package main

import (
	"errors"
	"fmt"
	"net/url"
	"strings"
	"time"

	"gardomatic.kleiax.de/internal/api"
	"gardomatic.kleiax.de/internal/mailer"
	"gardomatic.kleiax.de/internal/platform/environment"
	"gardomatic.kleiax.de/internal/platform/validate"
	"gardomatic.kleiax.de/internal/storage"
)

func configFromEnvironment() (api.Config, error) {
	var errs []error
	required := func(name string) string {
		value, err := environment.Required(name)
		if err != nil {
			errs = append(errs, err)
		}
		return value
	}
	integer := func(name string, fallback int) int {
		value, err := environment.Int(name, fallback)
		if err != nil {
			errs = append(errs, err)
		}
		return value
	}
	boolean := func(name string, fallback bool) bool {
		value, err := environment.Bool(name, fallback)
		if err != nil {
			errs = append(errs, err)
		}
		return value
	}
	duration := func(name string, fallback time.Duration) time.Duration {
		value, err := environment.Duration(name, fallback)
		if err != nil {
			errs = append(errs, err)
		}
		return value
	}
	floating := func(name string, fallback float64) float64 {
		value, err := environment.Float(name, fallback)
		if err != nil {
			errs = append(errs, err)
		}
		return value
	}

	cfg := api.Config{
		Host:       environment.String("GARDOMATIC_API_HOST", ""),
		Port:       integer("GARDOMATIC_API_PORT", 4000),
		Env:        environment.String("GARDOMATIC_ENV", "development"),
		WebBaseURL: environment.String("GARDOMATIC_WEB_BASE_URL", "http://localhost:4040"),
		DemoAccountEmail: strings.ToLower(strings.TrimSpace(
			environment.String("GARDOMATIC_DEMO_ACCOUNT_EMAIL", ""),
		)),
		DB: api.DatabaseConfig{
			Dsn: required("GARDOMATIC_DB_DSN"), MaxOpenConns: integer("GARDOMATIC_DB_MAX_OPEN_CONNS", 25),
			MaxIdleConns: integer("GARDOMATIC_DB_MAX_IDLE_CONNS", 25), MaxIdleTime: duration("GARDOMATIC_DB_MAX_IDLE_TIME", 15*time.Minute),
		},
		Limiter: api.LimiterConfig{Enabled: boolean("GARDOMATIC_RATE_LIMIT_ENABLED", true), Rps: floating("GARDOMATIC_RATE_LIMIT_RPS", 10), Burst: integer("GARDOMATIC_RATE_LIMIT_BURST", 40)},
		Session: api.SessionConfig{Lifetime: duration("GARDOMATIC_SESSION_LIFETIME", 12*time.Hour), IdleTimeout: duration("GARDOMATIC_SESSION_IDLE_TIMEOUT", 30*time.Minute), CookieName: environment.String("GARDOMATIC_SESSION_COOKIE_NAME", "gardomatic_session"), CookieSecure: boolean("GARDOMATIC_COOKIE_SECURE", false)},
		Mail:    mailer.Config{Mode: mailer.Mode(environment.String("GARDOMATIC_SMTP_MODE", string(mailer.ModeFile))), Host: environment.String("GARDOMATIC_SMTP_HOST", ""), Port: integer("GARDOMATIC_SMTP_PORT", 25), Username: environment.String("GARDOMATIC_SMTP_USERNAME", ""), Password: environment.String("GARDOMATIC_SMTP_PASSWORD", ""), Sender: environment.String("GARDOMATIC_SMTP_SENDER", "gardomatic@localhost"), FilePath: environment.String("GARDOMATIC_SMTP_FILE_PATH", "/tmp/gardomatic-mails.log")},
		Cors:    api.CORSConfig{TrustedOrigins: environment.CSV("GARDOMATIC_CORS_TRUSTED_ORIGINS")},
	}

	if cfg.Port < 1 || cfg.Port > 65535 {
		errs = append(errs, errors.New("GARDOMATIC_API_PORT must be between 1 and 65535"))
	}
	if cfg.Env != "development" && cfg.Env != "test" && cfg.Env != "production" {
		errs = append(errs, fmt.Errorf("GARDOMATIC_ENV has unsupported value %q", cfg.Env))
	}
	if cfg.DB.MaxOpenConns < 1 || cfg.DB.MaxIdleConns < 0 || cfg.DB.MaxIdleConns > cfg.DB.MaxOpenConns {
		errs = append(errs, errors.New("database pool limits are invalid"))
	}
	if cfg.Limiter.Rps <= 0 || cfg.Limiter.Burst < 1 {
		errs = append(errs, errors.New("rate limit values must be positive"))
	}
	if strings.TrimSpace(cfg.Session.CookieName) == "" {
		errs = append(errs, errors.New("GARDOMATIC_SESSION_COOKIE_NAME must not be empty"))
	}
	for _, origin := range cfg.Cors.TrustedOrigins {
		parsed, err := url.ParseRequestURI(origin)
		if err != nil || parsed.Scheme == "" || parsed.Host == "" {
			errs = append(errs, fmt.Errorf("invalid trusted origin %q", origin))
		}
	}
	if parsed, err := url.ParseRequestURI(cfg.WebBaseURL); err != nil || parsed.Scheme == "" || parsed.Host == "" {
		errs = append(errs, errors.New("GARDOMATIC_WEB_BASE_URL must be an absolute URL"))
	}
	if cfg.Env == "production" && !cfg.Session.CookieSecure {
		errs = append(errs, errors.New("GARDOMATIC_COOKIE_SECURE must be true in production"))
	}
	if cfg.DemoAccountEmail != "" {
		v := validate.New()
		if storage.ValidateEmail(v, cfg.DemoAccountEmail); !v.Valid() {
			errs = append(errs, errors.New("GARDOMATIC_DEMO_ACCOUNT_EMAIL must be a valid email address"))
		}
	}
	if _, err := mailer.New(cfg.Mail); err != nil {
		errs = append(errs, fmt.Errorf("mail configuration: %w", err))
	}
	return cfg, errors.Join(errs...)
}