#!/usr/bin/env bash
set -euo pipefail
#
# prdy-update.sh — Update an existing PRD via guided runtime session
#
# Usage:
#   prdy-update.sh [--project <path>]
#
# Launches a dedicated runtime session in yolo mode with a specialized
# system prompt that reads the existing PRD and guides targeted modifications.

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/_lib.sh"

# ─── Parse arguments ─────────────────────────────────────────────────────────

PROJECT="."

while [[ $# -gt 0 ]]; do
  case "$1" in
    --project) PROJECT="$2"; shift 2 ;;
    -h|--help)
      cat <<'USAGE'
prdy-update.sh — Update an existing PRD via guided runtime session

Usage: prdy-update.sh [--project <path>]

Options:
  --project <path>   Project directory (default: CWD)

Launches the selected runtime in yolo mode with a PRD-update prompt.
The agent will read the existing docs/PRD.md, summarize its state,
and ask what changes are needed.

Examples:
  mosaic prdy update
  mosaic prdy update --project ~/src/my-app
USAGE
      exit 0
      ;;
    *) echo "Unknown option: $1" >&2; exit 1 ;;
  esac
done

# Expand tilde if passed literally (e.g., --project ~/src/foo)
PROJECT="${PROJECT/#\~/$HOME}"

# ─── Preflight checks ───────────────────────────────────────────────────────

RUNTIME_CMD="$(prdy_runtime_command)"
_require_cmd "$RUNTIME_CMD"

# Require existing PRD
EXISTING="$(find_prd "$PROJECT")"
if [[ -z "$EXISTING" ]]; then
  fail "No PRD found in $PROJECT/docs/"
  echo -e "  Run ${C_CYAN}mosaic prdy init${C_RESET} to create one first."
  exit 1
fi

# ─── Build system prompt ─────────────────────────────────────────────────────

step "Launching PRD update session"

SYSTEM_PROMPT="$(build_prdy_system_prompt "update")"

KICKOFF="Read the existing PRD at ${EXISTING}, summarize its current state, then ask what changes or additions are needed."

# ─── Launch runtime ──────────────────────────────────────────────────────────

info "Updating: $EXISTING"
info "Mode: PRD Update (yolo, runtime: $RUNTIME_CMD)"
echo ""

cd "$PROJECT"
if [[ "$RUNTIME_CMD" == "claude" ]]; then
  exec claude --dangerously-skip-permissions --append-system-prompt "$SYSTEM_PROMPT" "$KICKOFF"
fi

if [[ "$RUNTIME_CMD" == "codex" ]]; then
  CODEX_PROMPT="$(cat <<EOF
Follow this PRD contract exactly.

$SYSTEM_PROMPT

Task:
$KICKOFF
EOF
)"
  exec codex --dangerously-bypass-approvals-and-sandbox "$CODEX_PROMPT"
fi

fail "Unsupported runtime: $RUNTIME_CMD"
exit 1