package app

import (
	"errors"
	"os"
	"time"
)

type Config struct {
	Environment, Address, PublicBaseURL, StudentPIN, InstructorPIN, SessionSecret, LogLevel, LogFormat string
	SessionDuration, ReadHeaderTimeout, ReadTimeout, WriteTimeout, IdleTimeout, ShutdownTimeout        time.Duration
}

func LoadConfigFromEnv() (Config, error) {
	c := Config{Environment: get("APP_ENV", "development"), Address: get("HTTP_ADDRESS", ":8080"), PublicBaseURL: os.Getenv("PUBLIC_BASE_URL"), StudentPIN: os.Getenv("STUDENT_PIN"), InstructorPIN: os.Getenv("INSTRUCTOR_PIN"), SessionSecret: os.Getenv("SESSION_SIGNING_SECRET"), LogLevel: get("LOG_LEVEL", "info"), LogFormat: get("LOG_FORMAT", "text")}
	var err error
	c.SessionDuration, err = duration("SESSION_DURATION", "4h")
	if err != nil {
		return c, err
	}
	values := []struct {
		target        *time.Duration
		key, fallback string
	}{{&c.ReadHeaderTimeout, "HTTP_READ_HEADER_TIMEOUT", "5s"}, {&c.ReadTimeout, "HTTP_READ_TIMEOUT", "30s"}, {&c.WriteTimeout, "HTTP_WRITE_TIMEOUT", "30s"}, {&c.IdleTimeout, "HTTP_IDLE_TIMEOUT", "60s"}, {&c.ShutdownTimeout, "HTTP_SHUTDOWN_TIMEOUT", "10s"}}
	for _, value := range values {
		*value.target, err = duration(value.key, value.fallback)
		if err != nil {
			return c, err
		}
	}
	if c.StudentPIN == "" || c.InstructorPIN == "" || len(c.SessionSecret) < 32 || c.PublicBaseURL == "" {
		return c, errors.New("STUDENT_PIN, INSTRUCTOR_PIN, PUBLIC_BASE_URL, and a 32+ character SESSION_SIGNING_SECRET are required")
	}
	return c, nil
}
func get(k, d string) string {
	if v := os.Getenv(k); v != "" {
		return v
	}
	return d
}
func duration(k, d string) (time.Duration, error) { return time.ParseDuration(get(k, d)) }