tbr

#!/bin/bash

_tbr_source_file_fast() {
  local file="$1"

  source "$file"
}

_tbr_is_sourceable_file() {
  local file="$1"
  local filename="${file##*/}"

  [ -f "$file" ] || return 1
  case "$file" in
    "$TBDIR/init/"*) return 1 ;;
  esac
  [[ "$filename" == *.* ]] && return 1
  [[ "$filename" == .* ]] && return 1
  [[ "$file" == "$TBDIR/tbr" ]] && return 1
  _tbr_is_live_source_file "$file" && return 1
  return 0
}

_tbr_is_live_source_file() {
  local file="$1"

  case "$file" in
    "$TBDIR/xgit") return 0 ;;
  esac

  return 1
}

_tbr_iter_core_files() {
  local file

  [[ -d "$TBDIR/core" ]] || return 0

  while IFS= read -r -d '' file; do
    if _tbr_is_sourceable_file "$file"; then
      printf '%s\0' "$file"
    fi
  done < <(find "$TBDIR/core" -type f -print0 | sort -z)
}

_tbr_iter_root_files() {
  local file

  while IFS= read -r -d '' file; do
    if _tbr_is_sourceable_file "$file"; then
      printf '%s\0' "$file"
    fi
  done < <(
    find "$TBDIR" \
      \( -type d \( -name "bin" -o -name "core" -o -name ".*" \) -prune \) -o \
      \( -type f -print0 \) | sort -z
  )
}

_tbr_source_files() {
  local file

  while IFS= read -r -d '' file; do
    _tbr_source_file_fast "$file"
  done < <(_tbr_iter_core_files)

  while IFS= read -r -d '' file; do
    _tbr_source_file_fast "$file"
  done < <(_tbr_iter_root_files)
}

_tbr_source_live_files() {
  local file

  for file in "$TBDIR/xgit"; do
    if [ -f "$file" ]; then
      _tbr_source_file_fast "$file"
    fi
  done
}

_tbr_cache_ttl() {
  echo "${TBR_CACHE_TTL:-604800}"
}

_tbr_cache_path() {
  local path

  if [ -n "$TBR_CACHE_PATH" ]; then
    path="$TBR_CACHE_PATH"
  elif [ -n "$XDG_CACHE_HOME" ]; then
    path="$XDG_CACHE_HOME/tbr.cache"
  else
    path="$TBDIR/.tbr.cache"
  fi

  if [[ "$path" != *.cache ]]; then
    path="${path}.cache"
  fi

  echo "$path"
}

_tbr_ensure_cache_dir() {
  local cache_path="$1"
  local cache_dir

  cache_dir="${cache_path%/*}"
  if [ -n "$cache_dir" ]; then
    mkdir -p "$cache_dir"
  fi
}

_tbr_mtime() {
  stat -c %Y "$1" 2>/dev/null || echo 0
}

_tbr_cache_signature() {
  local max=0
  local file
  local ts

  while IFS= read -r -d '' file; do
    ts=$(_tbr_mtime "$file")
    if [ "$ts" -gt "$max" ]; then
      max="$ts"
    fi
  done < <(_tbr_iter_core_files)

  while IFS= read -r -d '' file; do
    ts=$(_tbr_mtime "$file")
    if [ "$ts" -gt "$max" ]; then
      max="$ts"
    fi
  done < <(_tbr_iter_root_files)

  echo "$max"
}

_tbr_git_head() {
  command -v git >/dev/null 2>&1 || return 0
  git -C "$TBDIR" rev-parse HEAD 2>/dev/null
}

_tbr_read_cache_header() {
  local cache_path="$1"
  local line

  TBR_CACHE_HEADER_TIMESTAMP=""
  TBR_CACHE_HEADER_SIGNATURE=""
  TBR_CACHE_HEADER_TTL=""
  TBR_CACHE_HEADER_GIT_HEAD=""

  while IFS= read -r line; do
    [ -z "$line" ] && break
    case "$line" in
      timestamp=*) TBR_CACHE_HEADER_TIMESTAMP="${line#timestamp=}" ;;
      signature=*) TBR_CACHE_HEADER_SIGNATURE="${line#signature=}" ;;
      ttl=*) TBR_CACHE_HEADER_TTL="${line#ttl=}" ;;
      git_head=*) TBR_CACHE_HEADER_GIT_HEAD="${line#git_head=}" ;;
    esac
  done < "$cache_path"
}

_tbr_cache_valid() {
  local cache_path="$1"
  local ttl="$2"
  local signature="$3"
  local git_head="$4"
  local now

  [ -f "$cache_path" ] || return 1

  _tbr_read_cache_header "$cache_path"
  [ -n "$TBR_CACHE_HEADER_TIMESTAMP" ] || return 1

  if [ "$ttl" -gt 0 ] 2>/dev/null; then
    now=$(date +%s)
    if [ $(( now - TBR_CACHE_HEADER_TIMESTAMP )) -gt "$ttl" ]; then
      return 1
    fi
  fi

  [ "$TBR_CACHE_HEADER_SIGNATURE" = "$signature" ] || return 1

  if [ -n "$git_head" ]; then
    [ "$TBR_CACHE_HEADER_GIT_HEAD" = "$git_head" ] || return 1
  fi

  return 0
}

_tbr_append_file_to_cache() {
  local cache_path="$1"
  local file="$2"

  cat "$file" >> "$cache_path"
  printf '\n' >> "$cache_path"
}

_tbr_write_cache() {
  local cache_path="$1"
  local ttl="$2"
  local signature="$3"
  local git_head="$4"
  local file
  local tmp

  _tbr_ensure_cache_dir "$cache_path"
  tmp="$(mktemp "${cache_path}.XXXXXX")" || return 1

  {
    echo "timestamp=$(date +%s)"
    echo "signature=$signature"
    echo "ttl=$ttl"
    if [ -n "$git_head" ]; then
      echo "git_head=$git_head"
    fi
    echo ""
  } > "$tmp"

  while IFS= read -r -d '' file; do
    _tbr_append_file_to_cache "$tmp" "$file"
  done < <(_tbr_iter_core_files)

  while IFS= read -r -d '' file; do
    _tbr_append_file_to_cache "$tmp" "$file"
  done < <(_tbr_iter_root_files)

  mv "$tmp" "$cache_path"
}

_tbr_refresh_cache() {
  local force_refresh="$1"
  local cache_path
  local ttl
  local signature
  local git_head=""

  cache_path="$(_tbr_cache_path)"
  ttl="$(_tbr_cache_ttl)"
  signature="$(_tbr_cache_signature)"

  if [ "${TBR_CACHE_GIT_CHECK:-0}" = "1" ]; then
    git_head="$(_tbr_git_head)"
  fi

  if [ "$force_refresh" != "1" ] && _tbr_cache_valid "$cache_path" "$ttl" "$signature" "$git_head"; then
    return 0
  fi

  _tbr_write_cache "$cache_path" "$ttl" "$signature" "$git_head"
}

_tbr_should_force_rebuild() {
  local arg

  for arg in "$@"; do
    case "$arg" in
      -f|--force) return 0 ;;
    esac
  done

  return 1
}

tbr() {
  local cache_path
  local force_refresh="0"

  cache_path="$(_tbr_cache_path)"

  if _tbr_should_force_rebuild "$@"; then
    force_refresh="1"
  fi

  if [ "$force_refresh" = "1" ]; then
    _tbr_refresh_cache "1"
  fi

  if [ -f "$cache_path" ]; then
    _tbr_source_file_fast "$cache_path"
  else
    _tbr_refresh_cache "1" >/dev/null 2>&1 || true
    if [ -f "$cache_path" ]; then
      _tbr_source_file_fast "$cache_path"
    else
      _tbr_source_files
    fi
  fi

  _tbr_source_live_files

  if [[ $- == *i* ]] && [[ "${TOOLBOX_SKIP_BACKGROUND_INIT:-0}" != "1" ]] && typeset -f background_init >/dev/null 2>&1; then
    background_init
  fi
}