package config

import (
	"fmt"
	"os"
	"path/filepath"
	"strconv"
)

type Config struct {
	Host                string
	Port                int
	APIBaseURL          string
	TilePublicBaseURL   string
	VectorPublicBaseURL string
	SQLitePath          string
	BasemapScanRoot     string
	VectorScanRoot      string
	AutoScanOnStart     bool
	Env                 string
	ServiceName         string
	ServiceVersion      string
	Commit              string
}

func Load() (Config, error) {
	if err := LoadEnvDefaults(); err != nil {
		return Config{}, err
	}

	port, err := intEnv("API_PORT", 8910)
	if err != nil {
		return Config{}, fmt.Errorf("parse API_PORT: %w", err)
	}
	autoScanOnStart, err := boolEnv("AUTO_SCAN_ON_START", true)
	if err != nil {
		return Config{}, fmt.Errorf("parse AUTO_SCAN_ON_START: %w", err)
	}

	cfg := Config{
		Host:                stringEnv("API_HOST", "127.0.0.1"),
		Port:                port,
		APIBaseURL:          stringEnv("API_BASE_URL", ""),
		TilePublicBaseURL:   stringEnv("TILE_PUBLIC_BASE_URL", ""),
		VectorPublicBaseURL: stringEnv("VECTOR_PUBLIC_BASE_URL", ""),
		SQLitePath:          stringEnv("SQLITE_PATH", filepath.Clean(filepath.Join("data", "map-asset-gateway.db"))),
		BasemapScanRoot:     stringEnv("BASEMAP_SCAN_ROOT", filepath.Clean(filepath.Join("data", "tiles"))),
		VectorScanRoot:      stringEnv("VECTOR_SCAN_ROOT", filepath.Clean(filepath.Join("data", "geojson"))),
		AutoScanOnStart:     autoScanOnStart,
		Env:                 stringEnv("APP_ENV", "dev"),
		ServiceName:         stringEnv("SERVICE_NAME", "map-asset-gateway"),
		ServiceVersion:      stringEnv("SERVICE_VERSION", "0.2.0"),
		Commit:              stringEnv("SERVICE_COMMIT", "local"),
	}
	if cfg.APIBaseURL == "" {
		cfg.APIBaseURL = deriveBaseURL(cfg.Host, cfg.Port)
	}
	if cfg.TilePublicBaseURL == "" {
		cfg.TilePublicBaseURL = cfg.APIBaseURL
	}
	if cfg.VectorPublicBaseURL == "" {
		cfg.VectorPublicBaseURL = cfg.APIBaseURL
	}
	return cfg, nil
}

func (c Config) ListenAddr() string {
	return fmt.Sprintf("%s:%d", c.Host, c.Port)
}

func deriveBaseURL(host string, port int) string {
	if host == "" || host == "0.0.0.0" {
		host = "127.0.0.1"
	}
	return fmt.Sprintf("http://%s:%d", host, port)
}

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

func intEnv(key string, fallback int) (int, error) {
	value, ok := os.LookupEnv(key)
	if ok && value != "" {
		parsed, err := strconv.Atoi(value)
		if err != nil {
			return 0, err
		}
		return parsed, nil
	}
	return fallback, nil
}

func boolEnv(key string, fallback bool) (bool, error) {
	value, ok := os.LookupEnv(key)
	if ok && value != "" {
		parsed, err := strconv.ParseBool(value)
		if err != nil {
			return false, err
		}
		return parsed, nil
	}
	return fallback, nil
}