#!/usr/bin/env bash
# scripts/migrate-state-to-pg — One-shot migration from local SOPS state to PG backend.
# Prerequisites: vault login -method=oidc, PG terraform_state DB exists, Vault static role created.
# Usage: scripts/migrate-state-to-pg [--dry-run]
set -euo pipefail

REPO_ROOT="$(cd "$(dirname "$0")/.." && pwd)"
SYNC="$REPO_ROOT/scripts/state-sync"
STACKS_DIR="$REPO_ROOT/stacks"
STATE_DIR="$REPO_ROOT/state/stacks"

TIER0_STACKS="infra platform cnpg vault dbaas external-secrets"
is_tier0() {
  echo "$TIER0_STACKS" | tr ' ' '\n' | grep -qx "$1"
}

DRY_RUN=false
[ "${1:-}" = "--dry-run" ] && DRY_RUN=true

# Fetch PG credentials from Vault
echo "==> Fetching PG credentials from Vault..."
PG_CREDS=$(vault read -format=json database/static-creds/pg-terraform-state) || {
  echo "ERROR: Cannot read PG credentials. Run: vault login -method=oidc" >&2
  exit 1
}
PG_USER=$(echo "$PG_CREDS" | jq -r .data.username)
PG_PASS=$(echo "$PG_CREDS" | jq -r .data.password)
export PG_CONN_STR="postgres://${PG_USER}:${PG_PASS}@10.0.20.200:5432/terraform_state?sslmode=disable"
echo "    PG_CONN_STR set (user: $PG_USER)"

# Enable provider cache
export TF_PLUGIN_CACHE_DIR="${TF_PLUGIN_CACHE_DIR:-$HOME/.terraform.d/plugin-cache}"
export TF_PLUGIN_CACHE_MAY_BREAK_DEPENDENCY_LOCK_FILE=1
mkdir -p "$TF_PLUGIN_CACHE_DIR"

migrated=0
failed=0
skipped=0
failed_stacks=""

# Increment helpers (avoid arithmetic exit code 1 when value is 0)
inc_migrated() { migrated=$((migrated + 1)); }
inc_failed()   { failed=$((failed + 1)); }
inc_skipped()  { skipped=$((skipped + 1)); }

# Iterate over all stack directories that have state
for state_dir in "$STATE_DIR"/*/; do
  stack="$(basename "$state_dir")"

  # Skip Tier 0
  if is_tier0 "$stack"; then
    echo "--- SKIP (Tier 0): $stack"
    inc_skipped
    continue
  fi

  # Skip stacks with no state file
  if [ ! -f "$state_dir/terraform.tfstate.enc" ] && [ ! -f "$state_dir/terraform.tfstate" ]; then
    echo "--- SKIP (no state): $stack"
    inc_skipped
    continue
  fi

  # Skip stacks with no corresponding stack directory
  if [ ! -d "$STACKS_DIR/$stack" ]; then
    echo "--- SKIP (no stack dir): $stack"
    inc_skipped
    continue
  fi

  echo "==> Migrating: $stack"

  if $DRY_RUN; then
    echo "    [dry-run] Would migrate $stack"
    inc_skipped
    continue
  fi

  # Decrypt state if needed (call decrypt_state directly — state-sync skips Tier 1)
  if [ -f "$state_dir/terraform.tfstate.enc" ] && [ ! -f "$state_dir/terraform.tfstate" ]; then
    sops -d --input-type json --output-type json "$state_dir/terraform.tfstate.enc" > "$state_dir/terraform.tfstate" || {
      echo "    WARNING: decrypt failed, skipping"
      inc_skipped
      continue
    }
  fi

  # Migrate state
  cd "$STACKS_DIR/$stack"
  if terragrunt init -upgrade -migrate-state -force-copy -input=false 2>&1 | tee /tmp/tg-migrate-$stack.log; then
    echo "    init OK"

    # Verify — plan should show no changes
    if terragrunt plan -detailed-exitcode -input=false 2>&1 | tail -5 | grep -q "No changes"; then
      echo "    plan OK — no drift"
      inc_migrated
    else
      echo "    WARNING: plan shows changes (may be normal drift, not migration issue)"
      inc_migrated
    fi
  else
    echo "    FAILED: init error (see /tmp/tg-migrate-$stack.log)"
    inc_failed
    failed_stacks="$failed_stacks $stack"
  fi
done

echo ""
echo "========================================"
echo "Migration complete"
echo "  Migrated: $migrated"
echo "  Failed:   $failed"
echo "  Skipped:  $skipped"
if [ -n "$failed_stacks" ]; then
  echo "  Failed stacks:$failed_stacks"
fi
echo "========================================"