#!/bin/sh
# Reproduce: containerd-snapshotter pull-through mirror referrers failure
#
# Prerequisites: Docker Engine installed, root access
# This script:
#   1. Starts a pull-through registry mirror for Docker Hub
#   2. Enables containerd-snapshotter
#   3. Configures Docker to use the mirror via hosts.toml
#   4. Pulls an image — fails with "failed to decode referrers index"
#
# Run as root.
set -eu

MIRROR_PORT=5555
MIRROR_NAME=registry-mirror-test

cleanup() {
    echo "==> Cleaning up"
    docker rm -f "$MIRROR_NAME" 2>/dev/null || true
    rm -rf /etc/docker/certs.d/docker.io
    rm -f /tmp/mirror-config.yml

    # Restore daemon.json
    if [ -f /etc/docker/daemon.json.bak ]; then
        mv /etc/docker/daemon.json.bak /etc/docker/daemon.json
    else
        rm -f /etc/docker/daemon.json
    fi
    systemctl restart docker 2>/dev/null || true
}
trap cleanup EXIT

echo "==> Step 1: Start pull-through registry mirror"
cat > /tmp/mirror-config.yml <<EOF
version: 0.1
log:
  fields:
    service: registry
storage:
  filesystem:
    rootdirectory: /var/lib/registry
  delete:
    enabled: true
http:
  addr: :5000
proxy:
  remoteurl: https://registry-1.docker.io
EOF

docker rm -f "$MIRROR_NAME" 2>/dev/null || true
docker run -d \
    --name "$MIRROR_NAME" \
    -p "${MIRROR_PORT}:5000" \
    -v /tmp/mirror-config.yml:/etc/docker/registry/config.yml:ro \
    registry:2

echo "    Waiting for mirror to start..."
sleep 3

echo "==> Step 2: Enable containerd-snapshotter"
if [ -f /etc/docker/daemon.json ]; then
    cp /etc/docker/daemon.json /etc/docker/daemon.json.bak
fi
cat > /etc/docker/daemon.json <<EOF
{
  "features": {
    "containerd-snapshotter": true
  }
}
EOF

echo "==> Step 3: Configure mirror via hosts.toml"
mkdir -p /etc/docker/certs.d/docker.io
cat > /etc/docker/certs.d/docker.io/hosts.toml <<EOF
server = "https://docker.io"

[host."http://127.0.0.1:${MIRROR_PORT}"]
  capabilities = ["pull", "resolve"]
EOF

echo "==> Step 4: Restart Docker"
systemctl restart docker
sleep 3

echo "==> Step 5: Remove cached image and pull through mirror"
docker image rm alpine:latest 2>/dev/null || true
echo "    Pulling alpine:latest..."
if docker pull alpine:latest; then
    echo "    PASS: Pull succeeded (issue may be fixed)"
else
    echo "    FAIL: Pull failed with referrers error (issue reproduced)"
fi

echo
echo "==> Docker version:"
docker version --format '{{.Server.Version}}'
echo "==> Storage driver:"
docker info --format '{{.Driver}}'