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

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

// 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

	// UpdaterAPIKey is the bearer token for POST /update (UPDATER_API_KEY).
	// Empty disables the webhook.
	UpdaterAPIKey string
	// UpdateTimeout bounds how long one webhook request waits for its auto
	// jobs (UPDATE_TIMEOUT, default 5m).
	UpdateTimeout time.Duration
	// PollInterval is the time between registry polling cycles
	// (POLL_INTERVAL, default 6h).
	PollInterval time.Duration
}

// defaultUpdateTimeout is used when UPDATE_TIMEOUT is unset.
const defaultUpdateTimeout = 5 * time.Minute

// defaultPollInterval is used when POLL_INTERVAL is unset.
const defaultPollInterval = 6 * time.Hour

// 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"),
		UpdaterAPIKey:    os.Getenv("UPDATER_API_KEY"),
		UpdateTimeout:    defaultUpdateTimeout,
		PollInterval:     defaultPollInterval,
	}
	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://")
	}
	if v := os.Getenv("UPDATE_TIMEOUT"); v != "" {
		d, err := time.ParseDuration(v)
		if err != nil || d <= 0 {
			return nil, fmt.Errorf("UPDATE_TIMEOUT must be a positive duration such as 5m, got %q", v)
		}
		cfg.UpdateTimeout = d
	}
	if v := os.Getenv("POLL_INTERVAL"); v != "" {
		d, err := time.ParseDuration(v)
		if err != nil || d <= 0 {
			return nil, fmt.Errorf("POLL_INTERVAL must be a positive duration such as 6h, got %q", v)
		}
		cfg.PollInterval = d
	}
	return cfg, nil
}

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