#!/usr/bin/env bash

# Exit 1 if any command errors
set -e

# $1 here is the first argument to this script
BATCH_FILE="$1"

DOWNLOAD_DIR="/export/jellyfin"
YTDLP_LOG_FILE="/export/ytdlp.log"

# 'cat << 'EOF"' is used here to allow for newlines in the command
YTDLP_COMMAND=$(cat << EOF
  /srv/.local/bin/yt-dlp
    -P $DOWNLOAD_DIR
    --sub-format srt
    --write-subs
    --write-thumbnail
EOF
)

printUsage() {
  cat << EOF
Usage: $(basename "$0") <batch.txt>
EOF
}

# log() takes a log level and log line and uses the LOG_LEVEL env var to
# control how/when it is logged
# To enable debug logging set LOG_LEVEL=debug as an env var
log() {
  # '$1' is the first argument passed to this function
  passed_level="$1"

  # '$2' is the first argument passed to this function
  log_line="$2"

  # This is passed from the env as 'LOG_LEVEL='
  env_level="$LOG_LEVEL"

  # Convert env_level to int
  case $env_level in
    "DEBUG")
      min_level_int=0;;
    "INFO")
      min_level_int=1;;
    "ERROR")
      min_level_int=2;;
    *)
      min_level_int=1;;
  esac

  # Convert passed_level to int
  case $passed_level in
    "DEBUG")
      log_level_int=0;;
    "INFO")
      log_level_int=1;;
    "ERROR")
      log_level_int=1;;
    *)
      log_level_int=99;;
  esac

  if [ $log_level_int -ge $min_level_int ]; then
    echo "[$passed_level] $log_line"
  fi
}

validate_args() {
  # If no argument specified, exit 1
  if [ -z "$BATCH_FILE" ]; then
    printUsage
    exit 1
  fi

  # Exit 1 if passed batch file is not a file (or doesn't exist)
  if [ ! -f "$BATCH_FILE" ]; then
    echo "Error: Batch file '$BATCH_FILE' not found"
    printUsage
    exit 1
  fi

  # Exit 0 if passed file contains no urls
  if ! grep -q "^.*http.*" "$BATCH_FILE"; then
    echo "File '$BATCH_FILE' contains no URLs"
    exit 1
  fi

  if [[ ! -O "$BATCH_FILE" ]]; then
    echo "File '$BATCH_FILE' is not owned by user ID '${UID}'"
    echo "Run 'chown ${UID} $BATCH_FILE' before mounting"
    exit 1
  fi

  if [[ ! -O "$DOWNLOAD_DIR" ]]; then
    echo "Directory '$DOWNLOAD_DIR' is not owned by user ID '${UID}'"
    echo "Run 'chown -R ${UID} $DOWNLOAD_DIR' before mounting"
    exit 1
  fi
}

process_batchfile() {
  # Using `read` parse each line of the file as a '$line' while setting IFS=''
  # to prevent lines containing things such as `\n` from being parsed as a
  # literal newline
  while IFS='' read -r line; do
    # Ignore any commented lines RegEx explanation: https://regexr.com/7hs52
    regex_match_leading_comment='^\s*[#].*$'
    if [[ "$line" =~ $regex_match_leading_comment ]]; then
      # RegEx explanation: https://regexr.com/7i073
      line_without_comment=$(echo "$line" | sed 's/^\s*[#]\s*\(.*\)$/\1/')
      log "INFO" "Skipping: $line_without_comment"
      continue
    fi

    log "INFO" "Downloading: $line"

    # Temporarily allow commands to fail without exiting
    set +e

    # Run the command with $line as an argument
    # Quotes are used here as a measure to protect against "\n" and the like
    # '>' is used to overwrite the log file each call so only the last commands
    # output is shown
    $YTDLP_COMMAND "$line" > $YTDLP_LOG_FILE 2>&1

    # Save the exit code of the last command
    exit_code="$?"

    # Re-enable exiting 1 on command failure
    set -e

    if [ "$exit_code" -ne "0" ]; then
      log "ERROR" "Command failed: '$YTDLP_COMMAND'"
      cat $YTDLP_LOG_FILE
      continue
    fi

    log "INFO" "Finished downloading '$line'"

    # By here we can assume the file was downloaded successfully, thus we can
    # comment out the line in the file
    log "DEBUG" "Commenting out '$line' in '$BATCH_FILE'"

    # Prepend a '#" on the current line in the file
    # '|' is used because URLs contain '/' which is the usual sed delimiter
    # 'cp' to a buffer file is used because sed cannot modify the mounted
    # file's inode when using Docker ('-c' is not available in Ubuntu's sed)
    new_file="/export/$(basename "$BATCH_FILE").new"
    cp "$BATCH_FILE" "$new_file"
    sed -i "s|\($line\)|# \1|" "$new_file"
    cp "$new_file" "$BATCH_FILE"

    log "DEBUG" "Finished commenting '$line' from '$BATCH_FILE'"
  done <<< "$(cat "$BATCH_FILE")"
}

main() {
  validate_args

  log "INFO" "Processing $BATCH_FILE"
  process_batchfile
  log "INFO" "Finished processing $BATCH_FILE"
}

# Run main()
main