// Package config loads the master's configuration from environment variables.
package config

import (
	"fmt"
	"os"
	"strings"
)

// Config holds the master's runtime configuration.
type Config struct {
	DatabaseURL      string
	PublicURL        string // where people reach the UI, without trailing slash
	AgentURL         string // what agents dial, shown in the add-agent snippet
	AgentImage       string
	OIDCIssuer       string
	OIDCClientID     string
	OIDCClientSecret string
	AllowedGroup     string
	Port             string
	AgentPort        string
	LogLevel         string
}

// Load reads and validates the master configuration, failing fast on
// anything missing so a half-configured master never starts.
func Load() (*Config, error) {
	cfg := &Config{
		DatabaseURL:      os.Getenv("DATABASE_URL"),
		PublicURL:        strings.TrimSuffix(os.Getenv("PUBLIC_URL"), "/"),
		AgentURL:         os.Getenv("AGENT_URL"),
		AgentImage:       getenvDefault("AGENT_IMAGE", "gitea.shcizo.se/shcizo/package-updater:latest"),
		OIDCIssuer:       os.Getenv("OIDC_ISSUER"),
		OIDCClientID:     os.Getenv("OIDC_CLIENT_ID"),
		OIDCClientSecret: os.Getenv("OIDC_CLIENT_SECRET"),
		AllowedGroup:     os.Getenv("ALLOWED_GROUP"),
		Port:             getenvDefault("PORT", "8080"),
		AgentPort:        getenvDefault("AGENT_PORT", "8090"),
		LogLevel:         getenvDefault("LOG_LEVEL", "info"),
	}
	for _, r := range []struct{ name, value string }{
		{"DATABASE_URL", cfg.DatabaseURL},
		{"PUBLIC_URL", cfg.PublicURL},
		{"AGENT_URL", cfg.AgentURL},
		{"OIDC_ISSUER", cfg.OIDCIssuer},
		{"OIDC_CLIENT_ID", cfg.OIDCClientID},
		{"OIDC_CLIENT_SECRET", cfg.OIDCClientSecret},
		{"ALLOWED_GROUP", cfg.AllowedGroup},
	} {
		if r.value == "" {
			return nil, fmt.Errorf("%s is required", r.name)
		}
	}
	if !strings.HasPrefix(cfg.PublicURL, "http://") && !strings.HasPrefix(cfg.PublicURL, "https://") {
		return nil, fmt.Errorf("PUBLIC_URL must start with http:// or https://")
	}
	if !strings.HasPrefix(cfg.AgentURL, "wss://") {
		return nil, fmt.Errorf("AGENT_URL must start with wss://")
	}
	return cfg, nil
}

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