#!/usr/bin/env bash
# Summary: Configure the shell environment for pyenv
# Usage: eval "$(pyenv init [-|--path] [--no-push-path] [--no-rehash] [<shell>])"
#        pyenv init --install [<shell>]
#        pyenv init --detect-shell [<shell>]

set -e
[ -n "$PYENV_DEBUG" ] && set -x

# Provide pyenv completions
if [ "$1" = "--complete" ]; then
  echo -
  echo --path
  echo --install
  echo --no-push-path
  echo --no-rehash
  echo --detect-shell
  echo bash
  echo fish
  echo ksh
  echo pwsh
  echo zsh
  exit
fi

mode="help"

while [ "$#" -gt 0 ]; do
  case "$1" in
    -)
      mode="print"
      ;;
    --path)
      mode="path"
      ;;
    --install)
      mode="install"
      ;;
    --detect-shell)
      mode="detect-shell"
      ;;
    --no-push-path)
      no_push_path=1
      ;;
    --no-rehash)
      no_rehash=1
      ;;
    *)
      shell="$1"
      ;;
  esac
  shift
done

# If shell is not provided, detect it.
if [ -z "$shell" ]; then
  if shell=$(tr '\0' ' ' 2>/dev/null </proc/"$PPID"/cmdline);then
  	  :
  else
  	  shell=$(ps p "$PPID" -o 'args=' 2>/dev/null || true)
  fi
  shell="${shell%% *}"
  shell="${shell##-}"
  shell="${shell:-$SHELL}"
  shell="${shell##*/}"
  shell="${shell%%-*}"
fi

function main() {
  case "$mode" in
  "help")
    help_
    exit 1
    ;;
  "path")
    print_path
    print_rehash
    exit 0
    ;;
  "print")
    init_dirs
    print_path
    print_env
    print_completion
    print_rehash
    print_shell_function
    exit 0
    ;;
  "detect-shell")
    detect_profile
    print_detect_shell
    exit 0
    ;;
  "install")
    install_shell_startup_files
    exit 0
    ;;
  esac
  # should never get here
  exit 2
}

function detect_profile() {
  case "$shell" in
  bash )
    if [ -e "${HOME}/.bash_profile" ]; then
      profile='~/.bash_profile'
    else
      profile='~/.profile'
    fi
    profile_explain="~/.bash_profile if it exists, otherwise ~/.profile"
    rc='~/.bashrc'
    ;;
  fish )
    profile='~/.config/fish/config.fish'
    rc='~/.config/fish/config.fish'
    ;;
  pwsh )
    profile='~/.config/powershell/profile.ps1'
    rc='~/.config/powershell/profile.ps1'
    ;;
  zsh )
    profile='~/.zprofile'
    rc='~/.zshrc'
    ;;
  ksh | ksh93 | mksh )
    # There are two implementations of Korn shell: AT&T (ksh93) and Mir (mksh).
    # Systems may have them installed under those names, or as ksh, so those
    # are recognized here. The obsolete ksh88 (subsumed by ksh93) and pdksh
    # (subsumed by mksh) are not included, since they are unlikely to still
    # be in use as interactive shells anywhere.
    profile='~/.profile'
    rc='~/.profile'
    ;;
  * )
    profile=
    rc=
    profile_explain='your shell'\''s login startup file'
    rc_explain='your shell'\''s interactive startup file'
    ;;
  esac
}

function print_detect_shell() {
  echo "PYENV_SHELL_DETECT=$shell"
  echo "PYENV_PROFILE_DETECT=$profile"
  echo "PYENV_RC_DETECT=$rc"
}

function help_() {
  detect_profile
  {
    case "$shell" in
    fish )
      echo "# Add pyenv executable to PATH by running"
      echo "# the following interactively:"
      echo
      print_fish_user_path_setup
      echo
      echo "# Load pyenv automatically by appending"
      echo "# the following to ~/.config/fish/config.fish:"
      echo
      print_fish_shell_setup
      echo
      ;;
    pwsh )
      echo '# Load pyenv automatically by appending'
      echo "# the following to $profile :"
      echo
      print_pwsh_shell_setup
      ;;
    * )
      echo '# Load pyenv automatically by appending'
      echo -n "# the following to "
      if [[ "$profile" == "$rc" && -z $rc_explain ]]; then
        echo "${profile_explain:-$profile} :"
      else
        echo
        echo "# ${profile_explain:-$profile} (for login shells)"
        echo "# and ${rc_explain:-$rc} (for interactive shells) :"
      fi
      echo
      print_posix_shell_setup
      ;;
    esac
    echo
    echo '# Restart your shell for the changes to take effect.'
    echo
  } >&2
}

function print_posix_shell_setup() {
  echo 'export PYENV_ROOT="$HOME/.pyenv"'
  echo '[[ -d $PYENV_ROOT/bin ]] && export PATH="$PYENV_ROOT/bin:$PATH"'
  echo 'eval "$(pyenv init - '$shell')"'
}

function print_fish_shell_setup() {
  echo 'pyenv init - fish | source'
}

function print_fish_user_path_setup() {
  echo 'set -Ux PYENV_ROOT $HOME/.pyenv'
  echo 'if functions -q fish_add_path'
  echo '  test -d $PYENV_ROOT/bin; and fish_add_path $PYENV_ROOT/bin'
  echo 'else'
  echo '  test -d $PYENV_ROOT/bin; and set -U fish_user_paths $PYENV_ROOT/bin $fish_user_paths'
  echo 'end'
}

function print_pwsh_shell_setup() {
  echo '$Env:PYENV_ROOT="$Env:HOME/.pyenv"'
  echo 'if (Test-Path -LP "$Env:PYENV_ROOT/bin" -PathType Container) {'
  echo '  $Env:PATH="$Env:PYENV_ROOT/bin:$Env:PATH" }'
  echo 'iex ((pyenv init -) -join "`n")'
}

function expand_home_path() {
  local path="$1"
  printf '%s\n' "${path/#\~/$HOME}"
}

function install_shell_startup_files() {
  if [[ -z $HOME ]]; then
    echo "pyenv: HOME must be set to configure shell startup files" >&2
    return 1
  fi

  detect_profile

  local files=()
  local lines=()
  local profile_path rc_path setup

  case "$shell" in
  bash | zsh | ksh | ksh93 | mksh )
    rc_path="$(expand_home_path "$rc")"
    profile_path="$(expand_home_path "$profile")"
    setup="$(print_posix_shell_setup)"
    files=("$rc_path")
    lines=("$setup")
    if [[ $profile_path != "$rc_path" ]]; then
      files+=("$profile_path")
      lines+=("$setup")
    fi
    ;;
  fish )
    rc_path="$(expand_home_path "$rc")"
    files=("$rc_path")
    lines=("$(print_fish_shell_setup)")
    ;;
  pwsh )
    rc_path="$(expand_home_path "$rc")"
    files=("$rc_path")
    lines=("$(print_pwsh_shell_setup)")
    ;;
  * )
    echo "pyenv: cannot automatically configure startup files for $shell" >&2
    return 1
    ;;
  esac

  local index
  for ((index = 0; index < ${#files[@]}; index++)); do
    check_startup_file "${files[$index]}" || return 1
  done

  if [[ $shell == fish ]]; then
    install_fish_user_paths || return 1
  fi

  for ((index = 0; index < ${#files[@]}; index++)); do
    append_lines "${files[$index]}" "${lines[$index]}"
  done
}

function check_startup_file() {
  local file="$1"
  local grep_status

  if [[ ! -e $file ]]; then
    return 0
  fi

  if [[ ! -f $file || ! -r $file ]]; then
    echo "pyenv: failed to inspect $file" >&2
    return 1
  fi

  if grep -Fi pyenv "$file" >/dev/null; then
    echo "pyenv: cannot automatically apply changes to $file: it appears to already contain Pyenv-related code." >&2
    echo "pyenv: review the file's contents and apply changes manually if necessary." >&2
    echo "pyenv: run \`pyenv init $shell\` to see the suggested setup." >&2
    return 1
  else
    grep_status=$?
    if [[ $grep_status == 1 ]]; then
      return 0
    fi
    echo "pyenv: failed to inspect $file" >&2
    return "$grep_status"
  fi
}

function install_fish_user_paths() {
  local fish_setup

  if ! command -v fish >/dev/null; then
    echo "pyenv: fish is not available to configure fish universal variables" >&2
    return 1
  fi

  fish_setup="$(print_fish_user_path_setup)"
  if ! fish -c "$fish_setup"; then
    echo "pyenv: failed to configure fish universal variables" >&2
    return 1
  fi
}

function append_lines() {
  local file="$1"
  local lines="$2"
  local dir last_char

  dir="${file%/*}"
  if [[ $dir != "$file" ]]; then
    mkdir -p "$dir"
  fi

  if [[ -s $file ]]; then
    last_char="$(tail -c 1 "$file")" || return 1
    if [[ -n $last_char ]]; then
      echo >> "$file"
    fi
  fi

  printf '%s\n' "$lines" >> "$file"
}

function init_dirs() {
  mkdir -p "${PYENV_ROOT}/"{shims,versions}
}

function print_path() {
  # if no_push_path is set, guard the PATH manipulation with a check on whether
  # the shim is already in the PATH.
  if [ -n "$no_push_path" ]; then
    case "$shell" in
      fish )
          echo 'if not contains -- "'"${PYENV_ROOT}/shims"'" $PATH'
          print_path_prepend_shims
          echo 'end'
          ;;
      pwsh )
          echo 'if ( $Env:PATH -notmatch "'"${PYENV_ROOT}/shims"'" ) {'
          print_path_prepend_shims
          echo '}'
          ;;
      * )
          echo 'if [[ ":$PATH:" != *'\':"${PYENV_ROOT}"/shims:\''* ]]; then'
          print_path_prepend_shims
          echo 'fi'
          ;;
    esac
  else
    case "$shell" in
      fish )
        echo 'while set pyenv_index (contains -i -- "'"${PYENV_ROOT}/shims"'" $PATH)'
        echo 'set -eg PATH[$pyenv_index]; end; set -e pyenv_index'
        print_path_prepend_shims
        ;;
      pwsh )
        echo '$Env:PATH="$(($Env:PATH -split '"':'"' | where { -not ($_ -match '"'${PYENV_ROOT}/shims'"') }) -join '"':'"')"'
        print_path_prepend_shims
        ;;
      * )
        # Some distros (notably Debian-based) set Bash's SSH_SOURCE_BASHRC compilation option
        # that makes it source `bashrc` under SSH even when not interactive.
        # This is inhibited by a guard in Debian's stock `bashrc` but some people remove it
        # in order to get proper environment for noninteractive remote commands
        # (SSH provides /etc/ssh/sshrc and ~/.ssh/rc for that but no-one seems to use them for some reason).
        # This has caused an infinite `bashrc` execution loop for those people in the below nested Bash invocation (#2367).
        # --norc negates this behavior of such a customized Bash.
        echo 'PATH="$(bash --norc -ec '\''IFS=:; paths=($PATH); '
        echo 'for i in ${!paths[@]}; do '
        echo 'if [[ ${paths[i]} == "'\'\'"${PYENV_ROOT}/shims"\'\''" ]]; then unset '\'\\\'\''paths[i]'\'\\\'\''; '
        echo 'fi; done; '
        echo 'echo "${paths[*]}"'\'')"'
        print_path_prepend_shims
        ;;
    esac
  fi
}

function print_path_prepend_shims() {
    case "$shell" in
      fish )
          echo 'set -gx PATH '\'"${PYENV_ROOT}/shims"\'' $PATH'
          ;;
      pwsh )
          echo '$Env:PATH="'"${PYENV_ROOT}"'/shims:$Env:PATH"'
          ;;
      * )
          echo 'export PATH="'"${PYENV_ROOT}"'/shims:${PATH}"'
          ;;
    esac
}

function print_env() {
  case "$shell" in
  fish )
    echo "set -gx PYENV_SHELL $shell"
    ;;
  pwsh )
    echo '$Env:PYENV_SHELL="'"$shell"'"'
    ;;
  * )
    echo "export PYENV_SHELL=$shell"
    ;;
  esac
}

function print_completion() {
  completion="${_PYENV_INSTALL_PREFIX}/completions/pyenv.${shell}"
  if [ -r "$completion" ]; then
    case "$shell" in
    pwsh )
      echo "iex (gc $completion -Raw)"
      ;;
    * )
      echo "source '$completion'"
      ;;
    esac
  fi
}

function print_rehash() {
  if [ -z "$no_rehash" ]; then
    case "$shell" in
    pwsh )
      echo '& pyenv rehash'
      ;;
    * )
      echo 'command pyenv rehash'
      ;;
    esac
  fi
}

function print_shell_function() {
  commands=(`pyenv-commands --sh`)
  case "$shell" in
  fish )
    echo \
'function pyenv
  set command $argv[1]
  set -e argv[1]

  switch "$command"
  case '"${commands[*]}"'
    source (pyenv "sh-$command" $argv|psub)
  case "*"
    command pyenv "$command" $argv
  end
end'
    ;;
  pwsh )
    cat <<EOS
function pyenv {
  \$command=""
  if ( \$args.Count -gt 0 ) {
    \$command, \$args = \$args
  }

  if ( ("${commands[*]}" -split ' ') -contains \$command ) {
    \$shell_cmds = (& (get-command -commandtype application pyenv) sh-\$command \$args)
    if ( \$shell_cmds.Count -gt 0 ) {
      iex (\$shell_cmds -join "\`n")
    }
  } else {
    & (get-command -commandtype application pyenv) \$command \$args
  }
}
EOS
    ;;
  ksh | ksh93 | mksh )
    echo \
'function pyenv {
  typeset command=${1:-}'
    ;;
  * )
    echo \
'pyenv() {
  local command=${1:-}'
    ;;
  esac
  
  if [ "$shell" != "fish" ] && [ "$shell" != "pwsh" ]; then
    IFS="|"
    echo \
'  [ "$#" -gt 0 ] && shift
  case "$command" in
  '"${commands[*]:-/}"')
    eval "$(pyenv "sh-$command" "$@")"
    ;;
  *)
    command pyenv "$command" "$@"
    ;;
  esac
}'
  fi
}

main