#!/usr/bin/env bash

# our tiny drop in fake version of curl
# needs to support
# curl -V
# curl -L -s  --user-agent foo --write-out "%{http_code}" -o <path> -- uri

SOURCE_FILE=fake-curls
REPEAT_FILE=already-served

POSITIONAL_ARGS=()

while [[ $# -gt 0 ]]; do
  case $1 in
    -V)
      VERSIONINFO=YES
      shift # past argument
      ;;
    -L|-s|--)
      shift # past argument
      ;;
    -o|--extension)
      OUTPUT="$2"
      shift # past argument
      shift # past value
      ;;
    --user-agent|--write-out)
      shift # past argument
      shift # past value
      ;;
    -*|--*)
      echo "Unknown option $1"
      exit 1
      ;;
    *)
      POSITIONAL_ARGS+=("$1") # save positional arg
      shift # past argument
      ;;
  esac
done

set -- "${POSITIONAL_ARGS[@]}" # restore positional parameters

if [ "$VERSIONINFO" = "YES" ]; then
  echo "curl 0.0.0 (dune-fake)"
  exit 0
fi

# read the offset from the URL
PORT_OFFSET=$(echo "$POSITIONAL_ARGS" | grep -Eo ':[0-9]+' | grep -o '[0-9]*')

POSSIBLE_FILES=$(wc -l < "$SOURCE_FILE")

write_out() {
  # --write_out "${http_code}" does not write a newline
  echo -n \"$1\"
}

>&2 echo '$POSSIBLE_FILES' \""$POSSIBLE_FILES"\" '$PORT_OFFSET' \""$PORT_OFFSET"\"

if [ ! -f "$REPEAT_FILE" ]; then
  file_already_served=false
else
  if grep "^$PORT_OFFSET\$" "$REPEAT_FILE" 2>/dev/null 1>&2 ; then
    file_already_served=true
  else
    file_already_served=false
  fi
fi

>&2 echo File already served: $file_already_served

if [ $PORT_OFFSET -gt $POSSIBLE_FILES ] || [ $file_already_served = true ]; then
  >&2 echo "Failing the download"
  write_out 404
else
  >&2 echo "Succeeding the download"
  # read the line signified by the port from the file
  INPUT=$(head -n "$PORT_OFFSET" "$SOURCE_FILE" | tail -n 1)
  echo "$PORT_OFFSET" >> "$REPEAT_FILE"
  cp "$INPUT" "$OUTPUT"
  write_out 200
fi