#!/bin/sh

# Help messages:
export LONG_USAGE="Select changed files using fzf and print to standard output.

Optionally, give a tree-ish to list files changed between that and the working
tree.

For example, to select from files in the last 3 commits:

  git sel-changed HEAD@{3}
"

# Tell git-sh-setup we're ok with being in a subdir:
export SUBDIRECTORY_OK=1

. "$(git --exec-path)/git-sh-setup"

# Make sure we're in a working tree
require_work_tree_exists

# Jump to top level so we can use $PWD below to print absolute paths
# (this seems easier than trying to figure out relative paths from
# porcelained git-status output):
cd_to_toplevel

# For files in the working tree which are currently changed:
_list_from_status () {
  # -z does NUL-terminated outputs, puts new filenames first for renamed files,
  # etc.  -u includes untracked files.
  git status -u -z --porcelain | \

    # Take from the 4th character up to end-of-line (first 3 are status chars):
    cut -z -c4-
}

# For files changed since a particular tree-ish:
_list_from_treeish () {
  git diff-index -z --name-only "$1"
}

run_git="_list_from_status"
if [ -n "$1" ]; then
  run_git="_list_from_treeish $1"
fi

$run_git | \

  # IFF we're inside a tmux, fzf-tmux will pop up in a separate pane:
  fzf-tmux --multi --read0 --print0 | \

  # This is ridiculous, but I never know how to combine stdin and args:
  xargs -0 -I{} -n1 echo "$PWD/{}"