#!/usr/bin/env bash
# Simulated Crossplane composition: turns a learner-authored XR into an
# EngineeringTask that declares the construction work required to
# satisfy the request. Emits YAML only — writes no code and does not
# touch any repository. That is the whole point: Crossplane *requests*
# engineering work; it does not do it.
#
# Usage: compose.sh <xr-request.yaml> <work-root>
#   Writes <work-root>/task/engineering-task.yaml
set -euo pipefail

XR="${1:?xr request path required}"
WORK_ROOT="${2:?work-root path required}"

if [ ! -f "$XR" ]; then
  printf 'compose: xr request not found: %s\n' "$XR" >&2
  exit 2
fi

TASK_DIR="$WORK_ROOT/task"
TASK_OUT="$TASK_DIR/engineering-task.yaml"
mkdir -p "$TASK_DIR"

# Extract the three fields the composition promotes from the XR:
# metadata.name, spec.value, and (implicitly) the artifact kind
# selected by the XR's apiVersion/kind pair.
FIELDS="$(XR_PATH="$XR" python3 <<'PY'
import os, re, sys
path = os.environ.get("XR_PATH", "")
api_version = kind = name = value = None
for line in open(path):
    m_api  = re.match(r"^\s*apiVersion\s*:\s*(.+?)\s*$", line)
    m_kind = re.match(r"^\s*kind\s*:\s*(.+?)\s*$", line)
    m_name = re.match(r"^\s{2}name\s*:\s*(.+?)\s*$", line)
    m_val  = re.match(r"^\s{2}value\s*:\s*(.+?)\s*$", line)
    if m_api  and api_version is None: api_version = m_api.group(1)
    if m_kind and kind        is None: kind        = m_kind.group(1)
    if m_name and name        is None: name        = m_name.group(1)
    if m_val  and value       is None: value       = m_val.group(1)
def unquote(v):
    if v is None: return v
    v = v.strip()
    if len(v) >= 2 and v[0] == v[-1] and v[0] in ("'", '"'):
        v = v[1:-1]
    return v
missing = [k for k, v in {
    "apiVersion": api_version, "kind": kind,
    "metadata.name": name, "spec.value": value,
}.items() if not v]
if missing:
    sys.stderr.write(f"compose: xr missing required fields: {missing}\n")
    sys.exit(3)
print(unquote(api_version))
print(unquote(kind))
print(unquote(name))
print(unquote(value))
PY
)"

API_VERSION="$(printf '%s\n' "$FIELDS" | sed -n '1p')"
KIND="$(printf '%s\n' "$FIELDS" | sed -n '2p')"
NAME="$(printf '%s\n' "$FIELDS" | sed -n '3p')"
VALUE="$(printf '%s\n' "$FIELDS" | sed -n '4p')"

if [ "$KIND" != "XHelloWorldPico" ]; then
  printf 'compose: this composition only satisfies XHelloWorldPico requests (got %q)\n' "$KIND" >&2
  exit 2
fi

BRANCH="sandcastle/hello-world-pico-${NAME}"
REPO_URL="file://./work/compose-sandcastle-request/target-repo"

cat > "$TASK_OUT" <<EOF
# Generated by labs/compose-sandcastle-request/downloads/compose.sh
# Source XR: ${XR}
kind: EngineeringTask
metadata:
  name: ${NAME}
spec:
  requestedBy:
    apiVersion: ${API_VERSION}
    kind: ${KIND}
    name: ${NAME}
  artifact:
    kind: hello-world-pico
    producesFiles:
      - rules/hello.yaml
  inputs:
    greeting: "${VALUE}"
  target:
    repo: ${REPO_URL}
    branch: ${BRANCH}
  workspace:
    sandboxProvider: local-scratch-dir
    tools:
      - pico
      - git
      - python3
    permissions:
      - git.read:file:./target-repo
      - git.write:branch:${BRANCH}
      - fs.write:workspace-only
  artifactBoundary:
    survives: [branch]
    disposed: [workspace, tools, scratch_state]
EOF

printf 'compose: wrote %s (kind=%s name=%s greeting=%q branch=%s)\n' \
  "$TASK_OUT" "EngineeringTask" "$NAME" "$VALUE" "$BRANCH"
printf 'compose: the composition wrote no code and touched no repository.\n'