#!/bin/sh

# Open a GitHub file/blog page for FILE on LINE.

## Usage: git-open FILE [LINE]
## Open GitHub file/blob page for FILE on LINE. FILE is the path to the
## file on disk; it must exist and be tracked with the current HEAD
## revision. LINE is the line number or line number range (e.g., 10-50).
##
## Open foo/bar.rb in browser:
##   $ git-open foo/bar.rb
##
## Open foo/bar in browser w/ lines 50-57 highlighted:
##   $ git-open foo/bar.rb 50-57
##
## Open current file in vim on line 20:
##   :!git-open % 20
##
## https://github.com/jacobwg/dotfiles/blob/master/bin/github-open

set -e

FILE="$1"
LINE="$2"

# usage and help
test -z "$FILE" -o "$FILE" = '--help' && {
  cat "$0" | grep '^##' | cut -c4- 1>&2
  exit 1
}

# bail out with message to stderr and exit status 1
die() {
    echo "$(basename $0):" "$@" 1>&2
    exit 1
}

# figure out relative path to the file from the root
# of the work tree
path="$(basename $FILE)"
cd $(dirname $FILE)
while test ! -d .git ;
do
  test "$(pwd)" = / && {
    echo "error: git repository not found" 1>&2
    exit 1
  }
  path="$(basename $(pwd))/$path"
  cd ..
done

# get the current branch in refs/heads/<branch> form
ref=$(git symbolic-ref -q HEAD)
test -n "$ref" ||
die "you're not on a branch"

# just the branch name please
branch=$(echo "$ref" | sed 's@^refs/heads/@@')
test -n "$branch" ||
die "you're in a weird place; get on a local branch"

# remote we're tracking
remote=$(git config --get "branch.$branch.remote" || true)
test -n "$remote" ||
die "you're not tracking a remote branch"

# remote branch we're tracking
merge=$(
    (git config --get "branch.$branch.merge") |
    sed 's@refs/heads/@@'
)
test -n "$merge" ||
die "you're not tracking a remote branch"

# at this point we're in root of the work tree and $path is
# the relative path to file.
remote_url=$(git config --get remote.$remote.url)
repo=$(echo "$remote_url" | sed 's/^.*:\(.*\)\.git/\1/')
url="http://github.com/$repo/blob/$branch/$path"

# debugging
# echo "url: $remote_url"
# echo "repo: $repo"

# throw the line number on there if specified
test -n "$LINE" && url="$url#L$LINE"

open "$url"