package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"time"

	"gopkg.in/yaml.v3"
)

type Config struct {
	Listen      []string `yaml:"listen"`
	Checkpoints string   `yaml:"checkpoints"`
	Roots       string   `yaml:"roots"`
	Logs        []Log    `yaml:"logs"`
}

type Log struct {
	ShortName        string    `yaml:"shortname"`
	Domain           string    `yaml:"domain"`
	Inception        string    `yaml:"inception"`
	Period           int       `yaml:"period"`
	PoolSize         int       `yaml:"poolsize"`
	SubmissionPrefix string    `yaml:"submissionprefix"`
	MonitoringPrefix string    `yaml:"monitoringprefix"`
	CCadbRoots       string    `yaml:"ccadbroots"`
	ExtraRoots       string    `yaml:"extraroots"`
	Secret           string    `yaml:"secret"`
	Cache            string    `yaml:"cache"`
	LocalDirectory   string    `yaml:"localdirectory"`
	Listen           string    `yaml:"listen"`
	NotAfterStart    time.Time `yaml:"notafterstart"`
	NotAfterLimit    time.Time `yaml:"notafterlimit"`
	// Computed fields
	LogID           string
	PublicKeyPEM    string
	PublicKeyDERB64 string
	PublicKeyBase64 string
}

func main() {
	configFile := flag.String("c", "./tesseract-staging.yaml", "Path to the YAML configuration file")
	flag.Parse()

	args := flag.Args()
	if len(args) == 0 {
		showHelp()
		return
	}

	switch args[0] {
	case "gen-html":
		generateHTML(*configFile)
	case "gen-env":
		generateEnv(*configFile)
	case "gen-key":
		generateKeys(*configFile)
	case "gen-nginx":
		generateNginx(*configFile)
	case "gen-roots":
		generateRoots(args[1:])
	default:
		fmt.Fprintf(os.Stderr, "Unknown command: %s\n", args[0])
		showHelp()
		os.Exit(1)
	}
}

func loadConfig(yamlFile string) Config {
	data, err := os.ReadFile(yamlFile)
	if err != nil {
		log.Fatalf("Failed to read YAML file: %v", err)
	}

	var config Config
	err = yaml.Unmarshal(data, &config)
	if err != nil {
		log.Fatalf("Failed to parse YAML: %v", err)
	}

	// Set default listen port if not configured
	if len(config.Listen) == 0 {
		config.Listen = []string{":8080"}
	}

	// Checkpoints & Roots are not used in-code, not checking for being set/valid

	// Ensure there are logs configured
	if len(config.Logs) == 0 {
		log.Fatalf("Parsed YAML did not include any 'logs'")
	}

	// Set defaults for log entries and check for empty/missing values
	for i := range config.Logs {
		// Checks are in order of fields of the Log struct

		if config.Logs[i].ShortName == "" {
			log.Fatalf("Log %d is missing a ShortName", i)
		}

		if config.Logs[i].Domain == "" {
			log.Fatalf("Log %d (%s) is missing a value for Domain", i, config.Logs[i].ShortName)
		}

		// Inception is not used in-code

		if config.Logs[i].Period == 0 {
			config.Logs[i].Period = 200
		}

		if config.Logs[i].PoolSize == 0 {
			config.Logs[i].PoolSize = 750
		}

		if config.Logs[i].SubmissionPrefix == "" {
			log.Fatalf("Log %d (%s) is missing a value for SubmissionPrefix", i, config.Logs[i].ShortName)
		}

		if config.Logs[i].MonitoringPrefix == "" {
			log.Fatalf("Log %d (%s) is missing a value for MonitoringPrefix", i, config.Logs[i].ShortName)
		}

		// CCadbRoots is not used in-code
		// ExtraRoots is optional

		if config.Logs[i].Secret == "" {
			log.Fatalf("Log %d (%s) is missing a value for Secret", i, config.Logs[i].ShortName)
		}

		// Cache is not used in-code

		if config.Logs[i].LocalDirectory == "" {
			log.Fatalf("Log %d (%s) is missing a value for LocalDirectory", i, config.Logs[i].ShortName)
		}

		// Listen, NotAfterStart and NotAfterLimit are optional

		// These fields are exported due to HTML templates
		// but should not be provided/filled by the user
		if config.Logs[i].LogID != "" {
			log.Fatalf("Log %d (%s) has field LogID should not be configured (%s)", i, config.Logs[i].ShortName, config.Logs[i].LogID)
		}

		if config.Logs[i].PublicKeyPEM != "" {
			log.Fatalf("Log %d (%s) has field PublicKeyPEM should not be configured (%s)", i, config.Logs[i].ShortName, config.Logs[i].PublicKeyPEM)
		}

		if config.Logs[i].PublicKeyDERB64 != "" {
			log.Fatalf("Log %d (%s) has field PublicKeyDERB64 should not be configured (%s)", i, config.Logs[i].ShortName, config.Logs[i].PublicKeyDERB64)
		}

		if config.Logs[i].PublicKeyBase64 != "" {
			log.Fatalf("Log %d (%s) has field PublicKeyBase64 should not be configured (%s)", i, config.Logs[i].ShortName, config.Logs[i].PublicKeyBase64)
		}
	}

	return config
}

func writeFileWithStatus(filename string, content []byte) error {
	existingContent, err := os.ReadFile(filename)
	if os.IsNotExist(err) {
		fmt.Printf("Creating %s\n", filename)
	} else if err != nil {
		return fmt.Errorf("failed to read existing file %s: %v", filename, err)
	} else if string(existingContent) == string(content) {
		fmt.Printf("Unchanged %s\n", filename)
		return nil
	} else {
		fmt.Printf("Updating %s\n", filename)
	}

	err = os.WriteFile(filename, content, 0644)
	if err != nil {
		return fmt.Errorf("failed to write file %s: %v", filename, err)
	}
	return nil
}

func showHelp() {
	fmt.Printf("Usage: %s [options] <command>\n\n", os.Args[0])
	fmt.Printf("Options:\n")
	fmt.Printf("  -c <file>    Path to YAML configuration file (default: ./tesseract-staging.yaml)\n\n")
	fmt.Printf("Commands:\n")
	fmt.Printf("  gen-html     Generate index.html and log.v3.json files in each log's localdirectory.\n")
	fmt.Printf("               Creates HTML pages with log information and CT log metadata JSON.\n")
	fmt.Printf("               Computes LOG_ID and public keys from private keys.\n\n")
	fmt.Printf("  gen-env      Generate .env files and combined roots.pem in each log's localdirectory.\n")
	fmt.Printf("               Creates TESSERACT_ARGS environment variable with command line flags.\n")
	fmt.Printf("               Combines global roots and log-specific extraroots into roots.pem.\n\n")
	fmt.Printf("  gen-key      Generate prime256v1 private keys for each log (only if they don't exist).\n")
	fmt.Printf("               Creates EC private key files at the path specified in log.secret.\n\n")
	fmt.Printf("  gen-nginx    Generate nginx configuration files for each log's monitoring endpoint.\n")
	fmt.Printf("               Creates nginx-<hostname>.conf files in each log's localdirectory.\n\n")
	fmt.Printf("  gen-roots    Download root certificates from a Certificate Transparency log.\n")
	fmt.Printf("               Options: --source <url> (default: https://rennet2027h2.log.ct.ipng.ch/)\n")
	fmt.Printf("                        --output <file> (default: roots.pem)\n\n")
}