#include "client_send.h"
#include "config.h"
#include "delta.h"
#include "log.h"
#include "protocol.h"
#include "transport_tcp.h"
#include "transport_tls.h"
#include "utils.h"
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* Parse environment variables for source/destination directories and save-to-disk flag. */
static void parse_environment(const char** out_env_source, const char** out_env_dest,
                              bool* out_save_to_disk) {
  *out_env_source = getenv("FASTSYNC_SOURCE_DIR");
  *out_env_dest = getenv("FASTSYNC_DEST_DIR");
  const char* env_save = getenv("FASTSYNC_SAVE_TO_DISK");
  *out_save_to_disk = false;
  if (env_save && (strcmp(env_save, "true") == 0 || strcmp(env_save, "1") == 0))
    *out_save_to_disk = true;
}

/* Parse a string as a positive integer, returning true on success. */
static bool parse_positive_int(const char* s, int* out_val) {
  if (!s || *s == '\0')
    return false;
  char* endptr;
  errno = 0;
  long val = strtol(s, &endptr, 10);
  if (errno != 0 || *endptr != '\0' || val <= 0 || val > INT_MAX)
    return false;
  *out_val = (int)val;
  return true;
}

/* Parse a string as a non-negative integer, returning true on success. */
static bool parse_nonneg_int(const char* s, int* out_val) {
  if (!s || *s == '\0')
    return false;
  char* endptr;
  errno = 0;
  long val = strtol(s, &endptr, 10);
  if (errno != 0 || *endptr != '\0' || val < 0 || val > INT_MAX)
    return false;
  *out_val = (int)val;
  return true;
}

/* Duplicate a string argument into *dest, freeing the old value. Returns 0 on success, -1 on
 * failure. */
static int set_string_option(char** dest, const char* value, const char* option_name) {
  char* dup = str_dup(value);
  if (!dup) {
    fprintf(stderr, "Error: memory allocation failed for %s\n", option_name);
    return -1;
  }
  free(*dest);
  *dest = dup;
  return 0;
}

/* Parse a string as a positive integer into *dest. Returns 0 on success, -1 on error. */
static int set_positive_int_option(int* dest, const char* value, const char* option_name) {
  if (!parse_positive_int(value, dest)) {
    fprintf(stderr, "Error: %s must be a positive integer\n", option_name);
    return -1;
  }
  return 0;
}

/* Parse a string as a non-negative integer into *dest. Returns 0 on success, -1 on error. */
static int set_nonneg_int_option(int* dest, const char* value, const char* option_name) {
  if (!parse_nonneg_int(value, dest)) {
    fprintf(stderr, "Error: %s must be a non-negative integer\n", option_name);
    return -1;
  }
  return 0;
}

static void print_usage(void);
static int read_patterns_from_file(const char* filepath, char*** patterns, int* count);

/* Parse CLI arguments into config. Returns 0 on success, -1 on error, 1 for help/clean-exit. */
static int parse_args(Config* config, int argc, char* argv[], int* positional_args,
                      int* positional_count) {
  for (int i = 1; i < argc; i++) {
    if (strcmp(argv[i], "--help") == 0) {
      print_usage();
      return 1;
    } else if (strcmp(argv[i], "-a") == 0 || strcmp(argv[i], "--archive") == 0) {
      config->use_compression = true;
      config->use_multithreading = true;
      config->use_metadata = true;
      log_message(LOG_LEVEL_INFO, "Enabled archive mode (-c -m -M)");
    } else if (strcmp(argv[i], "-n") == 0 || strcmp(argv[i], "--dry-run") == 0) {
      config->dry_run = true;
    } else if (strcmp(argv[i], "-p") == 0 && i + 1 < argc) {
      if (!parse_positive_int(argv[++i], &config->ssh_port)) {
        fprintf(stderr, "Error: invalid --port/-p value: %s\n", argv[i]);
        return -1;
      }
    } else if (strcmp(argv[i], "--delete") == 0) {
      config->use_delete = true;
    } else if (strcmp(argv[i], "--exclude") == 0 && i + 1 < argc) {
      char** tmp = realloc(config->exclude_patterns, (config->exclude_count + 1) * sizeof(char*));
      if (!tmp) {
        fprintf(stderr, "Error: memory allocation failed for --exclude\n");
        return -1;
      }
      config->exclude_patterns = tmp;
      char* dup = str_dup(argv[++i]);
      if (!dup) {
        fprintf(stderr, "Error: memory allocation failed for --exclude\n");
        return -1;
      }
      config->exclude_patterns[config->exclude_count++] = dup;
    } else if (strcmp(argv[i], "--include") == 0 && i + 1 < argc) {
      char** tmp = realloc(config->include_patterns, (config->include_count + 1) * sizeof(char*));
      if (!tmp) {
        fprintf(stderr, "Error: memory allocation failed for --include\n");
        return -1;
      }
      config->include_patterns = tmp;
      char* dup = str_dup(argv[++i]);
      if (!dup) {
        fprintf(stderr, "Error: memory allocation failed for --include\n");
        return -1;
      }
      config->include_patterns[config->include_count++] = dup;
    } else if (strcmp(argv[i], "--max-size") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
      unsigned long long val = strtoull(argv[++i], &end, 10);
      if (errno != 0 || *end != '\0') {
        fprintf(stderr, "Error: --max-size must be a non-negative integer\n");
        return -1;
      }
      config->max_size = val;
    } else if (strcmp(argv[i], "--min-size") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
      unsigned long long val = strtoull(argv[++i], &end, 10);
      if (errno != 0 || *end != '\0') {
        fprintf(stderr, "Error: --min-size must be a non-negative integer\n");
        return -1;
      }
      config->min_size = val;
    } else if (strcmp(argv[i], "--incremental") == 0) {
      config->use_incremental = true;
    } else if (strcmp(argv[i], "--delta") == 0) {
      config->use_delta = true;
    } else if (strcmp(argv[i], "--delta-block") == 0 && i + 1 < argc) {
      unsigned long long val = strtoull(argv[++i], NULL, 10);
      if (val >= DELTA_BLOCK_SIZE_MIN && val <= DELTA_BLOCK_SIZE_MAX)
        config->delta_block_size = (uint32_t)val;
      else
        fprintf(stderr, "Warning: --delta-block value %llu out of range, using default\n", val);
    } else if (strcmp(argv[i], "--delta-max") == 0 && i + 1 < argc) {
      unsigned long long val = strtoull(argv[++i], NULL, 10);
      if (val >= DELTA_MIN_FILE_SIZE)
        config->delta_max_file_size = val;
      else
        fprintf(stderr, "Warning: --delta-max value %llu too small, using default\n", val);
    } else if (strcmp(argv[i], "-c") == 0 || strcmp(argv[i], "-z") == 0) {
      config->use_compression = true;
      log_message(LOG_LEVEL_INFO, "Enabled Compression");
      if (i + 1 < argc) {
        char* end_ptr;
        long level = strtol(argv[i + 1], &end_ptr, 10);
        if (*end_ptr == '\0') {
          config->compression_level = (int)level;
          log_message(LOG_LEVEL_INFO, "Set Compression level to %ld", level);
          i++;
        }
      }
    } else if (strcmp(argv[i], "--source-dir") == 0 && i + 1 < argc) {
      if (set_string_option(&config->send_directory, argv[++i], "--source-dir") != 0)
        return -1;
    } else if (strcmp(argv[i], "--dest-dir") == 0 && i + 1 < argc) {
      if (set_string_option(&config->receive_root_directory, argv[++i], "--dest-dir") != 0)
        return -1;
    } else if (strcmp(argv[i], "--save-to-disk") == 0) {
      config->save_to_disk = true;
    } else if (strcmp(argv[i], "-M") == 0 || strcmp(argv[i], "--preserve") == 0) {
      config->use_metadata = true;
      log_message(LOG_LEVEL_INFO, "Enabled metadata preservation");
    } else if (strcmp(argv[i], "-f") == 0 || strcmp(argv[i], "--sendfile") == 0) {
      config->use_sendfile = true;
      log_message(LOG_LEVEL_INFO, "Enabled sendfile");
    } else if (strcmp(argv[i], "-m") == 0) {
      config->use_multithreading = true;
      log_message(LOG_LEVEL_INFO, "Enabled Multithreading");
    } else if (strcmp(argv[i], "-s") == 0) {
      config->use_chunk_serialization = true;
      log_message(LOG_LEVEL_INFO, "Enabled Chunk Serialization");
    } else if (strcmp(argv[i], "--server-host") == 0 && i + 1 < argc) {
      if (set_string_option(&config->server_host, argv[++i], "--server-host") != 0)
        return -1;
    } else if (strcmp(argv[i], "--server-port") == 0 && i + 1 < argc) {
      if (!parse_positive_int(argv[++i], &config->server_port)) {
        fprintf(stderr, "Error: invalid --server-port value: %s\n", argv[i]);
        return -1;
      }
    } else if (strcmp(argv[i], "--bwlimit") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
      unsigned long long kbps = strtoull(argv[++i], &end, 10);
      if (errno != 0 || *end != '\0' || kbps == 0) {
        fprintf(stderr, "Error: --bwlimit must be a positive integer\n");
        return -1;
      }
      if (kbps > ULLONG_MAX / 1024) {
        fprintf(stderr, "Error: --bwlimit value too large\n");
        return -1;
      }
      io_set_bwlimit(kbps * 1024);
      log_message(LOG_LEVEL_INFO, "Set bandwidth limit to %llu KB/s", kbps);
    } else if (strcmp(argv[i], "--progress") == 0) {
      config->show_progress = true;
    } else if (strcmp(argv[i], "--chunk-size") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
      unsigned long long val = strtoull(argv[++i], &end, 10);
      if (errno != 0 || *end != '\0' || val == 0) {
        fprintf(stderr, "Error: --chunk-size must be a positive integer\n");
        return -1;
      }
      config->chunk_size = val;
    } else if (strcmp(argv[i], "--tls") == 0) {
      config->use_tls = true;
    } else if (strcmp(argv[i], "--cert") == 0 && i + 1 < argc) {
      if (set_string_option(&config->tls_cert, argv[++i], "--cert") != 0)
        return -1;
    } else if (strcmp(argv[i], "--key") == 0 && i + 1 < argc) {
      if (set_string_option(&config->tls_key, argv[++i], "--key") != 0)
        return -1;
    } else if (strcmp(argv[i], "--ca") == 0 && i + 1 < argc) {
      if (set_string_option(&config->tls_ca, argv[++i], "--ca") != 0)
        return -1;
    } else if (strcmp(argv[i], "--timeout") == 0 && i + 1 < argc) {
      if (set_positive_int_option(&config->timeout, argv[++i], "--timeout") != 0)
        return -1;
    } else if (strcmp(argv[i], "--contimeout") == 0 && i + 1 < argc) {
      if (set_positive_int_option(&config->contimeout, argv[++i], "--contimeout") != 0)
        return -1;
    } else if (strcmp(argv[i], "-q") == 0 || strcmp(argv[i], "--quiet") == 0 ||
               strcmp(argv[i], "--silent") == 0) {
      config->quiet = true;
    } else if (strcmp(argv[i], "--backup") == 0) {
      config->backup = true;
    } else if (strcmp(argv[i], "--backup-dir") == 0 && i + 1 < argc) {
      if (set_string_option(&config->backup_dir, argv[++i], "--backup-dir") != 0)
        return -1;
    } else if (strcmp(argv[i], "--stats") == 0) {
      config->stats = true;
    } else if (strcmp(argv[i], "--max-depth") == 0 && i + 1 < argc) {
      if (set_nonneg_int_option(&config->max_depth, argv[++i], "--max-depth") != 0)
        return -1;
    } else if (strcmp(argv[i], "--log-file") == 0 && i + 1 < argc) {
      FILE* lf = fopen(argv[++i], "a");
      if (!lf) {
        fprintf(stderr, "Error: could not open log file '%s': %s\n", argv[i], strerror(errno));
        return -1;
      }
      config->log_file = lf;
      log_set_file(lf);
    } else if (strcmp(argv[i], "--queue-size") == 0 && i + 1 < argc) {
      if (set_positive_int_option(&config->queue_size, argv[++i], "--queue-size") != 0)
        return -1;
    } else if (strcmp(argv[i], "--exclude-from") == 0 && i + 1 < argc) {
      if (read_patterns_from_file(argv[++i], &config->exclude_patterns, &config->exclude_count) !=
          0)
        return -1;
    } else if (strcmp(argv[i], "--include-from") == 0 && i + 1 < argc) {
      if (read_patterns_from_file(argv[++i], &config->include_patterns, &config->include_count) !=
          0)
        return -1;
    } else if (strcmp(argv[i], "--partial") == 0) {
      config->partial = true;
    } else if (strcmp(argv[i], "--fastsync-server-path") == 0 && i + 1 < argc) {
      if (set_string_option(&config->fastsync_server_path, argv[++i], "--fastsync-server-path") !=
          0)
        return -1;
    } else if (strcmp(argv[i], "-v") == 0 || strcmp(argv[i], "--verbose") == 0) {
      set_log_level(LOG_LEVEL_DEBUG);
    } else if (strcmp(argv[i], "-l") == 0 || strcmp(argv[i], "--links") == 0) {
      config->follow_symlinks = true;
    } else if (strcmp(argv[i], "--copy-links") == 0) {
      config->copy_links = true;
    } else if (strcmp(argv[i], "--safe-links") == 0) {
      config->safe_links = true;
    } else if (strcmp(argv[i], "--copy-unsafe-links") == 0) {
      config->copy_unsafe_links = true;
    } else if (strcmp(argv[i], "-H") == 0 || strcmp(argv[i], "--hard-links") == 0) {
      config->preserve_hard_links = true;
    } else if (strcmp(argv[i], "-A") == 0 || strcmp(argv[i], "--acls") == 0) {
      config->preserve_acls = true;
    } else if (strcmp(argv[i], "-X") == 0 || strcmp(argv[i], "--xattrs") == 0) {
      config->preserve_xattrs = true;
    } else if (strcmp(argv[i], "-D") == 0 || strcmp(argv[i], "--devices") == 0) {
      config->preserve_devices = true;
    } else if (strcmp(argv[i], "-S") == 0 || strcmp(argv[i], "--sparse") == 0) {
      config->preserve_sparse = true;
    } else if (strcmp(argv[i], "-i") == 0 || strcmp(argv[i], "--itemize-changes") == 0) {
      config->itemize_changes = true;
    } else if (strcmp(argv[i], "--out-format") == 0 && i + 1 < argc) {
      if (set_string_option(&config->out_format, argv[++i], "--out-format") != 0)
        return -1;
    } else if (strcmp(argv[i], "--info") == 0 && i + 1 < argc) {
      if (set_nonneg_int_option(&config->info_level, argv[++i], "--info") != 0)
        return -1;
    } else if (strcmp(argv[i], "--debug") == 0 && i + 1 < argc) {
      if (set_nonneg_int_option(&config->debug_level, argv[++i], "--debug") != 0)
        return -1;
    } else if (strcmp(argv[i], "--list-only") == 0) {
      config->list_only = true;
    } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--human-readable") == 0) {
      config->human_readable = true;
    } else if (strcmp(argv[i], "-u") == 0 || strcmp(argv[i], "--update") == 0) {
      config->update = true;
    } else if (strcmp(argv[i], "--inplace") == 0) {
      config->inplace = true;
    } else if (strcmp(argv[i], "--append") == 0) {
      config->append = true;
    } else if (strcmp(argv[i], "--append-verify") == 0) {
      config->append_verify = true;
    } else if (strcmp(argv[i], "--delete-excluded") == 0) {
      config->delete_excluded = true;
    } else if (strcmp(argv[i], "--delete-after") == 0) {
      config->delete_after = true;
    } else if (strcmp(argv[i], "--max-delete") == 0 && i + 1 < argc) {
      if (set_nonneg_int_option(&config->max_delete, argv[++i], "--max-delete") != 0)
        return -1;
    } else if (strcmp(argv[i], "--filter") == 0 && i + 1 < argc) {
      if (!config->filters)
        config->filters = array_list_create(free);
      char* dup = str_dup(argv[++i]);
      if (!dup)
        return -1;
      array_list_add(config->filters, dup);
    } else if (strcmp(argv[i], "--files-from") == 0 && i + 1 < argc) {
      if (set_string_option(&config->files_from, argv[++i], "--files-from") != 0)
        return -1;
    } else if (strcmp(argv[i], "--cvs-exclude") == 0) {
      config->cvs_exclude = true;
    } else if (strcmp(argv[i], "--prune-empty-dirs") == 0) {
      config->prune_empty_dirs = true;
    } else if (strcmp(argv[i], "-R") == 0 || strcmp(argv[i], "--relative") == 0) {
      config->relative = true;
    } else if (strcmp(argv[i], "-e") == 0 || strcmp(argv[i], "--rsh") == 0) {
      if (i + 1 < argc) {
        if (set_string_option(&config->rsh_command, argv[++i], "-e/--rsh") != 0)
          return -1;
      } else {
        fprintf(stderr, "Error: -e/--rsh requires a command argument\n");
        return -1;
      }
    } else if (strcmp(argv[i], "--rsync-path") == 0 && i + 1 < argc) {
      if (set_string_option(&config->rsync_path, argv[++i], "--rsync-path") != 0)
        return -1;
    } else if (strcmp(argv[i], "--temp-dir") == 0 && i + 1 < argc) {
      if (set_string_option(&config->temp_dir, argv[++i], "--temp-dir") != 0)
        return -1;
    } else if (strcmp(argv[i], "--compare-dest") == 0 && i + 1 < argc) {
      if (set_string_option(&config->compare_dest, argv[++i], "--compare-dest") != 0)
        return -1;
    } else if (strcmp(argv[i], "--copy-dest") == 0 && i + 1 < argc) {
      if (set_string_option(&config->copy_dest, argv[++i], "--copy-dest") != 0)
        return -1;
    } else if (strcmp(argv[i], "--link-dest") == 0 && i + 1 < argc) {
      if (set_string_option(&config->link_dest, argv[++i], "--link-dest") != 0)
        return -1;
    } else if (argv[i][0] == '-') {
      fprintf(stderr, "Unknown option: %s\n", argv[i]);
      print_usage();
      return -1;
    } else {
      if (*positional_count < 2)
        positional_args[(*positional_count)++] = i;
      else {
        fprintf(stderr, "Unexpected argument: %s\n", argv[i]);
        print_usage();
        return -1;
      }
    }
  }
  return 0;
}

/* Validate config after parsing. Returns true if valid. */
static bool validate_config(const Config* config) {
  if (!config->send_directory || !config->receive_root_directory) {
    fprintf(stderr, "Error: source and destination directories are required\n");
    print_usage();
    return false;
  }
  if (config->use_sendfile && (config->use_chunk_serialization || config->use_compression)) {
    fprintf(stderr, "Error: -f/--sendfile cannot be combined with -c (compression) or -s (chunk "
                    "serialization)\n");
    return false;
  }
  if (config->transport == TRANSPORT_SSH && config->use_sendfile) {
    fprintf(stderr, "Error: -f/--sendfile is not supported with SSH transport\n");
    return false;
  }
  if (config->use_incremental && config->use_chunk_serialization) {
    fprintf(stderr, "Error: --incremental is not supported with -s (chunk serialization)\n");
    return false;
  }
  if (config->use_delta && !config->use_incremental) {
    fprintf(stderr, "Error: --delta requires --incremental\n");
    return false;
  }
  if (config->use_delta && config->use_chunk_serialization) {
    fprintf(stderr, "Error: --delta cannot be combined with -s (chunk serialization)\n");
    return false;
  }
  if (config->use_delta && config->use_sendfile) {
    fprintf(stderr, "Error: --delta cannot be combined with -f (sendfile)\n");
    return false;
  }
  if (config->use_tls) {
    if (!config->tls_cert || !config->tls_key) {
      fprintf(stderr, "Error: --tls requires --cert and --key\n");
      return false;
    }
  }
  return true;
}

static void print_usage(void) {
  printf("Usage:\n");
  printf("  fastsync [options] <source> <destination>\n");
  printf("  fastsync [options] --source-dir <src> --dest-dir <dst>\n");
  printf("\n");
  printf("Destination formats:\n");
  printf("  user@host:/path     SSH transport (rsync-style)\n");
  printf("  host:/path          SSH transport (current user)\n");
  printf("  /local/path         TCP transport (requires server on localhost:8080)\n");
  printf("\n");
  printf("Options:\n");
  printf("  -c [level]          Enable compression (level 1-22, default 5)\n");
  printf("  -z [level]          Alias for -c\n");
  printf("  -a, --archive       Archive mode (-c -m -M)\n");
  printf("  -n, --dry-run       Show what would be transferred\n");
  printf("  -p <port>           SSH port (default: 22)\n");
  printf("  --progress          Show transfer progress\n");
  printf("  --delete            Delete files on receiver not in source\n");
  printf("  --exclude <pattern> Exclude files matching pattern\n");
  printf("  --include <pattern> Only include files matching pattern\n");
  printf("  --exclude-from <file> Read exclude patterns from file\n");
  printf("  --include-from <file> Read include patterns from file\n");
  printf("  --max-size <n>      Skip files larger than n bytes\n");
  printf("  --min-size <n>      Skip files smaller than n bytes\n");
  printf("  --incremental       Skip files unchanged since last transfer\n");
  printf("  --delta             Delta transfer for changed files (requires --incremental)\n");
  printf("  --delta-block <n>   Delta block size in bytes (default: %d)\n",
         DELTA_BLOCK_SIZE_DEFAULT);
  printf("  --delta-max <n>     Max file size for delta transfer (default: %llu)\n",
         DELTA_MAX_FILE_SIZE);
  printf("  -m                  Enable multithreading\n");
  printf("  -s                  Enable chunk serialization\n");
  printf("  -f                  Enable sendfile (TCP only, not with -c or -s)\n");
  printf("  -v, --verbose       Enable debug logging\n");
  printf("  -M, --preserve      Preserve file metadata\n");
  printf("  --chunk-size <n>    Chunk size in bytes (default: %d)\n", DEFAULT_CHUNK_SIZE);
  printf("  --source-dir <path> Source directory\n");
  printf("  --dest-dir <path>   Destination directory\n");
  printf("  --save-to-disk      Write received files to disk\n");
  printf("  --server-host <ip>  Server IP address (default: 127.0.0.1)\n");
  printf("  --server-port <n>   Server port (default: 8080)\n");
  printf("  --bwlimit <KB/s>    Bandwidth limit in kilobytes per second\n");
  printf("  --tls               Enable TLS encryption\n");
  printf("  --cert <path>       TLS certificate file (PEM)\n");
  printf("  --key <path>        TLS private key file (PEM)\n");
  printf("  --ca <path>         TLS CA certificate file (PEM)\n");
  printf("  --timeout <sec>     I/O timeout in seconds (default: 30)\n");
  printf("  --contimeout <sec>  Connection timeout in seconds (default: 10)\n");
  printf("  -q, --quiet         Suppress non-error output\n");
  printf("  --silent            Alias for --quiet\n");
  printf("  --backup            Backup existing files before overwriting\n");
  printf("  --backup-dir <dir>  Directory for backups (requires --backup)\n");
  printf("  --stats             Print transfer statistics at end\n");
  printf("  --max-depth <n>     Maximum directory depth (0=unlimited)\n");
  printf("  --log-file <path>   Write log messages to file\n");
  printf("  --queue-size <n>    Queue capacity for multithreaded mode (default: 100)\n");
  printf("  --partial           Keep partial files on interrupted transfer\n");
  printf("  --fastsync-server-path <path>\n");
  printf("                      Path to fastsync-server on remote (default: fastsync-server)\n");
  printf("  -l, --links         Copy symlinks as symlinks\n");
  printf("  --copy-links        Transform symlinks into referent files\n");
  printf("  --safe-links        Skip symlinks that point outside transfer tree\n");
  printf("  --copy-unsafe-links  Only transform unsafe symlinks into referent files\n");
  printf("  -H, --hard-links    Preserve hard links\n");
  printf("  -A, --acls          Preserve ACLs\n");
  printf("  -X, --xattrs        Preserve extended attributes\n");
  printf("  -D, --devices       Preserve device files\n");
  printf("  -S, --sparse        Handle sparse files efficiently\n");
  printf("  -i, --itemize-changes  Show per-file change summary\n");
  printf("  --out-format <fmt>  Custom output format string\n");
  printf("  --info <flags>      Info verbosity level\n");
  printf("  --debug <flags>     Debug verbosity level\n");
  printf("  --list-only         List files without transferring\n");
  printf("  -h, --human-readable  Human-readable numbers\n");
  printf("  -u, --update        Skip files newer on destination\n");
  printf("  --inplace           Update files in-place (no temp+rename)\n");
  printf("  --append            Append data to shorter files\n");
  printf("  --append-verify     Append with verify\n");
  printf("  --delete-excluded   Also delete excluded files\n");
  printf("  --delete-after      Delete after transfer, not before\n");
  printf("  --max-delete <n>    Maximum number of files to delete\n");
  printf("  --filter <rule>     Add file filtering rule\n");
  printf("  --files-from <file> Read file list from file\n");
  printf("  --cvs-exclude       Auto-ignore CVS files\n");
  printf("  --prune-empty-dirs  Omit empty directories from transfer\n");
  printf("  -R, --relative      Use relative paths\n");
  printf("  -e, --rsh <cmd>     Specify remote shell\n");
  printf("  --rsync-path <path> Path to remote binary\n");
  printf("  --temp-dir <dir>    Temporary directory for files\n");
  printf("  --compare-dest <dir>  Compare destination\n");
  printf("  --copy-dest <dir>   Copy destination\n");
  printf("  --link-dest <dir>   Link destination\n");
  printf("  --help              Show this help\n");
}

static int read_patterns_from_file(const char* filepath, char*** patterns, int* count) {
  FILE* fp = fopen(filepath, "r");
  if (!fp) {
    fprintf(stderr, "Error: could not open pattern file '%s': %s\n", filepath, strerror(errno));
    return -1;
  }
  char line[4096];
  while (fgets(line, sizeof(line), fp)) {
    char* p = line;
    while (*p == ' ' || *p == '\t')
      p++;
    if (*p == '#' || *p == '\n' || *p == '\0')
      continue;
    size_t len = strlen(p);
    while (len > 0 && (p[len - 1] == '\n' || p[len - 1] == '\r'))
      p[--len] = '\0';
    if (len == 0)
      continue;
    char** tmp = realloc(*patterns, (*count + 1) * sizeof(char*));
    if (!tmp) {
      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
      fclose(fp);
      return -1;
    }
    *patterns = tmp;
    char* dup = str_dup(p);
    if (!dup) {
      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
      fclose(fp);
      return -1;
    }
    (*patterns)[(*count)++] = dup;
  }
  fclose(fp);
  return 0;
}

int main(int argc, char* argv[]) {
  const char* env_source = NULL;
  const char* env_dest = NULL;
  bool save_to_disk = false;
  parse_environment(&env_source, &env_dest, &save_to_disk);

  int exit_code = 0;
  bool config_owned_by_pipeline = false;
  Config* config = config_create();
  if (!config) {
    fprintf(stderr, "Error: failed to allocate config\n");
    return 1;
  }
  config->save_to_disk = save_to_disk;

  int positional_args[2];
  int positional_count = 0;

  int parse_ret = parse_args(config, argc, argv, positional_args, &positional_count);
  if (parse_ret != 0) {
    if (parse_ret < 0)
      exit_code = 1;
    goto cleanup;
  }

  /* Handle positional arguments or fall back to environment variables */
  if (positional_count == 2) {
    free(config->send_directory);
    free(config->receive_root_directory);
    config->send_directory = str_dup(argv[positional_args[0]]);
    if (!config->send_directory) {
      fprintf(stderr, "Error: memory allocation failed\n");
      exit_code = 1;
      goto cleanup;
    }
    config->receive_root_directory = str_dup(argv[positional_args[1]]);
    if (!config->receive_root_directory) {
      fprintf(stderr, "Error: memory allocation failed\n");
      exit_code = 1;
      goto cleanup;
    }
    config->save_to_disk = true;
    config_parse_ssh_dest(config);
  } else if (positional_count == 1) {
    fprintf(stderr, "Error: missing destination argument\n");
    print_usage();
    exit_code = 1;
    goto cleanup;
  } else {
    if (!config->send_directory && env_source) {
      config->send_directory = str_dup(env_source);
      if (!config->send_directory) {
        fprintf(stderr, "Error: memory allocation failed\n");
        exit_code = 1;
        goto cleanup;
      }
    }
    if (!config->receive_root_directory && env_dest) {
      config->receive_root_directory = str_dup(env_dest);
      if (!config->receive_root_directory) {
        fprintf(stderr, "Error: memory allocation failed\n");
        exit_code = 1;
        goto cleanup;
      }
    }
  }

  if (!validate_config(config)) {
    exit_code = 1;
    goto cleanup;
  }

  /* Enable implicit flags */
  if (config->use_incremental && !config->use_metadata) {
    log_message(LOG_LEVEL_INFO, "Enabling metadata preservation for --incremental");
    config->use_metadata = true;
  }
  if (config->use_delta && !config->use_metadata) {
    log_message(LOG_LEVEL_INFO, "Enabling metadata preservation for --delta");
    config->use_metadata = true;
  }

  /* Initialize TLS if needed */
  if (config->use_tls)
    tls_global_init();

  tcp_set_timeouts(config->timeout, config->contimeout);

  /* Execute transfer */
  if (config->use_multithreading) {
    config_owned_by_pipeline = true;
    exit_code = send_files_multithreaded(config);
  } else {
    exit_code = send_files(config);
  }

cleanup:
  if (config) {
    if (config->log_file)
      fclose(config->log_file);
    if (!config_owned_by_pipeline)
      config_delete(config);
  }
  return exit_code;
}