package main

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"net/url"
	"os"
	"path/filepath"
	"strings"
	"time"

	"cmbuyer/admin/internal/deviceauth"
	"cmbuyer/admin/internal/storage/sqlite"
)

func main() {
	if err := run(context.Background(), os.Args[1:], os.Stdout, os.Stderr); err != nil {
		log.Print(err)
		os.Exit(1)
	}
}

func run(ctx context.Context, args []string, stdout, stderr io.Writer) error {
	flags := flag.NewFlagSet("device-credentials", flag.ContinueOnError)
	flags.SetOutput(stderr)
	databaseSource := flags.String("database", "", "explicit migrated SQLite data source")
	if err := flags.Parse(args); err != nil {
		return err
	}
	if *databaseSource == "" {
		return errors.New("-database is required")
	}
	if flags.NArg() < 1 {
		return errors.New("usage: device-credentials -database <sqlite-data-source> <issue|list|revoke> [options]")
	}
	command := flags.Arg(0)
	commandArgs := flags.Args()[1:]
	var issueName, revokeDeviceID string
	switch command {
	case "issue":
		commandFlags := flag.NewFlagSet("issue", flag.ContinueOnError)
		commandFlags.SetOutput(stderr)
		commandFlags.StringVar(&issueName, "name", "", "non-secret device display name")
		if err := commandFlags.Parse(commandArgs); err != nil {
			return err
		}
		if issueName == "" || commandFlags.NArg() != 0 {
			return errors.New("usage: device-credentials -database <sqlite-data-source> issue -name <display-name>")
		}
	case "list":
		if len(commandArgs) != 0 {
			return errors.New("usage: device-credentials -database <sqlite-data-source> list")
		}
	case "revoke":
		commandFlags := flag.NewFlagSet("revoke", flag.ContinueOnError)
		commandFlags.SetOutput(stderr)
		commandFlags.StringVar(&revokeDeviceID, "device-id", "", "canonical device UUID")
		if err := commandFlags.Parse(commandArgs); err != nil {
			return err
		}
		if revokeDeviceID == "" || commandFlags.NArg() != 0 {
			return errors.New("usage: device-credentials -database <sqlite-data-source> revoke -device-id <uuid>")
		}
	default:
		return fmt.Errorf("unsupported device credential command %q", command)
	}
	if command == "issue" && !deviceauth.ValidDisplayName(issueName) {
		return deviceauth.ErrInvalidCredential
	}
	if command == "revoke" && !deviceauth.ValidDeviceID(revokeDeviceID) {
		return deviceauth.ErrInvalidCredential
	}

	existingSource, err := existingSQLiteDataSource(*databaseSource)
	if err != nil {
		return err
	}
	database, err := sqlite.Open(existingSource)
	if err != nil {
		return fmt.Errorf("open SQLite database: %w", err)
	}
	defer database.Close()
	store, err := deviceauth.NewCredentialStore(database)
	if err != nil {
		return err
	}

	switch command {
	case "issue":
		issued, err := store.Issue(ctx, issueName)
		if err != nil {
			return err
		}
		// The token has json:"-" and is printed only by this explicit post-commit path. Generic
		// serialization, list, revoke, errors, and server responses therefore cannot disclose it.
		if _, err := fmt.Fprintf(stdout, "device_id=%s\ndisplay_name=%s\ntoken=%s\ncreated_at=%s\n",
			issued.DeviceID, issued.DisplayName, issued.Token, issued.CreatedAt.Format(time.RFC3339Nano)); err != nil {
			return errors.New("write issued device credential")
		}
		return nil
	case "list":
		credentials, err := store.List(ctx)
		if err != nil {
			return err
		}
		return writeJSON(stdout, credentials)
	case "revoke":
		credential, changed, err := store.Revoke(ctx, revokeDeviceID)
		if err != nil {
			return err
		}
		return writeJSON(stdout, struct {
			Credential deviceauth.Credential `json:"credential"`
			RevokedNow bool                  `json:"revoked_now"`
		}{Credential: credential, RevokedNow: changed})
	}
	return errors.New("unreachable device credential command")
}

func existingSQLiteDataSource(value string) (string, error) {
	if value == "" || strings.TrimSpace(value) != value {
		return "", errors.New("-database must name an existing file-backed SQLite database")
	}

	var parsed *url.URL
	var query url.Values
	if strings.HasPrefix(strings.ToLower(value), "file:") {
		var err error
		parsed, err = url.Parse(value)
		if err != nil || !strings.EqualFold(parsed.Scheme, "file") || parsed.User != nil || parsed.Host != "" || parsed.Fragment != "" {
			return "", errors.New("-database file URI is invalid")
		}
		// go-sqlite3 recognizes URI filenames only with the exact lowercase file: prefix.
		// Canonicalize accepted scheme casing before mode=rw reaches the driver, otherwise a
		// mixed-case input could be treated as a plain filename and recreate a missing database.
		parsed.Scheme = "file"
		query, err = url.ParseQuery(parsed.RawQuery)
		if err != nil {
			return "", errors.New("-database query parameters are invalid")
		}
		fileName := parsed.Path
		if parsed.Opaque != "" {
			fileName = parsed.Opaque
		}
		decodedName, err := url.PathUnescape(fileName)
		if err != nil || fileName == "" || strings.EqualFold(decodedName, ":memory:") {
			return "", errors.New("-database must name an existing file-backed SQLite database")
		}
	} else {
		pathPart, rawQuery, hasQuery := strings.Cut(value, "?")
		if pathPart == "" || strings.EqualFold(pathPart, ":memory:") || strings.Contains(pathPart, "://") {
			return "", errors.New("-database must name an existing file-backed SQLite database")
		}
		var err error
		query, err = url.ParseQuery(rawQuery)
		if err != nil {
			return "", errors.New("-database query parameters are invalid")
		}
		normalizedPath := filepath.ToSlash(pathPart)
		if filepath.VolumeName(pathPart) != "" && !strings.HasPrefix(normalizedPath, "/") {
			normalizedPath = "/" + normalizedPath
		}
		parsed = &url.URL{Scheme: "file", Path: normalizedPath}
		if !hasQuery {
			query = make(url.Values)
		}
	}

	modes := query["mode"]
	if len(modes) > 1 || len(modes) == 1 && modes[0] != "rw" {
		return "", errors.New("-database only permits SQLite mode=rw")
	}
	if len(modes) == 0 {
		query.Set("mode", "rw")
	}
	for _, name := range []string{"immutable", "_query_only"} {
		for _, setting := range query[name] {
			if setting != "0" && !strings.EqualFold(setting, "false") {
				return "", errors.New("-database contains a read-only SQLite option")
			}
		}
	}
	parsed.RawQuery = query.Encode()
	parsed.ForceQuery = false
	return parsed.String(), nil
}

func writeJSON(writer io.Writer, value any) error {
	encoder := json.NewEncoder(writer)
	encoder.SetEscapeHTML(true)
	if err := encoder.Encode(value); err != nil {
		return errors.New("write device credential metadata")
	}
	return nil
}