package main

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"

	"git.asio.asia/nixevol/NixMsg/internal/store"
)

func cmdBackup(args []string) error {
	outPath, err := parseBackupArgs(args)
	if err != nil {
		return err
	}
	cfg, err := loadAndValidateConfig()
	if err != nil {
		return err
	}
	dataAbs, err := filepath.Abs(cfg.DataDir)
	if err != nil {
		return fmt.Errorf("resolve data_dir: %w", err)
	}
	srcAbs, err := filepath.Abs(filepath.Join(dataAbs, store.DBFileName))
	if err != nil {
		return err
	}
	st, err := os.Stat(srcAbs)
	if err != nil {
		if os.IsNotExist(err) {
			return fmt.Errorf("database not found: %s", srcAbs)
		}
		return fmt.Errorf("stat database %s: %w", srcAbs, err)
	}
	if st.IsDir() {
		return fmt.Errorf("database path is a directory: %s", srcAbs)
	}

	if dir := filepath.Dir(outPath); dir != "" && dir != "." {
		if mkErr := os.MkdirAll(dir, 0o755); mkErr != nil {
			return fmt.Errorf("mkdir backup dir: %w", mkErr)
		}
	}
	absOut, err := filepath.Abs(outPath)
	if err != nil {
		return err
	}
	ctx := context.Background()
	write, err := store.OpenExistingWriter(dataAbs, cfg.SQLiteSynchronous)
	if err != nil {
		return err
	}
	defer func() { _ = write.Close() }()
	if err := store.VacuumInto(ctx, write, filepath.ToSlash(absOut)); err != nil {
		return err
	}
	if chErr := os.Chmod(absOut, 0o600); chErr != nil {
		return fmt.Errorf("chmod backup: %w", chErr)
	}
	fmt.Fprintf(os.Stderr, "backup written from %s to %s\n", srcAbs, absOut)
	return nil
}

func parseBackupArgs(args []string) (string, error) {
	var out string
	for i := 0; i < len(args); i++ {
		switch args[i] {
		case "--out":
			if i+1 >= len(args) {
				return "", errors.New("usage: nixmsg backup --out <file.db>")
			}
			out = args[i+1]
			i++
		default:
			return "", fmt.Errorf("unknown argument: %s", args[i])
		}
	}
	if out == "" {
		return "", errors.New("usage: nixmsg backup --out <file.db>")
	}
	return out, nil
}