#!/usr/bin/env bash
set -euo pipefail

repo_root=$(git rev-parse --show-toplevel)
proposals_dir="$repo_root/evolution/proposals"

auto_browse() {
  if command -v wisu >/dev/null 2>&1; then
    exec wisu -i -g --icons "$repo_root/evolution"
  fi
  exec ls -la "$repo_root/evolution"
}

usage() {
  cat <<'USAGE'
Usage: bep [command]

Commands:
  list [--status <Status>]   List BEPs, optionally filtered by status.
  open <BEP-XXXX|XXXX|X>     Open a BEP in $EDITOR.
  help                       Show this help.

If no command is provided, bep launches a simple browser for evolution/.
USAGE
}

normalize_id() {
  local raw="$1"
  if [[ "$raw" =~ ^BEP-[0-9]+$ ]]; then
    printf '%s' "$raw"
    return 0
  fi
  if [[ "$raw" =~ ^[0-9]+$ ]]; then
    printf 'BEP-%04d' "$raw"
    return 0
  fi
  return 1
}

read_status() {
  local file="$1"
  awk -F ': ' '/^Status:/ {print $2; exit}' "$file"
}

read_title() {
  local file="$1"
  local line
  line=$(head -n 1 "$file" || true)
  printf '%s' "$line" | sed -E 's/^# `[^`]+`[[:space:]]+//; s/^[^A-Za-z0-9]+//'
}

list_bep() {
  local filter="${1:-}"
  local filter_lower=""
  if [[ -n "$filter" ]]; then
    filter_lower=$(printf '%s' "$filter" | tr '[:upper:]' '[:lower:]')
  fi

  printf '%-10s %-18s %s\n' "BEP" "Status" "Title"
  local file
  local entries=()
  for file in "$proposals_dir"/BEP-*.md; do
    [[ -e "$file" ]] || continue
    local base
    base=$(basename "$file")
    local id
    id=$(printf '%s' "$base" | cut -d- -f1-2)
    local status
    status=$(read_status "$file")
    local status_lower
    status_lower=$(printf '%s' "$status" | tr '[:upper:]' '[:lower:]')
    if [[ -n "$filter_lower" && "$status_lower" != "$filter_lower" ]]; then
      continue
    fi
    local title
    title=$(read_title "$file")
    entries+=("$(printf '%-10s %-18s %s' "$id" "$status" "$title")")
  done
  if [[ ${#entries[@]} -gt 0 ]]; then
    printf '%s\n' "${entries[@]}" | sort
  fi
}

open_bep() {
  local raw="$1"
  local id
  if ! id=$(normalize_id "$raw"); then
    echo "Unknown BEP id: $raw" >&2
    exit 1
  fi
  local matches
  matches=("$proposals_dir"/"$id"-*.md)
  if [[ ${#matches[@]} -eq 0 || ! -e "${matches[0]}" ]]; then
    echo "No proposal found for $id" >&2
    exit 1
  fi
  if [[ ${#matches[@]} -gt 1 ]]; then
    echo "Multiple proposals match $id:" >&2
    printf '  %s\n' "${matches[@]}" >&2
    exit 1
  fi
  local editor="${EDITOR:-vi}"
  exec "$editor" "${matches[0]}"
}

command=${1:-}
case "$command" in
  "")
    auto_browse
    ;;
  list)
    if [[ ${2:-} == "--status" && -n ${3:-} ]]; then
      list_bep "$3"
    else
      list_bep
    fi
    ;;
  open)
    if [[ -z ${2:-} ]]; then
      echo "bep open requires an id" >&2
      exit 1
    fi
    open_bep "$2"
    ;;
  help|-h|--help)
    usage
    ;;
  *)
    echo "Unknown command: $command" >&2
    usage
    exit 1
    ;;
esac