_link.sh

#!/usr/bin/env bash

set -eu
set -o pipefail

cd "$(dirname "$(realpath "$0")")"

# repo meta files, everything else is linked into $HOME at the same relative path
ignore=(
    ".git"
    ".gitattributes"
    ".gitignore"
    ".idea"
    ".vscode"
    "_fmt.sh"
    "_link.sh"
    "_lint.sh"
    "AGENTS.md"
    "CLAUDE.md"
    "README.md"
    "renovate.json"
)

machine="machines/$(hostname -s)"

log() {
    echo >&2 "$*"
}

# tracked files can be symlinks themselves (the bash-completion aliases),
# so those are linked as they are instead of being followed
link_tree() {
    local root="$1"
    local src rel target source i

    while IFS= read -r -d '' src; do
        rel="${src#"${root}/"}"

        # "machines" is not repo meta, it is linked by the second pass below
        for i in "${ignore[@]}" "machines"; do
            if test "${rel}" = "${i}" || test "${rel#"${i}"/}" != "${rel}"; then
                continue 2
            fi
        done

        # the machine copy is the one that gets linked, so linking the shared
        # file first would leave both runs reporting a change every time
        if test "${root}" = "." && test -e "${machine}/${rel}"; then
            continue
        fi

        target="${HOME}/${rel}"
        source="${PWD}/${src#./}"

        # already linked, nothing to report
        if test -L "${target}" && test "$(readlink "${target}")" = "${source}"; then
            continue
        fi

        # ln would place the link inside it instead of replacing it
        if test -d "${target}" && ! test -L "${target}"; then
            log "skipping, target is a directory: ${target}"
            continue
        fi

        log "linking: ${rel}"
        if test -z "${DRY:-}"; then
            mkdir -p "$(dirname "${target}")"
            ln -sfn "${source}" "${target}"
        fi
    done < <(find "${root}" \( -type f -o -type l \) -print0)
}

link_tree "."

if test -d "${machine}"; then
    link_tree "${machine}"
else
    log "no machine directory: ${machine}"
fi

# a link into this repo whose target is gone was created by an earlier run for
# a file that no longer exists, which makes it ours to remove. no bookkeeping
# needed, the link itself says where it came from
while IFS= read -r dir; do
    test -d "${HOME}/${dir}" || continue
    while IFS= read -r link; do
        case "$(readlink "${link}")" in
            "${PWD}/"*) ;;
            *) continue ;;
        esac
        test -e "${link}" && continue
        log "removing stale link: ${link#"${HOME}"/}"
        if test -z "${DRY:-}"; then
            rm -- "${link}"
        fi
    done < <(find "${HOME}/${dir}" -maxdepth 1 -type l)
done < <(
    {
        find . \( -type f -o -type l \) -printf '%h\n' | sed 's|^\./||'
        # the machine dirs are stripped of their prefix here too, because that
        # is where in $HOME their links ended up
        if test -d "${machine}"; then
            find "${machine}" \( -type f -o -type l \) -printf '%h\n' \
                | sed -e "s|^${machine}/||" -e "s|^${machine}\$|.|"
        fi
    } | sort -u | grep -v '^\.git$\|^\.git/\|^machines$\|^machines/'
)