if err != nil {
		return nil, fmt.Errorf("invalid WORKER_BATCH: %w", err)
	}

	workerPendingTTL, err := time.ParseDuration(getEnv("WORKER_PENDING_TTL", "10m"))
	if err != nil {
		return nil, fmt.Errorf("invalid WORKER_PENDING_TTL: %w", err)
	}

	cfg := &Config{
		Postgres: Postgres{
			Host:     getEnv("PG_HOST", "pg.localnet"),
			Port:     pgPort,
			User:     getEnv("PG_USER", "album"),
			Password: getEnv("PG_PASSWORD", ""),
			Database: getEnv("PG_DATABASE", "shared_album"),
			SSLMode:  getEnv("PG_SSLMODE", "disable"),
		},
		S3: S3{
			Endpoint:     getEnv("S3_ENDPOINT", "http://s3.localnet:3900"),
			Region:       getEnv("S3_REGION", "garage"),
			AccessKey:    getEnv("S3_ACCESS_KEY", ""),
			SecretKey:    getEnv("S3_SECRET_KEY", ""),
			Bucket:       getEnv("S3_BUCKET", "albums"),
			UsePathStyle: pathStyle,
		},
		Storage: Storage{
			Backend:   getEnv("STORAGE_BACKEND", "fs"),
			FSRoot:    getEnv("FS_ROOT", "./data"),
			URLSecret: getEnv("URL_SECRET", ""),
			URLTTL:    urlTTL,
		},
		Database: Database{
			Backend:    getEnv("DB_BACKEND", "sqlite"),
			SQLitePath: getEnv("SQLITE_PATH", "./galo.db"),
		},
		Auth: Auth{
			AccessTTL:  accessTTL,
			RefreshTTL: refreshTTL,
		},
		Server: Server{
			Addr:    getEnv("HTTP_ADDR", ":8080"),
			BaseURL: getEnv("APP_BASE_URL", "http://localhost:8080"),
		},
		SSE: SSE{
			HeartbeatInterval: heartbeat,
			ClientBuffer:      bufSize,
		},
		Worker: Worker{
			Interval:   workerInterval,
			Batch:      workerBatch,
			PendingTTL: workerPendingTTL,
		},
	}

	switch cfg.Database.Backend {
	case "postgres":
		if cfg.Postgres.Password == "" {
			return nil, fmt.Errorf("PG_PASSWORD is required")
		}
	case "sqlite":
		if cfg.Database.SQLitePath == "" {
			return nil, fmt.Errorf("SQLITE_PATH is required when DB_BACKEND=sqlite")
		}
	default:
		return nil, fmt.Errorf("invalid DB_BACKEND %q (want postgres or sqlite)", cfg.Database.Backend)
	}

	switch cfg.Storage.Backend {
	case "s3":
	case "fs":
		if cfg.Storage.FSRoot == "" {
			return nil, fmt.Errorf("FS_ROOT is required when STORAGE_BACKEND=fs")
		}
	default:
		return nil, fmt.Errorf("invalid STORAGE_BACKEND %q (want s3 or fs)", cfg.Storage.Backend)
	}

	return cfg, nil
}

func getEnv(key, fallback string) string {
	if v, ok := os.LookupEnv(key); ok && v != "" {
		return v
	}
	return fallback
}