#!/usr/bin/env bash

# tmux-main-sequence — join the standard project session group
#
# Usage: tmux-main-sequence [--add-missing] [--no-attach]
#
# Windows: 0 dashboard (shell), 1 ~, 2 blog, then configured projects.
# Each client joins through its own main-N session, with independent window selection.
# Existing group windows are unchanged unless --add-missing is given.
# Per-client sessions are destroyed on detach; the base session stays available.
# Config: ~/.config/tmux-main-sequence/projects, one directory per line.
# Blank lines and full-line # comments are ignored; spaces in paths are supported.
# Example config (local and untracked):
#   ~/Source/Projects/tmux-agents
#   ~/Source/Projects/projects-stone-age
#   ~/Source/Projects/job-hunting/career-ops

set -euo pipefail

usage() {
  cat <<'EOF'
Usage: tmux-main-sequence [--add-missing] [--no-attach]

Create or join the main session group through a separate main-N client session.
Client sessions share windows but select them independently and vanish on detach.
An existing group or a base session named main is reused.
  --add-missing  Add missing window names with fresh agents, then join.
                Use the intended index if free; otherwise append at the end.
  --no-attach    Skip joining: do not create a per-client session or attach.
  -h, --help    Show this help.

Environment:
  TMUX_MAIN_SEQUENCE_SESSION  Group/base name (default: main; clients: main-N).
  TMUX_MAIN_SEQUENCE_CONFIG   Project list (default: ~/.config/tmux-main-sequence/projects).
  TMUX_MAIN_SEQUENCE_AGENT    Shell command (default: tmux-agents start claude -- "start the chain").
  TMUX_MAIN_SEQUENCE_SOCKET   Isolated tmux socket name (tmux -L).

Project list: one directory per line, with ~ expansion, blank lines and
full-line # comments. Missing directories are warned about and skipped.
EOF
}

add_missing=false
attach=true
for arg in "$@"; do
  case "$arg" in
    --add-missing) add_missing=true ;;
    --no-attach) attach=false ;;
    -h|--help) usage; exit 0 ;;
    *) printf 'tmux-main-sequence: unknown argument: %s\n' "$arg" >&2
       usage >&2; exit 2 ;;
  esac
done

session=${TMUX_MAIN_SEQUENCE_SESSION:-main}
config=${TMUX_MAIN_SEQUENCE_CONFIG:-$HOME/.config/tmux-main-sequence/projects}
script_dir=$(CDPATH= cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
tmux_cmd=(tmux)
if [[ -n ${TMUX_MAIN_SEQUENCE_SOCKET:-} ]]; then
  tmux_cmd+=(-L "$TMUX_MAIN_SEQUENCE_SOCKET")
fi

attach_session() {
  local number=1 client_id
  if "$attach"; then
    while "${tmux_cmd[@]}" has-session -t "=$session-$number" 2>/dev/null; do
      number=$((number + 1))
    done
    client_id=$("${tmux_cmd[@]}" new-session -d -t "$session_id" -s "$session-$number" -P -F '#{session_id}')
    if "$fresh"; then
      "${tmux_cmd[@]}" select-window -t "$client_id:1"
    fi
    # Queue the option and attach together: a standalone set-option would
    # immediately destroy this still-unattached session before we could join it.
    if [[ -n ${TMUX:-} ]]; then
      "${tmux_cmd[@]}" set-option -t "$client_id" destroy-unattached on \; switch-client -t "$client_id"
    else
      "${tmux_cmd[@]}" set-option -t "$client_id" destroy-unattached on \; attach-session -t "$client_id"
    fi
  fi
}

fresh=false
session_id=
base_id=
# A group may survive after its originally named session has been removed.
while IFS='|' read -r id name group; do
  if [[ $group == "$session" ]]; then
    session_id=$id
    break
  fi
  if [[ $name == "$session" ]]; then base_id=$id; fi
done < <("${tmux_cmd[@]}" list-sessions -F '#{session_id}|#{session_name}|#{session_group}' 2>/dev/null || true)
session_id=${session_id:-$base_id}
if [[ -n $session_id ]]; then
  if ! "$add_missing"; then
    attach_session
    exit 0
  fi
else
  fresh=true
  session_id=$("${tmux_cmd[@]}" new-session -d -s "$session" -n dashboard -c "$HOME" -P -F '#{session_id}')
  "${tmux_cmd[@]}" set-option -t "$session_id" base-index 0
  "${tmux_cmd[@]}" set-option -t "$session_id" renumber-windows off
  initial_index=$("${tmux_cmd[@]}" display-message -p -t "$session_id:" '#{window_index}')
  if [[ $initial_index != 0 ]]; then
    "${tmux_cmd[@]}" move-window -s "$session_id:$initial_index" -t "$session_id:0"
  fi
  "${tmux_cmd[@]}" set-window-option -t "$session_id:0" automatic-rename off
  "${tmux_cmd[@]}" set-window-option -t "$session_id:0" allow-rename off
fi

add_window() {
  local index=$1 name=$2 dir=$3 start_agent=$4 existing max=-1 occupied=false pane
  while IFS= read -r existing; do
    [[ $existing != "$name" ]] || return 0
  done < <("${tmux_cmd[@]}" list-windows -t "$session_id" -F '#{window_name}')
  if [[ ! -d $dir ]]; then
    printf 'tmux-main-sequence: skipping missing directory: %s\n' "$dir" >&2
    return 0
  fi
  while IFS= read -r existing; do
    if (( existing == index )); then occupied=true; fi
    if (( existing > max )); then max=$existing; fi
  done < <("${tmux_cmd[@]}" list-windows -t "$session_id" -F '#{window_index}')
  if "$occupied"; then
    printf 'tmux-main-sequence: index %s occupied; appending %s at %s\n' "$index" "$name" "$((max + 1))" >&2
    index=$((max + 1))
  fi
  if "$start_agent"; then
    "$script_dir/tmux-chain" "$dir" --target "$session_id:$index" --name "$name" >/dev/null
  else
    pane=$("${tmux_cmd[@]}" new-window -d -t "$session_id:$index" -n "$name" -c "$dir" -P -F '#{pane_id}')
    "${tmux_cmd[@]}" set-window-option -t "$pane" automatic-rename off
    "${tmux_cmd[@]}" set-window-option -t "$pane" allow-rename off
  fi
}

add_window 0 dashboard "$HOME" false
add_window 1 '~' "$HOME" true
add_window 2 blog "$HOME/Source/Projects/subspace-collection/blog.clooney.io" true
index=3
if [[ -f $config ]]; then
  while IFS= read -r dir || [[ -n $dir ]]; do
    # Trim surrounding whitespace, preserving spaces inside directory names.
    dir="${dir#"${dir%%[![:space:]]*}"}"
    dir="${dir%"${dir##*[![:space:]]}"}"
    case "$dir" in
      ''|'#'*) continue ;;
      '~') dir=$HOME ;;
      '~/'*) dir="$HOME/${dir:2}" ;;
    esac
    while [[ $dir != / && $dir == */ ]]; do dir=${dir%/}; done
    add_window "$index" "$(basename "$dir")" "$dir" true
    index=$((index + 1))
  done < "$config"
fi
if "$fresh"; then
  "${tmux_cmd[@]}" select-window -t "$session_id:1"
fi
attach_session