#!/usr/bin/env bash
#
# Add music to music-box: push it, tag it with beets, let Navidrome see it.
#
# WHY THIS SCRIPT EXISTS
# ----------------------
# The three steps are simple individually and easy to get subtly wrong together:
#
#   1. rsync to /srv/incoming, NOT to /srv/music. Navidrome reads /srv/music and
#      beets is the only thing that should ever write there. Dropping files
#      straight into the library skips tagging entirely, which is the whole
#      point of having beets.
#   2. `beet import` is INTERACTIVE, so the ssh needs a TTY (-t). Without it the
#      prompt never renders and the import appears to hang.
#   3. beets must run as counterweight. Under sudo it finds no config (the
#      config lives in ~counterweight), silently falls back to its defaults and
#      writes to a SECOND library database in root's home - so you end up with
#      files in the wrong place and two competing indexes.
#
# WHAT IT DOES NOT DO
#   It does not touch your local files. rsync copies; the `move: yes` in the
#   beets config only moves things around ON THE BOX, from /srv/incoming into
#   /srv/music. Your originals on this machine are never modified or deleted.
#
# Usage:  scripts/add-music.sh [path]        (prompts for the path if omitted)
# Needs:  rsync and ssh here, tailnet up (music-box resolves via MagicDNS)
set -euo pipefail

MUSIC_HOST="${MUSIC_HOST:-music-box}"
REMOTE_USER="${MUSIC_USER:-counterweight}"
INCOMING="/srv/incoming"
# Pre-filled into the prompt, editable in place. $HOME rather than a literal
# /home/counterweight so the script still behaves if it is ever run as anyone
# else; for the usual user it resolves to exactly /home/counterweight/music.
DEFAULT_SRC="${MUSIC_LOCAL_DIR:-$HOME/music}"
SSH_KEY="${MUSIC_SSH_KEY:-$HOME/.ssh/counterganzua}"
TARGET="${REMOTE_USER}@${MUSIC_HOST}"

# Colours, but only when we are actually on a terminal.
if [ -t 1 ]; then
    B=$'\033[1m'; DIM=$'\033[2m'; R=$'\033[31m'; G=$'\033[32m'; Y=$'\033[33m'; N=$'\033[0m'
else
    B=""; DIM=""; R=""; G=""; Y=""; N=""
fi

say()  { printf '%s==>%s %s\n' "$B" "$N" "$*"; }
warn() { printf '%s==>%s %s\n' "$Y" "$N" "$*" >&2; }
die()  { printf '%sERROR:%s %s\n' "$R" "$N" "$*" >&2; exit 1; }

# -n is load-bearing: without it ssh reads OUR stdin and swallows the answers
# meant for the read prompts below, so "Continue? [y/N]" gets EOF instead of
# your keypress. Under `set -e` that aborts the script with no message at all.
ssh_run() { ssh -n -i "$SSH_KEY" -o ConnectTimeout=15 "$TARGET" "$@"; }
# -t for anything that talks to a human (beets prompts, sudo password). No -n
# here - these deliberately DO want your terminal.
ssh_tty() { ssh -t -i "$SSH_KEY" -o ConnectTimeout=15 "$TARGET" "$@"; }

# --- 0. Preflight ------------------------------------------------------------
command -v rsync >/dev/null || die "rsync is not installed here."
[ -f "$SSH_KEY" ] || die "SSH key not found: $SSH_KEY  (override with MUSIC_SSH_KEY=)"

say "Checking ${MUSIC_HOST} is reachable..."
if ! ssh_run -o BatchMode=yes true 2>/dev/null; then
    die "Cannot reach ${TARGET}.
     Is the tailnet up?  tailscale status | grep ${MUSIC_HOST}
     MagicDNS resolving? getent hosts ${MUSIC_HOST}"
fi

# --- 1. Where is the music? --------------------------------------------------
SRC="${1:-}"
if [ -z "$SRC" ]; then
    printf '\n%sPath to the album or folder to add%s %s(edit or tab-complete)%s\n' "$B" "$N" "$DIM" "$N"
    # -e gives readline (tab completion, arrow keys); -i pre-fills the buffer
    # with the default so it is already typed and editable in place.
    # -i is ignored when stdin is not a terminal, hence the ${SRC:-} fallback:
    # piping into this script, or just pressing Enter, still yields the default.
    read -e -i "$DEFAULT_SRC" -r -p "> " SRC || true
    SRC="${SRC:-$DEFAULT_SRC}"
fi

# People paste paths with surrounding quotes (drag-and-drop does this) and with
# a trailing slash. Both change rsync's meaning, so normalise before using it.
SRC="${SRC%\"}"; SRC="${SRC#\"}"
SRC="${SRC%\'}"; SRC="${SRC#\'}"
SRC="${SRC/#\~/$HOME}"
while [ "${SRC}" != "/" ] && [ "${SRC: -1}" = "/" ]; do SRC="${SRC%/}"; done

[ -n "$SRC" ]  || die "No path given."
[ "$SRC" != "/" ] && [ "$SRC" != "$HOME" ] || die "Refusing to sync '$SRC' - that is almost certainly not what you meant."
[ -e "$SRC" ]  || die "Not found: $SRC"
[ -r "$SRC" ]  || die "Not readable: $SRC"

BASENAME="$(basename -- "$SRC")"
if [ -d "$SRC" ]; then
    COUNT=$(find "$SRC" -type f | wc -l | tr -d ' ')
    SIZE=$(du -sh "$SRC" 2>/dev/null | cut -f1)
    [ "$COUNT" -gt 0 ] || die "$SRC contains no files."
else
    COUNT=1
    SIZE=$(du -h "$SRC" 2>/dev/null | cut -f1)
fi

# --- 2. Does it fit? ---------------------------------------------------------
# /srv/incoming and /srv/music share one filesystem, so the beets move is a
# rename and costs nothing extra - but the transfer itself still needs room.
AVAIL=$(ssh_run "df -Pk ${INCOMING} | awk 'NR==2 {print \$4}'" 2>/dev/null || echo 0)
NEED=$(du -sk "$SRC" 2>/dev/null | cut -f1)
if [ "${AVAIL:-0}" -gt 0 ] && [ "${NEED:-0}" -gt "${AVAIL}" ]; then
    die "Not enough space on ${MUSIC_HOST}: need $((NEED/1024)) MB, have $((AVAIL/1024)) MB.
     The library shares the 50 GB root disk - see roles/navidrome/README.md."
fi

printf '\n'
say "About to add:"
printf '     source   %s\n' "$SRC"
printf '     files    %s  (%s)\n' "$COUNT" "${SIZE:-?}"
printf '     lands in %s:%s/%s\n' "$MUSIC_HOST" "$INCOMING" "$BASENAME"
printf '     free     %s MB on the box\n\n' "$((${AVAIL:-0}/1024))"
printf '%sYour local files are only read, never moved or deleted.%s\n\n' "$DIM" "$N"

read -r -p "Continue? [y/N] " REPLY
case "$REPLY" in [yY]*) ;; *) say "Nothing done."; exit 0 ;; esac

# --- 3. Push -----------------------------------------------------------------
printf '\n'
say "Pushing to ${MUSIC_HOST}:${INCOMING}/ ..."
# No trailing slash on "$SRC": that copies the DIRECTORY, not its contents, so
# the album arrives as its own folder and beets sees one album per directory.
# --chmod is not cosmetic. `rsync -a` preserves the SOURCE mode, and beets
# moves files into the library with rename(2), which keeps their group and
# mode. A track that leaves this machine mode 0600 therefore arrives in
# /srv/music mode 0600 owned by the curator's group - and Navidrome cannot read
# it. It does not error; the track is simply absent from the library. The beets
# `permissions` plugin also normalises this on the box; this is the same fix
# applied at the door so /srv/incoming is sane too.
rsync -av --info=progress2 --human-readable --chmod=D755,F644 \
      -e "ssh -i $SSH_KEY -o ConnectTimeout=15" \
      "$SRC" "${TARGET}:${INCOMING}/"

# --- 4. Tag ------------------------------------------------------------------
printf '\n'
say "Running beets. This is interactive - see the key guide below."
printf '%s   A apply   M more candidates   E enter search   I paste MB id%s\n' "$DIM" "$N"
printf '%s   U use tags as-is   S skip   T as tracks   G group albums%s\n\n' "$DIM" "$N"

# As counterweight (NOT sudo) so it finds ~/.config/beets/config.yaml.
# `|| true` because beets exits non-zero when you skip or abort an album, and
# that is a normal outcome, not a script failure.
ssh_tty "beet import ${INCOMING}/$(printf '%q' "$BASENAME")" || true

# --- 5. What is left behind? -------------------------------------------------
printf '\n'
LEFT=$(ssh_run "find ${INCOMING} -type f 2>/dev/null | wc -l" | tr -d ' \r')
if [ "${LEFT:-0}" -gt 0 ]; then
    warn "${LEFT} file(s) still in ${INCOMING} - skipped, or beets could not match them."
    warn "Re-run later with:  ssh ${MUSIC_HOST} 'beet import ${INCOMING}'"
    warn "Details:            ssh ${MUSIC_HOST} 'tail /var/lib/beets/import.log'"
else
    printf '%s==>%s %sEverything imported; %s is empty.%s\n' "$B" "$N" "$G" "$INCOMING" "$N"
fi

# --- 6. Optional post-processing ---------------------------------------------
# replaygain and lyrics are auto:no in the beets config on purpose - on a single
# core they turn a 2 minute import into a 20 minute one. Offered here so they do
# not get forgotten entirely, but off by default.
printf '\n'
read -r -p "Run replaygain now? (slow on 1 core) [y/N] " REPLY
case "$REPLY" in [yY]*) say "Running beet replaygain..."; ssh_tty "beet replaygain" || warn "replaygain reported a problem." ;; esac

# --- 7. Let Navidrome see it -------------------------------------------------
printf '\n'
say "Restarting Navidrome so it picks up the new files..."
ssh_tty "sudo systemctl restart navidrome"

say "Waiting for it to come back..."
for i in $(seq 1 20); do
    if ssh_run "curl -sf -m 5 -o /dev/null http://127.0.0.1:4533/app/" 2>/dev/null; then
        printf '%s==>%s %sNavidrome is up.%s\n' "$B" "$N" "$G" "$N"
        break
    fi
    [ "$i" -eq 20 ] && warn "Navidrome did not answer within ~60s. Check: ssh ${MUSIC_HOST} 'systemctl status navidrome'"
    sleep 3
done

# --- 8. Summary --------------------------------------------------------------
printf '\n'
say "Library now holds:"
ssh_run "beet stats" 2>/dev/null | sed 's/^/     /' || warn "could not read beet stats"
printf '\n%s==>%s %sDone.%s  https://music.contrapeso.xyz\n' "$B" "$N" "$G" "$N"