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

# ============================================================================
# DIDI Frontend - Build Script
# Checks prerequisites, builds Docker production image
# ============================================================================

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
WEB_DIR="$SCRIPT_DIR/web"
IMAGE_NAME="${DIDI_IMAGE_NAME:-didi-frontend}"
IMAGE_TAG="${DIDI_IMAGE_TAG:-latest}"
VITE_API_URL="${VITE_API_URL:-}"

# -- Colors ------------------------------------------------------------------
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
CYAN='\033[0;36m'
BOLD='\033[1m'
NC='\033[0m'

log()   { echo -e "${GREEN}[OK]${NC}    $*"; }
warn()  { echo -e "${YELLOW}[WARN]${NC}  $*"; }
err()   { echo -e "${RED}[ERR]${NC}   $*" >&2; }
step()  { echo -e "\n${CYAN}==> $*${NC}"; }

# -- Usage -------------------------------------------------------------------
usage() {
    cat <<EOF
Usage: $(basename "$0") [OPTIONS]

Build the DIDI frontend Docker image.

Options:
  --api-url URL      Set VITE_API_URL (default: reads from .env.local)
  --image NAME       Docker image name (default: didi-frontend)
  --tag TAG          Docker image tag (default: latest)
  --skip-verify      Skip smoke test after build
  --dry-run          Show what would be done without doing it
  -h, --help         Show this help

Environment variables:
  VITE_API_URL       Same as --api-url
  DIDI_IMAGE_NAME    Same as --image
  DIDI_IMAGE_TAG     Same as --tag

Examples:
  ./build.sh
  ./build.sh --api-url https://didi365.eu
  ./build.sh --image didi-frontend --tag v1.2.3
  ./build.sh --skip-verify --dry-run
EOF
    exit 0
}

# -- Parse args --------------------------------------------------------------
SKIP_VERIFY=false
DRY_RUN=false

while [[ $# -gt 0 ]]; do
    case "$1" in
        --api-url)      VITE_API_URL="$2"; shift 2 ;;
        --image)        IMAGE_NAME="$2"; shift 2 ;;
        --tag)          IMAGE_TAG="$2"; shift 2 ;;
        --skip-verify)  SKIP_VERIFY=true; shift ;;
        --dry-run)      DRY_RUN=true; shift ;;
        -h|--help)      usage ;;
        *) err "Unknown option: $1"; usage ;;
    esac
done

# -- Prerequisites -----------------------------------------------------------
check_prerequisites() {
    step "Checking prerequisites"
    local ok=true

    # Docker installed
    if command -v docker &>/dev/null; then
        log "Docker: $(docker --version 2>/dev/null | head -1)"
    else
        err "Docker not installed. https://docs.docker.com/get-docker/"
        ok=false
    fi

    # Docker daemon running
    if command -v docker &>/dev/null; then
        if docker info &>/dev/null; then
            log "Docker daemon: running"
        else
            err "Docker daemon not running. Try: sudo systemctl start docker"
            ok=false
        fi
    fi

    # Required files
    for f in package.json Dockerfile nginx.conf index.html; do
        if [[ -f "$WEB_DIR/$f" ]]; then
            log "$f: found"
        else
            err "$f not found in $WEB_DIR"
            ok=false
        fi
    done

    # src/ directory
    if [[ -d "$WEB_DIR/src" ]]; then
        log "src/: found"
    else
        err "src/ directory not found"
        ok=false
    fi

    if ! $ok; then
        err "Prerequisites check failed."
        exit 1
    fi
}

# -- Resolve API URL ---------------------------------------------------------
resolve_api_url() {
    if [[ -z "$VITE_API_URL" && -f "$WEB_DIR/.env.local" ]]; then
        VITE_API_URL=$(grep -E '^VITE_API_URL=' "$WEB_DIR/.env.local" 2>/dev/null | cut -d'=' -f2- || true)
    fi

    if [[ -n "$VITE_API_URL" ]]; then
        log "VITE_API_URL = $VITE_API_URL"
    else
        warn "VITE_API_URL is empty (same-origin mode)"
    fi
}

# -- Docker build ------------------------------------------------------------
docker_build() {
    step "Building Docker image: ${IMAGE_NAME}:${IMAGE_TAG}"

    local build_args=()
    if [[ -n "$VITE_API_URL" ]]; then
        build_args+=(--build-arg "VITE_API_URL=${VITE_API_URL}")
    fi

    if $DRY_RUN; then
        warn "[dry-run] docker build ${build_args[*]+"${build_args[*]}"} -t ${IMAGE_NAME}:${IMAGE_TAG} $WEB_DIR"
        return
    fi

    docker build \
        ${build_args[@]+"${build_args[@]}"} \
        -t "${IMAGE_NAME}:${IMAGE_TAG}" \
        "$WEB_DIR"

    log "Image built successfully"

    step "Image details"
    docker images "${IMAGE_NAME}:${IMAGE_TAG}" --format "table {{.Repository}}\t{{.Tag}}\t{{.Size}}\t{{.CreatedAt}}"
}

# -- Verify ------------------------------------------------------------------
verify_image() {
    step "Verifying image (smoke test)"

    if $DRY_RUN; then
        warn "[dry-run] Would start temp container, check /health, remove it"
        return
    fi

    local cname="didi-verify-$$"

    docker run -d --name "$cname" -p 0:80 "${IMAGE_NAME}:${IMAGE_TAG}" >/dev/null 2>&1
    local port
    port=$(docker port "$cname" 80 | head -1 | cut -d: -f2)

    local retries=10
    local healthy=false
    while (( retries > 0 )); do
        if curl -sf "http://localhost:${port}/health" >/dev/null 2>&1; then
            healthy=true
            break
        fi
        sleep 0.5
        (( retries-- ))
    done

    docker rm -f "$cname" >/dev/null 2>&1

    if $healthy; then
        log "Health check PASSED"
    else
        warn "Health check FAILED — image built but nginx may have issues"
    fi
}

# -- Summary -----------------------------------------------------------------
summary() {
    echo ""
    echo -e "  ${BOLD}Build complete${NC}"
    echo ""
    echo "  Image:  ${IMAGE_NAME}:${IMAGE_TAG}"
    echo "  API:    ${VITE_API_URL:-<same-origin>}"
    echo ""
    echo "  Run:    docker run -d -p 8080:80 ${IMAGE_NAME}:${IMAGE_TAG}"
    echo "  Test:   curl http://localhost:8080/health"
    echo ""
}

# -- Main --------------------------------------------------------------------
main() {
    echo ""
    echo -e "  ${BOLD}DIDI Frontend Build${NC}"
    echo ""

    check_prerequisites
    resolve_api_url
    docker_build

    if ! $SKIP_VERIFY; then
        verify_image
    fi

    summary
}

main