#!/bin/sh

# Replace the local `dotfiles` repository with a fresh install
# by re-running the latest `dotfiles-install` taken from the `origin`
#
# Refuses to run if there are uncommitted or unpushed changes,
# unless called with `--force`

set -eu


XDG_DATA_HOME="${XDG_DATA_HOME:-$HOME/.local/share}"

DOTFILES_DIR="${DOTFILES_DIR:-$XDG_DATA_HOME/dotfiles}"



_force=0

if [ "$#" -gt 1 ]; then
    echo "Usage: $(basename "$0") [--force]" >&2
    exit 1
fi

case "${1:-}" in
    "")      ;;
    --force) _force=1 ;;
    *)
        echo "Usage: $(basename "$0") [--force]" >&2
        exit 1
        ;;
esac



if [ ! -d "$DOTFILES_DIR" ]; then
    echo "" >&2
    echo "The dotfiles are not installed at: $DOTFILES_DIR" >&2
    echo "" >&2
    echo "=> See instructions at https://code.webartifex.de/alexander/dotfiles#installation" >&2
    echo "" >&2

    exit 1
fi



_git() {
    git --git-dir="$DOTFILES_DIR" --work-tree="$HOME" "$@"
}



# Keep the machine on its current branch (e.g., "desktop")
branch=$(_git symbolic-ref --short HEAD) || {
    echo "" >&2
    echo "Detached HEAD => Re-run after 'dotfiles checkout <branch>'" >&2
    echo "" >&2

    exit 1
}



if [ "$_force" -ne 1 ]; then

    if [ -n "$(_git status --porcelain)" ]; then
        echo "" >&2
        echo "There are uncommitted changes!" >&2
        echo "" >&2
        _git --no-pager diff HEAD --stat >&2
        echo "" >&2
        echo "=> Commit and push them, or re-run with '--force'" >&2
        echo "" >&2

        exit 1
    fi

    if _git rev-parse --verify --quiet "origin/$branch" >/dev/null \
        && [ -n "$(_git log --oneline "origin/$branch..$branch")" ]; then
        echo "" >&2
        echo "There are unpushed commits!" >&2
        echo "" >&2
        _git --no-pager log --oneline "origin/$branch..$branch" >&2
        echo "" >&2
        echo "=> Push them, or re-run with '--force'" >&2
        echo "" >&2

        exit 1
    fi

fi



# Take the latest installer out of the local repository,
# after fetching from the `origin`

_git fetch --prune origin

if ! _git rev-parse --verify --quiet "origin/$branch" >/dev/null; then
    echo "" >&2
    echo "Branch '$branch' does not exist on origin!" >&2
    echo "" >&2
    echo "=> Push it first, or 'dotfiles checkout' one that does" >&2
    echo "" >&2

    exit 1
fi

installer_path=$(mktemp)
trap 'rm -f "$installer_path"' EXIT

_git show "origin/$branch:.local/bin/dotfiles-install" > "$installer_path"

DOTFILES_BRANCH="$branch" sh "$installer_path" --force