#!/usr/bin/env bash
set -euo pipefail

# =============================================================================
# preflight.sh — Validate everything before running migration phases
# Installs nothing. Exits 0 only if ALL checks pass.
#
# Usage:
#   ./preflight.sh                    # Run all checks
#   ./preflight.sh --skip-port-checks # Skip port-free checks (for --start-from)
# =============================================================================

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
source "${SCRIPT_DIR}/lib/common.sh"

SKIP_PORT_CHECKS=false
for arg in "$@"; do
  case "$arg" in
    --skip-port-checks) SKIP_PORT_CHECKS=true ;;
  esac
done

log_info "=== Preflight Checks ==="

PASS_COUNT=0
FAIL_COUNT=0

# ---------------------------------------------------------------------------
# Check helper — runs a check function, tracks pass/fail count.
# Intentionally does NOT exit on failure — we want to run ALL checks
# so the user sees every issue at once, not one at a time.
# ---------------------------------------------------------------------------
check() {
  local num="$1" description="$2"
  shift 2

  if "$@" 2>/dev/null; then
    log_success "[${num}] ${description}"
    PASS_COUNT=$((PASS_COUNT + 1))
  else
    log_error "[${num}] FAIL: ${description}"
    FAIL_COUNT=$((FAIL_COUNT + 1))
  fi
}

# ---------------------------------------------------------------------------
# Check 1: Local machine is macOS (control plane uses brew, launchctl, macOS sed)
# ---------------------------------------------------------------------------
check_local_os() {
  [[ "$(uname -s)" == "Darwin" ]]
}
check 1 "Local machine is macOS (control plane)" check_local_os
if ! check_local_os 2>/dev/null; then
  log_error "  → This toolkit is designed to run from macOS. Detected: $(uname -s)"
fi

# ---------------------------------------------------------------------------
# Check 2: Unraid is Linux (via SSH)
# ---------------------------------------------------------------------------
check_unraid_os() {
  local remote_os
  remote_os="$(ssh_exec UNRAID "uname -s" 2>/dev/null)" || return 1
  [[ "$remote_os" == "Linux" ]]
}

# ---------------------------------------------------------------------------
# Check 3: Fedora is Linux with dnf (RPM-based)
# ---------------------------------------------------------------------------
check_fedora_os() {
  local remote_os
  remote_os="$(ssh_exec FEDORA "uname -s" 2>/dev/null)" || return 1
  [[ "$remote_os" == "Linux" ]] && ssh_exec FEDORA "command -v dnf" &>/dev/null
}

# ---------------------------------------------------------------------------
# Check 4: .env exists
# ---------------------------------------------------------------------------
check_env_exists() {
  [[ -f "${SCRIPT_DIR}/.env" ]]
}
check 4 ".env file exists" check_env_exists
if [[ ! -f "${SCRIPT_DIR}/.env" ]]; then
  log_error "  → .env not found. Copy .env.example to .env and fill in values."
  log_error "  → Or run: setup/configure_env.sh"
  # Can't continue without .env — run remaining checks but they'll mostly fail
fi

# ---------------------------------------------------------------------------
# Check 5: runners.conf exists
# ---------------------------------------------------------------------------
check_runners_conf() {
  [[ -f "${SCRIPT_DIR}/runners.conf" ]]
}
check 5 "runners.conf file exists" check_runners_conf
if [[ ! -f "${SCRIPT_DIR}/runners.conf" ]]; then
  log_error "  → runners.conf not found. Copy runners.conf.example to runners.conf."
fi

# ---------------------------------------------------------------------------
# Load env for remaining checks (may fail if .env missing)
# ---------------------------------------------------------------------------
if [[ -f "${SCRIPT_DIR}/.env" ]]; then
  load_env
fi

# ---------------------------------------------------------------------------
# Check 6: Required .env vars
# ---------------------------------------------------------------------------
REQUIRED_VARS=(
  UNRAID_IP UNRAID_SSH_USER UNRAID_GITEA_DATA_PATH
  FEDORA_IP FEDORA_SSH_USER FEDORA_GITEA_DATA_PATH
  GITEA_ADMIN_USER GITEA_ADMIN_PASSWORD GITEA_ADMIN_EMAIL
  GITEA_ORG_NAME GITEA_INSTANCE_NAME
  GITEA_DOMAIN GITEA_INTERNAL_URL
  GITEA_BACKUP_INTERNAL_URL BACKUP_STORAGE_PATH
  GITHUB_USERNAME GITHUB_TOKEN
  REPO_1_NAME REPO_2_NAME REPO_3_NAME
  GITHUB_MIRROR_TOKEN
  NGINX_CONTAINER_NAME NGINX_CONF_PATH SSL_EMAIL
)

check_required_vars() {
  local missing=0
  for var in "${REQUIRED_VARS[@]}"; do
    if [[ -z "${!var:-}" ]]; then
      log_error "  → Missing required var: $var"
      missing=1
    fi
  done
  return $missing
}
check 6 "All required .env vars are set" check_required_vars

# ---------------------------------------------------------------------------
# Check 7: SSH to Unraid
# ---------------------------------------------------------------------------
check_ssh_unraid() {
  ssh_check UNRAID
}
check 7 "SSH to Unraid (${UNRAID_IP:-<not set>})" check_ssh_unraid
if ! ssh_check UNRAID 2>/dev/null; then
  log_error "  → Cannot SSH to Unraid. Run setup/unraid.sh or check SSH config."
fi

# ---------------------------------------------------------------------------
# Check 8: SSH to Fedora
# ---------------------------------------------------------------------------
check_ssh_fedora() {
  ssh_check FEDORA
}
check 8 "SSH to Fedora (${FEDORA_IP:-<not set>})" check_ssh_fedora
if ! ssh_check FEDORA 2>/dev/null; then
  log_error "  → Cannot SSH to Fedora. Run setup/fedora.sh or check SSH config."
fi

# ---------------------------------------------------------------------------
# Checks 2-3: Remote OS checks (deferred until after SSH is confirmed)
# These are numbered 2-3 in the output but run after SSH checks because
# they require SSH connectivity to `uname -s` on the remote machines.
# ---------------------------------------------------------------------------
check 2 "Unraid is Linux" check_unraid_os
if ! check_unraid_os 2>/dev/null; then
  log_error "  → UNRAID_IP points to a non-Linux machine. Check your .env."
fi
check 3 "Fedora is Linux with dnf (RPM-based)" check_fedora_os
if ! check_fedora_os 2>/dev/null; then
  log_error "  → FEDORA_IP points to a machine that isn't RPM-based Linux. Check your .env."
fi

# ---------------------------------------------------------------------------
# Check 9: Docker on Unraid
# ---------------------------------------------------------------------------
check_docker_unraid() {
  ssh_exec UNRAID "docker --version" &>/dev/null
}
check 9 "Docker available on Unraid" check_docker_unraid
if ! check_docker_unraid 2>/dev/null; then
  log_error "  → Docker not found on Unraid. Run setup/unraid.sh."
fi

# ---------------------------------------------------------------------------
# Check 10: Docker on Fedora
# ---------------------------------------------------------------------------
check_docker_fedora() {
  ssh_exec FEDORA "docker --version" &>/dev/null
}
check 10 "Docker available on Fedora" check_docker_fedora
if ! check_docker_fedora 2>/dev/null; then
  log_error "  → Docker not found on Fedora. Run setup/fedora.sh."
fi

# ---------------------------------------------------------------------------
# Check 11: docker-compose on Unraid
# ---------------------------------------------------------------------------
check_compose_unraid() {
  ssh_exec UNRAID "docker compose version" &>/dev/null || ssh_exec UNRAID "docker-compose --version" &>/dev/null
}
check 11 "docker-compose available on Unraid" check_compose_unraid
if ! check_compose_unraid 2>/dev/null; then
  log_error "  → docker-compose not found on Unraid. Run setup/unraid.sh."
fi

# ---------------------------------------------------------------------------
# Check 12: docker-compose on Fedora
# ---------------------------------------------------------------------------
check_compose_fedora() {
  ssh_exec FEDORA "docker compose version" &>/dev/null || ssh_exec FEDORA "docker-compose --version" &>/dev/null
}
check 12 "docker-compose available on Fedora" check_compose_fedora
if ! check_compose_fedora 2>/dev/null; then
  log_error "  → docker-compose not found on Fedora. Run setup/fedora.sh."
fi

# ---------------------------------------------------------------------------
# Check 13: Port free on Unraid
# Uses ss (socket statistics) to check if any process is listening on the port.
# The ! negates the grep — we PASS if the port is NOT found in use.
# Skipped when --skip-port-checks is set (e.g. resuming with --start-from
# after phases 1-2 have Gitea already running on these ports).
# ---------------------------------------------------------------------------
if [[ "$SKIP_PORT_CHECKS" == "true" ]]; then
  log_info "[13] Port ${UNRAID_GITEA_PORT:-3000} free on Unraid — SKIPPED (--skip-port-checks)"
  log_info "[14] Port ${FEDORA_GITEA_PORT:-3000} free on Fedora — SKIPPED (--skip-port-checks)"
else
  check_port_unraid() {
    local port="${UNRAID_GITEA_PORT:-3000}"
    ! ssh_exec UNRAID "ss -tlnp | grep -q ':${port} '" 2>/dev/null
  }
  check 13 "Port ${UNRAID_GITEA_PORT:-3000} free on Unraid" check_port_unraid
  if ! check_port_unraid 2>/dev/null; then
    log_error "  → Port ${UNRAID_GITEA_PORT:-3000} already in use on Unraid."
  fi

  # ---------------------------------------------------------------------------
  # Check 14: Port free on Fedora
  # ---------------------------------------------------------------------------
  check_port_fedora() {
    local port="${FEDORA_GITEA_PORT:-3000}"
    ! ssh_exec FEDORA "ss -tlnp | grep -q ':${port} '" 2>/dev/null
  }
  check 14 "Port ${FEDORA_GITEA_PORT:-3000} free on Fedora" check_port_fedora
  if ! check_port_fedora 2>/dev/null; then
    log_error "  → Port ${FEDORA_GITEA_PORT:-3000} already in use on Fedora."
  fi
fi

# ---------------------------------------------------------------------------
# Check 15: DNS resolves
# ---------------------------------------------------------------------------
check_dns() {
  local resolved
  resolved=$(dig +short "${GITEA_DOMAIN:-}" 2>/dev/null | head -1)
  [[ "$resolved" == "${UNRAID_IP:-}" ]]
}
check 15 "DNS: ${GITEA_DOMAIN:-<not set>} resolves to ${UNRAID_IP:-<not set>}" check_dns
if ! check_dns 2>/dev/null; then
  log_error "  → ${GITEA_DOMAIN:-GITEA_DOMAIN} does not resolve to ${UNRAID_IP:-UNRAID_IP}."
fi

# ---------------------------------------------------------------------------
# Check 16: GitHub token valid
# ---------------------------------------------------------------------------
check_github_token() {
  [[ -n "${GITHUB_TOKEN:-}" ]] && curl -sf -H "Authorization: token ${GITHUB_TOKEN}" https://api.github.com/user -o /dev/null
}
check 16 "GitHub token valid" check_github_token
if ! check_github_token 2>/dev/null; then
  log_error "  → GitHub token invalid. Check GITHUB_TOKEN in .env."
fi

# ---------------------------------------------------------------------------
# Check 17: GitHub repos exist
# ---------------------------------------------------------------------------
check_github_repos() {
  local all_ok=0
  for var in REPO_1_NAME REPO_2_NAME REPO_3_NAME; do
    local repo="${!var:-}"
    if [[ -z "$repo" ]]; then
      continue
    fi
    if ! curl -sf -H "Authorization: token ${GITHUB_TOKEN:-}" "https://api.github.com/repos/${GITHUB_USERNAME:-}/${repo}" -o /dev/null 2>/dev/null; then
      log_error "  → GitHub repo ${repo} not found under ${GITHUB_USERNAME:-}"
      all_ok=1
    fi
  done
  return $all_ok
}
check 17 "All GitHub repos exist" check_github_repos

# ---------------------------------------------------------------------------
# Check 18: Nginx running on Unraid
# ---------------------------------------------------------------------------
check_nginx() {
  local status
  status=$(ssh_exec UNRAID "docker ps --filter name=${NGINX_CONTAINER_NAME:-nginx} --format '{{.Status}}'" 2>/dev/null)
  [[ "$status" == *"Up"* ]]
}
check 18 "Nginx container '${NGINX_CONTAINER_NAME:-<not set>}' running on Unraid" check_nginx
if ! check_nginx 2>/dev/null; then
  log_error "  → Nginx container '${NGINX_CONTAINER_NAME:-}' not running on Unraid."
fi

# ---------------------------------------------------------------------------
# Check 19: Nginx conf dir writable
# ---------------------------------------------------------------------------
check_nginx_conf() {
  ssh_exec UNRAID "test -w '${NGINX_CONF_PATH:-/nonexistent}'" 2>/dev/null
}
check 19 "Nginx config path writable (${NGINX_CONF_PATH:-<not set>})" check_nginx_conf
if ! check_nginx_conf 2>/dev/null; then
  log_error "  → Nginx config path ${NGINX_CONF_PATH:-} not writable on Unraid."
fi

# ---------------------------------------------------------------------------
# Check 20: Local tool minimum versions
# Validates that tools on the MacBook meet minimum requirements.
# ---------------------------------------------------------------------------
check_local_versions() {
  local fail=0
  check_min_version "jq"        "jq --version"        "1.6"    || fail=1
  check_min_version "curl"      "curl --version"      "7.70"   || fail=1
  check_min_version "git"       "git --version"       "2.30"   || fail=1
  return $fail
}
check 20 "Local tool minimum versions (jq>=1.6, curl>=7.70, git>=2.30)" check_local_versions

# ---------------------------------------------------------------------------
# Check 21: Unraid tool minimum versions
# ---------------------------------------------------------------------------
check_unraid_versions() {
  local fail=0
  check_remote_min_version "UNRAID" "docker"        "docker --version"        "20.0" || fail=1
  check_remote_min_version "UNRAID" "docker-compose" "docker compose version 2>/dev/null || docker-compose --version" "2.0" || fail=1
  check_remote_min_version "UNRAID" "jq"            "jq --version"            "1.6"  || fail=1
  return $fail
}
check 21 "Unraid tool minimum versions (docker>=20, compose>=2, jq>=1.6)" check_unraid_versions

# ---------------------------------------------------------------------------
# Check 22: Fedora tool minimum versions
# ---------------------------------------------------------------------------
check_fedora_versions() {
  local fail=0
  check_remote_min_version "FEDORA" "docker"        "docker --version"        "20.0" || fail=1
  check_remote_min_version "FEDORA" "docker-compose" "docker compose version"  "2.0"  || fail=1
  check_remote_min_version "FEDORA" "jq"            "jq --version"            "1.6"  || fail=1
  return $fail
}
check 22 "Fedora tool minimum versions (docker>=20, compose>=2, jq>=1.6)" check_fedora_versions

# ---------------------------------------------------------------------------
# Summary
# ---------------------------------------------------------------------------
TOTAL_CHECKS=$((PASS_COUNT + FAIL_COUNT))
printf '\n'
log_info "Results: ${PASS_COUNT} passed, ${FAIL_COUNT} failed (out of ${TOTAL_CHECKS} checks)"

if [[ $FAIL_COUNT -gt 0 ]]; then
  log_error "Preflight FAILED — fix the issues above before proceeding."
  exit 1
else
  log_success "All preflight checks passed. Ready to run migration phases."
  exit 0
fi