#!/bin/bash
# Usage: curl -sL https://your-cdn/migrate.sh | bash -s -- <LOCAL_ID> <USER@REMOTE_IP> <REMOTE_ID>

LOCAL_SEARCH="$1"
DEST_CONN="$2"
REMOTE_SEARCH="$3"

RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# --- 1. PRE-FLIGHT & SSH CHECK ---
if [ -z "$REMOTE_SEARCH" ]; then
  echo -e "${RED}Usage: $0 <Local_Container_Name> <User@Remote_IP> <Remote_Container_Name>${NC}"
  echo -e "Example: $0 postgres-old root@10.0.0.5 postgres-new"
  exit 1
fi

echo -e "⚠️  ${YELLOW}REMINDER:${NC} Ensure SSH keys are set up: ${GREEN}ssh-copy-id $DEST_CONN${NC}"
if ! ssh -o BatchMode=yes -o ConnectTimeout=5 "$DEST_CONN" echo "SSH OK" >/dev/null 2>&1; then
    echo -e "${RED}Error: SSH connection to $DEST_CONN failed.${NC}"
    exit 1
fi

# --- 2. IDENTIFY CONTAINERS ---
echo -e "\n🔍 Finding containers..."

# Local
L_ID=$(docker ps -aq --filter "name=${LOCAL_SEARCH}" | head -n 1)
L_NAME=$(docker ps -a --filter "name=${LOCAL_SEARCH}" --format "{{.Names}}" | head -n 1)

# Remote (via SSH)
R_ID=$(ssh "$DEST_CONN" "docker ps -aq --filter 'name=${REMOTE_SEARCH}' | head -n 1")
R_NAME=$(ssh "$DEST_CONN" "docker ps -a --filter 'name=${REMOTE_SEARCH}' --format '{{.Names}}' | head -n 1")

if [ -z "$L_ID" ] || [ -z "$R_ID" ]; then
  echo -e "${RED}Error: Could not find containers.${NC}"
  echo "Local Found: ${L_ID:-None} | Remote Found: ${R_ID:-None}"
  exit 1
fi

echo -e "   Source: ${GREEN}$L_NAME${NC} ($L_ID)"
echo -e "   Target: ${GREEN}$R_NAME${NC} ($R_ID) on $DEST_CONN"

# --- 3. STOP CONTAINERS (SAFE MODE) ---
echo -e "\n🛑 ${RED}Stopping BOTH containers to ensure safe data transfer...${NC}"
docker stop "$L_ID"
ssh "$DEST_CONN" "docker stop $R_ID"

# --- 4. MAP & SYNC VOLUMES ---
echo -e "\n📦 Analyzing Volume Maps..."

# Get list of internal mount targets from Source (Where data lives inside the container)
# Format: Type|SourcePath|DestinationPath
L_MOUNTS=$(docker inspect -f '{{range .Mounts}}{{.Type}}|{{.Source}}|{{.Destination}} {{end}}' "$L_ID")

for MOUNT in $L_MOUNTS; do
    TYPE=$(echo "$MOUNT" | cut -d'|' -f1)
    L_PATH=$(echo "$MOUNT" | cut -d'|' -f2)
    INTERNAL_TARGET=$(echo "$MOUNT" | cut -d'|' -f3)

    # skip bind mounts that are likely system files (docker.sock, etc)
    if [[ "$INTERNAL_TARGET" == *".sock" ]] || [[ "$INTERNAL_TARGET" == *".conf" ]]; then
        echo "   Skipping config/system file: $INTERNAL_TARGET"
        continue
    fi

    echo -e "\n   🔄 Processing mount at ${YELLOW}$INTERNAL_TARGET${NC}"

    # Find the corresponding volume/path on the REMOTE container
    # We look for the mount that shares the same INTERNAL destination
    R_PATH_RAW=$(ssh "$DEST_CONN" "docker inspect -f '{{range .Mounts}}{{if eq .Destination \"$INTERNAL_TARGET\"}}{{.Source}}{{end}}{{end}}' $R_ID")

    if [ -z "$R_PATH_RAW" ]; then
        echo -e "      ${RED}Warning: Target container has no matching volume for $INTERNAL_TARGET. Skipping.${NC}"
        continue
    fi

    # If it's a Docker volume, we need the real filesystem path (Mountpoint)
    if [ "$TYPE" == "volume" ]; then
        # L_PATH is already the volume name, we need the path
        REAL_L_PATH=$(docker volume inspect --format '{{.Mountpoint}}' "$L_PATH")
        # Remote might be a volume too, get its path
        R_VOL_NAME=$(basename "$R_PATH_RAW") # Assuming standard docker volume path structure or just name
        # Safest way: inspect the remote volume name if it looks like a volume
        REAL_R_PATH=$(ssh "$DEST_CONN" "docker volume inspect --format '{{.Mountpoint}}' $R_PATH_RAW 2>/dev/null || echo $R_PATH_RAW")
    else
        REAL_L_PATH="$L_PATH"
        REAL_R_PATH="$R_PATH_RAW"
    fi

    echo "      Source (A): $REAL_L_PATH"
    echo "      Target (B): $REAL_R_PATH"

    # RSYNC
    echo "      🚀 Syncing..."
    # Ensure trailing slashes for rsync to copy CONTENTS, not the folder itself
    rsync -az --info=progress2 -e ssh "${REAL_L_PATH}/" "$DEST_CONN:${REAL_R_PATH}/"
done

# --- 5. RESTART ---
echo -e "\n✅ Migration Complete."
echo -e "   Starting Remote Container ($R_NAME)..."
ssh "$DEST_CONN" "docker start $R_ID"

echo -e "   Starting Local Container ($L_NAME)..."
docker start "$L_ID"

echo -e "\n🎉 ${GREEN}Done! Check your new server.${NC}"